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The Oxford Handbook of the Use of Force in International Law edited by Weller, Marc (1st January 2015)

Part VI Emerging Areas?, Ch.53 Private Military Companies and the Jus Ad Bellum

Ian M. Ralby

From: The Oxford Handbook of the Use of Force in International Law

Edited By: Marc Weller

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 19 November 2019

UN Charter — Armed forces — Armed attack

(p. 1131) Chapter 53  Private Military Companies and the Jus Ad Bellum

I.  Introduction

When Article 2(4) of the UN Charter was adopted in 1945, the world had not yet seen the first ‘private military company’. Indeed, it would be another 20 years before the seeds for the industry were planted by the retired Colonel Sir David Stirling when he founded WatchGuard International to advise Middle Eastern states on securing their oil infrastructure;1 it would be 50 years before the world would witness the combat capabilities of companies like Executive Outcomes and Sandline International;2 and it would be 60 years before Blackwater Worldwide, a company based in the Great Dismal Swamp of North Carolina, would draw attention to the use of private armed (p. 1132) contractors in the conflicts in Iraq and Afghanistan.3 The prohibition of the use of force as it intersects with such private companies remains murky. While most of the legal analysis regarding these companies has centred on issues of international humanitarian law and other matters of jus in bello, the jus ad bellum implications of private military contracting are nevertheless relevant to modern international law and international relations and have the potential to become more so in the coming years.

One of the reasons there has not, as yet, been any literature produced on private military companies and the prohibition on the use of force is that, at first glance, it appears a non-issue. State practice does not indicate any likelihood that a company would be used in lieu of armed forces to attack another state. But international affairs are rarely so simple. The nuances surrounding the use of force by states have caused countless volumes, including the present, to be produced over the last six decades. Private military companies are a relatively new phenomenon. The highest profile issues surrounding their use have concerned violations of international humanitarian law and human rights law. Consequently, accountability and the absence of regulation have dominated the debate and literature surrounding the industry. Many issues pertaining to these companies, however, have yet to be examined. It will only be in niche circumstances that a state could violate the prohibition on the use of force by virtue of its relationship with a private military company. But niche circumstances are precisely what should be given the most attention, as they are the most likely to be exploited by virtue of the inherent uncertainty and twilight which surrounds them.

This chapter begins by differentiating between mercenaries and the various terms applied to private companies that offer services in conflict areas, seeking as well to distinguish myth from reality in terms of what the industry actually does. Once the subject matter has been sufficiently identified and clarified, the attention turns to instances where private military companies have had engagements relevant to questions of prohibited or lawful use of force by states. The real-world examples set the stage for a more in-depth and theoretical examination of the nuances of where private companies may be used by states in a manner contrary to jus ad bellum. As this is the first real foray into this topic, this chapter does more to pose questions than offer answers. Significant further analysis will be necessary to comprehensively analyse private military companies and the jus ad bellum. The chapter concludes by recognizing that, while most private companies offering armed services are not and will not be used by a state as a means of using force against another state, such companies in certain situations can nevertheless be used by states in a manner that could violate the international legal prohibition on the use of force.

(p. 1133) II.  The Subject Matter

A.  What are Private Military Companies?

Many different terms have been used to describe the activities of private companies that provide military-related services.4 The expression ‘private military and security company’ or PMSC is the broadest and most common term, but it has become somewhat controversial and remains an imprecise and colloquial appellation. Many companies today recognize the negative connotations of a privatized military and are thus strongly inclined to abandon the ‘military’ portion of the expression.5 The argument is that the services they provide are defensive, rather than combat-oriented, so ‘security’ is a more accurate description of what they do, and either ‘private security company’ or ‘private security (service) provider’ more accurately describes what they are.6 Critics and commentators, however, maintain the use of the term ‘military’ (and they often exclude ‘security’) in part by convention, and in part to indicate that, regardless of the nuances of the services these companies perform, some of what they do falls within the historic ambit of functions performed by the military. Some companies have and still do specifically provide private military services, including training of military personnel and activities that fall in a grey area between defensive and offensive operations.

Some commentators go further and persist in using the term ‘mercenary’ to describe these companies.7 While the Oxford English Dictionary defines a mercenary as ‘a soldier paid to serve in a foreign army or other military organisation’,8 which would include such notable forces as the Nepalese Gurkhas who serve in the British and Indian Armies and the French Foreign Legion,9 the term ‘mercenary’ is defined in several different conventions and thus has a specific meaning in international (p. 1134) law.10 An in-depth analysis of such laws would reveal that these companies are not mercenaries and only in the rarest of cases could the personnel working for them potentially fit the legal criteria for classification as a mercenary.11 Section III of this chapter will examine the second of the two definitions of ‘mercenaries’ under the International Convention Against the Recruitment, Use, Financing and Training of Mercenaries, but for a private military company (PMC) contractor to meet the primary definition, they would have to meet a rigid five-prong test.12 As one commentator boldly claimed: ‘any mercenary who cannot exclude himself from this definition deserves to be shot—and his lawyer with him.’13

In one of the most in-depth analyses of the terms pertaining to this industry, Sarah Percy distinguishes between ‘mercenaries’, ‘combat PMCs’, and ‘non-combat PMCs’.14 Since the present analysis will not address mercenaries, it is useful to look at her nuanced definitions of PMCs. She defines ‘combat PMCs’ as companies that ‘provide military services, including offensive combat, in exchange for payment’, and ‘non-combat PMCs’ as companies ‘that exchange military services stopping short of combat for payment’.15 In evaluating the two variants of PMCs, some, including Percy herself, argue that no ‘combat PMCs’ still exist.16 Both Sarah Percy and the UK Foreign and Commonwealth Office in its 2002 Green Paper on options for regulating private military and security companies17 assert that there have only been two private military companies, Executive Outcomes of South Africa and Sandline of the UK, both of which are now out of business.18 While this analysis will not specifically seek to refute that statement, anecdotal evidence would suggest that such entities do still exist and are still operating in various parts of the world. While several companies are alleged to have engaged in conduct that is indistinguishable from ‘combat’, one of the best examples involves a 2004 incident in Najaf that was (p. 1135) captured on camera. The video shows contractors, who at the time were working for the American company Blackwater Worldwide, not only participating in a roof-top shoot-out, but actually giving directions to the uniformed US Marines with them.19

Other commentators use the terms private military company/PMC versus private security company/PSC to denote a similar distinction as that of Percy’s combat versus non-combat PMCs. Consequently, many argue that there are no PMCs, only PSCs left in existence. The line, however, between what is included in military versus security services is virtually impossible to distinguish with any consistently applicable rule. Rather than spending time to set such boundaries, therefore, the present analysis will examine both privatized military and privatized security services in the specific context of the jus ad bellum obligations of states. The term ‘private military company’ or PMC is therefore used, not in an inflammatory way, but to focus on the activities of companies that provide services that might trigger the prohibition on the use of force.

