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Principles of Evidence in International Criminal Justice edited by Khan, Karim A A; Buisman, Caroline; Gosnell, Christopher (28th October 2010)

Part III The Trial, 12 Expert Evidence

Avi Singh

From: Principles of Evidence in International Criminal Justice

Edited By: Karim A. A. Khan, Caroline Buisman, Christopher Gosnell

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 28 January 2020

Expert evidence

(p. 599) 12  Expert Evidence

… fact-like opinion or opinion-like fact …

Ibukunolu Babajide1

There is a general feeling that expert witnesses are … close to being professional liars.

Anthony Good2

Reliance on experts is one method by which judges recognize and legitimise the existence of facts … no one will deny that the law should in some way effectively use expert knowledge wherever it will aid in settling disputes.

Judge Learned Hand3

(p. 600) 1.  Introduction

As in domestic criminal proceedings, expert witnesses are critical,4 seemingly more than eye witnesses, to adduce evidence in inherently complex international trials.5 According to one prosecutor at the International Criminal Tribunal for Rwanda (ICTR), speaking off the record, experts are essential to connect the factual dots adduced through lay witnesses in complex international cases. The reliance upon and widespread usage of expert witnesses has progressed in the absence of clear rules and regulations with regard to the what and how of expert witnesses. Initially, the Statutes and Rules of Procedure and Evidence of the ad hoc tribunals (with the exception of the Extraordinary Chambers in the Courts of Cambodia (ECCC))—only specify the notice necessary for expert witnesses, but have no particular rules specifically addressing what type, and in what form, expert evidence could be adduced. The consequent party-driven adducing of expert witnesses in trials at the ICTR and the International Criminal Tribunal for the former Yugoslavia (ICTY), and the objections, initially from defence counsel, regarding the relevance and reliability of these expert witnesses, have led to varying reactions from individual Trial Chambers, with a gradual evolution towards settled norms that are largely influenced by common law, and in particular, United States (US) practice. In the absence of particularized rules about expert witnesses, the ad hoc tribunals’ jurisprudence has shoehorned the issues of an expert’s reliance, and their reliability, into the general rules of evidence, with reliance on mostly common law customary practice. In doing so, the ad hoc tribunals have sought to address the contested, and obvious, due process issues and the relevance and reliability of expert evidence, particularly when the experts were social scientists.

(p. 601) The issues with expert evidence differ depending on whether the experts are party driven, or, as is common in civil law jurisdictions, judicially appointed and/or instructed. In both situations, however, the expert evidence, conformant with customary principles of evidence, must be relevant and probative. The opinion of the expert, who is duly qualified and unbiased, assists the trier of fact in interpreting the evidence in the trial, without straying into the realm of adducing hearsay evidence and proffering opinion on issues of ultimate fact, which is the sole province of the trier of fact. Also, the trier of fact can only rely on expert opinion if it is reliable—but the means of determining reliability, and whether such reliability is quantifiable and challengeable, is less consistent between the two practices. US codification and jurisprudence on expert evidence has focused on a quasi-scientific testability of expert opinion, with complete disclosure of the underlying basis of the expert’s opinions, and reliance on the acceptance of the expert’s opinions or methodology generally. The civil law tradition has an implicit acceptance of the expert’s reliability, as the expert is appointed and/or instructed by the trier of fact, and presumably is not partisan in his or her opinions. The variation between these two approaches leads to stark differences when social scientists are adduced as experts, as their opinion—at best testable only using academic peer review—is sought to clarify often conflicting and scattered factual evidence that has been presented through a prism of cultural particularities. Unlike fact witnesses, which testify to what they saw, and without proscription on hearsay, what they heard; expert witnesses have a potentially problematic ability to introduce unreliable opinion and/or rebroadcast hearsay opinion without basis. As in all social sciences, the reliability of social science experts is based on the validity of the underlying assumptions. Thus, assessing the reliability of such evidence is fraught with difficulties. This issue has troubled the ad hoc tribunals, who have adopted an adversarial system, and will likely concern the ongoing trials at the international criminal court, where joint and/or judicially appointed and instructed experts have been prescribed in the rules. Thus, the ability to evaluate and reach a reasoned conclusion on the reliability of expert evidence has, and continues to be, a challenge to the international criminal tribunals.

The three central issues of relevance, probative value, and reliability of expert witnesses absorb the specific questions with regard to each expert. The adversarial practice of determining, as a preliminary matter, whether the expert is qualified and the appropriateness of the expert opinion goes to relevance and probative value. The cross-examination of the expert on methodology and the certainty of the conclusions concerns reliability. Also, disclosure of the basis of an expert’s report is essential to forming a reasonable judgement on its reliability.

Reliance on experts, particularly those testifying on social science subjects, which are difficult to test and often based on hearsay sources, has a natural tendency to be based on extraneous considerations such as the credibility or demeanour of the (p. 602) experts themselves. Such reliance, while understandable, has significant fair trial and due process implications, and even more so than in domestic criminal trials. International criminal trials usually occur with an accompanying international consensus, in public opinion and academic discourse, that is prejudiced against the accused. Experts who opine in favour of the defence, particularly on key issues of political and historic significance, are usually dissidents from the mainstream, with less institutional credibility. Regardless of the correctness of the international consensus, such opinion should be entirely extraneous to the trial process, where the judges are the sole triers of fact and the evidence is adduced as openly as possible, supposedly without being prejudiced by such opinion. An expert’s opinion on key issues, namely issues of ultimate fact, and those opinions that cannot be challenged as they are presented without disclosed basis, mitigate against the right to a fair trial.

The International Criminal Court (ICC) has prescribed a judge driven process for expert evidence. Article 69(4) of the Rome Statute6 expressly sets forth a gatekeeping judicial role, which must balance relevance and probative value against any prejudice that may arise from the admissibility of evidence, a role that the ad hoc tribunals have generally read into Rule 89 of the ICTY and ICTR Rules, which states that the ‘[c]ourt may rely on the relevance or admissibility of any evidence, taking into account, inter alia, the probative value of the evidence and prejudice.’7 There are no corresponding rules on notice for expert witnesses, but the ICC Regulations detail the chamber’s expanded role in appointing and instructing experts, detailed below.

2.  International Tribunal Rules

The ad hoc tribunals’ rules on expert witnesses are substantially sparse,8 and the subtitle ‘Testimony of Expert Witnesses’ for Rule 94bis9 is a misnomer, for it (p. 603) concerns only the timely disclosure of expert reports and outlines a procedure whereby the non-moving party may accept or reject the expert report, with the latter choice resulting in the expert witness being called to testify. The ad hoc rules are silent on the power to appoint experts, the role of an expert witness, their threshold standards, and whether the judges can accept any testimony from them. The judicially interpreted practice of determining the admissibility of expert witnesses, usually through voir dire proceedings, is based on the omnibus residual evidence rule—Rule 8910—at the ICTR, ICTY and the Special Court for Sierra Leone (SCSL), although Rule 94bis of the ICTY,11 is slightly different in that it expressly allows the non-moving party to challenge the expert on relevance and reliability, it has not led to any differences in the implementation of the rules at the ICTY and ICTR.

Rule 89 of the ICTR, ICTY and SCSL permits a Trial Chamber, albeit at their discretion, to admit all relevant and probative (or reliable) evidence.12 Trial chambers have exercised their discretion to exclude evidence that would be ‘unduly prejudicial.’13 However, the gatekeeping function derived from Rule 89 is (p. 604) de minimus. As interpreted, Rule 89, in particular subparagraph (C), establishes a low threshold of admissibility for all evidence, with chamber’s preferring to give marginally reliable or relevant evidence less weight in the final determination. In practice, there has been little consistency in determining the threshold of admissibility of evidence between the different tribunals, and even between different chambers within the same tribunal. The treatment of expert evidence is not unique. Determinations of relevance and reliability of expert evidence, as well as the appropriate stage for such determinations, varies between tribunals and chambers within the tribunals.

Expert witnesses are not defined in any of the ad hoc tribunal’s rules. However, a largely common definition has emerged from jurisprudence borrowing from domestic, particularly, US law. Experts are thus those ‘whose testimony is intended to enlighten the Judges on the specific issue of a technical nature requiring special knowledge in a special field.’14

The ad hoc tribunals have struggled with these admissibility issues vis-à-vis expert witnesses. For the ICC, it is still too early to state how the issues will be determined, though the interjection between the ICC’s reference to ad hoc tribunal’s jurisprudence and the departure of the Regulations and Statute from the party driven system of experts will be of interest.

Rule 94bis has been less contentious. Subrule (A) of Rule 94bis concerns notice, and in accordance with the rule requiring notice to the non-moving party ‘as early as possible’ but no later than 21 days before testimony, the moving party must disclose the expert’s particulars, including his or her curriculum vitae,15 expert report, and any other relevant material, in a language that can be understood by the accused,16 as early as possible.17 If earlier notice is possible, Trial Chamber’s have not been averse to ordering it disclosed. For example, Human Rights Watch’s Dr Alison Des Forges,18 an expert for most cases before the ICTR on Rwanda, was ordered to file her report two months prior to her testifying. The prosecutor had argued, unsuccessfully, that the report was similar to her previous (p. 605) six reports, even though those reports were purportedly prepared individually and specifically for each of the prior cases.19 However, a delay in timely disclosure of the expert’s report and curriculum vitae is not fatal as chambers have cured the prejudice to the non-moving party simply through the remedy of granting more time.20

A 94bis notice, once filed, triggers the 21 day notice rule, and requires an acceptance or rejection with regard to the admissibility of the expert report. Till date, Trial Chambers have not penalized or sought to penalize the failure to respond to a timely notice with the prejudice of the report being admitted, for the failure to respond did not waive the right to cross-examination.21 At the ICTY, a party can explicitly oppose the admissibility of an expert witness under the rules. But even at the ICTR, the non-moving party may oppose an expert within the 21 day statutory notice period during which objections to an expert witness or evidence being adduced may be raised or waived.22

The ICC Rules represent a marked departure from the generally common rules and practices adopted at the ad hoc tribunals, though issues of admissibility, relevance, and reliability are still unaddressed due to the paucity of cases at the ICC. The rules of evidence, as seen with Article 69(4) of the Rome Statute above, require that evidence be both relevant and probative to be admitted, with the explicit caveat that the bench has the judicial discretion to exclude evidence that is prejudicial. Pursuant to Article 64(9), a Trial Chamber is explicitly granted a gatekeeping role. In addition, a Pre-Trial Chamber, reflecting the strong civil law influence on the Rome Statute and the rules and regulations of the ICC, exemplified in the investigative role for a chamber prior to confirmation of the indictment, may appoint an expert to assist (Article 56).

The ICC Rules of Procedure and Evidence (RPE) are entirely silent on the issue of experts. However, the regulations of the ICC, legislated by the judges of the ICC, as amended on 14 June and 14 November 2007, pursuant to the power to (p. 606) set regulations ‘necessary for its routine functioning’ set forth in Article 52 of the Rome Statute, articulate rules on experts. Regulation 44 of the ICC Regulations is significant in that it explicitly rejects party driven expert witnesses. Instead, it directs the registry to maintain a list of qualified experts, to which joint instructions will be issued. The Regulation also provides that a party can request separate instructions to another expert if they are dissatisfied by the jointly or judicially instructed expert, presumably with either the instructions or with the expert’s final report.23 Pursuant to Regulation 44(2), the ‘Chamber may direct the joint instruction of an expert by the participants.’24 The Regulation even allows a Trial Chamber to instruct an expert proprio motu.25 The chamber has wide powers with broad discretion with regard to experts. According to Regulation 44(5) of the Regulations:

The Chamber may issue any order as to the subject of an expert report, the number of experts to be instructed, the mode of their instruction, the manner in which their evidence is to be presented and the time limits for the preparation and notification of their request.26

The issue of disclosure specific to experts did not find merit with the drafters of the Rome Statute, and disclosure for an expert is no different from other evidence, except for the lack of any need to grant protective orders.27 Thus, the plenary of the ICC, perhaps mindful of the experiences of the ad hoc tribunals, have replaced a party driven system with one where the bench has an active role, both in gatekeeping with regard to evidence and with appointment of experts.

The ECCC, which is a unique hybrid (or compromise) between Cambodian law and international practice, with investigating judges and a Trial Chamber, have prescribed a civil law based system for experts. Rule 31 of the Internal Rules provide wide discretion to the co-investigating judges (all functions at the ECCC are (p. 607) shared between national and international personal) and the chamber, to appoint experts ‘on any subject deemed necessary for their investigations or proceedings …’. The investigating judges or chambers are responsible for instructing the appointed experts, and providing their mandate, and the experts must function under their ‘supervision’. They also control and direct the experts’ access to evidence, including confidential evidence, and their ability to interview witnesses, and may even, in their discretion, provide access to the accused.

The role of the parties, including the civil parties, is limited to requesting additional experts ‘to conduct new examinations or to re-examine a matter already the subject of an expert report.’ If such a request is denied, a party can appeal the refusal pursuant to Rule 74(3)(3) of the rules.28

3.  Voir Dire‎ or In Limine‎ Motion: The Gatekeeping Function

The gatekeeping function, evident from the rules outlined above, has evolved. At the ad hoc tribunals, it took place through the non-moving party pursuing either of, or both, a voir dire and in limine motion challenging the expert witness on relevance and/or reliability. At the ICC, joint instruction from the pre-trial or Trial Chamber, and the parameters of the reference to the expert witness is effectively the gatekeeping function.

3.1  Judicially driven experts at the ICC

The ICC pre-trial and Trial Chambers are highly involved in choosing and instructing the expert witness. The choice is already limited by the ICC Regulations requiring that the expert be chosen from a list maintained by the registry, granting the registry administrative discretion as to who may potentially be an expert at the ICC. In some cases, the chamber merely sets forth the field of expertise, and directs the registry to appoint an expert from the list when the prosecutor’s expert stated that he was not competent to assist the chamber with regard to the parameters of his reference.29

The ICC, as it begins to settle on procedural best practices, seems to be evolving towards inviting submissions from all parties, including victims’ representatives, on questions or instructions for the expert, and then drafting the instructions to the expert based on these submissions.30 These procedures have been a deliberate (p. 608) attempt by the chamber to establish trial procedures specific to their trials proactively, although the results of this exercise are still unclear. The Trial Chamber in Lubanga held that:

In principle, all parties supported joint instructions while reserving the right to call independent witnesses. [With reference to Regulation 44, and to save time and costs], the Bench has concluded that the work of the court and the interests of justice as reflected in Regulation 54(4) would be significantly assisted if a single, impartial and suitably qualified expert is afforded the best possible opportunity to investigate areas of dispute, having been provided with the details of the rival contentions.31

However, a party, in principle, may, after the chamber has instructed an expert, presumably if dissatisfied, appoint their own expert from the registry’s list. The prosecutor in Lubanga has sought to instruct and adduce evidence from at least one independent expert on the recent history of the region—an expertise that prosecutor’s prosecuting crimes in any conflict find extremely necessary to adduce evidence on. It remains to be seen whether the expertise of the jointly instructed chamber-appointed experts will enjoy primacy over independent experts, but such a bias would not be unreasonable to presume. A Trial Chamber, in appointing a jointly, or judicially instructed expert, would be making an explicit or implicit decision on the expert’s impartiality and qualifications.

The ICC’s choice is an explicit rejection of the ostensible delays in time caused by party driven experts. As held in Lubanga, the ‘procedure avoids any later disappointment as to the qualification and impartiality of the expert instructed by a single party with all the potential for delay and disruption to the trial proceedings.’32 Thus, the ICC Trial Chamber has, at the same time, a stronger and a weaker role. It effectively selects, although delegating the parameters of its choice to the registry, the expert from a list maintained by the registry. It then invites submissions from all the parties, and instructs the expert through a single judicial instruction based on all the parties’ (including the victims’ representatives) submissions. However, once the expert has been selected, there is no further gatekeeping role for the Trial Chamber. Were the consequent expert report to reveal substantial infirmities that warranted exclusion of the expert, the objecting parties would be hard pressed to convince a chamber that had both appointed and instructed the expert to exclude him, and the chamber would find it hard to justify a loss of faith in a person it had itself appointed. There is little remedy considered in the rules (p. 609) and regulations of the ICC for bad appointments, whether caused by intent or administrative negligence or judicial error, or a combination thereof.33

The remedy may lie in the appointment of additional party experts, but the ECCC’s limited experience indicates the difficulties of such an approach. At the ECCC, the accuseds’ requests for appointment of experts, whether on examination of medical issues (as fitness and competence to participate in, and stand trial, is a substantive issue at the Cambodia tribunal), or on other subjects, have not fared well. The Pre-Trial Chamber has rules that the investigating judges are ‘not obliged under the Internal Rules to consult the parties before appointing an expert.’34 The appointment of an independent expert has been sought to challenge the alleged partiality of an expert appointed, on a subject-matter requested by the accused, by the chamber. The chamber held, with reference to Cambodian law, that an additional expert on an issue already the subject of existing instructions to expert could only be contemplated after the filing of the expert’s report.35

3.2  Ad hoc‎ approach through 89(C) relevance and reliability determinations

The ICC’s embrace of deference to administrative reasonableness and chamber driven process on appointment of experts is an obvious reaction to the contentions regarding appointment of party driven expert witnesses at the ad hoc tribunals. However, there has been a variance between the practice at the ICTR and the ICTY. At the ICTR, expert witnesses’ admissibility is commonly contested. At the ICTY, perhaps because there has been less use of sociological experts, expert reports are often agreed to between the parties without cross-examination being requested.36

Expert reports are still nevertheless governed by Rule 94bis, and cannot be admitted as witness statements pursuant to Rule 92bis.37 However, somewhat strangely, at least one Trial Chamber has allowed an expert’s transcripts in another trial to be admitted pursuant to Rule 92bis, without cross-examination, when the expert has testified on the same issue in another trial, and been extensively cross-examined (p. 610) there, but without the supporting exhibits.38 However, the expert transcripts could not refer to the acts and conduct of the accused, as is the rule pursuant to Rule 92bis.39 The ICTY practice seems to be evolving towards a greater reliance on admitting written evidence, driven perhaps due to the need to speed trial time, and experts’ reports may increasingly be the subject of Rule 92bis admissions.

