1  Positive complementarity can be defined as activities and actions of cooperation aimed at promoting national proceedings, with specific reference to the prosecutorial policy of an international criminal court, whereby the International Prosecutor encourages genuine national proceedings when possible, by way of relying on national and international networks, and invites relevant States to participate in a system of international cooperation. The positive approach to complementarity implies that an international criminal tribunal and the State have agreed upon a consensual division of labour.

2  With respect to the International Criminal Court (ICC), a division of labour arises where the International Prosecutor ‘seeks to prosecute those crimes meeting the gravity threshold articulated in Article 17 [of the Rome Statute of the International Criminal Court (‘Rome Statute’)] and a state seeks accountability (whether criminal or non-criminal) for lower level offenders who are not likely to be the subjects of an ICC investigation’ (Burke-White, 2008, 101). Positive complementarity is a prosecutorial policy of focused prosecutions and investigations without an explicit legal basis in the Rome Statute in order for the International Prosecutor to investigate and prosecute those who bear the greatest responsibility for the most serious crimes.

3  Article 17 Rome Statute lays down the principle of complementarity according to which the ICC may only exercise jurisdiction where the national legal system is ‘unwilling or unable genuinely to carry out the investigation or prosecution’. The ICC adopts the system of complementary jurisdiction rather than primary jurisdiction in order to respect sovereignty and enhance effectiveness of bridging impunity gaps (International Criminal Courts and Tribunals, Complementarity and Jurisdiction). Knowing that many international crimes are, by nature, committed in the context of the lack of checks and balances within the domestic structure of a government, the complementarity principle may have a greater impact on monitoring domestic criminal proceedings of international crimes than the primary jurisdiction of States (International Relations, Principal Theories).

4  The rationale for the original concept of the principle of complementarity is derived both from respect for State sovereignty and from practical considerations regarding the effectiveness of the ICC with its limited resources to investigate and prosecute the most serious crimes of concern to the international community as a whole. Generally speaking, the system of international criminal justice has limited resources to investigate atrocities. As a result, international criminal jurisdictions cannot be effective operating on their own, and must consider a division of roles between international criminal jurisdictions and domestic criminal jurisdictions. Positive complementarity shares this rationale and bridges the impunity gap.

5  Within the jurisdiction of international criminal institutions, the principle of complementarity can be seen as a specific application of the subsidiarity principle. In other words, it is a preference for the allocation and exercise of governmental functions at the lowest level of governance (Subsidiarity). The rationale behind subsidiarity is to protect values associated with governance at a lower level, and the complementarity principle similarly prioritizes national adjudication of individual criminal responsibility for the most serious violations of international law. Today, the concepts of subsidiarity and complementarity are found in various forms and areas of international law. For example, the Preamble of the Protocol on the Statute of the African Court of Justice and Human Rights introduces the African Court’s complementarity to the functions of the African Commission on Human and Peoples’ Rights (Ebobrah, 2011, 671).

6  Whereas the principle of complementarity is provided for in Article 17 Rome Statute, its positive declination is not, as such, a statutory requirement. Rather, it originated as an interpretation of the principle of complementarity by the Office of the Prosecutor (‘OTP’) of the ICC. Famously, Article 93 (10) Rome Statute constitutes the legal basis for the OTP’s prosecutorial policy on positive complementarity (OTP, Prosecutorial Strategy 2009–2012, 5, para 17). Article 93 (10) (a) allows the ICC to ‘cooperate with and provide assistance to a State Party conducting an investigation into or trial in respect of conduct which constitutes a crime within the jurisdiction of the Court or which constitutes a serious crime under the national law of the requesting State’. The assistance from the Court to the State constitutes the so-called ‘reverse cooperation’ (Gioia, 2011, 807). Rule 194 Rules of Procedure and Evidence of the International Criminal Court (‘RPE’) further provides the procedure relating to reverse cooperation. Normally, vertical cooperation suggests cooperation between States and international criminal courts and an efficient legal assistance relationship attributing decisive powers with regard to the cooperation duties to the requesting authority (Surrender, Non-Aliens). The idea of reverse cooperation also implies a vertical relationship, but the direction of cooperation is reverse as the requested authority, the ICC, has the decisive power to provide assistance to the requesting authority.

7  The idea of positive complementarity emerged as a prosecutorial policy of interpreting the principle of complementarity in the Rome Statute. It first appeared in the publications of the OTP of the ICC in 2003 (OTP, Paper on Some Policy Issues before the Office of the Prosecutor; OTP, Informal Expert Paper: The Principle of Complementarity in Practice) issued in accordance with Regulation 14 Regulations of the Office of the Prosecutor (‘OTP Regulations’), which obligates the Office to make public its Prosecutorial Strategy and public policy papers that reflect the key principles and criteria of the Prosecutorial Strategy.

8  As early as 2003, the OTP clarified that its prosecutorial policy would function with a two-tiered approach to combat impunity (OTP, Paper on Some Policy Issues before the Office of the Prosecutor, 3). This two-tiered approach consists of focusing on prosecuting those most responsible for crimes at the international level and of encouraging national prosecutions, where possible, for lower-ranking perpetrators (OTP, Paper on Some Policy Issues before the Office of the Prosecutor, 3). The two-tiered approach implies two distinct layers of governance authority engaged in political and legal interactions between national and international structures (Burke-White, 2005, 558). Although the concept of positive complementarity was developed and promoted mainly by the OTP, it was also later acknowledged and promoted by the Assembly of States Parties (‘ASP’) of the ICC.