B.  What Do PMCs Do?

In ‘Politics as a Vocation’, Max Weber defines the state as ‘a human community that (successfully) claims the monopoly of the legitimate use of physical force within a given territory.’20 While states may be the only legitimate source of warfare according to Weber, they have long outsourced the performance of violence to private entities.21 As Peter W. Singer writes in one of the most famous works on private military companies, ‘the monopoly of the state over violence is the exception in world history, rather than the rule. The state itself is a rather new unit of governance, appearing only in the last four hundred years. Moreover, it drew from the private violence market to build its public power.’22 In some ways, states and international organizations have returned to this traditional approach after a relatively short hiatus.

Often called the ‘second oldest profession’, the earliest evidence of mercenary activity dates to the reign of the Akkadian King Sargon in roughly 2350–2300 BC.23 Throughout history, private soldiers have been employed to augment, support, and even replace military forces. While the present analysis is about PMCs, not mercenaries, the history of mercenaries colours some of the issues that will be addressed (p. 1136) and is thus worth reviewing. As a fairly central figure in the early days of PMCs has explained: ‘Mercenary soldiering has a long and honorable history. . . When something is both widespread and long lasting, there must be some fundamental reason for it.’24 Despite conflicting views,25 mercenaries were an integral part of warfare for most of history. Indeed, it has been less than 150 years since, as a result of the Franco-German War, the ‘nation-in-arms’ concept took hold, dramatically changing the composition of the world’s armies.26 ‘The idea, now so widely accepted that a man can be obliged to fight for his country could only be accepted when a man had a country that was more than a geographical expression to fight for.’27 With this increase in military participation by the citizenry, the role of mercenaries had to be reconsidered, and by the early 20th century, mercenaries constituted perhaps the most minor portion of combat forces at any point in history.28

In 1941, Captain David Stirling founded the Special Air Service (SAS) as an elite fighting force within the British military.29 A quarter-century later, in 1965, Stirling collected a group of ex-SAS personnel and formed the first modern company offering private military services, WatchGuard International.30 This company sought employment training the armies of Persian Gulf states in Western military tactics. In other words, the ex-SAS personnel were able to draw on their training with the British Army and pass it on to Arab militaries for much higher pay than they had received as uniformed soldiers.31 Though WatchGuard was never a great success, several SAS alumni spawned other similar companies including Control Risks Group, Keenie Meenie, Saladin Security, and Risk Advisory Group. Many of these British companies founded in the late 1960s and 1970s are still in operation today.

During the same period in which the British PMCs were taking shape, traditional mercenaries, willing to fight in combat for the right price, became involved in African decolonization.32 In the process, mercenaries garnered a reputation for being cruel and brutal. But the new PMCs managed to stay under the radar as much as possible and sought to offer something different than mercenary outfits. (p. 1137) Consequently, by the beginning of the 1990s, the UN had already drafted a convention outlawing mercenaries but had clearly not considered PMCs in the drafting process.

The end of the Cold War brought about a great sense of hope for peace and stability throughout the world. Suddenly, decades of hardened realist policies appeared obsolete.33 The collapse of the bipolar balance of powers, which had dominated nearly half a century, left scholars, politicians, and policymakers guessing as to the future of international relations. In 1992, Francis Fukuyama famously wrote ‘What we may be witnessing is not just the end of the Cold War, or the passing of a particular period of post-war history, but the end of history as such: that is, the end point of mankind’s ideological evolution and the universalisation of Western liberal democracy as the final form of human government.’34 With the end of the Cold War, and the end of apartheid, the so-called ‘peace dividend’ led to massive demilitarization policies around the world.35 National militaries shrank dramatically, leaving highly trained soldiers, sailors, and airmen out of jobs. In this period of transition, private military companies as corporate entities began to enter the fray of international security in a more significant and noticeable way.

Throughout the 1990s, numerous brutal conflicts plagued the African continent. These wars showcased the concept of a private military company equipped to engage in combat. Two companies featured at the forefront of this phenomenon in the 1990s: Sandline International of the UK and Executive Outcomes of South Africa. Both companies were involved primarily in African affairs, though Sandline was infamously involved in Bougainville’s self-determination struggle as well.36 Executive Outcomes (EO) played a major part in ending the war in Angola for the first time (it restarted later), and in fighting against the Revolutionary United Front (RUF) rebels of Sierra Leone (another war which restarted after EO left).37 In the process, EO caused numerous controversies. According to one scholar, EO found it too difficult to distinguish between combatants and civilians during one (p. 1138) military operation in Sierra Leone, so company officials ordered their employees to initiate air strikes and simply ‘kill everybody’.38 Yet this anecdote is contrasted with the strong and irrefutable evidence that between 250 and 350 employees of EO were able to work with the Republic of Sierra Leone armed forces and, in only a few months, to defeat the RUF rebels more convincingly and successfully than any other intervening force in the course of the decade-long war.39 The company, which was founded in 1989, dissolved in 1998 when South Africa changed its laws.

Sandline International, headed by former British Army Lieutenant Colonel Tim Spicer and legally based in the Bahamas, was contracted by the government of Papua New Guinea in 1997 for US$36 million to train an elite force and to fight in pursuit of resolving an internal domestic conflict.40 The contract, however, came to light, causing a major scandal, and was never fully executed.41 Sandline was also involved in assisting the fighting in Sierra Leone in 1998 and Liberia in 2003. On 16 April 2004, Sandline closed its operations with the following message:

The general lack of governmental support for Private Military Companies willing to help end armed conflicts in places like Africa, in the absence of effective international intervention, is the reason for this decision. Without such support the ability of Sandline to make a positive difference in countries where there is widespread brutality and genocidal behaviour is materially diminished.42

A large number of other companies, however, have found plenty of work in recent years providing armed services in those same areas. Tim Spicer himself went on to found Aegis, one of the largest PMCs currently in operation.43

As a result of the wars in Iraq and Afghanistan, the private military industry has boomed since 2001. ‘Where, ten years ago, such a category was composed of individuals tasked with personal and installation protection primarily, private security companies have grown to such a degree that many of them now include capabilities in transport, intelligence, combat-firepower, and para-medical skills.’44 In many ways, developments in this area have occurred so quickly that international policies and existing guidance on the applicability of international law have been outpaced. ‘The privatization of [war-fighting and security] activities cannot be controlled in the [traditional] manner, given that enterprises which enter into commercial (p. 1139) agreements with other governments have not, traditionally, fallen under the rubric of military oversight or arms control.’45 While these issues point at the myriad jus in bello concerns surrounding PMCs, the present analysis will focus on the force regime of the UN Charter and the jus ad bellum.