The gatekeeping practice at the ICTR and ICTY has evolved from comparative jurisprudence, and judicial interpretations of Rule 89(C), and is similar to the role prescribed in Rule 69(4) of the Rome Statute, without the explicit articulation of the latter. With regard to expert witnesses, the gatekeeping exercise usually concerns decisions on relevance—whether they are on the qualification of the expert witness, or the subject-matter of the proposed expertise. A diligent review of the reliability of the expert witness’ report and proposed testimony is usually deferred to a later stage, but some Trial Chambers have conducted a critical inquiry into reliability or the probative value of the testimony at the gatekeeping stage.40

The evolution of procedure has resulted in most chambers at the ad hoc tribunals conducting a preliminary inquiry or voire dire into the admissibility of expert testimony prior to the expert evidence being adduced, either in the form of introduction of the report, or through calling the witness for examination-in-chief and cross-examination. However, at least in decisions from a few years ago, and more recently at the SCSL, determining the relevance and minimum probative value of the expert witnesses proposed testimony prior to the expert evidence being adduced was often entirely deferred to final deliberations based on arguments adduced in cross-examination.41 For some chambers who did conduct a prior voir dire or inquiry into the admissibility of expert evidence, the threshold for admission of expert evidence was de minimus. For instance, although the (p. 611) SCSL rules were adopted mutatis mutandis from the ICTR, Rule 94bis(B)(i) was amended to only offer one choice to the non-moving party—whether the proposed expert witness may be accepted. An SCSL Trial Chamber, on the basis of this supposed limitation in the rules, declared in a 2-1 decision, accompanied by a persuasive dissenting opinion,42 that ‘[t]here is no … option under the rule whereby the Trial Chamber is permitted, at the request of the opposing party, to exclude or lock out an expert witness or her evidence.’43 The SCSL Chamber did not consider the Rule 89(C) requirement of relevance, probative value, and a minimum indicia of reliability, and deferred the question of whether the expert testimony was to be adduced, countered, and ultimately considered entirely to final determination.

In stark contrast, a recent Trial Chamber decision at the ICTR as to its gatekeeping function, which is a discretionary exercise of the Chamber,44 held that the following criteria must satisfied:

  1. (i)  the witness has to be an expert;

  2. (ii)  the statement/report has to be reliable;

  3. (iii)  the statement has to relevant and of probative value; and

  4. (iv)  the contents of the statement/report has to fall within the expertise of the witness.45

The definition of an expert, at least theoretically, as derived from common law jurisprudence, is fairly settled in international customary law. An expert is one who possesses relevant specialized knowledge acquired through education, experience or training in this proposed field who can assist the judges, the trier of facts, to understand and assess the fact in issue.46

(p. 612) From a plain meaning of the rules, both at the ICC and at the ad hoc tribunals, expert testimony, like all evidence, must be relevant to warrant admission. The ICC explicitly grants the Trial Chamber the power to rule on admissibility based on relevance, but also on the balancing of the evidence’s probative value with any prejudice to ‘a fair trial or to a fair evaluation of the testimony of a witness,’ inter alia.47 Expert evidence, like all other evidence, must be relevant to the proceedings to be admitted. At this stage in the ICC procedure, it is unclear whether a challenge to an expert’s relevance will happen during the appointment and instruction of an expert, or at the stage when the expert’s report is sought to be admitted, or the testimony sought to be adduced.

Relevance has been variously interpreted by the ICTR in particular. For instance, Dr Alison Des Forges, a Human Rights Watch expert on Rwanda, and a historian with broad knowledge of Rwandan polity, had testified in many trials at the ICTR, but was rejected, as seen below, by the Trial Chamber in Karemera, partly because her testimony was not considered relevant because it impermissibly intruded into the Trial Chamber’s role as a trier of fact.48 In another earlier decision, in Simba, Dr Des Forges’s testimony had also been explicitly rejected because it did not satisfy the Rule 89(C) criteria of relevance. There, the Chamber held that as it was a single accused case, it was unconvinced that ‘the broad historical evidence offered by Alison Des Forges has any value in proving of the charges against the accused.’49

Trial chambers, however, have been inconsistent in their application of the Rule 89(C) threshold of relevance, probative value, and minimum indicia of reliability in admitting evidence. At the SCSL, as seen earlier, a Trial Chamber held, in an arguably incorrect decision, that it had no such power due to a reading (p. 613) of Rule 94bis without any consideration of Rule 89(C) of the SCSL Rules. The SCSL has undoubtedly dealt with the issues of relevance in the judgment. It held that ‘[wh]ere an expert report went beyond the parameters by drawing conclusions touching upon the “ultimate issue” in this case, i.e. the individual criminal responsibility of the accused, the Trial Chamber disregarded its findings.’50

The SCSL’s approach outlined above, which has sometimes been followed by Trial Chambers at the ICTR,51 is potentially prejudicial to the fair trial rights of the accused, and contravenes Rule 89(C) of the Rules, whereby only relevant evidence which is probative and has a minimum indicia of reliability may be admitted. Evidence that is biased, or is impermissibly invasive of the Trial Chamber’s powers by addressing ultimate issues of fact or law, outside the scope of the expertise, entirely unreliable, or otherwise irrelevant or not probative, should not be admitted. To defer such a decision is prejudicial to the accused’s right to know the nature and causes of the charges brought, and the evidence that must be countered. If relevance or probative value is deferred, the accused is without notice of the nature of the charges against him or her, and must waste already inadequate and constrained resources in countering an expert whose evidence may be declared irrelevant in the final determination. To ignore expert evidence before it has been declared irrelevant would be overly presumptive. Further, such an approach is entirely contrary to judicial efficiency, as valuable judicial time is spent adducing what may be ultimately irrelevant testimony, and evidence in opposition to it.

Thus, the SCSL decisions in Brima and Taylor, cited above, and similar ICTR decisions are wrong in law and practice. A ruling on relevance or probative value cannot be fudged to final determination. However, the issue of reliability, as seen in more detail below, may appropriately be deferred to a later stage.

4.  Qualification of An Expert

The qualification of an expert is a preliminary issue to determine the relevance of proposed expert testimony. An unqualified expert’s evidence is simply not relevant. As articulated recently, citing English jurisprudence, ‘it is settled jurisprudence in common law that the judge has to determine whether a witness is qualified to give evidence as an expert.’52 The decision also finds support for (p. 614) testing the qualification of a judge as a preliminary matter from the civil law tradition.53 The testimony of an unqualified expert is irrelevant because the person’s opinion cannot assist the trier of fact due to his or her lack of expertise.

The judicial exercise of discretion on the qualification of an expert is essentially a subjective one, with normative judgements being formed on the basis of an expert’s education, experience, and other pedigrees, and often, the quantum of his or her white hair. For instance, an expert on the history of Rwanda with a chair in African studies at a western university would usually be beyond question.54 Academic qualifications, even when they are not precisely the proposed subjectmatter of the expertise, are a positive consideration for an assessment of qualification. Pedigree of national universities in Rwanda, however, have often not been sufficient, especially when situated in the faculty of law. In other instances, however, academic credentials have been considered inadequate in the absence of first hand knowledge of the proposed subject-matter. For instance, proposed expert witness Jean Rubaduka was not qualified as an expert in Rwandan constitutional law, although he was a member of the Rwandan constitutional court and conseil d’etat, and had taught law at the National University of Rwanda, ostensibly because he had decided only four to five constitutional cases and had no specialized academic training in constitutional law.55 Generally, scholars of Rwandan law have been not been held in high regard by the ICTR—Charles Ntampaka was not deemed to be qualified as an expert on Rwandan constitutional law, although he had taught the subject in Rwanda, because a lawyer in one area of the law may not be an expert in another, as legal studies are complex and no longer a discipline where one could be expected to be knowledgeable in all aspects.56

Part-time expertise has also been held to be insufficient for qualification. An academic teaching on Rwanda at the School of African and Oriental Studies (p. 615) (SOAS), London, was not qualified as an expert despite his teaching because he lacked a PhD in the subject, he was working part-time as an optometrist, and had never conducted field research in Rwanda, and the journals in which he had been published lacked pedigree.57

Past experience is sufficient for qualification. For instance, a Trial Chamber rejected the plea that a former employee of the Macedonian Ministry of Interior and a criminal law professor was not qualified to be an expert because she no longer worked at the ministry.58

Expertise need not be derived from academic studies, or research, and can be the result of work experience. An ICTY Trial Chamber, citing ICTR cases, held that expertise could be acquired even through working for the Office of the Prosecutor (OTP), arguably not the source of an objective knowledge of a subject-matter at issue in a trial.59 Mere knowledge is also at times sufficient, reflecting the wide discretion enjoyed by Trial Chambers—as the ICTR Appeals Chamber upheld, the Trial Chamber’s qualification of a prosecution expert, Kabanda, on print media, who was qualified in part because ‘out of a list of 51 publications, newspaper publication journals that were put to him, he was familiar or aware of 43 of those.’60

However, at other times, chambers have excluded general knowledge, citing the need for specialized knowledge. A British Army General with ample knowledge of, and experience with, military structures, was not allowed to be an expert on the function and operation of the Bosnian Serb Army general staff, as he had no prior expertise on the subject.61

5.  Outside the Scope of Expertise

Even if the expert is qualified, to be relevant, his or her qualification must match the proposed subject-matter of the evidence to be adduced. Often, the scope of an expert’s proposed testimony will be beyond the scope of his or her recognized (p. 616) skill or knowledge, rendering the proposed testimony irrelevant as it would be unable to assist the trier of fact on a subject-matter where he or she does not possess the requisite expertise.62 In Bizimungu et al also called the Government II case, the Trial Chamber held that although the proposed expert was qualified as an ‘expert in the field of sexual violence in Rwanda’ and her testimony would assist the Chamber in ‘better understanding’ factual evidence, the Chamber nevertheless did not allow her to testify on the most critical part of her proposed expert report—‘testimony related to genocide propaganda, the political goals of perpetrators of the crimes, the culpability of authorities, and the knowledge that officials are alleged to have possesses’, as these were ‘matters that lie beyond the scope of her expertise[.]’63 Dr Nowrojee’s testimony was thus, according to the Trial Chamber, only relevant when within the bounds of her competence or expertise—the ‘investigations of sexual crimes in Rwanda, based on her interviews and investigations in the field’—the expertise held to be possessed by a human rights rapporteur.64 Parts of Dr Nowrojee’s expertise ‘relating to genocide propaganda, the political goals of perpetrators of the crimes, the culpability of authorities, and the knowledge that officials are alleged to have possessed’ were thus inadmissible.65 In addition, the Chamber also ruled inadmissible parts of Dr Nowrojee’s testimony ‘[t]o the extent that Dr. Nowrojee expresses opinions on ultimate issues of fact[.]’66 The proscription against testimony outside the parameters of an expert’s competence, at least for one testimony, could not however be applied to de minimus transgressions because ‘consideration could be confined by the Chamber to its proper limits.’67

6.  On Ultimate Issues of Law or Fact

For the evidence to be relevant and probative, the evidence adduced from experts must be limited to issues that assist the trier of fact permissibly; there cannot be expertise of issues such as ultimate issues of fact, or law, which are presumably, the province of the chamber,68 and the competence of the judges,69 respectively. Such evidence, even if logically relevant, would not be of any probative value, and is thus under the purview of Rule 89(C) of the ad hoc tribunals. Only the (p. 617) Chamber—the trier of fact—is competent to make a judicial determination on ultimate issues. An expert testimony cannot offer ‘opinions that are determinative of the guilt or innocence of the Accused or by adverting to the acts, conduct and mental state of the Accused.’70 Thus, in a recent decision with regard to the admissibility of experts, part of the expert reports were not admitted because, in the case of Bernard Lugan, a historian qualified as an expert on history, politics and military affairs concerning the 1994 Rwandan events, his report contained legal opinions on the Indictment against Captain Sagahutu, one of the co-accused, and these parts were excluded; and in the case of Strizek’s report, a similar transgression rendered part of it inadmissible at the preliminary stage.71

In another instance, however, prosecution expert Hanne Sophie Greve, a former member of the UN Committee of Experts, was allowed to testify as to the ‘background, nature, and extent of the conflict’ at the ICTY.72 The defence counsel, Steven Kay, objected on the grounds that Greve’s testimony ‘stray[ed] beyond the traditional band of expertise that would be required into an area of opinion and comment that is seeking to provide conclusions to the Tribunal based on research otherwise provided to it.’73 The prosecutor, in response, and to the Chamber’s satisfaction, argued that the Chamber had ‘nothing to lose’ as they could determine ‘credibility’ during final determination.

Experts have frequently testified on ultimate issues of fact.74 Although the evidence adduced on ultimate fact has not always been relied upon,75 the evidence on ultimate issues of fact, not probative, should be excluded from consideration altogether, to ensure that the right to a fair trial is protected, and in order to improve judicial efficiency.

(p. 618) Parties are tempted to use such experts when confronted with complex cases with disconnected fragments of evidence adduced through oral testimony. The ICTR Karemera Chamber’s recent decision, mentioned above, was an emphatic statement on the inconsistencies of the Tribunal’s jurisprudence on this issue. The Chamber rejected the prosecutor’s claim that ‘the evidence of Alison Des Forges is necessary to the extent that the testimony of a factual witness heard thus far may require expert historical analysis to make a conceptual link to a Conspiracy to Commit Genocide that took form in mid-1992.’ It held that admitting Des Forges ‘would amount to usurping the functions of the Chamber in determining the guilt or not of the accused.’76 Des Forges had been admitted as an expert on the same issues in almost every other trial at the ICTR. The Chamber also rejected the expert evidence of Dr Bernard Lugan as to the planning of genocide, the legitimacy of civil defence, and evidence regarding the conduct of the accused as inadmissible as these were issues falling within the province of the Trial Chamber and thus of no assistance to it.77

Such evidence is not probative, and pursuant to Rule 89(C), it has been held to be inadmissible. In Kovacevic, the Trial Chamber held that expert opinion littered with ‘conclusions, drawing inferences, drawing conclusions, which is the duty of the Trial Chamber to consider and to draw if appropriate or reject[,]’ would ‘invade[] the right, power and duty of the Trial Chamber to rule upon this issue[.]’ As Rule 89(C) requires that only relevant material which is probative should be admitted, such evidence which ‘is dealing with matters that [the Chamber has] to deal with ultimately, drawing the conclusions and inference which [the Chamber has] to draw, … does not assist and is, therefore, not of probative value’ and accordingly excluded.78

At the SCSL, where as seen earlier, the gatekeeping function with regard to experts had been entirely obviated, such evidence was admitted in the RUF case. However, the Trial Chamber disregarded the expert’s testimony in the Judgment where it made conclusions on the acts and conduct of the accused persons.’79 However, this standard was not applied consistently throughout the Judgment, and the Chamber accepted the experts’ conclusion that sexual violence was intentionally perpetrated in Sierra Leone to alienate victims from communities, thus inflicting physical and psychological injury on the civilian population as a whole.80

(p. 619) Allowing expert evidence forces the other party, and in particular the defence, to counter evidence that was never relevant and probative in the first place, and is prejudicial to their fair trial rights to have a fair and impartial trial, which a chamber which is not prejudiced through non probative and non relevant evidence adduced against the accused.

With regard to ultimate issues of law, the underlying principle to this proscription is that judges are experts on their law. However, it is contentious whether in the international arena that expertise is presumed limited to international law, as that of US judges is presumed on US law. Experts have been qualified on Rwandan constitutional law, though with some issues as to qualification. Further, a chamber rejected proposed expert witness testifying about the state of international criminal law,81 a usual field for expert evidence in municipal jurisdictions, as it held that it was itself perfectly competent to pronounce on such issues without the assistance of a legal expert. However, expert opinion on the issues such as the legal obligations of the crisis staff in Bosnia Herzegovina have been admitted as assisting the Trial Chamber,82 thus reversing the national-international law rule found in domestic jurisdictions. Similarly, Professor Schabas’ (a respected legal academic) expert opinion on the state of the Genocide Convention was rejected because it was a ‘legal matter which might be addressed by Counsel in oral or written arguments.’83

At the ICC, joint or judicial instructions to the expert, modulated by the Trial Chamber, would likely not lead to any subsequent challenges with regard to the scope of the expert’s testimony being outside the scope of his or her expertise, unless the terms of reference are misinterpreted or issued erroneously. In such cases, the standard of review by the ICC chamber will likely be higher in regard to a chamber appointed and instructed expert witness.

7.  Bias

Expert witnesses, particularly those appointed by parties, even though briefed and adduced through adversarial parties, must, by the very nature of their role, (p. 620) be neutral.84 Neutrality is of course partially nominal, as they are necessarily biased in terms of their reference being party driven, which is a problem not likely to be suffered in the ICC’s adoption of a judicially driven process. Impartiality, however, has been read into Rule 89’s role of excluding irrelevant evidence, with the assumption that an overly partisan expert would offer no assistance to the trier of fact.