9  Even after the establishment of the permanent ICC and many international and internationalized criminal tribunals, prosecution before national courts remains the principle method of enforcing international criminal law (Individual Criminal Responsibility). To encourage genuine national proceedings, the OTP actively encourages national proceedings, including in countries where the OTP is conducting preliminary examinations (Preliminary examination) or investigations by relying on its various networks of cooperation, but without involving the Office directly in capacity building or financial and technical assistance. Despite uncertainty surrounding positive complementarity, it may ‘entail legislative assistance, technical assistance and capacity building, and assistance in terms of constructing physical infrastructure’, and provides the basis on which all capacity building can be executed (Bekou, 2016, 140).

10  Passive or negative complementarity is sometimes used as an antonym for positive complementarity. Passive complementarity was described as the original idea behind the principle of complementarity by the drafters at the Rome Conference. However, diverse interpretations of its meaning exist. According to one academic, passive complementarity means that the jurisdiction of the ICC is dormant until its jurisdiction is triggered by referrals from the States Parties or the Security Council (Imoedemhe, 2017, 45). Another proposes that ‘passive complementarity suggests that the ICC would step in to undertake its own prosecutions only when national governments fail to prosecute and where the Court has jurisdiction’ (Burke-White, 2008, 79).

11  This entry mainly concerns positive complementarity before the ICC as prosecutorial policy. The entry firstly explores the history and legal basis of positive complementarity within the system of the ICC (see sec B below). Secondly, the core elements or various forms of positive complementarity are introduced in connection with actual practices of not only the ICC but also the other internationalized criminal tribunals (see sec C below).

12  Positive complementarity is indisputably a product of prosecutorial policy of the OTP at the ICC. Therefore, the practices of the ICC present a real picture of what positive complementarity is. It grows on an ICC prosecutorial policy rootstock, and later develops into a sort of Court policy at the level of the ASP.

13  The origin of a positive approach to complementarity can arguably be traced back to an informal expert paper on the principle of complementarity in practice, published in 2003 (OTP, Informal Expert Paper: The Principle of Complementarity in Practice). Between May and October 2003 a group of twelve experts, including Antonio Cassese and Darryl Robinson, was invited by the Office to discuss, in their individual capacity, complementarity in practice. This was in accordance with the suggestion from the start-up team of the OTP in April 2003. These experts identified two guiding principles for their approach to complementarity, namely partnership and vigilance. Here, positive complementarity was implied by the inclusion of the principle of partnership through which the Prosecutor can encourage the concerned State to initiate national proceedings. The informal expert paper also suggested the consensual division of labour between the OTP and the concerned State, such as when, for example, ‘a conflict-torn State is unable to carry out effective proceedings against persons most responsible’ (OTP, Informal Expert Paper: The Principle of Complementarity in Practice, 4) for atrocities. It is interesting to note that such division of labour in accordance with the level of responsibility is an idea common to the completion strategy of the International Criminal Tribunal for the Former Yugoslavia (ICTY) and the International Criminal Tribunal for Rwanda (ICTR). The so-called Rule 11bis referral practices of the ICTY and the ICTR based on Rule 11bis of their RPE may have impacted such an interpretation, or the positive approach, of the complementarity principle of the Rome Statute (see sec C below). The overarching idea is that the ICC may deal with the people most responsible, while domestic courts may handle lower-rank offenders and lesser offences.

14  The first Chief Prosecutor of the ICC, Mr Luis Moreno Ocampo, upheld positive complementarity as one of the three essential principles at the heart of the Prosecutorial Strategy of 2006–2009 (OTP, Report on Prosecutorial Strategy, 4, para 2). The Prosecutorial Strategy of 2009–2012 was also based on the principle of positive complementarity (OTP, Prosecutorial Strategy 2009–2012, 4–6, paras 15–21). In both strategies, any intervention by the OTP of the ICC is exceptional. Although the Office has encouraged genuine national proceedings where possible, the Office is not willing to involve itself directly in capacity building or the provision of financial or technical assistance. ‘[T]he fact that positive complementarity is based on policy rather than law makes its catalysing effect [on domestic proceedings] difficult to predict’ (Nouwen, 2013, 108).

15  The second Chief Prosecutor, Ms Fatou Bensouda, was sworn in on 15 June 2012, and also adopted a prosecutorial strategy based on the principle of a positive approach to complementarity in the strategic plan published in 2013 (OTP, Strategic Plan June 2012–2015, 13, para 21). It is to be noted that the subsequent strategic plan of 2016–2018 exhibits a lack of reference to ‘positive complementarity’ (OTP, Strategic Plan 2016–2018). Whereas the policy paper on case selection and prioritization published on 15 September 2016 also lacks a reference to positive complementarity (OTP, Policy Paper on Case Selection and Prioritisation), the policy paper on preliminary examinations sets the goal of ending impunity for serious crimes by encouraging genuine national proceedings enacted through positive complementarity (OTP, Policy Paper on Preliminary Examinations, 23–24, paras 100–3). The latest Office document of policy on children also shows the Office’s continuous adherence to the principle of positive complementarity (OTP, Policy on Children).