III.  Case Studies

Before delving into a technical legal analysis of PMCs and jus ad bellum, it is helpful from a practical standpoint to have a sense of how PMCs have been used and how they could be used by states. To illustrate the ways in which PMCs may trigger the international legal prohibition on the use of force, this analysis will examine three real-world incidents involving companies working at the behest of a state. While the objective is not to claim that these incidents constituted violations of the prohibition on the use of force, Section III will explore how each type of activity represented could be used in a manner contrary to jus ad bellum.

A.  MPRI in Croatia

In the midst of the Balkan war of 1992–5, the US government licensed an American private military company, Military Professional Resources, Inc (MPRI) to train Croatian forces under a contract with the Croatian government.46 Shortly after MPRI began performance on the contract, the Croats had tremendous success in repelling Serbian forces from their territory.47 That success was then augmented in Operation Storm, a major offensive aimed at expelling Serbs from the Krajina region.48 Operation Storm bore the markings of US strategic preparation and tactical execution, leading many to believe that MPRI provided the planning and support to make the mission possible.49 Furthermore, Croats involved in the operation (p. 1140) attributed their success to the training and assistance received from MPRI.50 Even MPRI officials themselves bragged of the capacity of the company, calling it ‘the greatest corporate assemblage of military expertise in the world’.51

The significance of Operation Storm cannot be understated.52 Not only did it change the course of the war and lead to the reclamation of 30 per cent of Croatian territory, it also proved to observers that a PMC did not have to directly engage in combat (like Executive Outcomes or Sandline) in order to have dramatic effect on a state’s use of force. Since Croatia had already been embroiled in conflict prior to hiring MPRI, the prohibition on the use of force was not triggered in this instance. But the potential is unmistakable.

Another dynamic of this particular case study is the role of the US government. Prior to MPRI’s contract with the Croatian government, the US had hired the company to provide 45 border monitors to assist with enforcing a UN sanctions regime.53 On the back of that small contract came the much more extensive relationship between MPRI and the Croats. Commentators and the UK government alike have noted that MPRI’s activity in Croatia was tantamount to US ‘foreign policy by proxy’.54 The US was not paying MPRI, but between strong governmental ties and exclusively ex-US military personnel, MPRI seemed to some to be operating as an (p. 1141) extension of the US as much as it was a client of Croatia.55 Indeed, these relationships combined with an express opinion from the US government that MPRI’s services were not in violation of an arms embargo has led some to argue that this contract constituted a surreptitious attempt by the US to use force against the Serbs.56

B.  Blackwater in Colombia

On 1 March 2008, the Colombian military crossed national borders and entered Ecuadorian territory.57 In what was a planned raid, the military launched an air strike with a coordinated ground attack against the Revolutionary Armed Forces of Colombia (FARC), a paramilitary organization that has been a violent rebel element in Colombia for decades.58 While the attack was successful with regard to its military objectives, it was a political disaster as it significantly strained relations between the neighbouring countries.59 Ecuador was exceedingly displeased with the violation of its territorial integrity, especially as the incident was not one of hot pursuit, but of premeditation.60

In the Ecuadorian government’s report on the incident, however, the most striking and noteworthy revelation was that armed contractors from the PMC Blackwater Worldwide, an American company best known for its activities in Iraq, were accompanying the Colombian forces at the time of the incursion on Ecuadorian soil.61 Those contractors had been hired not by the Colombian government but by the US government.62 Section IV will discuss this matter further, but depending on the (p. 1142) degree of effective control the US government was exercising over the Blackwater personnel, the US may have violated the territorial integrity of Ecuador.63

C.  CACI and Titan in Iraq

Consolidated Analysis Centers, Inc (CACI),64 a PMC, and Titan, a translation division of L-3 Communications (which is also now the parent company of MPRI),65 are companies that have been linked to the Abu Ghraib Prison scandal with allegations that their employees participated in the illegal interrogation tactics for which the Iraqi detention facility has become infamous.66 According to the US Army’s own investigation of the abuses at Abu Ghraib by Major General Antonio Taguba, CACI and Titan employees were directly involved in the violations which took place at the prison.67 Taguba found that ‘U.S. civilian contract personnel (Titan Corporation, CACI, etc. . .), third country nationals, and local contractors do not appear to be properly supervised within the detention facility at Abu Ghraib.’68 The lack of proper supervision, however, was only a threshold problem, as the report continues to suggest that several employees of CACI and Titan directly participated in the abuse. In fact, he goes on to allege that a CACI civilian interrogator, in addition to making false statements about the activities in which he engaged during the interrogations, actually directed the US Army’s Military Police to do things that were not allowed under the applicable regulations or policy. Furthermore, Taguba specifically states: ‘he clearly knew his instructions equated to physical abuse.’69 In addition, an interpreter with Titan lied about having been present for interrogations and was operating without security clearance. A second interpreter with Titan was also suspected of wrongdoing.

According to Colonel Jill Morgenthaler, six soldiers were charged with ‘indecent acts, for ordering detainees to publicly masturbate; maltreatment, for non-physical abuse, piling inmates into nude pyramids and taking pictures of them nude; battery, for shoving and stepping on detainees; dereliction of duty; and conspiracy to maltreat detainees.’70 Colonel Morgenthaler, speaking for US Central Command, (p. 1143) which manages all military operations in the Middle East, said that ‘one contractor was originally included with six soldiers, accused for his treatment of the prisoners, but we had no jurisdiction over him. It was left up to the contractor on how to deal with him.’71 No CACI or Titan employees have been charged with criminal offences in any jurisdiction, though civil claims have been brought against both companies in US domestic courts.72

While this incident occurred amid an armed conflict between states, the significance for the present analysis concerns the threat of force. It demonstrates the ability of PMCs to be used extraterritorially in a manner so as to intimidate or display the willingness and ability to use force. Additionally it hints at the ‘fly in, fly out’ possibilities of using PMCs; namely that a PMC can be hired for a specific purpose, sent in, and brought back out more easily than military personnel in many cases.