The first judgment of the ICTR—Akayesu—stated that, in order to adduce evidence, an expert witness must not only be a recognized expert in his field, but must also be impartial in the case. In that instance, the principle was applied to exclude a defence expert who happened to be a co-detainee, an accused in another trial.85 As held by the Appeals Chamber, an expert is ‘obliged to testify ‘with the utmost neutrality and with scientific objectivity’.86 Such a threshold has not, however, been strictly applied, and most expert witnesses at the tribunals would be hard pressed to pass the muster of scientific objectivity and utmost neutrality.

Akayesu may have been an example of bad facts—as the prospect of an accused being called to assist the court in adjudicating against another accused was a peculiar case—and although Akayesu is often cited, Trial Chambers have been reluctant to exclude experts on grounds of bias. The ICTY Appeals Chamber, in Popović, found no error in the Trial Chamber’s holding that ‘objectivity and independence are not prerequisites for an expert to be qualified as an expert.’87 A proposed expert witness relationship, even when it pecuniary or an employer-employee relationship has not usually been held to be a sufficient demonstration of bias. As held in Nahimana, an ICTR case, ‘the mere fact that an expert witness was employed or paid by a party does not disqualify him or her from testifying as an expert witness.’88 As seen above, a chamber has even held that knowledge of a particular subject-matter gained from employment with the OTP was sufficient (p. 621) to qualify a person as an expert on the subject-matter.89 However, in Milutinović, the Trial Chamber directed the prosecutor to call a former investigator as a fact, rather than an expert, witness, because ‘he [was] too close to them’.90 Further, in Ðorđević, prosecution expert Philip Coo, who was an employee of the OTP had interviewed witnesses and alleged members of the joint criminal enterprise charged against the accused, was too involved with the prosecution to be impartial, and the involvement ‘may have affected the reliability of the opinion to such an extent that the Chamber would be unable to rely on them in making its findings on the issue in the case.’91

Putting aside what constitutes bias at the ad hoc tribunals, decisions have also been mixed on whether bias is an issue to be decided at the preliminary stage. During the admission of Jean Rubaduka, Trial Chamber II at the ICTR held that the issue of bias was best left for cross-examination during the expert’s testimony as ‘the first phase of the witness’ testimony would be devoted solely to the question of whether this witness, by virtue of his qualification or experience, qualifies as an expert witness on the subject matter he intended to provide assistance to the Chamber.’92 Some ICTY Trial Chambers have similarly held that the issue of bias, and a proposed expert’s alleged relationship to the accused, are matters that go to the weight of the testimony rather than its admissibility. The Appeals Chamber, in Popović, held that the Trial Chamber did not err in holding that questions of bias are not relevant considerations for qualification, and may be addressed during cross-examination.93 Even in Ðorđević, the exclusion of the expert witness Coo’s expert testimony was exceptional, as bias is usually a matter of weight, ‘the extent of [the expert’s] involvement in the preparation of the Prosecution case may have affected the reliability of his opinions to such an extent that the Chamber would be unable to rely on them in making its findings on the issues in the case.’94

It is assumed that the ICC’s appointment of experts from a list drawn up by the registry would avoid any instances of bias, but one can envisage scenarios where a chamber may be asked, nevertheless, to consider bias, real or perceived, on behalf (p. 622) of an expert. For instance, in one hypothetical, an expert may be qualified to be on the registry’s expert list as an expert on the historical and social context of a country, but one party may perceive his previous writings to be biased against a party, and thus seek his disqualification as an expert. Such a scenario is not entirely hypothetical, for historical experts are frequently not neutral on their treatment of protagonists in conflict. History requires normative judgments, but these judgments are ill suited for the ‘utmost neutrality’ required of experts.

8.  Reliability as a Preliminary Contention

The party opposing a proposed expert often raise issues of the expert’s reliability, through methodology or otherwise, at the initial gatekeeping stage, pursuant to Rule 89 of the ad hoc tribunals’ rules. In response, but without consistency, Trial Chambers have articulated a test that states that ‘[p]rima facie proof of reliability on the basis of sufficient indicia is enough at the admissibility stage.’95 At other times, as seen above, Trial Chambers have deferred all issues of reliability to a credibility determination at the time of final deliberations.96 Thus, although there is theoretically a possibility that the reliability of an expert report is so poor that it renders the expert report and any evidence from that expert is thus liable to be rejected under Rule 89(C), such a determination is almost never made at the gatekeeping stage.97 Such practice is consistent with national practice.98

At the ICC, presumably, reliability as a preliminary contention is less maintainable when the chamber appointed expert has a de facto rebuttable presumption of reliability. A party will have to challenge the expert on specific issues of reliability and/or seek permission to adduce additional contrary expert evidence, either on the subject-matter of the expert’s proposed testimony, or on the methodology employed by the expert witness.

(p. 623) 9.  Fact or Expert Witnesses

Hybrid witnesses are not unique to international criminal tribunals. A doctor who witnesses an accident or attends to its victims is both an eyewitness, and an expert with opinions based on his expertise and facts observed. However, fact witnesses opining on issues based on supposed expertise, and its corollary, have troubled the ad hoc tribunals. This problem is somewhat unique to professionals or academics from the affected countries, who have both an opinion and a factual narrative to recount, which are difficult to separate and categorize.

In one instance, during an extensive viva voce to admit the report of a factual witness, Joseph Ngarambe, an Rwandan politician in exile, who had produced the report as a consultant to the prosecutor, Trial Chamber II of the ICTR held that ‘while a non-expert, like a consultant or an investigator, may prepare a report which contains opinion evidence on matters of a technical nature for the consideration of the Chamber, such a report should be based on the factual circumstances the witnesses observed and heard,’ and not on matters ‘which the Trial Chamber considers calls for special skill or knowledge of an expert’.99

The principle is difficult to apply in practice. Ben Gumpert, a defence counsel contesting the admittance of Ngarambe’s report, stated that it is a ‘well known dictum that a man’s state of mind is as much a question of fact as the state of his digestion …’.100

Curiously, the Chamber’s legal findings relating to Ngarambe’s report—an analysis of radio summaries from Rwanda concerning the events alleged—could be considered dicta, as the report was excluded not because it contained opinion that should have been adduced from an expert witness, but because the basis of the report—the underlying broadcasts and radio summaries—had not been fully disclosed to the defence teams and the Chamber, precluding both effective cross-examination and a determination of the report’s reliability.101 Such disclosure would have been entirely appropriate to require of an expert, which Ngarambe was not, but such requirements were not enforced on other expert witnesses, such as Dr Des Forges, by the same Chamber.

Another chamber at the ICTR may have handled the same issue better. In Ndindiliyimana, it was held that when a party chooses to call a witness as a factual witness rather than an expert witness, it implicitly makes the choice to limit the witness’ testimony to matters that he personally saw, heard or experienced, (p. 624) and any irrelevant details and matters of personal opinion or expertise beyond the remit of a factual witness must be excluded.102

As stated above, the ICC’s approach lies more within the civil law tradition. In common law, a lay witness may testify as to their opinions or state of facts based on their observations of relevant facts. In civil law systems generally, there are no such rules of proscription, and it is ‘entirely within the discretion of the court to determine who can be qualified as an expert.’103 It remains to be seen how the ICC will handle the issue of hybrid witnesses.

To conclude on the issue of gatekeeping, it is a case-by-case determination, with any articulated threshold difficult to apply, and often an ad hoc determination irrespective of the legal standards set forth. The focus on relevance makes admission of an expert an exercise of judicial discretion, although the treatment of an expert by other chambers is a good indicator on how subsequent chambers will treat the expert.104 However, it has been held that an expert witness’ qualification turns on the contribution he or she can make to the chamber in the instant case and the same person might be qualified, logically, in one case but not another.105 In practice, however, prior qualifications are a potent tool for determination admission and are entirely relevant for the viva voce proceedings.

10.  Need an Expert Testify?

It is evident from a reading of the rules of the ICTY, ICTR, and SCSL that it was not considered absolutely necessary for experts to testify, as the non-moving party is granted the discretion to allow the expert report to be admitted without cross-examination, as an impartial aid to assist the judges in reaching their reasoned decision. Indeed, pursuant to Rule 94bis(B)(iii) of these three tribunals’ rules, the opposing party has to affirmatively seek to cross-examine an expert even if it does not accept the expert’s expert report. It was likely intended that expert reports would be admitted as documentary evidence, largely uncontroverted. To a large extent, however, expert reports have been vigorously contested.

(p. 625) At the ICTY, for instance, in Limaj, the prosecutor chose not to cross-examine a defence expert on identification, Professor Wagenaar, in return for the defence entering only the non-analytical portion of his report into evidence.106 In the same case, a prosecution expert’s report regarding DNA evidence of a victim was admitted without opposition from the defence.107 At the ICTR, however, non-moving parties have consistently asserted their right to cross-examine experts, and experts have been cross-examined comprehensively. For instance, in Military I, Dr Alison Des Forges was on the stand for 15 days. These variances do not arise from any difference in the rules, but are norms developed from practice, and reflect perhaps the type of experts that have been proposed and admitted at the ICTR. Parties at the ICTR, as seen in this report, have been more prone to call sociological and historical experts. Also, the ICTY, perhaps reflecting the greater documentary record of the events in Yugoslavia, has been more willing to admit documentary evidence. Such variances, determined by particular circumstances confronting these tribunals, will remain irrespective of the black letter rules concerning expert witnesses.

From that perspective, the ICC and the Cambodia Tribunal’s practices on admission of expert reports are hard to predict. As stated above, the tribunals’ rules and practice direction favour a judicially driven and determined process. Regulation 44(5) of the ICC Regulations gives broad powers to the chamber to inter alia ‘issue any order as to… the manner in which the evidence is to the presented[.]’ This power may be limited by Article 69(2) of the Rome Statute, which states that ‘[t]he testimony of a witness at trial shall be given in person, except to the extent provided by the measures set forth in Article 68 or in the Rules of Procedure and Evidence.’ Regardless, the chamber will have a strong role at the ICC in determining whether expert evidence will be adduced documentarily or through live testimony. Given the discretion granted to the Trial Chamber, it is not inconceivable that the practices may diverge between chambers.

11.  Reliability

Once expert evidence has been admitted, it is presumably prima facie reliable—sufficient for the threshold of relevance, but a chamber’s reliance on the evidence is dependent on its consideration of the reliability of the evidence. In practice, as we have seen above, expert evidence is often admitted without a serious consideration of relevance, and it is left to the chamber’s final determination to accord reasonable and appropriate weight to the expert evidence, if at all. Thus, through cross-examinations and production of counter experts, the non-moving party (p. 626) usually challenges the reasonability of the expert opinion based on the methodology, best practices and supporting evidence. According to ICTY jurisprudence, the factors in evaluating expert testimony are the competence of the expert, the methodologies used, and the credibility of the findings made.108

Expert’s are supposedly subject to scrutiny for their opinions, even when the opinions are within the scope of their expertise. Ancient Roman law may have stipulated blind and binding faith in expert opinions,109 but modern jurisprudence in national jurisdictions, as in the United States Federal Rules of Evidence, with a common law system consider the reliability of an expert’s opinion before assessing the expert’s reliability and consequence weightage to be assigned to their evidence.

Reliability of methodology, or the inability to test reliability because of the unavailability of the basis of the expert’s opinion, have not been rationales to exclude expert evidence at the gatekeeping stage.110 However, it is arguable that without access to underlying sources of an expert’s opinion, the expert’s opinion is not probative, and thus may not be admitted subject to ICC, Article 69(4) or the ad hoc tribunals’ Rule 89(C). Non-testable opinion would likely not prove or disprove a fact in issue, and should be excluded.111

12.  Access to Sources of Opinion

To consider the reasonability of expert evidence, it is necessary to have access to, and analyze, often with the assistance of an expert, the sources and information on which the expert opinion evidence is based and relies upon.112 Even if one were to accept, without reserve, the legal fiction that considers professional judges impervious to the emotive and irrational decision-making habits of mortal juries, and grants them wide discretion to consider evidence usually excluded from a juries’ consideration, determination of an expert’s reliability without access to sources is impossible unless the subject is so common that an expert is not relevant as he or she can offer no additional assistance to the professional judge. As professional (p. 627) judges, they are presumed to be able to separate the wheat from the chaff, and weigh the probative value of even marginally reliable witnesses, or extremely prejudicial evidence with little probative value, but they cannot credit reliability appropriately without a reasonable basis. Without such access, a judicial determination of the expert’s opinion, and the weight to be accorded to the opinion, must rest solely on such considerations as the expert’s demeanour and credentials, which are necessary but not sufficient criteria for admitting evidence.113

Unlike Rule 94bis, there is no specific provision in the Rome Statute or the ICC Rules of Procedure and Evidence and Regulations that govern disclosure of expert reports. Instead, disclosure is governed by the general rules on disclosure—Article 67(2) of the Rome Statute for the continuing obligation to disclose exculpatory information, Article 84(3)(1) of the Rome Statute with regard to disclosure in sufficient time ‘to enable adequate preparation for trial,’ and Rule 77 of the Rules which allows for inspection of anything in possession or control of the prosecutor. However, given the use of ICTR and ICTY jurisprudence at the ICC, the till date preference for judicially or jointly instructed experts, and the need for a fair trial, will likely ensure that expert report’s are disclosed far in advance to the 21 day minimum notice requirement in Rule 94bis.114

The more difficult question remains as to whether the sources of expert reports will also be subject to disclosure. The ICTR and ICTY Trial Chambers have struggled, as explained below, with reconciling the need to allow expert witnesses the ability—a requirement in conflict zones—to have confidential sources, and the need to ensure that an accused, consistent with a fair trial, has the ability to test an expert’s opinions for their reasonableness. This problem has been particularly acute with historical or sociological experts whose opinion is often based on hearsay evidence which stretch the boundaries of appropriate subject-matter for experts. For instance, at the ICTR, Dr Des Forges had insisted on a hitherto unknown privilege of not disclosing her confidential sources,115 in contrast to the decision with regard to expert witness Robert Donia in the Milošević trial.116

(p. 628) A recent ICC decision may be instructive on this issue. According to the Appeals Chamber in Lubanga, Article 67(2) disclosure obligations are applicable to information the prosecutor had received, primarily from the UN, with restrictions against allowing even the Trial Chamber an in camera review of the material before it, pursuant to Article 54(3)(e), which allows the prosecutor to obtain information to ensure further information.117 The requirement to disclose the source material of experts, even if subject to a private privilege between the expert and the source, perhaps exculpatory, may be subject to the same test, and require at least an in camera review by the Chamber so that any prejudice to the fair trial rights may be considered, even it is in the context of the need to protect an expert’s sources due to the exigencies of safety particular to conflict zones. In the absence of such a requirement, expert witnesses could be used to circumvent, to some extent, Article 67(2)’s strict obligation to disclose exculpatory information to ensure a fair trial.

At the ICTY, there is arguably settled jurisprudence, derived from common law, that the opposite parties must have notice of, and the judges’ access to, the basis of an expert’s report so as to be able to assess the reliability of their opinions. An expert is expected to give his or her expert opinion with full transparency of the established or assumed facts that he or she relies upon and of the methods used when applying his or her knowledge, experience, or skills to form his or her expert opinion.118 As stated in Milošević,

[T]he expert statement or report must meet the minimum standards of reliability. There must be sufficient information as to the sources used in support of the statements. The sources must be clearly indicated and accessible in order to allow the other party or the Trial Chamber to test or challenge the basis on which the expert witness reached his or her conclusions. In the absence of clear reference to accessible sources, the Trial Chamber will not treat such a statement or report as an expert opinion, but as the personal opinion of the witness, and weigh the evidence accordingly.119

In contrast to practice at the ICTR, the Milošević Trial Chamber required access to sources necessary to meet a minimum standard of reliability, indicating that (p. 629) a Rule 89(C) challenge of an expert report that withholds evidence should, in principle, be successful. However, even at the ICTY, it has been held that the failure to list sources can be remedied when the witness testifies, and the prosecutor need not disclose all the sources, as it is the defence’s responsibility to seek them out.120 In Tadić, the conclusions of expert Greve, discussed earlier, were based on anonymous witnesses, and according to one commentator, allowed the prosecutor to ‘use the expert hearsay expert evidence to convict [Tadić].’121 In contrast, the Delalić Trial Chamber was able to review and consider the underlying facts relied upon by an expert in psychiatry, and rejected the testimony as unreasonable in the exercise of its discretion.122

The ICTR, on the other hand, has failed to apply the principle that an expert’s sources must be disclosed such that the reasonability of, and the weight to be assigned to, the opinion could be challenged and tested. In particular, with social/political/historical experts, who rely primarily on confidential sources for their opinions, the ICTR has accepted such evidence without requiring notice or access to the source material to opposing parties, or even the chamber. For instance, in Government II, Dr Des Forges explicitly refused to reveal the sources of her report and testimony without seeking their permission, an implicit assertion of a hitherto unknown evidentiary privilege—that of a human rights researcher and her sources.123 In another case, the Trial Chamber held that the refusal of an expert witness to reveal his or her sources did not violate the rights of the accused.124

The ICTR jurisprudence on this issue in particular has been an illustration in inconsistency and has been disputed. It is far from settled law, as Trial Chambers, and the Appeals Chamber, has not explicitly stated the principle articulated by the Milošević Trial Chamber that a minimum indicia of reliability requires notice of, and access to, the expert’s sources. Even an in camera review by the chamber, a means to consider the assertion of privilege by the ICC Appeals Chamber, has not been available to the Trial Chamber for experts such as Dr Des Forges who have refused disclosure of their sources on the basis of their own assessment on the need to disclose such information.