16  At the fifth session of the ASP in 2006, the Assembly included the issue of positive complementarity in its strategic plan. The aim of this plan was to maximize the Court’s activities in harmony with the Chief Prosecutor’s prosecutorial strategy. The ASP adopted a resolution encouraging ‘States Parties to further discuss issues related to the principle of complementarity and to explore proposals by States Parties introduced as “positive complementarity”’ (ASP, Resolution ICC-ASP/8/Res.3, 2, para 6). The stocktaking exercises took place at the Review Conference held in Kampala from 31 May to 11 June 2010. In preparation for the Review Conference, the Bureau of the Assembly published the Bureau’s report on stocktaking and complementarity, titled ‘Taking Stock of the Principle of Complementarity: Bridging the Impunity Gap’. This report defined positive complementarity as:

The Bureau’s latest Report on complementarity in 2017 stressed that national ownership is essential and is a requirement to engage in, and ensure the success of, such activities (ASP, Report of the Bureau on Complementarity, 2, para 5). Positive complementarity presupposes capacity building without much involvement from the Court. However, as previously noted, for positive complementarity to work, it is not sufficient to rely only on the OTP to steer the national process toward more investigations and prosecutions. The ICC, especially the Secretariat of the ASP was given the mandate to facilitate ‘the exchange of information between the Court, States Parties, signatory States, international organizations, civil society, and other stakeholders aimed at strengthening domestic jurisdictions’ (ASP, Report of the Bureau on Stocktaking, 7, para 36). The efforts made by the Secretariat in this respect were acknowledged by the latest resolution by the Assembly of States Parties (ASP, Resolution ICC-ASP/16/Res.6).

17  Due to the lack of explicit legal provision for positive complementarity in the Rome Statute, the meaning and interpretation of positive complementarity in international law is not necessarily monolithic among academics. Therefore, the elements of positive complementarity exemplified here are necessarily deductive and are to be reviewed in the light of the most recent practice of the ICC and the other international criminal jurisdictions. This section takes up especially the following elements: burden sharing (division of labour), support for national prosecution, and capacity building.

18  The policy of division of labour presupposes the strategy of an International Prosecutor to focus on those who bear the greatest responsibility for the crimes. Positive complementarity presupposes focused investigation and prosecution. During the first three years of its activities (June 2003–June 2006), the OTP of the ICC applied its prosecutorial policy of focusing the prosecutorial effort on the most serious crimes and on the persons bearing the greatest responsibility therefor (OTP, Report on the Activities Performed during the First Three Years (June 2003–June 2006), 7–8). Such a focused strategy was adopted in the former international criminal tribunals other than the ICC. From an historical perspective, both the International Military Tribunal (‘IMT’) and the International Military Tribunal for the Far East (‘IMTFE’) focused on prosecuting high-ranking Axis leaders, while suspects from the lower ranks remained under the jurisdiction of national courts (International Military Tribunals). The concurrent jurisdictions between international criminal jurisdictions and domestic criminal jurisdictions were not raised as an issue, and both the IMT Charter and the IMTFE Charter focused on ‘major war criminals’.

19  When the United Nations Security Council (‘UNSC’; United Nations, Security Council) decided to establish the ICTY and the ICTR, the Tribunals and national courts were given concurrent jurisdiction to prosecute people for crimes within the subject matter jurisdiction of both Tribunals (Art 9 Statute of the International Criminal Tribunal for the Former Yugoslavia (‘ICTY Statute’); Art 8 Statute of the International Criminal Tribunal for Rwanda (‘ICTR Statute’)). The relationship between the Tribunals and national courts stood in stark contrast to the relationship between the ICC and national courts in that the former’s Statutes stipulated the Tribunals’ primacy over the national courts, while the latter’s stipulates the principle of complementarity, such as is explained above. The Tribunals may have had the possibility to intervene national proceedings at any time to take over a trial.

20  Under Rule 9 (iii) of each Tribunal’s RPE, the Prosecutor could propose to the Trial Chamber that it issue a request for deferral when it appeared to the Prosecutor that a domestic investigation or criminal proceedings overlapped with an indictment issued by the Tribunals. This stands in marked contrast to the admissibility criteria under Article 17 Rome Statute, which only allows the ICC to take up a case if and when States that would normally have jurisdiction are either unwilling or genuinely unable to exercise their jurisdiction.