IV.  Analysis

Having introduced the subject matter and a few instances where PMCs have been used that point further at how they could be used, this section now delves into the question of how PMCs interface with jus ad bellum. After a recapitulation of relevant laws, this analysis explores several different issues traditionally discussed in the literature surrounding the prohibition on the use of force. Drawing on the examples presented in the last section, the analysis is enriched by realistic hypotheticals, helping to tease out some of the less obvious ways in which PMCs might end up triggering the prohibition on the use of force.

A.  The Prohibition on the Use of Force

Yoram Dinstein describes 1928, the year of the Kellogg–Briand Pact, as ‘a watershed date in the history of the legal regulation of the use of inter-State force.’73 The renunciation of war as an instrument of national policy should have made the remainder (p. 1144) of the 20th century one of the most peaceful periods in human history. The Second World War and the numerous conflicts that followed it, however, highlighted the shortcomings of the 1928 Pact. As Dinstein points out, there were four crucial flaws: ‘(i) the issue of self-defence was not addressed in the text; (ii) no agreed-upon limits were set on the legality of war as an instrument of international policy; (iii) the abnegation of war did not embrace the entire international community; and (iv) forcible measures “short of war” were eliminated from consideration.’74 The attempt to shift from jus ad bellum to jus contra bellum, as Dinstein describes, failed to account for the realities of interstate relations.

The UN Charter in 1945 recast the jus ad bellum and developed a bifurcated approach to war: prohibition on the one hand and legitimate resort to force on the other. Article 2(4), the centrepiece of the prohibition on the use of force, provides: ‘All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.’75 As an exception to that prohibition, Article 51 provides:

Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace.76

These two provisions are further clarified, insofar as interpretation is concerned, by the 1970 Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the UN Charter.

The 1970 Declaration sets forth a series of principles in support of the prohibition on the use of force, clarifying some of the parameters of jus ad bellum in the modern legal context. The most obviously relevant to the present analysis is the principle that ‘every State has the duty to refrain from organizing or encouraging the organisation of irregular forces or armed bands including mercenaries, for incursion into the territory of another state.’77 PMCs could potentially fall within the ambit of this principle, suggesting that states are dissuaded from using PMCs for any transnational incursions. Their use, however, is not strictly prohibited. While far more could be said about these cornerstones of jus ad bellum, to address the question (p. 1145) whether PMCs can be used to violate the prohibition on the use of force, the issues of attribution and state responsibility must first be examined.

B.  PMCs and State Responsibility

In the most obvious case of a PMC being used to violate the prohibition on the use of force, a state could hire a company to use armed personnel to enter another country by force in pursuit of a specific mission, possibly even taking control of the foreign state’s territory and engaging its armed forces. Not only would this action likely violate the principles of the 1970 Declaration, such activity is highly unlikely as it would almost certainly draw the ire of the international community at large.78 The first issue in such an instance, however, would be one of attribution. When a state hires a PMC to operate anywhere, it has no doubt ‘acted’, but the analysis of that action is necessarily different under the law of state responsibility than if the same state had sent its own military to perform the same function. Both Hannah Tonkin and Carsten Hoppe provide excellent analyses of some of the twilight surrounding state responsibility and the use of PMCs.79 As Hoppe discusses, the International Law Commission’s (ILC) Articles on the Responsibility of States for Internationally Wrongful Acts clarify that when a state sends soldiers to a conflict, it does not matter for what specific activity those soldiers are sent; the state is responsible regardless.80 ‘On the other hand, unless incorporation of the personnel into the national army can be proven, attribution of contractor conduct to a state under the conventional reading of the ILC Articles requires a much more complex factual inquiry.’81 As will be discussed later, de jure incorporation of PMC personnel into the armed forces is extremely unlikely, and the de facto incorporation of PMC personnel into the armed forces can only occur in rare circumstances.82 Hoppe points out as a preliminary matter, therefore, that since PMCs would not fall under Article 4 responsibility (for organs of a state such as the armed forces),83 the principles of Articles (p. 1146) 5 (Conduct of persons or entities exercising elements of governmental authority)84 and 7 (Excess of authority or contravention of instructions)85 create a situation in which states are responsible for the conduct of soldiers at all times, but would not be responsible for the off-duty actions of PMC personnel.86 Here there is a legal gap that makes states less responsible for PMCs than for military personnel, but an analysis of state responsibility in triggering the prohibition on the use of force reveals even more problematic ambiguity.

As Hoppe contends, ‘there is growing agreement in the literature that the conduct of contractors undertaking combat missions or detention and interrogation for a state in armed conflict or occupation is attributable to the hiring state as exercise of governmental authority.’87 Article 8 seems to support this notion by pinning responsibility on states for conduct of entities such as PMCs when that conduct is directed or controlled by a state,88 a position further supported by the International Criminal Tribunal for the former Yugoslavia (ICTY) Appeals Chamber decision in Prosecutor v. Tadić.89 Looking beyond Hoppe and the ILC, in Nicaragua, the International Court of Justice (ICJ) held that the crucial matter is whether the state exercises ‘effective control’ over the party in question.90 Since it is possible and indeed common for a state to exercise effective control over a PMC, the actions of a PMC could be attributed to the state that has hired it, depending on the particular set of facts. Given that relationship, it would appear that a state could theoretically use force against the territorial integrity or political independence of another state without deploying its military.

Returning to the example of Blackwater in Colombia, several questions arise. Was the US in effective control of the Blackwater contractors when they entered Ecuador? Was the Colombian government exercising effective control over those contractors, even though the US had hired them? Alternatively, were the Colombian forces operating under the control of the PMC? Albrecht Randelzhofer claims ‘an incursion into the territory of another State constitutes an infringement of Art 2(4), even if it is not intended to deprive that state of part of its territory and if the invading troops are meant to withdraw immediately after completing a temporary and limited operation. . .’91 It would appear, therefore, that Blackwater’s involvement in this incursion on Ecuadorian soil may have violated the prohibition on the use of force, but it is unclear on whose behalf that violation occurred. In other words, a (p. 1147) more in-depth adjudication of the facts would be required to ascertain which, if any, of the governments was responsible for Blackwater’s action and thus operating contrary to Article 2(4).