(p. 630) The problem of lack of disclosure is particularly acute when experts, particularly sociological or historical experts, rely on hearsay evidence to reach a conclusion. It is extremely difficult for the chamber to reasonably judge, and the opposing party to challenge, the reliability of an expert’s conclusion that is based on an expert’s own finding that his or her hearsay source was credible.125 The reliance of experts on hearsay evidence, in the absence of disclosure, has not been specifically prohibited by the Appeals Chamber.

In a dissenting opinion, Judge Shahabuddeen stated that:

I respectfully agree with the Appeals Chamber that, although hearsay evidence is admissible, in the absence of disclosure of the basis of reliability, the [expert] evidence is not admissible.126

As can be seen from the lack of majority opinions, the ICTR and ICTY Appeals Chamber is yet to opine on the issue on whether disclosure of the sources of expert witnesses is required, and under what exceptions may it be withheld from the non-moving party.

Another separate opinion, by Judge Thompson of the SCSL, offers a comprehensive explanation, with a comparative look at national jurisdictions, on the principle that sources of expert opinion, particularly if they are hearsay evidence, are necessary to consider the opinion. Further, the quotient of reliance on hearsay evidence has a relative diminishing effect on the expert opinion’s reliability.127 The comparative explanation has a logical coherence—reliance on hearsay evidence, particularly confidential hearsay evidence—militates strongly against the reliability of expert opinion. Indeed, it is arguable that the right to cross-examine (p. 631) expert witnesses, without access to the hearsay basis of an expert’s opinions, is a meaningless exercise.

Thus, access to an expert’s sources, hearsay or otherwise, has been considered as just one of the factors in the evaluation of expert evidence at the ICTR. As stated:

The standard for admission of expert testimony is whether the specialised knowledge possessed by the expert, applied to the evidence which is the foundation of the opinion, may assist the Chamber in understanding the evidence.128

Indeed, expert opinion reliant on undisclosed hearsay sources has been considered by Trial Chambers in their final determinations. Expert witness Dr Andre Guichaoua, without disclosure of his sources, opined that Bagilishema, who had been a bourgemestre for 14 years, in not resigning given the situation, could not ‘disclaim responsibility’ as he was capable of analyzing the situation correctly, as had another bourgemestre, Juvenile Rwazegushira, in 1993.129 Although this opinion is fatally deficient for intruding on the chamber’s province as an ultimate trier of fact, a sweeping generalization, and defying the rules of inductive analysis, it is also made without any explanation for its basis, and thus incapable of being challenged, tested, and ultimately relied upon.130

Although the Chamber has still not reached a judgment in Government II, expert Mbonyinkebe, who conducted a field survey in Rwanda on the prosecutor’s specific instructions, had opined in his report without any supporting data or numerical conclusions from his report. The only supporting data revealed by Mbonyinkebe was that he had interviewed 71 people, 65 of whom were interviewed with a guarantee of confidentiality. However, even data from the six nonconfidential interviews was not disclosed. No redacted data on the disclosures was disclosed. Irrespective of whether Mbonyinkebe is relied upon, his conclusions, which reveal nothing of his sources, or their responses, in addition to suffering from other infirmities, cannot be tested for reliability by the Chamber, and thus arguably should not have been admitted.131

(p. 632) In Semanza, however, expert witness Ndemgejeho’s testimony was discounted because his expert opinion was based on information relayed to him from ‘unidentified sources’—hearsay—and ‘lack[ed] sufficient detail to be reliable[.]’132 In contrast, in the same case, the Appeals Chamber held that Professor Guichaou’s ‘willingness to disclose particular resources and contacts if asked about specific matters[]’ was sufficient disclosure of his ‘methodology and his sources’.133

Rwanda expert Dr Filip Reyntjens,134 who has testified as an expert at numerous trials at the ICTR, has been candid about the fact that the use and reliance on confidential sources, often leading to the reproduction of hearsay testimony without the opportunity for challenging and testing the basis of the reproduction, could lead to due process violations and mitigate against a fair trial. Dr Reyntjens has himself relied on, and reproduced, hearsay evidence in his conclusions. He acknowledges the dichotomy and contradiction between his obligations as a scholar, for whom fealty to his confidential sources is important, and does not negate his academic scholarship and its validity;135 and his role as an expert witness. The same fealty to confidential sources, according to Dr Reyntjens, would likely cause concern were a Trial Chamber to rely upon his conclusions in its findings of fact. The contradiction is resolvable, according to him, as his expert opinions cannot form the basis of a conviction. Such a position, however, renders them lacking in any probative value, and depending on their content, likely to be prejudicial to the accused. Even if his conclusions, based on undisclosed sources and unchallengeable for their reasonableness, are included not for the truth of its contents, it is still unreliable and should be excluded entirely from consideration, not set aside in the final determination.136

(p. 633) Dr Reyntjens points out a key concern: often, experts are not merely basing their conclusions on confidential undisclosed sources, but they are reproducing hearsay evidence and circumventing the due process guarantees that even if hearsay evidence is allowed, it must be tested for reliability.137 The effectively double hearsay is further problematic because it is adduced through expert witnesses, who have been presumably admitted because their opinion is sought by the trier of fact on a particular subject-matter because they possess specialized knowledge in that matter.

The problem of reproducing hearsay evidence is amplified when the source is also a factual witness, a problem not usually discovered if the identity of the source is never disclosed. In such a scenario, an expert may be used to corroborate a hearsay factual witness, who the chamber is treating with caution, when the factual witness is the basis of the expert’s own evidence. For instance, Dr Des Forges, in the book—Leave None to Tell the Story—which accompanies her expert report into evidence, uses as one of her non-confidential primary sources, Mr Fidele Uwuziye, the former préfet of Gitarama, who according to Dr Des Forges resisted the genocide unsuccessfully even though he remained in his position through most of the time the genocide occurred. Mr Uwizeye has testified in the same trial as Dr Des Forges.138 Such amplification of factual evidence is likely not the expected rationale for the inclusion of expert evidence.

Experts assist, not replace, the trier of facts, and cannot be used to circumvent the rules and guarantees of a fair trial that, with limited exceptions, require witnesses to testify in person. Too often, the conclusions of experts at the ad hoc tribunals, neither technical nor scientific, have been ‘based on second, third, and even fourth hand testimony of victims and witnesses[.]’139 Professional judges, without access to confidential sources, cannot review the opinion for its reasonableness, a necessary condition for reliance. The accused, if the non-moving party, has the right to challenge the opinions, a right which is vitiated in such circumstances.140 Without access to sources, cross-examination is merely a grope in the dark with the hope that an expert would somehow whither under the brilliant eloquence of counsel. With apologies to master craftsmen of cross-examination, effective cross-examination of experts requires the notice of, and access to, their sources, so as to ensure that their opinions, if not reasonable, are vigorously challenged for their deficiencies. The chamber’s discretion on credibility and reasonableness cannot be delegated to expert witnesses, irrespective of their credentials.

(p. 634) An expert’s reproduction of hearsay testimony from confidential sources also implicates an accused’s fair trial right to be present and be tried in his presence. The right to be present is consonant with the US Constitution’s Confrontation Clause, which states that ‘[i]n all criminal prosecutions, the accused shall enjoy the right … to be confronted with the witnesses against him.’141 As here, the US courts admit hearsay where it is necessary and reliable,142 but experts rebroadcasting hearsay testimony is not one such case.

13.  Expert’s Methodology

One of the considerations for reliability that requires consideration is the expert’s methodology and whether it is sufficiently scientifically valid to be reliable. Methodology is one of the factors used in evaluating experts.143 As articulated by Judge Thompson in his concurring opinion, in relevant part, ‘the reasoning or methodology underlying the testimony must be valid and properly applicable to the facts in issue[.]’144 Issues of methodology almost always go to weight rather than admissibility.145

US jurisprudence, which has a strong focus on testing methodology, is instructive on this issue. The principles for determining the admissibility of expert opinion, first postulated by the US Supreme Court in Daubert, and codified in the Federal Rules of Evidence subsequently, conflate relevance and reliability. Experts in the US, beyond having the ‘scientific, technical or other specialized knowledge [that] will assist the trier of fact to understand the evidence or to determine a fact in issue’146, must meet the threshold four part test: (1) is the subject of expert testimony falsifiable or testable?;147 (2) is the testimony derived from techniques with known error rates; (3) has the testimony been subject to peer review? and (4) is the testimony generally accepted in the scientific community?148 The Daubert test (p. 635) is applicable, with some flexibility, to all types of expert testimony, including the socio-historical-political experts that prosecutors rely upon.149 US Federal Rules of Evidence 705 explicitly allows for cross-examination to solicit and question the underlying rationales of an expert’s conclusions. The US rules are not dispositive, but have informed the interpretation of Rule 89(C) of the ad hoc tribunals, and are instructive with regard to experts.

The ad hoc tribunals, beyond the few cases of shockingly poor and thus grossly unreliable methodology, have not yet been troubled by the methodology of the experts before it. In the Semanza appeal, the Appeals Chamber held that the Trial Chamber ‘appropriately admitted and considered the expert evidence,’ in part because Professor Guichaoua explained that his methodology was to consult his resources first, including administrative reports, and ‘indicated his willingness to disclose particular resources and contacts if asked about specific matters.’150 However, in the Military I Trial Judgment, the Trial Chamber concluded that it was not proven beyond a reasonable doubt that the accused were members of a death squad, even though it found the expert evidence on the issue ‘compelling’ and considered the methodology of Dr Reyntjen’s appropriate, but stated that ‘he conceded that his research was not a judicial inquiry and that a more serious international inquiry was required.’151 It will be thus uncontroversial to conclude that there are not even broad guidelines, as in Daubert, for testing the reliability of methodology and that Trial Chambers continue to have wide discretion.

14.  A Note on Social Scientists as Expert Witnesses

As discussed earlier in this chapter, there has been a widespread use, particularly at the ICTR,152 of what may be described as ‘soft’ experts—historians, (p. 636) sociologists, experts on genocide etc whose evidence, while useful to understand the complexities of protracted conflicts and the pieces of complex political puzzles, has raised troubling issues with regard to fair trial rights. For example, Dr Des Forges, a historical expert, has testified and been accepted as credible in most trials at the ICTR. However, recently, a Trial Chamber rejected her proposed testimony stating that:

[T]he Chamber is not persuaded that the disciplinary field of social-political science is sufficiently organised or recognised as a reliable body of knowledge or experience with which the witness could potentially provide assistance to the Chamber.153

The Chamber further held that ‘… although the historical dissertations are interesting and informative, the Chamber does not require assistance of the expertise to understand the evidence and come to its conclusion on the guilt or innocence of the accused.’154 The Chamber based it rejection on numerous reasons, some which may be considered specific to the case itself. For instance, based on its determination of the allegations, it did not consider the historical context as relevant to its determination of the case. Although such a consideration was at odds with the determinations of other chambers, it was within the Chamber’s discretion to make such a holding.155

However, the Karemera Trial Chamber’s dismissal of the field of social-political science had larger implications. In one sense, it contradicts the Semanza Appeals Chamber, which held, albeit specifically for Professor Guichaoua, that he was qualified as an expert, and upheld the Chamber’s ruling on the reliability of his evidence.156 Also, socio-political experts have been admitted previously without pause. Experts such as Dr Des Forges, Professor Guichaoua, Sebahire Deo Mbonyinkebe, and defence experts such as Dr Bernard Lugan, have testified to historical, social and political subjects in numerous trials.157 Even at the ICTY, where such experts have not been used as extensively, witnesses have testified, for (p. 637) instance, on the ‘social, cultural, political and historical background of the former Yugoslavia [and] the Greater Serbia ideology in the 19th and 20th Centuries.’158

To be sure, some social experts fit the more customary, at least as seen in common law jurisdictions, role and use of experts at trial. Dr Matthias Ruzindana for instance, testified on linguistic and translation issues in Akayesu.159 In Kayishema, an expert on mob psychology testified on the subject, although his evidence was rejected.160

Commentators have expressed concern about social scientists and human rights rapporteurs giving evidence as expert witnesses in criminal trials. Although increasing standard operating procedure in many domestic jurisdictions, particularly in complex trials, or trials with issues such as foreign laws or practices, there is disquiet with this practice that is shared by the author. Surely social scientists, miserly with certainty, and expert witnesses who must state with certainty their conclusion for any party worth their barrister tag to put them on the stand, should be ‘foreign, if not overtly antithetical to each other.’161 Social scientists often depend on theoretical assumptions that make a trade-off between absolute truth beyond a reasonable doubt, to put it one way, and the need to reach probable conclusions. It is impossible to discount the fact that assumptions from the testimony of sociological experts, perhaps reasonable in academic research, but they are unacceptable leaps of faith when determining criminal liability. As stated by Lawrence Rosen:

Categories that courts may regard as conclusionary, social scientists might see as shorthand formulations, general glosses, or purposely ambiguous rubrics covering details that cannot be summed up as categorical responses to certain kind of questions.162

According to Rosen, social scientists themselves remain ‘deeply troubled by the ethical implications of their work and alienated by some aspects of American trial procedure and tactics.’163 Notwithstanding the gravity of the charges faced by those accused before international tribunals, social scientists, recalling the underlying assumption of the presumption of innocence, must critically evaluate whether their conclusions are necessarily precise to assist, rather than mislead, (p. 638) the court and not evade responsibility solely on the grounds that the professional judge will discount imperfect social science in the final determination.

15.  A Comparative Exercise

As expert evidence jurisprudence has developed at the ad hoc international tribunals, it has often, but not always, referenced comparative law, particularly common law jurisdictions, as the basis of its principles. The ICC’s approach, thus far, however, has represented a more civil law approach,164 and it will be interesting if there is a greater influence of civil law practice and procedure on expert evidence due to this implicit choice in the Rome Statute, and the practice of the ICC thus far. However, even civil law and common law practice on expert evidence, particularly where it impacts fair trial rights, have begun to converge to some point because of the European Court of Human Rights (ECtHR) rulings on some of the issues on which concern has been expressed above.

15.1  Civil law

As is the case with the ICC, civil law systems are judicially—or magisterially—driven, rather than party driven, in contrast to the practice at the ad hoc tribunals. Appropriate subject-matters of expertise have enjoyed wider latitude under the civil law system perhaps due to the presumptions that judicially instructed experts will be neutral; that the judges require the assistance for which they instruct; and the civil law institutional bias in favour of the magistrate. In the Netherlands, for instance, expertise has been defined as ‘all special knowledge one possesses or is assumed to posses even though such knowledge does not qualify as “science” in the more limited sense of the word’.165

Reliability of experts has not traditionally been a central issue for civil law magistrates.166 However, with the harmonization of procedure in Europe, reliability (p. 639) through access to the basis for the expert’s opinion has been introduced. The ECtHR recent jurisprudence recognizes that expert opinion, even when experts are court appointed, must be accompanied by an airing and consideration of the process in reaching the conclusion. In Mantovanelli v. France, the court-appointed expert in a medical malpractice case did not provide any notice or information to the complainants/civil parties, which rendered any challenge they may bring to the report deficient.167 Further, in interpreting the fair trial rights of Article 6 of the European Convention of Human Rights (ECHR), the ECtHR held that it ‘require[s] that an accused be given an adequate and proper understanding to challenge or question a witness against him, either at the time the witness was making his statement or at some later stage of proceedings.’168

This jurisprudence is instructive as the ICC tackles issues of reliability vis-à-vis judicially or jointly instructed experts. There is an implicit acknowledgement of an expert’s relevance and probity when they are appointed judicially, and any challenge to them will require a full understanding of their basis.

There are, of course, advantages of non-partisan expert opinion aiding the trier of fact in the civil law system, and the system has often been considered conducive to a more amenable truth-seeking exercise. However, if the civil law system is a guide to the ICC, the system does not always produce the fair and neutral expert who provides clinical and reasoned opinion, rising above the adversarial fray. Judges in the civil law system, as investigators and often adjudicators of fact, are not limited to expert opinion on matters outside their competence, but may rely on expert evidence more broadly.169 The ICC, in contrast to France or Belgium, allows a party expert to be appointed subsequently, while in these civil law countries, the parties have no role, and experts—temoigne du contexte, are court officers, without an appearance of bias.170

Article 156 to 169-1 of the French Criminal Procedure Code concerns expertise. The parties to a trial have no capacity to appoint experts, as only judges possess such capacity. The expert does not belong to the defence or to the prosecutor but is designated by the judge. However, the parties and the Ministére Public can only request the judge/magistrate to instruct a particular expert. Experts work closely with the magistrate, and are supposed to assist the judge. Consistent with the (p. 640) jurisprudence of international tribunals so far, the expert is not allowed to express his views on the accused’s culpability. The parties can question the expert witness, but it is not what those of us accustomed to adversarial common law proceedings would term full cross-examination. As the ICC has followed, the French practice only allows instruction of experts if they are registered on a list. Each expert is accredited through a specific examination procedure.171 The process, however, must of course be consistent with the right to a fair trial.172

In the Netherlands, a civil law jurisdiction, has important variances with the French civil law system.173 Firstly, expert evidence is a legal means of proof. Secondly, the system is weighted towards the prosecution, as it has non-appealable discretion to rule on the validity of defence requests for independently instructed expert witnesses.174 Further, the magistrate only has discretion to exclude defence expert witnesses on relevance, not prosecution expert witnesses. Thus, defence in Dutch criminal trials does not usually instruct independent expert witnesses.175 The prosecutor thus has an arguable advantage with regard to expert witnesses, implicating the fair trial guarantee of an equality of arms.