21  Nonetheless, the completion strategies of the ICTY and the ICTR eventually resulted in an increasing resemblance to the complementarity principle of the Rome Statute. Since the ICTY and the ICTR were not permanent courts but rather so-called ad hoc tribunals, they later developed the practice of referring their own cases to national jurisdictions under the time pressure to meet the deadlines of the completion strategy. These referral practices were called ‘Rule 11bis referrals’ as Rules 11bis of the RPE of the Tribunals provide for such procedures (International Criminal Courts and Tribunals, Procedure). The completion strategies of the Tribunals were carried out in accordance with UNSC Resolution 1503 (2003). The two main components of the Completion Strategies aimed at prosecuting as a priority ‘the most senior leaders suspected of being most responsible for crimes within the ICTY’s jurisdiction and transferring cases involving those who may not bear this level of responsibility to competent national jurisdictions, as appropriate, as well as the strengthening of the capacity of such jurisdictions’ before the International Tribunals (UNSC Res 1503 (2003), preambular para 7). This division of labour between the international criminal jurisdiction and national criminal jurisdiction resembles the rationale behind the positive complementarity of the ICC in that it closes the impunity gap created by limited prosecution of only high-level figures while the lower-level perpetrators may be left untouched.

22  Rule 11bis proceedings of the ICTY and ICTR are good examples of positive complementarity, representing burden sharing between international and domestic criminal justice, and promoting the capacity building of domestic criminal justice. The Rule 11bis (A) procedure allows the OTP of the ad hoc tribunals to transfer their cases to national jurisdictions, if a Referral Bench of three Permanent Judges selected from the Trial Chambers determines that a case should be referred to a national court after an indictment has been confirmed and prior to the commencement of trial. The Rule 11bis procedure may be either referral proprio motu by the Referral Bench or the referral request by the Prosecutor in accordance with Rule 11bis (B). The relationship between Bosnia, the United States, the European Union, and the ICTY illustrates the successful outcome of positive complementarity. In the former Yugoslavia, Bosnia created a domestic Special War Crimes Chamber within the Bosnian state court system (War Crimes Chamber of the Court of Bosnia and Herzegovina) with funding from the United States and the European Union to handle lower-rank perpetrators of the atrocities committed in the former Yugoslavia (Foster, 2016, 464). While, the ICTY successfully turned cases over to Bosnia and Herzegovina and Serbia by way of Rule 11bis referrals including Foča of Radovan Stanković and Gojko Janković, Prijedor and Srebrenica, the ICTR faced difficulties finding the appropriate States to refer its own cases to.

23  France was the only State to accept two indicted cases from the ICTR, Bucyibaruta and Munyeshyaka, as it constituted a suitable State for Rule 11bis referrals since France met Rule 11bis conditions, such as the guarantee of a fair trial and the fact that the death penalty did not exist. Indeed, Rule 11bis (C) requires the Trial Chamber to satisfy itself that the accused will receive a fair trial in the courts of the State concerned and that the death penalty will not be imposed or carried out (Prosecutor v Bucyibaruta, 2007, 2; Prosecutor v Munyeshyaka, 2007, 2). These conditions were not met in Rwanda, and the Referral Bench of the ICTR rejected some of the referral requests made by the Prosecutor (specifically Prosecutor v Kayishema, 2008; Prosecutor v Kanyarukiga, 2008; Prosecutor v Munyakazi, 2008; Prosecutor v Hategekimana, 2008; and Prosecutor v Gatete, 2008) as safeguards for fair trials were not in place. Subsequently, Rwanda enacted significant legal reforms so that the ICTR then transferred two cases, Prosecutor v Uwinkindi and Prosecutor v Munyagishari, in 2011 and 2012, respectively, as well as six fugitive files, to Rwanda for domestic prosecution. Interestingly, the decision of the ICTR to refer cases to Rwanda was referred to in a case brought before the European Court of Human Rights (ECtHR) (Ahorugeze v Sweden, 2011, paras 51–61). In this case, the ECtHR decided that the transfer of a genocide suspect to Rwanda would not risk a flagrant denial of justice in accordance with the European Convention for the Protection of Human Rights and Fundamental Freedoms (1950) (‘European Convention on Human Rights’; ‘ECHR’).

24  In December 2010, the Security Council decided to establish the International Residual Mechanism for Criminal Tribunals (United Nations Mechanism for International Criminal Tribunals (MICT)) with the two branches for the ICTY and the ICTR (UNSC Resolution 1966 (2010), para 1). One of the functions of the MICT was referrals of cases to national jurisdictions in accordance with Article 6 Statute of the International Residual Mechanism for Criminal Tribunals. In June 2018, the single judge of the MICT ordered the case against the two Serbian defendants to be referred for trial to the Serbian authorities (Prosecutor v Jojić and Radetta, 2018). The Prosecutor appealed this decision on 26 June 2018.

25  Even though the Special Tribunal for Lebanon (STL) has primacy over only national courts of Lebanon under Article 4 (1) Statute of the Special Tribunal for Lebanon instead of national courts of all States, the issue of concurrent jurisdiction is not likely to be raised due to the limited personal jurisdiction and political nature of the subject matter jurisdiction. In fact, the highly political nature of the subject matter jurisdiction of the STL made domestic prosecution almost impossible. It was posited that domestic prosecution failed due to a lack of evidence, political meddling, or third-party pressure (Knudsen and Hanafi, 2013, 195). This outcome proves that the highly political nature of the crimes would make positive complementarity impossible to apply under these circumstances.

26  Another component of positive complementarity is dialogue since positive complementarity suggests interactions with the government and the International Prosecutor (Gioia and Politi, 2008, 148–49). The component of dialogue with state officials by the ICC poses a risk of partiality. The interactions with the government could suggest that the ICC Prosecutor prioritizes the views of states and the demands of international organizations over the needs of victims (Kambale, 2015). In other words, there is a fear that the ICC may be seen as a political device to tackle the anti-government forces by the government (Soares, 2013, 205).