C.  PMCs and the Prohibition on the Use of Force

1.  Incorporation into the armed forces

The analysis of the Blackwater case would be much clearer if the company’s personnel had been incorporated into the armed forces of one of the states. Every state has the sovereign right to determine who is and is not a part of its armed forces.92 Furthermore, ‘there is no general obligation on states requiring them to use their public forces rather than private actors to carry out military and security functions.’93 In Sierra Leone, for example, Executive Outcomes’ personnel, mentioned in Section I, were actually brevetted into the Republic of Sierra Leone Armed Forces. While that conflict was a non-international armed conflict, the integration of the PMC personnel meant that, if Sierra Leone had decided to use force against another state and requested the Executive Outcomes personnel to be involved, the PMC would have been directly and unequivocally involved in Sierra Leone’s violation of Article 2(4). While such an eventuality remains a theoretical possibility, it is unlikely to arise in reality at this point. Based on customary practices over the last decade, it is doubtful that a state will ever incorporate a PMC into its armed forces, de jure.94

Nils Melzer, however, in the International Committee of the Red Cross (ICRC) Interpretive Guidance on Direct Participation in Hostilities, notes that some PMCs are de facto incorporated into the armed forces of a party to non-international armed conflicts by virtue of being given a ‘continuous combat function’, even when such incorporation does not occur under national law.95 ‘Individuals whose continuous function involves the preparation, execution, or command of acts or operations amounting to direct participation in hostilities are assuming a continuous combat function…even before he or she first carries out a hostile act.’96 This commentary, however, only applies to non-state parties to a conflict and is, much like Tonkin’s analysis of de facto incorporation into the armed forces, a matter primarily of jus in bello significance, focused on international humanitarian law. That (p. 1148) said, there might arise a strange eventuality whereby a state were to intervene in a conflict without invitation as discussed later, and find itself fighting a belligerent party partially comprised of a PMC. Such a case would require further analysis. In general, however, incorporation, either de jure or de facto into the armed forces could theoretically cause a PMC to be involved in the use of force by a state but, in practice, is unlikely to occur.

2.  Facilitation of the use of force

Keeping the dynamics of both the Executive Outcomes engagement in Sierra Leone and that of Blackwater in Colombia in mind, the case of MPRI in the Balkans provides another potential point of intersection between PMCs and the jus ad bellum: facilitation of the use of force. The Croatian example demonstrates the ability of a PMC to significantly increase a state’s military capabilities—strategic, operational, and tactical—in a short amount of time. In that situation, Croatian forces were already involved in an armed conflict before their government hired MPRI to assist them. As the current industry evolves, however, companies are increasingly focused on providing training services, drawing on the elite expertise of ex-military personnel from the world’s most advanced national forces. A state with aggressive intention could hire a PMC to assist in building its capacity specifically in order to project force against another state. As will be discussed further later, such an activity could be considered either a form of using force, if the intended target state were known and obvious, or at a minimum, a threat of force. Such arrangements also raise questions of the responsibility of PMCs to vet their clients in order to avoid aiding and abetting illegal activity97—a matter beyond the scope of the present analysis, though nevertheless of substantial importance.

3.  Protection of nationals overseas

The use of force to rescue nationals overseas remains a contentious issue with regard to Article 2(4). The only way force could be legal in such circumstances is if the following criteria are met: (1) the host state must be unable or unwilling to protect the individuals; (2) the individuals must be in immediate danger of life-threatening harm; (3) force is only used as last resort; and (4) the intervening state may only use force that is reasonably necessary and the personnel involved must vacate immediately.98 Again it would be theoretically possible for a state to use a PMC in such targeted operations. The use of contractors in detention and interrogation operations in Abu Ghraib, as shown by the CACI and Titan case, (p. 1149) suggests an appetite to use contractors in contexts where they can be flown in and flown out. While not a completely parallel inference, it could be seen in certain circumstances as politically expedient to use contractors, unaffiliated with the armed forces, to carry out such rescue operations. There would be legal risk, however, as the individuals would almost certainly be operating in violation of other laws, even if the state’s own use of force was not strictly prohibited. Unfortunately, it is difficult to discern whether such activity is actually occurring as the contracts to engage in such activity would, if they existed, almost certainly be classified. Nevertheless, it is conceivable that a state might use a PMC in this grey area of the force regime.

As a corollary, it is worth noting that the US Central Intelligence Agency (CIA) has allegedly hired contractors, including from Blackwater, to conduct overseas assassinations on its behalf.99 This conduct is illegal on several fronts, but it is certainly a violation of the prohibition on the use of force. Consequently, evidence suggests the possibility that PMCs may be used in this manner, as well.

4.  Invitation

If a state invites another state to assist in an armed conflict or other situation in which force might be necessary, it almost certainly does not expect a PMC to come on behalf of the invited state. The UK government considered such a scenario in 2002, but came to the conclusion that, while the Ministry of Defence effectively outsources support functions like food supply to private companies, security was a different matter. If the UK government has received a formal request from the UN, another state, or another international body to provide support to a humanitarian mission, and has accepted a mandate to do so, the expectation is ‘that the front-line tasks will be undertaken by the UK’s Armed Forces, with their known skills and experience. The government would therefore not consider it appropriate for the UK to agree to undertake such tasks and then to subcontract them to private companies.’100 Only if major state militaries became so overstretched as to be unable to provide requested assistance would it be conceivable for a state to send a PMC on its behalf when invited to intervene. This remains, however, a remote possibility.