As can be seen, the ICC has borrowed many aspects of the civil law practice on expert witnesses, perhaps as a reaction to the concerns with the usage of party driven, partisan expert witnesses at the ad hoc international criminal tribunals, particularly the historical and political experts. It remains to be seen, however, whether judicially appointed or instructed experts will solve the problem. As stated above, the chamber’s instruction may easily become a delegation of its fact-finding role. The judicial expert enjoys a de facto presumption of reliability. According to some commentators, these pitfalls give the judicial expert the ‘false air of neutrality,’ when in fact only one viewpoint can be represented and an expert may not be truly neutral.176 There is also an argument as to whether partisan experts, admitted appropriately, allow the parties to theoretically present a case as best they see fit.

(p. 641) Although the ICC has firmly taken direction from the civil law practice on expert witnesses, there is likely to be an effect from the ad hoc tribunals’ jurisprudence on this issue, which has been firmly influenced by common law practices. The Karemera decision on experts at the ICTR, which departs from ICTR practices in restricting the admissibility of previously admitted expert witnesses, is perhaps a nod, even at the common law influenced ad hoc tribunals, to the civil law notion of the chamber being the primary party in adducing expert evidence. In disallowing experts who have frequently given testimony in other ICTR trials, the Chamber implies that the ability to call expert testimony is best determined by itself, not the parties, and the Chamber may determine that there is sufficient factual evidence on a point, thus precluding expert opinion.177 However, the civil law tradition is not without its pitfalls, depending as it does on presumed reasonableness of the chamber as an institution, and thus often failing to incorporate, at least until the harmonization of the ECtHR, the fair trial protections granted in common law countries. The confrontation clause, for instance, according to Scalia J, was ‘directed [against] the civil law mode of criminal procedure, and particularly its use of ex parte examinations as evidence against the accused.’178

15.2  Common law

As stated above, the ad hoc tribunals’ jurisprudence on expert evidence has been influenced largely by the practice in common law jurisdictions, particularly the US However, the essentially common law system exists without one of the most important principles of common law rules of evidence: the proscription against hearsay. This and other divergences lead to distortions in the implementation of any rule derived from domestic practice.

There is a great amount of commonality of practice between the different common law systems. Judges act as gatekeepers. Experts must meet the tests for relevance— as helpers of the trier of fact—and reliability. The tests for reliability vary, but a common core of threshold tests have emerged that took their cue from that technocratic test of threshold—articulated by the US Supreme Court in Daubert. The Daubert test was explicitly cited in Thompson J’s separate opinion with regard to the test for expert evidence.179

(p. 642) United States

Expert evidence in the US is perhaps subject to a more elaborate structural framework, with detailed rules outlined in the Federal Rules of Evidence (‘FRE’) and extensive jurisprudence on these rules. The FRE defines an expert testimony as:

… If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon scientific facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.180

The US Trial Court’s role and rule with regard to expert witnesses was articulated by the Supreme Court first, and then codified in the FRE (Rule 703181). Daubert sets forth a four prong test for admissibility of expert opinion. A lay may consider, and assign the appropriate weight to, expert evidence if (1) the subject-matter of the proposed opinion is falsifiable or testable; (2) was the expert opinion derived from techniques with known error rates; (3) has the methodology of the expertise or the opinion itself been subject to peer review; and (4) is the expertise generally accepted in the scientific community. Thus, Daubert’s four-prong test is focused on requiring expert opinion to possess a minimum threshold of reliability, a threshold that most expert opinion at the ad hoc tribunals has not been held to. Also, Daubert’s reliability-centric test is not limited to traditionally categorized scientific expert evidence, such as forensics, but has, in subsequent decisions of the US Supreme Court, been explicitly extended to all types of expert opinion, including social science expert opinion and its nebulous variations that have been the subject of expert opinion at the ICTR, for instance.182 They may be considered for evaluation of admission of even ‘experience-based testimony,’ but they are not exclusive.183

Despite the Kumho Tire Co. extension of the Daubert test to social scientists, the practice in US courts has not been overly divergent with that of international ad hoc tribunals. For instance, in Garcia v. Ramagoza, a case bought in US federal (p. 643) court pursuant to the Alien Claims Tort Act, expert witnesses were used as key evidence of the civil liability of the defendants—high ranking El Salvador military officials who were accused of being liable for their subordinates’ criminal conduct in, inter alia, committing torture against the plaintiffs. Although the trial was civil, thus avoiding the fair trial rights implications, experts were key to their successful prosecution, and it is arguable whether they would have cleared an objectively applied Daubert test. Colonel Garcia, a retired Argentine officer testified, inter alia, about the international law of war—‘the operative rule of war, as set out in the 1949 Geneva Convention and other governing treaty’, laws which are part of US domestic law.184 Former US ambassador to El Salvador, Robert White, testified as an expert that the El Salvadorian command was ‘unified’, an arguable issue of ultimate fact with no requirement that it be adduced through an expert.185 Professor Terry Karl of Stanford University provided ‘historical context’ for the military’s dominant role in the region.186 Lastly, Michael McClintock, a former Amnesty International researcher for Latin America testified that ‘torture techniques employed throughout the country were common, even within detention centres under the authority of different military and security forces’—certainly an issue of ultimate fact on which expert opinion should not have been adduced, for it was not probative.187

Traditionally, common law experts used to be limited by having to base their opinions on facts presented at trial. The obvious concerns with ensuring that expert opinion was consistent with the evidence on which it was based no longer requires a limitation of source material. According to the FRE, an expert may rely on ‘outside data … so long as other experts in the field reasonably rely on such data.’188 Thus, the data relied on still needs to be disclosed, to be challenged (p. 644) and verified on the coherence of the conclusions and whether it is consistent with established practice, and if such a practice is established or novel.

The centrality of reliability in US jurisprudence has not been without critique. According to one commentator, Daubert relies on ‘[p]opperian notions of falsifiability, which asserts that the defining feature of scientific statements is that they can be empirically tested and hence, potentially, shown to be false.’189 Daubert and subsequently, Frye and Kumho define reliability in terms of techniques of methodology, rather than the contents themselves. It is perhaps a normative granting of an indicia of reliability for technocratic methodology and opinion that work with easy quantifiable conclusions based on data, a trend in all social sciences. The concern with reliability is the use of expanded expert testimony to circumvent the proscriptions against hearsay evidence, which is not a strict exclusion given the wide variety of exceptions under which hearsay may be admitted, usually when it has an indicia of reliability.190

As stated earlier, to be challenged and verified, reliability requires that the reasonability of the opinion be tested. US FRE 705 explicitly allows for cross-examination to elicit and question the underlying rationales of an expert’s conclusions.191 An expert must provide sufficient information, including disclosure of the source material relied upon, for such an exercise to be possible. To resort to popular culture for illustration, Marissa Tomei’s character in the film My Cousin Vinny may be entirely incredible, but as on the screen, have a reasonable basis for an expert opinion on automobiles, which were tested by opposing counsel’s own deep understanding of the makes and mechanics of American automobiles on cross-examination.192 This author, on the other hand, would require disclosure of the expert’s basis, and perhaps instruct another automotive expert to verify her opinions.

Violations of the fundamental right to confront one’s accusers through the use of expert opinion raises more concern in the US, which has a more expanded (p. 645) constitutional protection than the one guaranteed by the ICCPR, and consequently, the statutes of the ICC and the ad hoc international tribunals, that ‘[i]n all criminal prosecutions, the accused shall enjoy the right … to be confronted with the witnesses against him.’193 The proscription or rather the limitations on hearsay, as it is an exception, but a broad one, is thus constitutionally grounded in the US194 The issue of expert witnesses violating constitutional protections is really a question of whether there can be a limitation on the confrontation clause for necessary and reliable hearsay, with reliability being presumed if the hearsay is rooted in an exception codified in the FRE, or ‘that it possessed particularised guarantees of trustworthiness.’195 However, in a recent ruling, the US Supreme Court, with Scalia J writing for the majority, addressed the confrontation clause issues for hearsay, holding that ‘testimonial hearsay may be used against the accused only when the declarant is unavailable and the defendant has had the opportunity to cross-examine the declarant.’ Thus, any statements made ‘under circumstances that would lead an objective witness to reasonably believe that the statement would be available for use at a later trial.’

One of the facets of expert opinion, which leads to trials being dubbed the battle of the experts, is the taint that experts are motivated or biased by their partisan instructions. Payments to experts from parties are often criticized. The parties either determine the funding, or determine who will receive administrative funding as an expert, subject to administrative oversight and discretion. The latter is the system at the ICTR and ICTY. As one commentator has stated:

The mode in which expert evidence is obtained is such as not to give the fair result of scientific opinion to the Court. A man may go, and does sometimes, to a halfdozen experts … He takes their honest opinions, he finds three in his favour and three against him; he says to the three in his favour, ‘will you be kind enough to give evidence?’ and he pays the three against him their fees and leaves them alone; the other side does the same. It may not be three out of six, it may be three out of fifty. I was told of one case … that they went to sixty-eight people before they found one. I am sorry to say the result is that the Court does not get that assistance from the experts which, if they were unbiased and fairly chosen, it would be their right to expect.196

International tribunals have not only had to address issues of monetary compensation, but also other factors, such as political ideology or ethnic affinity, which (p. 646) taint the credibility of an expert. In Kajelijeli, the Chamber declined to consider defence expert Dr Bangamwabo’s testimony on the historical and political background as relevant, rather inconsistently, and emphasized for good measure that the expert witness was ‘not neutral.’197 The Special Court has reiterated the general principle in dicta that ‘[a]n expert does not take the side of any party.’198 At the ICTY, it was held that the issue of neutrality of an expert was one of weight rather than admissibility, and one that ‘can be properly addressed during cross-examination.’199 As seen earlier, much of the jurisprudence on the issue of bias is muddled at the international tribunals.


This is a brief glance at an unreconstructed, nominally common law, but in reality a pluralistic legal tradition, incorporating even elements of civil law systems not generally associated with a legal transplant recipient. The Indian experience with criminal law and jurisprudence has not been used for guidance by the international tribunals, but offer instructive lessons, both examples and warnings, for operating in developing contexts and complex situations, a scenario found in many of the countries where post conflict international justice is situated. The Indian Penal Code, 1861, and the Indian Code of Criminal Procedure, 1973, are both much amended eighteenth century codifications by the British, which borrowed from their Irish experience and ‘introduced into the basic structure of the English law elements from other existing systems, including Muslim law.’ With regard to expert opinion, s 45 of the Indian Evidence Act states:

When the Court has to form an opinion upon a point of foreign law, or of science, or art, or as to identify of handwriting or finger impression, the opinion upon which that point of persons specially skilled in such foreign law, science or art, or any questions as to identity of handwriting or finger impressions are relevant facts. Such persons are called experts.200

Expert opinion has been narrowly construed in India, though the practice has been growing, and the jurisprudence has not undergone the development available internationally and nationally. Experts must of course be independent and reliable.201 There is even an instance of an expert’s opinion being disregarded because he did not supply copies of notes on the basis of which opinion was (p. 647) prepared to the accused.202 In Madan Gopal Kakkad v. Naval Dubey the Indian Supreme Court held that the underlying data must be produced for the court so that it could be used ‘for its own judgement on these materials after giving due weight to the expert’s opinion.’203 This may be a futile exercise considering that the expert possesses some qualifications that make his or her opinion relevant to the judge, but there is a requirement, practised unevenly, for disclosure of the basis for opinion.

Some other issues faced are also similar. For example, there is no uniform civil code in India, and succession, marriage, and divorce are governed by one’s religious identity. Muslim law is largely codified and derived from customary laws. Yet, there is no special Muslim law court or bench, and thus, frequently, non-Muslim judges must adjudicate on questions of the implementation of customary sharia law, and they cannot be aided by expert opinion.204 The Delhi High Court has held that:

The Shiah [sic] law of marriage is the law of the land and is in force in India [for Muslims]. It can by no means be called foreign law, nor is such law a science or art within the meaning of [ § 45].205

16.  Conclusion

As it stands, the key difference between civil law and common law practice seems to be who kicks the ball and who stands in the goal. The judicially or jointly instructed expert and the gatekeeping role are the procedural differences that impact on the different uses of expert evidence. All expert opinion should be tested substantially for independence and reliability. It is this procedural difference that is the evolution from the ad hoc tribunals to the ICC. The ICC is magisterially driven and managed. Even in the context of the ICC decisions being persuaded by the jurisprudence of the ad hoc tribunals, the evolution of the jurisprudence will perhaps be substantial.

The pressure for ‘country experts’ to explain the fog of war in a foreign land, to indulge in another cliché, which is the context for international tribunals, explains the often expedient jurisprudence on expert testimony. However, expert opinion must be approached with caution, particularly where judges, unlike in (p. 648) domestic jurisdictions, lack the exposure necessary to have formed their opinions on the political and social context that experts are referring to.

Expert testimony does not transcend the well-developed evidentiary rules. It must be relevant and probative, and objectively so. There must be notice, and the ability to cross-examine the basis of the opinion, and the expertise and credibility of the expert. Although the rules of the ad hocs have been concerned mainly with the mechanics of disclosure, jurisprudence relying on comparative law has forged a set of rules, that when applied consistently, may allow expert testimony to be used judicially, though some of the uses of expert testimony to date are open to significant criticism for violating due process.

On relevance, the Trial Chamber must ensure exclusion of legally and factually non-relevant expert evidence in order to both avoid judicial inefficiency and protect the right of the accused to know the nature of the charges and evidence against him. The international tribunals have largely dealt with qualification at this stage, but must also consistently test subject-matter, opinion on issues in the province of the fact-finder, and neutrality. The oscillating jurisprudence, illustrated by the shift from a largely blanket acceptance of Dr Des Forges to her recent rejection at the ICTR, is not just inconsistent but makes the current procedure of qualification irrational.

Although reliability is a determination that is appropriately deferred to final determination, there should be a prima facie finding of reliability, and the parties and the trier of fact must have notice of the underlying basis for opinion, the opportunity to challenge that basis, and the ability to make a reasoned decision on the conclusions of the expert. A final determination on the reasonability of expert opinion is not possible in situations where the experts are amplifying hearsay evidence, particularly confidential hearsay evidence, as opinion, Therein lies the nub—a determination of reliability in such a situation is necessarily arbitrary, and not a proper exercise of judicial discretionary power, as it is dependant largely on the expert’s credentials and demeanour.

These concerns with expert evidence are not academic, but implicate the most basic right to a fair trial and due process. The judge is the trier of fact, and cannot delegate that duty and responsibility. The accused has a right to a fair trial, with an open airing of the evidence against him. To be sure, hearsay is not proscribed, but confidential hearsay in the guise of expert opinion poses more acute challenges. The accused’s right to effective cross-examination and a proper defence are implicated. The recent decisions at the ICTR are encouraging in their acknowledgement of some of these issues.

The ICC’s Rome Statute and regulations represent a departure from the ad hoc tribunals’ jurisprudence on the issue. The practice thus far, of seeking submissions (p. 649) on, and jointly instructing experts has already been a departure from the practice in ad hoc tribunals. Whether parties strive to have independent experts, and the role expert evidence will play, especially evidence provide by social scientists who are scholars of politics and history, will be determined hopefully with the ad hoc tribunals’ jurisprudence, and the lessons, hopefully, learnt from their experience.


*  Avi Singh is a criminal attorney who is admitted to practice law in California and India, and is a member of the Supreme Court Bar Association. Having studied in India, the Netherlands, UK, and the US, Mr Singh has extensive experience appearing before the international tribunals in the Hague and Arusha. Avi Singh is the litigation partner with International Law Affiliates in New Delhi, India, where he specializes in white collar crime, and environmental litigation, particularly those with transnational implications. He is also a legal consultant on the Kardzic case. In addition, he a visiting fellow at the International University College, Turin, Italy, where he teaches a seminar to Masters students.

I would like to thank those who have assisted me for their critical and valuable advice and most of all, patience. Any errors that remain in this chapter are of course mine, probably because I did not heed all the advice of my colleague, Lauren Tipton, my cousin, Poonam Singh, and my intern Bhabhna Das, of the National Law School University of India, for their invaluable help as editors, and their assistance. Their red markups were not a pretty sight. My first research on experts was conducted under the guidance of Professor Naomi Roht-Arriaza, and her patience and encouragement are even more appreciated in hindsight.

1  Prosecutor v. Bizimungu et al (Transcript) ICTR-99-50-T (8 October 2004).

2  A. Good, ‘Expert Evidence in Asylum and Human Rights Appeals: An Expert’s View’ (2004) 16 Intl J of Refugee L 6.

3  Robert F. Taylor, ‘A Comparative Study of Expert Testimony in France and the United States: Philosophical Underpinnings, History, Practice, and Procedure’ (1996) 31 Tex Intl L J 182, 183–4 citing Learned Hand, ‘Historical and Practical Considerations Regarding Expert Testimony’ (1902) 15 Harv L Rev 40.

4  Expert witnesses are neither a contemporary peculiarity of international criminal tribunals nor are they a recent introduction into criminal trials, though their use has perhaps not been as extensive in the past. Experts, mostly in religious robes, have aided judicial determination throughout history. In ancient Rome, experts were secular, but that was an aberration in history. These experts were not beyond dispute. Justinian, writing on Roman law, expressed concern on the bias of handwriting experts. With the advent of Christianity, the secular experts of the Roman Republic were replaced by religiously inspired church ordeals. In Talmudic law, Rabbis were often experts, for instance, to interpret a bloodied cloth to the charge of a ‘tainted bride’. In England, experts, or ‘helpers’ of the court, were appointed to ‘instruct the [fact-finder] on points where the judge deemed opinion testimony to be required.’ See Robert F. Taylor, ‘A Comparative Study of Expert Testimony in France and the United States: Philosophical Underpinnings, History, Practice, and Procedure’ (1996) 31 Tex Intl L J, 182, 183–184, citing Learned Hand, ‘Historical and Practical Considerations Regarding Expert Testimony’ (1902) 15 Harv L Rev, 40, 184–188.