27  In the early practice of the ICC, such a dialogue between the Prosecutor and the government was explicit. When the Ugandan government referred the first situation to the ICC in December 2003, the Ugandan President Yoweri Museveni and the ICC Prosecutor met and held a press conference together in London on 29 January 2004 (ICC, Press Release, 2004). The objective was to establish the basis for the future cooperation between Uganda and the ICC, and at that time the key issue was locating and arresting the leadership of the Lord’s Resistance Army (ICC, Press Release, 2004). The referred situation concerned the crimes committed in the context of a conflict between anti-government militia and the national authorities within the country’s own territory, Northern Uganda. Since Uganda did not contest the admissibility of the situation, the ICC Prosecutor took a positive approach to complementarity, whereby the ICC and Uganda agreed to a consensual division of labour, with the ICC prosecuting the leaders and the State prosecuting lower-ranking perpetrators. The political motives of President Museveni using the referral to confer moral ground status on the Ugandan government to attract international support for a legitimate government fighting the anti-governmental forces were obvious (Kambale, 2015, 193).

28  Uganda seemingly preferred to hand the prosecutions over to the Court, and the country could not be deemed as unable, since Uganda had one of Africa’s better criminal justice systems and did not allege that the national courts were unable to prosecute (Schabas, 2008, 18). Nonetheless, in Uganda, the International Crimes Division (‘ICD’), a special Division of the High Court of Uganda, was established in July 2008 originally in order to fulfil the duties under the Rome Statute. The ICD is intended to deal with those who have committed ‘serious crimes’, which are war crimes, crimes against humanity, genocide, terrorism, human trafficking, and piracy and other international crimes under Section 6 of the High Court Practice Directions, Legal Notice No 10 of 2011 (Uganda Gazette, 2011).

29  In March 2004, the Democratic Republic of Congo (‘DRC’; Congo, Democratic Republic of the) followed Uganda and referred the national situation in the Ituri region to the ICC. The first ICC Prosecutor Ocampo was active in seeking a dialogue with the Congolese government and judicial authorities on the scope and impact of the referral (Kambale, 2015, 176). In the situation of the DRC, the Prosecutor envisaged a clear division of labour whereby the ICC would prosecute those bearing the greatest responsibility, while the Congolese judiciary would deal with the remaining cases (Kambale, 2015, 177). However, the crimes charged by the ICC Prosecutor and the targets of arrest warrants were hardly thought of as the most serious ones and have been the subject of criticism (deGuzman, 2012, 265). The first case adjudicated by the ICC was for a defendant in the situation of the DRC, Prosecutor v Thomas Lubanga Dyilo (Lubanga Case). When the Prosecutor obtained an arrest warrant against Lubanga for charges concerning the enlistment and conscription of child soldiers, Lubanga was in custody in the DRC for the alleged charges of genocide and crimes against humanity (Schabas, 2008, 11). This situation illustrates that the dialogue between the government and the ICC Prosecutor sometimes poses an issue of opportunism. The single charge of war crimes against Lubanga triggered criticism on the part of victims, and it was pointed out that the domestic case against Lubanga was doing a better job by addressing crimes of greater gravity (Schabas, 2008, 25).

30  The Kenyan situation before the ICC is an example of an attempt by Kenya to obtain reverse cooperation from the ICC. On 26 September 2009, for the first time the Prosecutor of the ICC filed a request for the authorization of an investigation into the situation in the Republic of Kenya, in relation to the post-election violence of 2007–2008. The Pre-Trial Chamber II authorized the request on 31 March 2010. The Kenyan situation demonstrated the high level of interaction between the Prosecutor, national authorities and other groups as a consequence of the principle of complementarity under Article 93 (10) Rome Statute. In the case of Kenya, after the Prosecutor targeted senior leaders of the government of Kenya, the Kenyan government refused to cooperate and the OTP was unable to investigate effectively inside the country (Foster, 2016, 453). Instead of cooperating with the Court, the government of the Republic of Kenya filed a Cooperation Request under Article 93 (10) of the Statute (Situation in the Republic of Kenya, Request for Assistance on behalf of the Government of the Republic of Kenya pursuant to Article 93(10) and Rule 194, 2011). As a principle, the OTP would provide information collected by the Office to national judiciaries in accordance with Article 93 (10) Rome Statute, subject to the existence of a credible local system of protection for judges or witnesses and other security-related caveats, such as sharing databases of non-confidential materials or crimes. However, in the Kenyan case, the Prosecutor opposed cooperating with Kenya. Pre-Trial Chamber II eventually rejected the Cooperation Request from the government of Kenya on the grounds that it had failed to launch an ongoing investigation with respect to conduct established as constituting a crime in Article 5 Rome Statute or with respect to a serious crime committed under the national law of Kenya (Situation in the Republic of Kenya, Decision, 2011, 12, para 34). In the Kenyan situation, Kenya was denied its admissibility challenge by both the Pre-Trial Chamber and the Appeals Chamber on 30 May 2011 and 30 August 2011 respectively. Pre-Trial Chamber II interpreted Article 93 (10) as discretionary rather than obligatory assistance by the Court to a State. In essence, Pre-Trial Chamber II considered that the Prosecutor has discretion to provide assistance to a State. It is suggested that ‘[i]t is highly probable that Pre-Trial Chamber II rejected Kenya’s request because there was no evidence that Kenya had complied with the requirements in article 93(10) of the Statute’ (Olugbuo, 2017, 83–84).