5.  Self-determination and assistance to rebels

Another controversial area in the force regime is the use of force in assistance of rebel movements and self-determination efforts. Without exploring the general concerns (p. 1150) surrounding such interventions, focusing on the legality of using PMCs in such situations reveals a rather unusual dynamic. As noted in Section I, the personnel of PMCs do not, in most instances, meet the definition of mercenaries, especially the primary definition contained in the UN International Convention Against the Recruitment, Use, Financing and Training of Mercenaries. The Convention, however, has two definitions. The second definition of ‘mercenary’ is far less restrictive in some ways than the principal definition, though far more restrictive in terms of its scope of application. Article 1.2 provides:

A mercenary is also any person who, in any other situation:

  1. a.  is specially recruited locally or abroad for the purpose of participating in a concerted act of violence aimed at:

    1. i.  overthrowing a Government or otherwise undermining the constitutional order of a State; or

    2. ii.  undermining the territorial integrity of a State;

  2. b.  is motivated to take part therein essentially by the desire for significant private gain and is prompted by the promise or payment of material compensation;

  3. c.  is neither a national nor a resident of the State against which such an act is directed;

  4. d.  has not been sent by a State on official duty; and

  5. e.  is not a member of the armed forces of the State on whose territory the act is undertaken.101

The history behind this provision helps to contextualize it, as fragile African states were calling for a ban on mercenaries who were being hired to fight against self-determination, but were nevertheless also worried about their own ability to stay in power.102 Oddly, however, this definition, part of a convention whose explicit aim was to protect self-determination efforts, may now actually hinder such movements and other efforts to overthrow oppressive regimes.

If the forces rebelling against the regime of Mu’ammer Gaddafi in Libya—a state party to the UN Mercenary Convention—in March to June 2011, for example, wanted to hire foreign PMCs to assist them, such PMC personnel could potentially be considered mercenaries under Article 1.2 of the UN Convention. They could be deemed to have been recruited to participate in a concerted act of violence aimed at overthrowing a government.103 They may have been motivated by financial gain,104 were not sent by a state on official duty,105 were not residents or nationals of Libya106 and were not members of the Libyan armed forces.107 If, on the other hand, an intervening state sent that same company to assist the rebels, the Mercenary Convention would likely not be triggered. The prohibition on the use of force, on the other (p. 1151) hand, might be implicated by such activity, as the legality of the use of force against a legitimate government in support of rebel activities remains an unresolved matter. Interestingly, if the North Atlantic Treaty Organization (NATO) or the UN hired the PMC in these same circumstances, the contract would likely be prohibited, as international organizations are not states, so the personnel of the PMC hired would fall within the definition of mercenaries. This is thus an area of legal twilight that has significant practical implications as the individual members of the PMCs as well as those involved in hiring them could face criminal liability. Ironically, as well, therefore, this definition of ‘mercenary’ could potentially hinder and inhibit self-determination efforts by denying popular movements the opportunity to seek assistance in their struggle; the exact phenomenon that generated anti-mercenary sentiments in the first place.

6.  Humanitarian intervention

Another area that requires further exploration is humanitarian intervention—perhaps the most controversial subject within the discourse surrounding the prohibition on the use of force. Adding to the existing controversy as to whether a state can legally intervene to stop a humanitarian crisis is the question of whether a state can do so by way of a PMC. Furthermore, what are the legal implications if a state-funded humanitarian organization hired a PMC to assist in intervening in a humanitarian disaster? What if the PMC hired is fully licensed in the host state and comprised exclusively of local nationals? Is this perhaps a new option for dealing with humanitarian crises? While far more could and indeed should be said on this topic, this is not the venue for a complete explication of the matter. These issues will be at the heart of further investigation into the relationship between PMCs and jus ad bellum.

D.  PMCs and the Prohibition on the Threat of Force

As Nikolas Stürchler points out, ‘even the most comprehensive discussions of the force regime have turned a blind eye to one of its components.’108 Not only is the use of force prohibited by Article 2(4), but also the threat of force. Stürchler examines this matter in considerable depth, engaging in historical, contextual, judicial, and empirical reviews of the law and its implementation in practice. His focus, however, is on military threats. Having established previously that PMCs and their personnel are not likely to be incorporated into the military at this point, especially not in (p. 1152) the context of jus ad bellum, it is worth examining whether PMCs can be used as a means of threatening force in violation of Article 2(4).

Stürchler makes a distinction between threatening force as a means of upholding the peaceful aims of the UN Charter and threatening force with the intent to use it.109 Based on his analysis, it seems the first could be legal, as it is a preferable means of avoiding the use of force, whereas the second would always be unlawful. Conceivably, therefore, PMCs could be used in either fashion in certain circumstances. A government could hire PMCs in any number of ways to effectively threaten force without either using its military or even using armed PMCs.

As Stürchler concludes, there is one question that needs to be answered when assessing the threat of force: ‘does a state credibly communicate its readiness to use force in a particular instance?’110 Examples include: an ultimatum;111 open, explicit, or verbal indications of the use of force;112 demonstration of force;113 militarized acts;114 and the actual use of force.115 Returning to the three examples from Section III, it is possible to see how PMCs could be used to threaten force. Blackwater accompanying the Colombian forces could be considered a threat by use of force, MPRI’s involvement with Croatia could be seen either as militarization or indication of the use of force were the engagement to have begun before the armed conflict, and the CACI and Titan involvement in interrogations could be seen as a demonstration of force or at least an explicit indication of the use of force. This is an area that will need to be explored further, especially as PMCs become more involved in training armed forces and facilitating improved military capacity.

E.  PMCs, International Organizations, and the Prohibition on the Use of Force

In addition to the prohibition in Article 2(4) and the exception in Article 51, Chapter VII of the UN Charter in its entirety forms a cornerstone of the force regime. While Chapter VII is less relevant to this discussion in general, it is important to note the relationship between PMCs, the prohibition on the use of force, and the UN itself, as well as other international organizations. Through Chapter VII, the UN Security Council has the power to authorize armed force116 to ‘maintain or restore international peace and security’.117 While Article 42 of the Charter states that forceful (p. 1153) measures taken by the Security Council may include actions by the ‘air, sea or land forces of the Members of the United Nations’, nothing in the Charter prohibits using forces that do not belong to the member states. Thus it is theoretically possible that the UN Security Council could, within the force regime, authorize a PMC to use force under Chapter VII. While that may seem far-fetched, it is worth noting that numerous international organizations, including various organs of the UN have contracted and continue to contract with PMCs in a range of areas from de-mining operations to law enforcement to armed security.118

The use of PMCs by international organizations raises an important question: could the UN, NATO, or another international organization hire a PMC to do exactly the same thing as a state’s military without triggering the prohibition on the use of force? Under basic agency law, it can be assumed that action by a PMC under a contract with an international organization, much like with a private company, would be attributable to the hiring entity.119 States are prohibited from infringing the territorial integrity or political independence of other states, but international organizations are not subject to Article 2(4).