5  ‘In light of the complexity and scale of events in Rwanda in 1994, it is unsurprising that Chambers of this Tribunal have adopted a liberal approach to the admission of expert testimony.’ Bagosora et al (Decision of Motion for Exclusion of Expert Witness Statement of Filip Reyntjens) ICTR-98-41-T (28 September 2004) [8] cited with approval in Bizimungu et al (Decision on the Admissibility of the Expert Testimony of Dr Binafair Nowrojee) ICTR-99-50-T (8 July 2005) [8].

6  Article 64(a) of the Rome Statute states that ‘[t]he Trial Chamber shall have, inter alia, the power on application of a party or its own motion to: (a) rule on the admissibility of evidence or relevance of evidence …’. Article 69(4) of the Rome Statute states, in relevant part, that the ‘[c]ourt may rule on the relevance or admissibility of any evidence, taking into account, inter alia, the probative value of the evidence and any prejudice that such evidence may cause to a fair trial or to a fair evaluation of the testimony of a witness, in accordance with the Rules of Procedure and Evidence’.

7  Rule 89, ICTR Rules.

8  Rule 94bis ‘does not provide any details on how one could qualify as an expert …’ Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Preclude Testimony By Charles Ntampaka), ICTR-98-44-T (26 September 2007) [7].

9  Rule 94bis of the ICTR Rules provides,

  1. (A)  Notwithstanding the provisions of Rule 66 (A)(ii), Rule 73bis (B)(iv)(b) and Rule 73ter (B) (iii)(b) of the present Rules, the full statement of any expert witness called by a party shall be disclosed to the opposing party as early as possible and shall be filed with the Trial Chamber not less than twenty-one days prior to the date on which the expert is expected to testify.

  2. (B)  Within fourteen days of filing of the statement of the expert witness, the opposing party shall file a notice to the Trial Chamber indicating whether:

    1. (i)  It accepts or does not accept the witness’s qualifications as an expert;

    2. (ii)  It accepts the expert witness statement; or

    3. (iii)  It wishes to cross-examine the expert witness.

  3. (C)  If the opposing party accepts the statement of the expert witness, the statement may be admitted into evidence by the Trial Chamber without calling the witness to testify in person.

10  Rule 89 of the ICTR Rules is as follows:

The rules of evidence set forth in this Section shall govern the proceedings before the Chambers.

  1. (A)  The Chambers shall not be bound by national rules of evidence.

  2. (B)  In cases not otherwise provided for in this Section, a Chamber shall apply rules of evidence which will best favour a determination of the matter before it and are consonant with the spirit of the Statute and general principles of law.

  3. (C)  A Chamber may admit any relevant evidence which it deems to have probative value.

  4. (D)  A Chamber may request verification of the authenticity of evidence obtained out of court.

11  In relevant part, sub-part (B) of ICTY Rules, Rule 94bis states that ‘[w]ithin thirty days of disclosure of the statement and/or report of the expert witness, or such other time prescribed by the Trial Chamber or pre-trial judge, the opposing party shall file a notice indicating whether: (i) it accepts the expert witness statement and/or report; or (ii) it wishes to cross-examine the expert witness; and it challenges the qualifications of the witness as an expert or the relevance of all or parts of the statement and/or report, and, if so, which parts’.

12  ‘… sets out three distinct aspects of the process of determining admissibility. First, the evidence must be in some way relevant to an element of the crime. Second, the evidence must have some value in proving the elements of the crimes. Probative value is a different and more complex hurdle than relevance. Third, even there these two criteria are met, Rule 89 (C) does not command, but merely permits, admission of the evidence’. Prosecutor v. Bagosora et al (Decision on Admissibility of Proposed Testimony of Witness DBY) ICTR-98-41-T (18 September 2003) [4].

13  Prosecutor v. Milutinović et al (Decision on Prosecution’s Rule 92bis Motion) IT-05-87-PT (4 July 2006) [5].

14  Prosecutor v. Bizimungu et al (Transcript) ICTR-99-50-T (8 October 2004) 1–2.

15  The curriculum vitae of expert witnesses should be submitted as verification or in support of their expert status. Prosecutor v. Bizimungu et al (Decision on Mugenzi’s Confidential Motion for the Filing, Service, or Disclosure of Expert Reports and/or Statements) ICTR-99-50-T (10 November 2004) [hereinafter the ‘Bizimungu 10 November 2004 Decision’] [22].

16  Prosecutor v. Perišić (Order on Defence Submissions Regarding Various Experts’ Reports Disclosed by the Prosecution Pursuant to Rule 94bis) IT-04-81-PT (2 February 2007).

17  Bizimungu 10 November 2004 Decision [19]; Prosecutor v. Bagosora et al (Decision on Prosecution Motion for Addition of Witnesses Pursuant to Rule 73bis (E)), ICTR-98-41-T (26 June 2003) [23].

18  Dr Alison Des Forges was tragically killed on 12 February 2006 in a plane crash while returning to her home in Buffalo. Dr Des Forges’s good faith, commitment to her work, her body of academic work, and her tireless work in documenting human right abuses, is without question, and she was held in high respect by this author.

19  Bizimungu 10 November 2004 Decision [21]. See also Milutinović et al (Decision on Prosecution Motion for Leave to Amend its Rule 65ter Witness List to Add Michael Phillips and Shaun Byrnes ) IT-05-87-T (15 January 2007) [27].

20  See, eg, Prosecutor v. Karemera et al (Decision on Defence Motions to Exclude Testimony of Professor Andre Guichaoua) ICTR-98-44-T (20 April 2006) [8].

21  Prosecutor v. Zigirinayirazo (Decision on the Prosecution Motion for Dismissal of the Defence Notice Due to Failure to Meet the Time Limit) ICTR-2001-73-T (24 February 2006); Prosecutor v. Karemera et al (Decision on Prosecution Prospective Expert Witnesses Alison Des Forges, Andre Guichaoua, and Binaifer Nowrojee) ICTR-98-44-T (25 October 2007) [6]; Prosecutor v. Bizimungu et al (Decision on Jerome-Clement Bicamumpaka’s Motion to Admit Report of Expert Dr. Bernard Lugan) ICTR-99-50-T (21 February 2008); Prosecutor v. Popović et al (Decision Regarding Prosecution’s Rule 94bis Notice ) IT-05-88-T (6 March 2007) [20].

22  The 21 day notice does not start from the filing of the witness list. Prosecutor v. Bizimungu et al (Decision on Jerome-Clement Bicamumpaka’s Motion to Admit Report of Expert Dr. Bernard Lugan) ICTR-99-50-T (21 February 2008) [8].

23  Regulation 44 of the ICC Regulations of the Court, ICC-BD/01-02-07 (18 December 2007).

24  Ibid.

25  Ibid, and is as follows:

  1. (1)  The Registry shall maintain a list of experts accessible at all times to all organs of the Court and to all participants. Experts shall be included on such a list following an appropriate indication of expertise to the relevant field …

  2. (2)  The Chamber may direct the joint instruction of an expert by the participants.

  3. (3)  On receipt of the report prepared by an expert jointly instructed, a participant may apply to the Chamber to instruct a further expert.

  4. (4)  The Chamber may proprio motu instruct an expert.

  5. (5)  The Chamber may issue an order as to the subject of an expert report, the number of experts to be instructed, the mode of their instruction, the manner in which their evidence is to be presented and the time limits for the preparation and notification of their report.

26  Ibid.

27  Prosecutor v. Thomas Lubanga Dyilo (Decision on Prosecutor’s Application for Authorization to Add the Non-Redacted Version of an Expert Report on Age Determination to the Evidence to be Relied Upon at the Trial) ICC-01/04-01/06 (20 May 2008) (expert reports have to be received pre-trial in a non-redacted format).

28  ECCC, Internal Rules (rev. 5), as revised on 9 February 2010.

29  Prosecutor v. Thomas Lubanga Dyilo (Instructions to the Court’s Expert on Names and other Social Connections to the DRC) ICC-01/04-01/06 (5 June 2009) [hereinafter the ‘Lubanga 5 June 2009 Decision] [3], [17]. See also Dyilo (Instructions to the Court’s Expert on Child Soldiers and Trauma) ICC-01/04-01/06 (6 January 2009) [hereinafter Lubanga 6 February 2009 Decision] [4].

30  Lubanga 5 June Decision [3]; See Lubanga 6 February Decision [4].

31  Dyilo (Decision on the Procedures to be Adopted for Instructing Expert Witnesses) ICC-01/04-01/06 (10 December 2007) [hereinafter ‘the Lubanga 14 December 2007 Decision] [14]. See also Prosecutor v. Katanga et al (Order Instructing Experts Pursuant to Regulation 44 of the Regulation of the Court) ICC-01/04-01/07 (14 June 2009).

32  Lubanga 14 December 2007 Decision [13].

33  Article 69(4) of the Rome Statute grants the Trial Chamber a gatekeeping function to rule on relevance and admissibility but Regulation 44, which concerns the power of the appointment of experts, is silent on the procedure to be followed if the expert appointed by the chamber is not relevant or reliable despite the expert’s qualifications being judged by the chamber, and the expert’s subject-matter being the subject of the chamber’s, or the parties’, instructions.

34  Prosecutor v. IENG Sary (Decision on Ieng Sary’s Appeal Against the Co-Investigating Judges’ Order on Request for Additional Expert) 002-19-09-2007-ECCC/OCIJ(PTC28) (14 December 2009) [4].

35  Ibid, [15].

36  See Prosecutor v. Milošević, (Decision on Admission of Expert Report of Robert Donia) IT-98-29-1-T (15 February 2007) [13].

37  Prosecutor v. Popović et al (Decision on Prosecution’s Confidential Motion for Admission of Written Evidence in Lieu of Viva Voce Testimony Pursuant to Rule 92bis) Case No. IT-05-88-T (12 September 2006) [52].

38  Prosecutor v. Martić (Decision on Prosecutor’s Motion for Admission of Transcripts Pursuant to Rule 92bis (D) and of Expert Reports Pursuant to Rule 94bis) IT-95-11-T (13 January 2006) [23], [35] and [47].

39  Prosecutor v. Milutinović et al (Decision on Prosecution Motion for Leave to Amend its Rule 65ter Witness List to Add Michael Phillips and Shaun Byrnes) IT-05-87-T (15 January 2007) [32].

40  See Prosecutor v. Milošević (Decision on Admission of Expert Report of Robert Donia) IT-98-29-1-T, (15 February 2007) [8]; Prosecutor v. Stanišić and Simatović (Decision on Prosecution’s Submissions of the Expert Report of Nena Tromp and Christian Nielson Pursuant to Rule 94bis) IT-03-69-PT (18 March 2008) [9]; Prosecutor v. Perišić (Decision on Admissibility of Expert Report of Patrick Treanor) IT-04-81-T (27 November 2008) [14], [17] (and Separate Opinion of Judge Moloto [3]); Prosecutor v. Milošević (Decision on Defence Expert Witnesses) IT-98-29-1-T (21 August 2007) [23].

41  Prosecutor v. Alex Tamba Brima et al (Decision on Prosecution Request for Leave to Call an Additional Witness (Zainabl Hawa Bangura) Pursuant to Rule 73bis (E), and on Joint Defence Notice to Inform the Trial Chamber of its Position vis-à-vis the Proposed Expert Witness (Mrs Bangura) pursuant to Rule 94bis), SCSL-2004-16-T (5 August 2005) [hereinafter ‘Brima 5 August 2005 Decision’] [11]. See also Prosecutor v. Taylor (Decision on Defence Motion to Exclude, and in the Alternative, Limit the Admittance of Stephen Ellis’ Testimony and Expert Report), SCSL-03-1-T (31 October 2007) [hereinafter the ‘Taylor 31 October 2007 Decision’].

42  J. Doherty’s dissenting opinion set forth four criteria for expert witnesses, consonant with the other tribunal’s jurisprudence on this issue. Prosecutor v. Alex Tamba Brima et al (Separate and concurring opinion of J. Doherty on Prosecution Request for Leave to Call an Additional Witness (Zainabl Hawa Bangura) pursuant to Rule 73bis (E) and on Joint Defence Notice to Inform the Trial Chamber of its Position vis-à-vis the Proposed Expert Witness (Mrs. Bangura) Pursuant to Rule 94bis) SCSL-2004-16-T (21 October 2005) [hereinafter the ‘Brima 21 October 2005 Decision’].

43  Brima 5 August 2005 Decision [11]. See also Taylor 31 October 2007 Decision (The Trial Chamber held that the issue of admittance was one for final determination, and the motion was premature). It should be noted that the author was part of Mr Taylor’s defence team, and instrumental in drafting the in limine challenge.

44  Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Preclude Testimony by Charles Ntampaka) ICTR-98-44-T (26 September 2007) [hereinafter ‘Karemera 26 September 2007 Decision’] [7].

45  Ibid, [8]. See also Prosecutor v. Milošević (Decision on Defence Expert Witnesses) IT-98/29-1-T (21 August 2007) [6]–[10]; Prosecutor v. Popović et al (Appeals Chamber Decision on Joint Defence Interlocutory Appeal Concerning the Status of Richard Butler As An Expert Witness) (30 January 2008) [21].

46  Prosecutor v. Bizimungu et al (Oral Decision on Qualification of Prosecution Expert Sebahire Deo Mbonyikebe) ICTR-99-50-T (2 May 2005); Simba v. Prosecutor, (Judgment) ICTR-01-76-A (28 November 2007) [174]; Prosecutor v. Nyiramasuhuko et al (Oral Decision on the Qualification of Mr Edmond Babin as Defence Expert Witness) ICTR-98-42-T (13 April 2005) [5].

47  The Rome Statute, in relevant part, reads:

Article 64(9): 

The Trial Chamber shall have, inter alia, the power on application of a party or on its motion to:

  1. (a)  Rule on the admissibility or relevance of evidence; …

Article 69: 

  1. (3)  The parties may submit evidence relevant to the case, in accordance with article 64. The Court shall have the authority to request the submission of all evidence that is considers necessary for the determination of the truth.

  2. (4)  The Court may rule on the relevance or admissibility of any evidence, taking into account, inter alia, the probative value of the evidence and any prejudice that such evidence may cause to a fair trial or to a fair evaluation of the testimony of a witness, in accordance with the Rules of Procedure and Evidence.

48  Karemera (Decision on Prosecution Motion for Reconsideration on Prospective Experts Guichaoua, Nowrojee and Des Forges, or for Certification) ICTR-98-44-T (16 November 2007) [hereinafter the ‘Karemera 16 November 2007 Decision’] [17].

49  Prosecutor v. Simba (Decision on Prosecutor’s Motion for Admission of Testimony of an Expert Witness) ICTR-2001-76-I (14 July 2004) [6].

50  Prosecutor v. Brima et al (Judgment ) SCSL-2004-16-T (20 June 2007) [151].

51  See Bizimungu (Decision on Defence Motion for Exclusion of Portions of Testimony of Expert Witness Dr. Alison Des Forges) ICTR-99-50-T (2 September 2005).

52  Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Preclude Testimony by Charles Ntampaka) ICTR-98-44-T (26 September 2007) [hereinafter the ‘Karemera 26 September 2007 Decision’] [7] n 3, citing R v. Silverbook (1894) 2 QB 766; R v. Robb (1991) 93 Cr App R 161; R v. Ian Hersey (1997) EWCA Crim 3106; Queen v. O’Doherty (Re Application for Judicial Review) (2002) NICA 20.

53  Ibid. (‘In civil law system, the investigative judge or the court in some rare instances will call the expert, each party having equal rights to challenge the expert evidence. In such procedure, the assessment of the qualification is a step ahead of the appointment as an expert.’); Prosecutor v. Karemera et al (Decision on Prosecution Expert Witnesses Alison Des Forges, Andre Guicaoua and Binafair Nowrojee) ICTR-98-44-T (25 October 2006) [13] citing Prosecutor v. Gacumbitsi, (Appeals Judgment) ICTR-2001-64-A (7 July 2006) [31]; Karemera 26 September 2007 Decision [7] n 3 (the civil law gatekeeping role is derived from the fact that the judge determines the expert’s qualification by choosing him).

54  See, for instance, Prosecutor v. Nyiramasuhuko et al (Decision on Ntahobali and Nyiramasuhuko’s Extremely Urgent Motions to Limit the Extent and Nature of the Report and Testimony of Filip Reyntjens) ICTR-98-42-T (18 September 2007).

55  Prosecutor v. Bizimungu et al (Oral Decision on Qualification of Prosecution Expert Witness Jean Rubaduka) ICTR-99-50-T (24 March 2004).

56  Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Preclude Testimony by Charles Ntampaka) ICTR-98-44-T (26 September 2007) [6], [12], and [13] (he was disqualified prior to voir dire, in an in limine motion challenging his expertise).

57  Prosecutor v. Bizimungu et al (Transcript) ICTR-99-50-T (25 April 2006) 3 and 4.

58  Prosecutor v. Boskovski and Tarčulovski (Decision on Prosecution’s 94bis Notice re Expert Witness Slagjana Taseva) IT-04-82-T (8 February 2008).