31  Reverse cooperation may include sharing information, evidence and analysis relevant to both the ICC and national prosecution as is the case of the DRC even without a request from a State Party (Carter and others, 2016, 61; ASP, Report of the Court on Complementarity, paras 43–44).

32  Capacity building in the context of positive complementarity ‘is understood as the strengthening of national jurisdictions in order to be able to oversee national investigations and prosecutions at a suitable level, and to cooperate with the Court’ (Bekou, 2015, 1245–46). The admissibility procedure may be seen ‘as a type of dialogue with States on their judicial systems’ (Carter and others, 2016, 62).

33  In the situation of Libya before the ICC, Libya’s capacity to carry out genuine proceedings was at issue, though the ICC itself seemingly did not commit to capacity building of Libya. Libya went through the Arab Spring in early 2011 (Regime Change), and the situation in Libya since 15 February 2011 was referred by the Security Council to the ICC in Security Council Resolution 1970 of 26 February 2011. In a case against Abdullah Al-Senussi, the brother-in-law of Muammar Gaddafi, the government of Libya claimed that this was ‘a unique opportunity for the Court to embrace the concept of positive complementarity’ and to encourage other States emerging from conflict and mass atrocities in pursuit of genuine national proceedings (Prosecutor v Gaddafi and Al-Senussi, Application on behalf of the Government of Libya, 2013, 90–91, para 200). Mr Al-Senussi and the ICC’s Office of Public Counsel for Victims alleged certain facts that indicated Libya’s unwillingness and/or inability genuinely to carry out the proceedings against Al-Senussi within the meaning of Article 17 Rome Statute (Prosecutor v Gaddafi and Al-Senussi, Decision on the Admissibility, 2013, 109, para 218). In the end, Pre-Trial Chamber I found that the case against Al-Senussi was inadmissible, since the domestic proceedings in the case against Al-Senussi have so far not been prejudiced by domestic security challenges (Prosecutor v Gaddafi and Al-Senussi, Decision on the Admissibility, 146, para 299). In the appeals proceedings, the Defence argued that Article 17 (2) (c) Rome Statute requires the ICC to interpret the article in accordance with internationally recognized human rights (Prosecutor v Gaddafi and Al-Senussi, Judgment on the Appeal of Mr Abdullah Al-Senussi against the Decision of the Pre-Trial Chamber I of 11 October 2013, 2014, 79, para 206). The Appeals Chamber noted that Rule 51 RPE specifically permits States to bring to the attention of the Court, in considering Article 17 (2), information showing that its courts meet internationally recognized norms and standards. However, the Appeals Chamber considered that Article 17 was not designed to make principles of human rights per se determinative of admissibility (Prosecutor v Gaddafi and Al-Senussi, Judgment on the Appeal of Mr Abdullah Al-Senussi against the Decision of the Pre-Trial Chamber I of 11 October 2013, 83 and 88, paras 220 and 229).

34  The situation in Colombia currently under preliminary investigation by the OTP of the ICC is also seen as an example of positive complementarity (Transitional Justice in Post-Conflict Situations). Colombia ratified the Rome Statute on 5 August 2002. The situation has been under preliminary examination since June 2004. The OTP has focused on the alleged war crimes committed in Colombia since 1 November 2009 and the alleged crimes against humanity committed since 1 November 2002. In March 2005, the Prosecutor informed the government of Colombia that he had received information on alleged crimes committed in Colombia. In the Interim Report of the OTP on the situation in Colombia in 2012, the Office concluded that there was no basis at that stage to determine whether cases handled by the Colombian authorities were vitiated by an unwillingness or a genuine inability to carry out the proceedings (OTP, Situation in Colombia: Interim Report, para 208). On 24 November 2016, the government of Colombia and the Revolutionary Armed Forces of Colombia People’s Army (‘FARC-EP’) signed the Final Agreement to End the Armed Conflict and Build a Stable and Lasting Peace. While the OTP monitored the implementation of the Peace agreement, the Prosecutor appeared to be pleased with the high standards of Colombian courts, which prevented the OTP from intervening in the situation, thus serving as a model of positive complementarity. Colombia has been under intense pressure from the OTP, through which the Office implicitly promoted capacity building. The first Chief prosecutor’s goal ‘was to apply political pressure to a government reluctant to prosecute its historical allies—a standard illustration of the positive complementarity dynamic’ (Urueña, 2017, 117), and thereby encouraged the Columbian authorities to enhance their capacity to investigate and prosecute. Nonetheless, burden sharing between national prosecutions focused on lower-level accused and prosecutions focused on the most senior leaders as a function of positive complementarity has not been identified in the case of Colombia.