The military authority of the UN and NATO comes from their member states. A number of commentators and scholars have suggested that these combined state forces use PMCs in place of state forces for certain missions, even amid armed conflicts, and most of these organizations already do hire PMCs to assist their military efforts.120 If a PMC is working directly for an international organization and not one of its member states, could that organization circumvent the prohibition on the use of force? Long-standing law establishes that multi-state forces like the UN or NATO cannot themselves be party to an armed conflict because they lack legal personality in this context.121 ‘Traditionally, only States and armed groups can be Party to a conflict and have, as such, clear rights and obligations. For armed groups this is only possible under certain conditions. . . . [I]‌nternational organisations cannot be Party to an armed conflict, despite the fact that they regularly run military operations.’122 If, therefore, a state hired a PMC to be involved in a multi-state military intervention (p. 1154) not authorized under Chapter VII, and incorporated the PMC into its armed forces, that PMC could be providing prohibited force. If that same PMC in the exact same operation, however, were hired by NATO rather than one of the member states, it would not be implicating Article 2(4). This inconsistency in international law creates a loophole that could prove significant in the future as multi-state missions are increasingly privatized.

F.  The Montreux Document

Just as 1928 was a watershed date insofar as the relationship between states and war was concerned, 2008 was a watershed date for the relationship between states and PMCs. Recognizing the growing need for clarity regarding the place of PMCs in international law, especially given the increased role of such companies in conflict areas around the globe, the Swiss Federal Department of Foreign Affairs and the ICRC jointly initiated in 2006 what has become known as the Montreux Process.123 Between 2006 and 2008, 17 key countries collaborated via four expert meetings and five intergovernmental meetings in an attempt to clarify what international laws apply to the operation of PMCs in armed conflicts, and what best practices should be in place to ensure that the various entities involved in the private military and security industry maintain compliance with those laws.124 The participating countries were Afghanistan, Angola, Australia, Austria, Canada, China, France, Germany, Iraq, Poland, Sierra Leone, South Africa, Sweden, Switzerland, Ukraine, the UK, and the US: effectively the countries with the strongest ties to PMSCs.125 On 17 September 2008, those states ratified the Montreux Document on Pertinent International Legal Obligations and Good Practices for States related to Operations of Private Military and Security Companies during Armed Conflict, the product of their efforts.126 The Document contains 27 ‘Pertinent International Legal Obligations’ and 73 ‘Good Practices’.127

While the Document expressly ‘recalls existing legal obligations of States and PMSCs and their personnel . . . and provides States with good practices (p. 1155) to promote compliance with international humanitarian law and human rights law during armed conflict’,128 it is a non-binding instrument. The Document explicitly neither creates nor alters any legal obligations.129 The parties to the Montreux Document specifically state that they do not seek to endorse the use of PMSCs—the term used in the document—but rather to use multilateral collaboration in order to clarify what laws and practices should constrain states and indeed other contracting entities130 when the decision to use a PMSC has been made.131

Unfortunately, however, it appears that only the jus in bello aspects of private military contracting were considered when drafting the Montreux Document.132 While a few provisions obliquely address jus ad bellum issues, the prohibition on the use of force is not directly mentioned. As Keiichiro Okimoto explores, there is a relationship between international humanitarian law and the use of force, just as there is a relationship between jus in bello and jus ad bellum, but the nature of that relationship does not provide for a wholesale application of the Montreux Document to the jus ad bellum aspects of private military contracting.133 A few discrete portions, however, do provide some guidance to states regarding the intersection of PMCs and the force regime. The Document establishes that contracting states retain their international legal obligations even after contracting with a PMSC134 and thus cannot outsource to PMSCs what they cannot legally do themselves.135 Beyond this broad platitude, however, most of the more detailed provisions are specific to either international humanitarian law or human rights law.

One of the most significant provisions of the Document, however, regards the responsibility of contracting states for the actions of the PMSCs they hire. Paragraph 7 of the Legal Obligations section reads:

Although entering into contractual relations does not in itself engage the responsibility of Contracting States, the latter are responsible for violations of international humanitarian law, human rights law, or other rules of international law committed by PMSCs or their personnel where such violations are attributable to the Contracting State, consistent with customary international law, in particular if they are:(p. 1156)

  1. a.  incorporated by the State into its regular armed forces in accordance with its domestic legislation;

  2. b.  members of organised armed forces, groups or units under a command responsible to the State;

  3. c.  empowered to exercise elements of governmental authority if they are acting in that capacity (i.e. are formally authorised by law or regulation to carry out functions normally conducted by organs of the State); or

  4. d.  in fact acting on the instructions of the State (i.e. the State has specifically instructed the private actor’s conduct) or under its direction or control (i.e. actual exercise of effective control by the State over a private actor’s conduct).136

Though this paragraph was undoubtedly focused on jus in bello issues, the inclusion of violations of ‘other rules of international law’ potentially expands this provision to cover the use of PMSCs in situations in which they might be used to violate the prohibition on the use of force. This is a significant statement of obligation, therefore, on the part of the states which endorse the Document.

Finally, out of the 73 paragraphs providing best practices for states, only one is somewhat relevant to the present analysis. ‘To determine which services may or may not be contracted out to PMSCs; in determining which services may not be contracted out, Contracting States take into account factors such as whether a particular service could cause PMSC personnel to become involved in direct participation in hostilities.’137 Before contracting with a PMC to engage in activity that might be attributed to the state as prohibited force being used against another state, the hiring state must first give full consideration to the legal restrictions and implications.

Though the Montreux Document may have been a watershed accomplishment in the regulation of PMCs and in the relationship between states and private companies in armed conflict settings, it provides little guidance on issues of jus ad bellum. As the Montreux Document is reviewed and revised, the endorsing states may wish to consider such issues. As yet, however, the issues discussed in this analysis remain, for the most part, open for debate.

V.  Conclusion

This is a topic that has not been previously explored. While numerous works in recent years have sought to review jus ad bellum in light of new developments in international (p. 1157) affairs,138 and numerous more have taken on legal issues surrounding PMCs,139 there has yet to be an extensive and in-depth study of the intersection of the use of PMCs and the prohibition on the use of force. As the use of PMCs by states continues to evolve, new areas, yet unimagined, may arise, which will further implicate the prohibition on the use of force. One area that needs further examination, for example, is in the context of self-defence. Noam Lubell points out that Article 51 does not restrict the source of the threat against which a state may use force.140 In other words, non-state actors, potentially including PMCs hired by non-state clients could pose sufficient threat to territorial integrity so as to necessitate the resort to force by a state in self-defence. Could activity in self-defence against a PMC include violating the territorial integrity of another state? This is just one of the many significant questions that will arise when examining the relationship between PMCs and Article 51.