59  Prosecutor v. Popović et al (Appeals Chamber Decision on Joint Defence Interlocutory Appeal Concerning the Status of Richard Butler As An Expert Witness) IT-05-88-AR73.2 (30 January 2008) [27] and [29]; Nahimana et al (Appeal Judgment) ICTR-99-52-A (28 November 2007) [199].

60  Prosecutor v. Nahimana (Appeal Judgment) 9-52-A (28 November 2007) [287]–[291]; Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Preclude Testimony by Charles Ntampaka) ICTR-98-44-T (26 September 2007) [12].

61  Prosecutor v. Popović (Second Decision Regarding the Evidence of General Rupert Smith) IT-05-88-T (11 October 2007) [4]. But contra Prosecutor v. Delić (Decision on Paul Cornish’s Status as an Expert) IT-04-83-T (20 March 2008) [11], [12].

62  Prosecutor v. Casimir Bizimungu et al (Decision on the Admissibility of the Expert Testimony of Dr. Binafair Nowrojee) ICTR-99-50-T (8 July 2005) [11].

63  Ibid, [9] and [11].

64  Ibid, [9].

65  Ibid, [11].

66  Ibid, [12].

67  Prosecutor v. Boskovski and Tarkulovski (Decision on Motion to Exclude the Prosecution’s Proposed Evidence of Expert Bezruchenko and his Report) IT-04-82-T (17 May 2007) [14].

68  Prosecutor v. Casimir Bizimungu et al (Decision on the Admissibility of the Expert Testimony of Dr. Binafair Nowrojee) ICTR-99-50-T (8 July 2005) [12].

69  ‘[T]he judge … can determine equally well … [and] thus the special legal knowledge of the judge [renders the witness’ opinion unnecessary].’ Deon J. Nossel, ‘The Admissibility of Ultimate Issue Expert Testimony by Law Enforcement Officers in Criminal Trials’ (1993) 93 Colum L Rev 231, 454, citing J. Wigmore, Evidence in Trials at Common Law (3rd edn, 1952), 103.

70  Karemera 16 November 2007 Decision [21].

71  Prosecutor v. Ndindiliyimana et al (Decision on the Prosecutor’s Objections to Expert Witness Lugan and Strizek) ICTR-00-56-T (23 October 2008) [10], [12], [16], and [17].

72  Kelly L. Fabian, ‘Proof and Consequences: An Analysis of the Tadić & Akayesu Trials (2000) 49 DePaul L Rev 981, 1023.

73  Ibid.

74  Prosecutor v. Kordić and Čerkez (Transcript) IT-95-15-T (28 January 2000) 1330–7; In Nahimana, the Trial Chamber considered, in its Judgment, that Prof Guichaoua ‘testified that, subsequent to 6 April 1994, there were widespread attacks against the Tutsi population across Rwanda[,]’ a legal conclusion. Prosecutor v. Nahimana (Decision on the Defence Witnesses for the Defence) ICTR-99-52-A (24 January 2003). In the same case, the Judgment used as an evidential basis Dr Des Forges conclusion in her testimony that ‘RTLM (a private Rwandan radio station) had an enormous impact on the situation, encouraging the killings of Tutsis and of those who protected Tutsis.’ Nahimana (Trial Judgment) ICTR-99-52-T (3 December 2003) [458]. The Chamber’s use of such evidence as a basis for its Judgment, in part, was confirmed by the Appeals Chamber. Nahimana (Appeals Judgement) ICTR-99-52-A (28 November 2007) [71]; see also, Bagosora (Oral Decision on Objection to Exclude Testimony) ICTR-98-41-T (4 September 2002) [9], allowing evidence which contained a chapter on the guilt of each of the accused.

75  Contra, in Nahimana, the Judgment used as an evidential basis for its findings Dr Des Forges’ conclusion in her testimony that ‘RTLM (a private Rwandan radio station) had an enormous impact on the situation, encouraging the killings of Tutsis and of those who protected Tutsis.’ Nahimana (Trial Judgment) ICTR-99-52-T (3 December 2003) [458].

76  Prosecutor v. Karemera (Decision on Prosecution Motion for Reconsideration on Prospective Experts Guichaoua, Nowrojee and Des Forges, or for Certification) ICTR-98-44-T (16 November 2007) [17].

77  Prosecutor v. Karemera (Order Relating to Defence Witness Bernard Lugan) ICTR-98-44-T (5 May 2008) [7].

78  Prosecutor v. Kovacevic (Transcript of 6 July 1998) IT-97-24-T (6 July 1998) 13305–7.

79  Prosecutor v. Sesay et al (RUF Judgment) (Trial Judgment) SCSL-04-15-2 [538]. See also Thompson J’s Concurring Opinion [523] (‘For instance, evidence by a military expert purporting to comment on the command or superior responsibility of an accused is inadmissible’).

80  Ibid, [1349].

81  As a corollary, in domestic systems, experts can testify with regards to foreign or domestic law. The US Federal Rules of Evidence (FRE) ‘allows proof of ‘legislative facts’ defined as ‘facts which have relevance … in the formulation of legal principles … by a judge or a court. Since the norms of customary law are inferred from the facts of community conduct, this definition necessarily permits proof of such activities. Harold G. Maier, ‘Problems of Proving International Human Rights Law in U.S. Courts: The Role of Experts in Proving International Human Rights Law in Domestic Courts: A Commentary’ (1995/1996) 25 Ga J Intl & Comp L 205, 209, citing Advisory Committee’s Note of Judicial Notice of Law, ‘Rule 201 (g)’, Fed R Evid 201.

82  Prosecutor v. Stakić (Judgment) IT-97-24-A (22 March 2006) [164], [292]–[294].

83  Prosecutor v. Popović et al (Decision on the Admissibility of the Expert Report and Proposed Expert Testimony of Professor Schabas) IT-05-88-T (1 July 2008) [7] and [8].

84  Prosecutor v. Nahimana (Appeals Chamber Judgment) ICTR-99-52-A (28 November 2007) [279].

85  Prosecutor v. Akayesu (Decision on Defence Motion for the Appearance of an Accused as an Expert Witness) ICTR-96-4-T (9 March 1998).

86  Prosecutor v. Nahimana (Appeals Chamber Judgment) ICTR-99-52-A (28 November 2007) [199].

87  Prosecutor v. Popović et al (Appeals Chamber Decision on Joint Defence Interlocutory Appeal Concerning the Status of Richard Butler As An Expert Witness) IT-05-88-AR73.2 (30 January 2008) [19], [21].

88  Nahimana (Appeals Chamber Judgment) ICTR-99-52-A (28 November 2007) [282] citing Prosecutor v. Brđanin (Decision on Prosecution’s Submission of Statement of Expert Witness Ewan Brown) IT-99-36-T (3 June 2003) [2]. See also Prosecutor v. Popović et al (Decision on Joint Defence Interlocutory Appeal Concerning the Status of Richard Butler as an Expert Witness) IT-05-88-AR73.2 (30 January 2008) [29] (Prosecution military expert qualified to give opinion evidence on functions and operations of Bosnian Serb Army, even if his expertise was developed while working for the prosecution’). Prosecutor v. Milošević (Decision on Defence Expert Witnesses) IT-98/29-I-T (21 August 2007) [31] (Defence expert who copied large portions of material in his report without acknowledgement would be disqualified from appearing as an expert).

89  Prosecutor v. Popović et al (Decision on Joint Defence Interlocutory Appeal Concerning the Status of Richard Butler as an Expert Witness) IT-05-88-AR73.2 (30 January 2008) [27] to [29].

90  Prosecutor v. Milutinović et al (Decision on Ojdanic Motion to Preclude Parties from Calling Expert Witnesses) IT-05-87-T (16 November 2006) [15], citing Transcript of 13 July 2006, T. 839-842.

91  Prosecutor v. Ðorđević (Decision on Defence Notice Under Rule 94bis) IT-05-87/1-T (5 March 2009) [19].

92  Prosecutor v. Bizimungu et al (Written Reasons for Oral Ruling of 23 March 2005 on the Stage for Determining an Expert Witness’ Credibility) ICTR-99-50-T (27 April 2005) [16].

93  Prosecutor v. Popović et al (Appeals Chamber Decision on Joint Defence Interlocutory Appeal Concerning the Status of Richard Butler As An Expert Witness) IT-05-88-AR73.2 (30 January 2008) [23].

94  Prosecutor v. Ðorđević (Decision on Defence Notice Under Rule 94bis) IT-05-87/1-T (5 March 2009) [19], [20].

95  Prosecutor v. Popović et al (Decision Regarding Prosecution’s Rule 94bis Notice) IT-05-88-T (6 March 2007) [22].

96  The Trial Chamber, in Bizimungu et al in response to the prosecutor’s objections to counsel for Mr Mugenzi cross-examining putative expert Rubaduka on the factual basis of his opinion, states that the question was more appropriate to cross-examination, as voir dire was solely concerned with ‘whether this witness is a competent witness to give evidence as an expert.’ Prosecutor v. Bizimungu et al (Written Reasons for Oral Ruling of 23 March 2005 on the Stage for Determining an Expert Witness’ Credibility) ICTR-99-50-T (27 April 2005) [16].

97  Prosecutor v. Milošević (Decision on Defence Expert Witnesses) IT-98/29-I-T (21 August 2007) [31] (Defence expert who copied large portions of material in his report without acknowledgement would be disqualified from appearing as an expert).

98  Even in the US, where the Daubert principles and the Federal Rules of Evidence enshrine a gatekeeping role for the judge, who is not the fact-finder, one appeals court held that in the admission of expert evidence of a dog handler in an arson prosecution, the defendant’s citations to the unreliability of dog sniffs went to the weight rather than admission. US v. Marji 158 F 3d 60, 62–3 (1998).

99  Prosecutor v. Bizimungu et al (Transcript) ICTR-99-50-T (8 October 2004) 29–31.

100  Ibid, 26–7. To this point, Mr Pierre Gaudreau, lead counsel for Jerome Bicamumpaka had stated that ‘[the factual witness] may be questioned on facts which are contemporary to those he himself experienced. Any fact part of the testimony which is not contemporary to what the witness experienced is therefore an opinion and analysis and an interpretation.’

101  Ibid, 31.

102  Prosecutor v. Ndindlilyimana et al (Decision on the Prosecutor Opposing the Testimony of Witness DE4-30 as a Factual Witness) ICTR-00-56-T (16 May 2007) [9].

103  Illias Bantekas & Susan Nath, International Criminal Law (2003) 307–316, citing R v. Robb (1991) 93 Cr App R 161; C. Allen, Practical Guide to Evidence (2nd edn, 2001).

104  Contra, see Nahimana (Appeals Judgment, Partly Dissenting Opinion of Judge Shahabuddeen) ICTR-99-51-A (28 November 2007) [71] stating, in relevant part, that Dr Des Forges ‘might be challenged in other fora (Mugesera) on other points, but this does not affect her testimony in the Trial Chamber …’.

105  Gacumbitsi v. Prosecutor (Judgment) ICTR-2001-64-A (7 July 2006) [32]; Rutaganda v. Prosecutor (Judgment) ICTR-96-3-A (26 May 2003) [16].

106  See generally Prosecutor v. Limaj et al (Decision on Prosecution’s Motion for Admission of Expert Report) IT-03-66-T (8 July 2005).

107  Ibid.

108  Prosecutor v. Blagojević and Jokić (Judgment) IT-02-60-T (17 January 2005) [27].

109  Robert F. Taylor (n 3 above) 185.

110  Where methodology is shockingly poor, experts have not been admitted. In Martić, a defence expert on history who had copied two thirds of his report from the Federal Republic of Yugoslavia’s submissions before the ICTY without acknowledgement was disqualified from appearing as an expert. Prosecutor v. Martić (Decision on Prosecution’s Motions for Admission of Transcripts Pursuant to Rule 92bis and of Expert Reports Pursuant to Rule 94bis) IT-95-11 (13 January 2006) [23]. Contra Perišić (Decision on Admissibility of Expert Report of Patrick Treanor) IT-04-81-T (27 November 2008) [14].

111  Prosecutor v. Karemera et al (Interim Order for the Prosecution to Identify Relevant and Probative Passages of Certain Materials it Intends to Tender into Evidence Under Rule 89(C) of the Rules of Procedure and Evidence) ICTR-98-44-T (8 August 2007) [7].

112  Prosecutor v. Milošević (Decision on Admission of Expert Evidence of Robert Donia) IT-98/29-1-T (15 September 2007) [9].

113  See Kelly L. Fabian, ‘Proof and Consequences: An Analysis of the Tadić & Akayesu Trials’ (2000) 49 DePaul L Rev 981, citing Michael P. Scharf, Balkan Justice (1997) 128.

114  See Prosecutor v. Katanga and Chiu (Corrigendum to the Decision on Evidentiary Scope of the Confirmation Hearing, Preventive Relocation and Disclosure under Article 67(2) of the Statute and Rule 77 of the Rules) ICC-01/04-01/07 (25 April 2008) [76]; Prosecutor v. Dyilo (Decision Regarding the Practices Used to Prepare and Familiarise Witnesses for Giving Testimony at Trial) ICC-01/04-01/06 (30 November 2007) [43]; Prosecutor v. Dyilo (Decision on the Prosecution and Defence applications for leave to appeal the Decision on the Confirmation of Charges) ICC-01/04-01/06 (24 May 2007) [20] n 19.

115  Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Limit the Scope of Testimony of Expert Witnesses Alison Des Forges and Andre Guichaoua) ICTR-98-44-T (21 August 2007) [5].

116  Prosecutor v. Milošević (Decision on Admission of Expert Evidence of Robert Donia) IT-98/29-1-T (15 September 2007) [9].

117  See Lubanga (Appeals Chamber, Judgment on the Appeal of the Prosecutor Against the Decision of Trial Chamber I entitled ‘Decision on the consequences of non-disclosure of exculpatory material covered by Article 54(3)(e) agreements and the application to the stay the prosecution of the accused, together with certain other issues raised at the Status Conference on 10 June 2008) ICC-01/04-01/06 (21 October 2008) [43].

118  Prosecutor v. Martić (Decision on Prosecution’s Motions for Admission of Transcripts Pursuant to Rule 92bis and of Expert Reports Pursuant to Rule 94bis) IT-95-11-T (13 January 2006) [37].

119  Prosecutor v. Milošević (Decision on Admission of Expert Evidence of Robert Donia) IT-98/29-1-T (15 September 2007) [9]. See also Milošević (Decision on Defence Expert Witnesses) IT-98/29-1-T (21 August 2007) [7]; Prosecutor v. Stanišić and Simatović (Decision on Prosecution’s Submission of the Expert Report of Nena Tromp and Chistian Nielsen Pursuant to Rule 94bis) IT-03-69-PT (18 March 2008) [9].

120  Prosecutor v. Delić (Decision on Paul Cornish’s Status as an Expert) IT-04-83-T (20 March 2008) [14]; Prosecutor v. Perišić (Decision on Defence Motion to Exclude the Expert Report of Morton Torkildsen) IT-04-81-T (30 October 2008) [16].

121  Kelly L. Fabian, ‘Proof and Consequences: An Analysis of the Tadić & Akayesu Trials’ (2000) 49 DePaul L Rev 981, 1028.

122  Judge Richard May & Marieka Wierda, International Criminal Evidence (2002) 6.89.

123  Bizimungu (Decision on Defence Motion for Exclusion of Portions of Testimony of Expert Witness Dr Alison Des Forges) ICTR-99-50-T (2 September 2005) [31].

124  Prosecutor v. Karemera et al (Decision on Joseph Nzirorera’s Motion to Limit the Scope of Testimony of Expert Witnesses Alison Des Forges and Andre Guichaoua) ICTR-98-44-T (21 August 2007) [5].

125  Expert Dr Des Forges proposed that the Chamber should find her expert opinion reliable because as a historian, she was trained to test the credibility of her hearsay sources. Kelly L. Fabian, ‘Proof and Consequences: An Analysis of the Tadić & Akayesu Trials’ (2000) 49 DePaul L Rev 981, citing Michael P. Scharf, Balkan Justice (1997) 128.

126  Ndindabahizi v. Prosecutor (Appeals Court Judgment) ICTR-01-71-A (16 January 2007) J. Shahabuddeen’s Separate Opinion [12]; Majority Opinion [115].

127  ‘Where expert evidence contains hearsay, this fact will diminish the weight to be attached to such expert evidence. By comparison, the Australian law is close to the Canadian counterpart. In Australia, it is explicitly required that when experts use hearsay evidence as a basis of their opinions, their reliance on such information must be reasonable. The formula is that the greater the hearsay remainder of an opinion’s basis, the less reliable it will be. In the United States, the approach to expert evidence is two-pronged: reliability and relevance. In determining reliability, the court must engage in a preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and whether the reasoning can properly be applied to the facts in issue. In addition, when determining scientific reliability, the trial judge should consider: (a) whether the proffered knowledge can be or has been tested, (b) whether the theory or technique has been subjected to peer review, (c) the known or potential rate of error, and (d) whether the theory or technique has gained general acceptance in the relevant scientific discipline: See Daubert v. Merrel Dow Pharmaceuticals Inc (113) S.Ct. 2786 (1993) [United States of America], a leading decision in the USA; see also the earlier case of Frye v. United States, 293 F. 1013 (DC. Cir.) (1923)’ Prosecutor v. Sesay et al (Judgment) SCSL-04-15-T (2 March 2009) Separate Concurring Opinion Justice Bankole Thompson Filed Pursuant to Article 18 of the Statute, [53] n 30.