35  Positive complementarity entails legal assistance. The Legal Tools Project, together with the Case Matrix Network, is identified as a means of strengthening national jurisdictions and enabling them to address core international crimes (Carter and others, 2016, 56–57). These projects are promoted by the Centre for International Law Research and Policy (‘CILRAP’). The Legal Tools Project provides a free online knowledge-system as well as legal documents and range of reference tools. These tools must serve the goal of capacity building and provide legislative and technical assistance, based on the principle of positive complementarity. Other than the Legal Tools Project, there is no systematic infrastructure for positive complementarity, especially within the Court system. As a result, such an initiative is indispensable to facilitate a sustainable international criminal justice and the efficiency of the ICC.

36  The existence of mixed criminal tribunals presupposes the existence of burden sharing and capacity building because of the mixed nature of international and domestic staff and applicable laws (Mixed Criminal Tribunals (Sierra Leone, East Timor, Kosovo, Cambodia)). The Special Court for Sierra Leone (SCSL) was established by an agreement between the United Nations and the government of Sierra Leone to prosecute people bearing ‘the greatest responsibility’ for war crimes during the internal armed conflict of Sierra Leone (Art 1 Agreement between the United Nations and the Government of Sierra Leone on the Establishment of a Special Court for Sierra Leone). Whereas the ICTY and the ICTR had primacy over every national court against the background of the power of the Security Council vested by Article 39 United Nations Charter, the SCSL had primacy over only the national courts of Sierra Leone under Article 8 (2) Statute of the Special Court for Sierra Leone (‘SCSL Statute’). The SCSL and the national courts of Sierra Leone had concurrent jurisdiction, and at any stage of the procedure, the SCSL could formally request that a national court defer to its competence. Although the SCSL had primacy over the national jurisdiction of Sierra Leone, concurrent jurisdiction never arose as an issue. Unlike the ICTY and the ICTR, the SCSL did not refer cases to national jurisdictions. The national courts of Sierra Leone were considered unable to take over cases from the SCSL, so the Residual SCSL was established by an agreement between the United Nations and the government of Sierra Leone to oversee the continuing legal obligations of Sierra Leone after its closure in 2013 (Mphepo, 2014, 181). However, evaluations have revealed that the so-called hybrid nature of the SCSL probably made it possible for the SCSL to promote the capacity building of the country’s domestic judiciary because of the SCSL’s location in Freetown, Sierra Leone, and its broader utilization of domestic local staff (Burke-White, 2008, 97). The Defence Office of the SCSL made an effort to include local lawyers on the teams (Office of United Nations High Commissioner for Human Rights, 2008, 32).

37  As a hybrid tribunal, the Extraordinary Chambers in the Courts of Cambodia (ECCC) (Cambodia Conflicts (Kampuchea)) are also considered to have contributed to the Cambodian judiciary’s capacity building (Office of United Nations High Commissioner for Human Rights, 2008, 32). First and foremost, the ECCC provided much needed legal training and job training in order to strengthen human resources (Coughlan and others, 2012, 26). Second, one of the major successes of the ECCC is victims’ support, especially for female victims through the Victims Support Section (‘VSS’), which was established under Rule 12 ECCC Internal Rules. The UN Trust Fund to End Violence against Women set up a joint project, named ‘Promoting Gender Equality and Improving Access to Justice for Female and GBV Survivors under the Khmer Rouge Regime’ and recognized as a successful capacity building model, and funded $632,000 to the VSS and international non-governmental organizations from 2011 to 2014 (Arthur and Yakinthou, 2018, 164).

38  Positive complementarity polarizes opinion in academic circles. First, positive complementarity has been criticized for increasing the risk of sham tribunals. On the one hand, universal application of the law is fundamental to the rule of law. On the other hand, it is fair to say that prosecuting lower-level perpetrators may not necessarily be an indispensable component of a fundamental solution to the end of the impunity of the most serious crimes of concern to the international community, considering their mechanisms.

39  The second downside of positive complementarity is the politicization of investigation and prosecution at both international and domestic levels as a consequence of consultations between an International Prosecutor and the government on the division of labour between international and national criminal jurisdictions. Political calculation is a predictable by-product of positive complementarity, but political compromise should be avoided for the sake of maintaining trustworthy international criminal justice (Takemura, 2009, 611). The close relationship between international and national authorities brought about the practices of so-called self-referral, where the territorial State itself expressed its will that the offenders be brought to justice by the ICC. The first three situations addressed by the Court, namely Uganda, the DRC and the Central African Republic, were submitted to the Court by means of self-referral. These self-referrals are hardly regarded as spontaneous (Gaeta, 2004, 949; Schabas, 2006, 31) since both the OTP and the self-referral States may have had motives to promote self-referrals, including, in the former case, facilitating national cooperation and the effectiveness of the Court due to uncontested admissibility, representing a waiver of complementarity.

40  Positive complementarity definitely has its strong points. Firstly, it facilitates international cooperation in criminal matters since positive complementarity suggests the presence of both national and international networks. Notably, Article 86 Rome Statute obligates States Parties to cooperate fully with the Court in its investigation and prosecution of crimes within the jurisdiction of the Court. Furthermore, Article 88 ICC Statute requires States Parties to prepare procedures available under their national laws for all forms of cooperation that are specified under Part 9 Rome Statute. Secondly, as is the case in Rule 11bis procedures of the ICTY and the ICTR, if successful, positive complementarity may provide an impetus for local capacity building and reforms, even though the ICC itself cannot provide financial and human resources. ‘[C]ountries under investigation by the ICC annually try on average four times as many State agents such as police officers or low-level soldiers, for physical integrity abuses […] than do other African nations experiencing violent conflicts’ (Dancy and Montal, 2017, 691). Thirdly, even though the Statute does not provide for the duty to criminalize crimes in the Rome Statute using domestic legislation, positive complementarity promotes the voluntary investigation and prosecution of crimes in the Rome Statute, if it works properly. Positive complementarity would allow the ICC to catalyse national judiciaries to fulfil its obligations to prosecute international crimes (Burke-White, 2016, 207). The primary duties to prosecute international crimes are found in the Geneva Conventions of 1949 (Geneva Conventions I–IV (1949)), the Convention on the Prevention and Punishment of the Crime of Genocide, and the Preamble of the Rome Statute. Fourthly, positive complementarity eliminates psychological fears concerning the possible impact the ICC will have on the ability of a State to pursue domestic prosecutions, as the idea of positive complementarity operates within the scheme of a consensual division of labour. There is a legitimate expectation that the OTP would not exercise its proprio motu powers pursuant to Article 15 Rome Statute. In this regard, positive complementarity would provide the foreseeability and flexibility necessary to facilitate the ICC investigation and prosecution for the States concerned.

41  Certain arguments rebut these strengths. For example, it is fair to point out that targeting those who are most responsible for crimes committed under the Rome Statute does not appear to be a statutory requirement (Ambos and Stegmiller, 2012, 401). Positive complementarity is a prosecutorial policy adopted by the OTP to focus on those who bear the greatest responsibility, expecting and encouraging domestic prosecutions of the rest of the offenders. Whereas the gravity test for crimes committed under the Rome Statute is explicit, in its admissibility tests and its case selection by the OTP under Articles 17 (1) (d), 53 (1) (c), 53 (2) (c) Rome Statute, as well as Regulation 29 (2) OTP Regulations, the requirement to focus on those who bear the most responsibility cannot be found in either the Statute or the Regulations.

42  The ICC itself lacks sufficient resources to become involved in building a national capacity (Ambos and Stegmiller, 2012, 404). If the OTP and the ASP adopt positive complementarity, they should demonstrate a sense of ownership of the development of criminal justice capacity in the conflict States and the countries involved in the ICC proceedings, the so-called situation countries.

43  The lack of a clear strategy on the positive complementarity invoked by some organizations has met with criticism (Jurdi, 2017, 200). The jurisprudence of the ICC Appeals Chamber and Pre-Trial Chambers have demanded the so-called ‘same person/same conduct’ test (Prosecutor v Lubanga, 2006, 20 and 23, paras 31 and 38–39), meaning that a case will be inadmissible only when the same person is facing domestic proceedings for the same conduct with which she or he is charged before the ICC (Soares, 2013, 322). The more recent jurisprudence of the ICC Appeals Chamber demands the ‘substantially the same conduct’ test (Prosecutor v Ruto, Kosgey and Sang, 2011, 15, paras 40–41). However, the broader interpretation of unwillingness or inability criteria in the admissibility test of Article 17 Rome Statute would arguably run counter to the primary obligation of the States concerned to investigate and prosecute crimes under the Rome Statute. The narrower interpretation of the Article 17 admissibility test may have originated from prosecutorial policy based on the Informal Expert Paper of 2003, in which uncontested admissibility and consensual division of labour are implied (OTP, Informal Expert Paper: The Principle of Complementarity in Practice, 18, para 59).

44  In conclusion, positive complementarity is merely one way of interpreting the principle of complementarity and prosecutorial policy. In order for the ICC to be truly effective and serve the spirit of the Rome Statute, rather than sharing a burden by reaching a political compromise between the OTP and the territorial State, the ICC should seek to encourage and take optimal advantage of the capabilities of domestic investigation and prosecution. Although this approach reflects the original concept of positive complementarity (Burke-White, 2008, 57), positive complementarity in action, especially based on the Chamber’s narrow interpretation, makes it extremely difficult for some willing and able States to exercise their primary duty to prosecute crimes under the jurisdiction of the ICC (Jurdi, 2017, 200). Returning to the original concept complementarity suggests the primacy of national jurisdictions to the ICC, as opposed to the ICTY’s and the ICTR’s primacy over national jurisdictions. By deferring jurisdiction, the ICC gains the opportunity to encourage national proceedings, thereby achieving the ideal of positive complementarity (Jalloh, 2012, 285). Accordingly, it is fair to point out that there is no one-size-fits-all approach to complementarity (Jalloh, 2012, 285; Foster, 2016, 444).

45  Positive complementarity in action leaves little doubt that improvement is needed. Proposals for improvement include enhancing the Prosecutor’s diplomatic capabilities, rather than aspiring to an apolitical Court (Burke-White, 2016, 211), and coordinating the understanding and planning of positive complementarity between each organ of the Court (Hall, 2011, 1047).