128  Bagosora et al (Transcript) ICTR-98-41-T (4 September 2002) [6]; Semanza (Appeals Chamber) ICTR-97-20-A (20 May 2005) 303.

129  Prosecutor v. Bagilishema (Judgment) ICTR-95-1A-T (7 June 2001) [139]. See also Prosecutor v. Rwamakuba (Judgment) ICTR-98-44C-T (20 September 2006) [67], [68], [191] (Dr Des Forges stated that as Anastase Gasana was a moderate, it was unlikely that he was participating in meetings of extremists that the accused was present at. This evidence was corroborated by other prosecution witnesses, and used to discredit another prosecution witness who had alleged that the accused travelled with Gasana inciting violence against Tutsis).

130  This opinion in Bagilishema was ultimately rejected due to the jurisprudence of the Nuremburg trials, but its consideration is in itself problematic. Bagilishema (Trial Judgment) ICTR-95-1A-T (7 June 2001) [146].

131  The defence for Mugarineza adduced evidence from expert witness Mark McPhail who pointed out numerous infirmities even with the extremely limited source data provided by Mbonyinkebe. According to McPhail, 71 people as a representative sample size for a descriptive survey is an ‘infinitesimal number’ for the population of Rwanda, and the interviews did not record the ethnicity or political viewpoints of the participants, key data points that effect any conclusions reached. Further, a testing of the validity of the questions, methodology, and the logical coherence, consistent with the expectations of scholarship, would require disclosure of the details of the interview and the specific statement, even if redacted. Bizimungu (Transcript) ICTR-99-50-T (24 March 2008) 37, 71–4.

132  Prosecutor v. Semanza (Judgment) ICTR-97-20-T (15 May 2003) [279].

133  Prosecutor v. Semanza (Appeals Judgment) ICTR-97-20-A (20 May 2005) [305].

134  Dr Reyntjens has publicly refused to testify further on behalf of the ICTR prosecutor because of the prosecutor’s failure to bring indictments against members of the RPF. See <http://archive.salon.com/news/feature/2005/01/13/rwanda_genocide/index.html>.

135  The use of confidential sources in academic work, according to one commentator, is a professional ethical question, at least for anthropologists, who according to the American Anthropological Association, ‘should undertake no secret research or any research whose results cannot be freely derived and publicly reported.’ Lawrence Rosen, ‘The Anthropologist as Expert Witness’, (1977) 79(3) American Anthropologist, New Series 555, citing American Anthropological Association, 1973, § 3 (a).

136  Author’s interview with Dr Filip Reyntjens, Arusha, Tanzania, September 2007 (notes available on file).

137  Prosecutor v. Ntakirutimana (Judgment) ICTR-96-10-A (13 December 2004) [211].

138  See Prosecutor v. Bizimungu ICTR-99-50-T, Exh. 2D59(E), 170–4 (relevant extracts from her book).

139  Kelly L. Fabian, ‘Proof and Consequences: An Analysis of the Tadić & Akayesu Trials’ (2000) 49 DePaul L Rev 981, citing Michael P. Scharf, Balkan Justice (1997) 128.

140  Ibid.

141  US Constitution, Sixth Amendment.

142  Ohio v. Roberts 448 US 56 (1980).

143  Prosecutor v. Blagojević and Jokić (Judgment) IT-02-60-T (17 January 2005) [27].

144  Prosecutor v. Sesay et al (Judgment) SCSL-04-15-T (2 March 2009), Separate Concurring Opinion Justice Bankole Thompson Filed Pursuant to Article 18 of the Statute [53].

145  Prosecutor v. Perišić (Decision on Admissibility of Expert Report on Patrick Treanor) IT-04-81-T (27 November 2008) [14] citing Milošević (Decision on Admissibility of Expert Report of Vasilije Krestić) IT-02-54-T (7 December 2005) [5]; Prosecutor v. Galić (Decision on Admissibility of Documents Tendered During the Testimony of Radoslav Radinovic, Dusan Dunjic and Svetlana Radovanovic and on ‘Motion Regarding Document of 14 May 2002’) IT-98-29-T (11 April 2003) [14] and [15].

146  FRE 702 (United States Federal Rules of Evidence).

147  The Daubert principles give practical effect to FRE 703’s concerns with reliability by relying on ‘[p]opperian notions of falseability, which asserts that the defining feature of scientific statements is that they be empirically tested, and hence, potentially, shown to be false.’ Anthony Good, ‘Expert Evidence in Asylum and Human Rights Appeals: An Expert’s View’ (2004) 16 Intl J of Refugee L 9.

148  Daubert v. Merrell Dow Pharmaceuticals Inc 509 US 579, 113 S Ct 2786 (1993). US rules are primarily concerned with reliability, with relevance being an assumption dealt with in other parts of the rules. The US FRE 703 is the result of the drafters being exercised by the issue of reliability requiring reasonable basis. FRE 703 states that ‘Basis of opinion testimony by experts. The facts or data in the particular case upon which an expert based an opinion or inference may be those perceived by or made to be known to the expert at or before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence in order for the opinion or inference to be admitted. Facts or data that are otherwise inadmissible shall not be disclosed to the jury by the proponent of the opinion or inference unless the court determines that their probative value in assisting the jury to evaluate the expert’s opinion substantially outweighs their prejudicial effect.’ FRE 703 (US).

149  Kumho Tire Co. v. Carmichael 526 US 137, 147, 250 (1999). The Daubert factors are ‘not holy writ[;]’ they are neither exhaustive nor required. Ibid, 159 (Scalia, J concurring).

150  Prosecutor v. Semanza (Appeals Chamber Judgment) ICTR-97-20-A (20 May 2005) [305]–[306].

151  Prosecutor v. Bagosora et al (Judgment) ICTR-98-41-T (18 December 2008) [615] and [619].

152  There has been a diversion in practice, despite there being no difference in rules. A survey of experts at ICTR and ICTY, or even a cursory glance (which is all the author can claim), shows that the ICTY prosecutor has generally adduced more traditional—military, forensic—experts, while the ICTR prosecutor has relied more on ‘soft’ experts.

153  The Chamber, while acknowledging Dr Des Forges as an expert who will assist the Chamber ‘in placing the artefacts of the period 1990–1994 in their social and political context and to delineate patterns in history and social organization that will assist the Chamber in its appreciation of evidence’ found that the ‘factual questions to be decided in the case do not require expert assistance. Review of the proposed testimony of Dr Des Forges indicates that her opinion addresses issues on which the Chamber has taken judicial notice or heard testimony.’ Prosecutor v. Karemera et al (Decision on Prosecution Prospective Expert Witnesses Alison Des Forges, Andre Guichaoua, and Binaifer Nowrojee) ICTR-98-44-T (25 October 2007) [21] and [22].

154  Ibid, [15].

155  Ibid, generally.

156  Prosecutor v. Semanza (Appeals Chamber Judgment) ICTR-97-20-A (20 May 2005) [305]–[306].

157  See Prosecutor v. Ndindabahizi (Transcript of 15 July 2004) ICTR-2001-71-T (15 July 2004), [61]–[66], [84]–[85]; Prosecutor v. Bizimungu et al (Oral Decision on Qualification of Prosecution Expert Sebahire Deo Mbonyinkebe) ICTR-99-50-T (2 May 2005).

158  Prosecutor v. Šešelj (Decision on the Qualifications of Expert Yves Tomic) IT-03-67-T (15 January 2008).

159  Prosecutor v. Akayesu (Appeals Chamber Judgment) ICTR-96-4-A (17 June 2001) 31–32, cited from Prosecutor v. Ntawukulilyayo (Decision on the Defence Request for Reconsideration of the Chamber’s Decision Rejecting Joseph Ufiteyezu As An Expert Witness) ICTR-05-82-T (16 December 2009) (reaffirming that an expert on linguistics was not relevant to understand the evidence adduced).

160  Kayishema and Runzindana (Judgment and Sentence) ICTR-95-1-T (21 May 1999) [22].

161  Lawrence Rosen, ‘The Anthropologist as Expert Witness’, (1977) 79/3 American Anthropologist, New Series 555.

162  Ibid, 566.

163  Ibid, 569.

164  There are exceptions. For instance, the ICTR Appeals Chamber, during the appeal of Hassa Ngeze, instructed a handwriting expert on an application for new evidence. Prosecutor v. Nahimana (Public Order Appointing a Handwriting Expert With Confidential Annexes) ICTR-99-52-A (7 February 2007).

165  Van Kampen, Expert Evidence Compared: Rules and Practices in the Dutch and American Criminal Justice System (1998) 108 (whether the expert’s ‘specialized knowledge also concerned research on, and analysis of, shoeprints, and if so, which method the expert use in investigating the prints, why the expert considered the method to be reliable, as well as to the extent the expert was capable of professionally utilizing that method’).

166  In a recent Dutch case, an ‘orthopedic technician’ expert opinion on matching shoeprints was discarded because the lower court had not examined whether the opinion was formed with a reasonable basis. However, most expert opinion is not rendered defective due to a lack of reasonable basis, and neither is such basis the subject of examination. The Dutch system is often formulaic, and has been criticized by Professor Willem Wagenaar for not being concerned with a determination of the truth. Professor Wagenaar describes a case where a rape conviction resulted from the expert opinion of two witch doctors from Surinam. Van Kampen, Expert Evidence Compared: Rules and Practices in the Dutch and American Criminal Justice System (1998) 113–14, citing Vogt v. Germany (on merits) Series A No. 323 (Application No. 17851/91) (1995) (where a legal conclusion on ultimate issue in an expert report was accepted without any reasonable basis).

167  Mantovenelli v. France (Application No. 21497/93) (18 March 1997), ECtHR Reports of Judgments and Decisions 1997-II.

168  Van Kampen, Expert Evidence Compared: Rules and Practices in the Dutch and American Criminal Justice System (1998) 113–14, citing Kostovski v. the Netherlands Series A. No. 166. (Application No. 11454/85) (1989).

169  Ibid, 191.

170  Ibid, 192, 193.

171  Law No. 2004-230 of 11 February 2004, and its décret d’application No. 2004-1463 of 23 December 2004.

172  Mantovenelli v. France (Application No. 21497/93) (18 March 1997), ECHR Reports of Judgments and Decisions 1997-II.

173  Continental in its geography, The Netherlands’ criminal justice system, though characterized as inquisitorial, and originating in Code Napoleon, has important variations, based perhaps on its reception of the Napoleonic Code through its brief colonization by France in the 1800s, and the rejection of many of the Codes’ characteristics subsequent to its independence. As a consequence, it developed unique characteristics—lack of a jury trial, reliance on ‘reconciliatory professionalism,’ limitations on public, open trials, and a negative system of proof (negatuefwettelijk bewijsstelsel). Van Kampen, Expert Evidence Compared: Rules and Practices in the Dutch and American Criminal Justice System (1998) 51–3.

174  Ibid, 57, 60–7, 69–71.

175  Ibid, 82–3, 96.

176  Lawrence Rosen, ‘The Anthropologist as Expert Witness’ (1977) 79/3 American Anthropologist, New Series 570.

177  Prosecutor v. Karemera et al (Decision on Prosecution Prospective Expert Witnesses Alison Des Forges, Andre Guichaoua, and Binaifer Nowrojee) ICTR-98-44-T (25 October 2007) [37] (‘The Chamber is not persuaded by the Prosecution’s arguments on the necessity of admitting the expert evidence at this stage. As Joseph Nzirorera has submitted, it will be open to the Chamber to call upon expert testimony if at any future time issues arise which require such assistance. However at this point such a need is not foreseen by the Chamber. The argument that the evidence that the Defence may adduce may require expert analysis is also a matter that can be addressed if the need arises, including by calling for the testimony of experts if in the Chamber’s opinion it is required.’)

178  Crawford v. Washington 541 US 36, 57–61, 72 (2004).

179  Prosecutor v. Fofana et al (Judgment) SCSL-04-14-T (2 August 2007) Thompson J, [52].

180  FRE 702.

181  Ibid, 703: ‘Basis of opinion testimony by experts. The facts or data in the particular case upon which an expert based an opinion or inference may be those perceived by or made to be known to the expert at or before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence in order for the opinion or inference to be admitted. Facts or data that are otherwise inadmissible shall not be disclosed to the jury by the proponent of the opinion or inference unless the court determines that their probative value in assisting the jury to evaluate the expert’s opinion substantially outweighs their prejudicial effect.’

182  Kumho Tire Co. v. Carmichael 526 US 137, 147, 150 (1999); but the Daubert factors are ‘not holy writ[;]’ they are neither exhaustive nor required. Ibid, 159 (Scalia, J concurring).

183  Ibid, 149, 151.

184  Beth Van Schaak, Command Responsibility, The Anatomy of Proof in Ramagoza v. Garcia, (2003) 36 Univ C Davis L Rev. 1213, 1240–1.

185  Ibid, 1243.

186  Ibid, 1245–6. ‘[Professor Karl] described the way in which consistent strategies of repression were employed to terrorize the population, such as “draining the sea” by eliminating popular support for rebel forces. Further, she demonstrated that the violence was too coordinated, and those responsible were too well equipped, to have been attributable to rogue military factions or random acts by individual abusers. Relying on Freedom House’s scale of terror, she discussed the way in which the nature of the repression in El Salvador changed from widespread state terror to more targeted terror at different times over the period of the defendants’ tenure depending upon the prevailing political climate. To describe the phenomenon of violence in El Salvador to the jury, Professor Karl utilized the metaphor of the “spigot”, implying that the violence could be turned on and off as was politically expedient or as pressure from the United States for reform increased.’

187  Ibid, 1245. To be fair to the conduct of the trial, the judge did not allow a question as to the state of the defendant’s knowledge, holding that such a question presupposed prescient knowledge, and was outside the scope of the witness’ expertise. Ramagoza Arce v. Garcia et al (Trial Transcripts) No. 99-8364 (S. D. Fla. July 31, 2002)/(US), (July 8, 2002) 1217–8.

188  Eric Ilhyung Lee, ‘Expert Evidence in the Republic of Korea and Under the U.S. Federal Rules of Evidence: A Comparative Study’ (1997) 19 Loy LA Intl & Comp L J 585, 615, citing FRE 703 Advisory Committee Note.

189  Anthony Good, ‘Expert Evidence in Asylum and Human Rights Appeals: An Expert’s View’ (2004) 16 Intl J of Refugee L 9.

190  Ronald L. Carlson, ‘Is Revised Expert Witness Rule 703 a Critical Modernization for the New Century’ (2000) 52 Fla L Rev 715, 726, citing US v. Tran Trong Cuong 18 F 3d 1132 (4th Cir.), 1994; Hutchinson v. Groskin 927 F 2d 722, 725 (2nd Cir) 1991; Kim v. Nazarian 576 NE 2d 427, 428–9, 435 (Ill Ct of Apps, 1991); Towne 453 A 2d 1135.

191  Joanne A. Epps, ‘Clarifying the Meaning of Federal Rule of Evidence 703’ (1994) 36 BCL Rev 53, 66.

192  The following defence objection in that movie, however—‘I object to this witness being called at this time. We’ve been given no prior notice he would testify. No discovery of any tests he’s conducted or reports he’s prepared. And as the court is aware, the defense is entitled to advance notice of all witness who will testify, particularly those who will give scientific evidence, so that we can properly prepare for cross-examination, as well as give the defense an opportunity to have his reports reviewed by a defense expert, who might then be in a position to contradict the veracity of his conclusions’ was not upheld.

193  Article 14(e) of the ICCPR states, ‘(e) [t]o examine, or have examined, the witnesses against him and to obtain the attendance and examination of witnesses on his behalf under the same conditions as witnesses against him’.

194  The Appeals Chamber has also recently excluded video-link witness testimony on a strict interpretation of the phrase ‘presence’ in Arts 20(4)(d), and 20(4)(e), which mirror the ICCPR wording. Prosecutor v. Zigiranyirazo (Decision on Interlocutory Appeal) ICTR-2001-73-AR73 (30 October 2006) [11]–[13].

195  Ohio v. Roberts 448 US 56 (1980).

196  Plimpton v. Spiller (1877) 6 Ch D 412, 415–18, n 2 (reprinting a motion in a action by Thorn, a licensee of Plimpton, against the Worthington skating rink).

197  Prosecutor v. Kajelijeli (Judgment) ICTR-98-44A-T (1 December 2003) [63], [81].

198  Prosecutor v. Brima et al (Separate and concurring opinion of Justice Doherty on Prosecution request for leave to call an additional witness pursuant to rule 73bis(E) and joint Defence application to exclude the expert evidence of Zainab Hawa Bangura or alternatively to cross-examine her pursuant to Rule 94bis) SCSL-04-16-T-420 (21 October 2005) [61].

199  Prosecutor v. Radoslav Brđanin (Decision on Prosecution’s Submission of Statement of Expert Witness Ewan Brown) IT-99-36-T (3 June 2003) [4].

200  The Evidence Act 1872, Pt I, § 45 (India).

201  Subhod Kumar v. Soshi Kumar AIR 1958 Cal 264 (India).

202  Vithal Mahadev Patil v. State of Karnataka [1996] Cr LJ 1796 (Kant) (India).

203  [1992] 3 SCC 204.

204  Thyssen Stahhunion GmbH v. SAIL, AIR 2002 Delhi 255 (India), citing Aziz Bano v. Muhamad Ibrahim Hussain (1925) 47 All 823, 835 (India).

205  Ibid. ‘[t]he Shiah [sic] law of marriage is the law of the land and is in force in India [for Muslims]. It can by no means be called foreign law, nor is such law a science or art within the meaning of [§ 45].’