This chapter has perhaps raised more questions than it has answered. It has sought, however, to highlight some of the realistic points of intersection and conflict between states’ use of private military companies and their use of force. The various examples and hypotheticals have indicated that, while it may only be in unusual circumstances that the use of a PMC might trigger the prohibition on the threat or use of force, such circumstances are well within the realm of possibility and may already have occurred in several instances. Further research and analysis will be necessary to probe the contours of this issue. As the private military industry continues to develop, evolve, and mature, so too must the legal discourse around it. This chapter, therefore, will hopefully serve as the starting point for an ongoing and rigorous examination of private military companies and the jus ad bellum in the coming years and decades.


Kevin A. O’Brien, ‘Private Military Companies and African Security 1990–98’ in Abdel-Fatau Musah and J. Kayode Fayemi (eds), Mercenaries: An African Security Dilemma (London: Pluto Press, 2000), 43, 46.

E. L. Gaston, ‘Mercenarism 2.0? The Rise of the Modern Private Security Industry and its Implications for International Humanitarian Law Enforcement’ (2008) 49 Harvard International Law Journal 221, 225–6.

Major Jeffrey S. Thurnher, ‘Drowning in Blackwater: How Weak Accountability Over Private Security Contractors Significantly Undermines Counterinsurgency Efforts’ (July 2008) Army Lawyer 64.

Todd S. Millard, ‘Overcoming Post-Colonial Myopia: A Call to Recognize and Regulate Private Military Companies’ (2003) 176 Military Law Review 1, 8.

Discussion at the First Meeting of the Security in Complex Environments Group, Aerospace Defence Security Group, Ltd (13 Jan 2011).

Sarah Percy, ‘Morality and Regulation’ in Simon Chesterman and Chia Lehnardt (eds), From Mercenaries to Market: The Rise and Regulation of Private Military Companies (Oxford: Oxford University Press, 2007), 12–14; UK Foreign and Commonwealth Office, Private Military Companies: Options for Regulation, 2002, HC 577, para 9, available at <http://www.globalsecurity.org/military/library/report/2002/mercenaries.pdf>.

See eg Jeremy Scahill, Blackwater: The Rise of the World’s Most Powerful Mercenary Army (New York: Nation Books, 2007).

The Oxford English Dictionary Online, ‘Mercenary’, Definition 2 (2010), available at <http://www.oed.com/view/Entry/116635?redirectedFrom=mercenary#eid>.

UK Foreign and Commonwealth Office, Private Military Companies: Options for Regulation, para 4. The 2002 Green Paper claims that the Oxford English Dictionary defines ‘mercenary’ as ‘a professional soldier serving a foreign power’. This is not accurate.

10  International Convention Against the Recruitment, Use, Financing and Training of Mercenaries, GA Res 44/34, A/RES/44/34 (4 Dec 1989), Art 1; Organisation of African Unity, Convention for the Elimination of Mercenarism in Africa (opened for signature), 3 July 1977, OAU Doc CM/817 (XXIX), Annex II, Art 1 (3rd rev 1977) (entered into force 22 Apr 1985); Protocol Additional to the Geneva Conventions of 12 Aug 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I), Art 47, 8 June 1977, 1125 UNTS 17512, available at <http://www.icrc.org/ihl.nsf/FULL/470?OpenDocument>.

11  See eg Ian Ralby, ‘Private Military and Security Companies in the Uncharted Spaces of the Law’, unpublished dissertation, Cambridge University Library, 2011, 54–64.

12  International Convention against the Recruitment, Use, Financing and Training of Mercenaries, GA Res 44/34, A/RES/44/34 (4 Dec 1989), Art 1.

13  Geoffrey Best, Humanity in Warfare: The Modern History of the International Law of Armed Conflicts (London: Routledge, 1980), 328, 374–5 fn 83.

14  Percy, ‘Morality and Regulation’ in Chesterman and Lehnardt, From Mercenaries to Market, 12–14.

15  Percy, ‘Morality and Regulation’ in Chesterman and Lehnardt, From Mercenaries to Market, 12–14.

16  Percy, ‘Morality and Regulation’ in Chesterman and Lehnardt, From Mercenaries to Market, 12–14.

17  UK Foreign and Commonwealth Office, Private Military Companies: Options for Regulation, para 9.

18  Percy, ‘Morality and Regulation’ in Chesterman and Lehnardt, From Mercenaries to Market, 12–14; UK Foreign and Commonwealth Office, Private Military Companies: Options for Regulation, para 9.

19  Video of Blackwater in Najaf, available at <http://www.dailymotion.com/video/x9hi6f_ blackwater-sniper-in-najaf_sport>.

20  Max Weber, ‘Politics as a Vocation’ in David Owen and Tracey Strong (eds), The Vocation Lectures ([1919] Indianapolis, IN: Hackett, 2004), 33.

21  Anthony Mockler, Mercenaries (New York: Macmillan, 1969), 13.

22  Peter W. Singer, Corporate Warriors: The Rise of the Privatized Military Industry (Ithaca, NY: Cornell University Press, 2003), 19.

23  Serge Yalichev, Mercenaries of the Ancient World (London: Constable, 1997), 13.

24  Lt Col Tim Spicer, An Unorthodox Soldier: Peace and War in the Sandline Affair (Edinburgh: Mainstream Publishing, 2000), 29–30.

25  Compare Thomas More, Utopia ([1516] trans Paul Turner, London: Penguin, 2009), 107–9 and Niccolò Machiavelli, The Prince ([1532] trans George Bull, London: Penguin, 1999), 51.

26  Millard, ‘Overcoming Post-Colonial Myopia’, 6.

27  Mockler, Mercenaries, 13.

28  G. T. Griffith, The Mercenaries of the Hellenistic World (Cambridge: Ares Publishing, 1984), 1.

29  See eg Virginia Cowles, The Phantom Major: The Story of David Stirling and the S.A.S. Regiment (Barnsley: Pen and Sword Military, 2010); Alan Hoe, David Stirling: The Authorised Biography of the Founder of the SAS (New York: Time Warner Paperbacks, 1992), 41–225.

30  Captain Daniel P. Ridlon, ‘Contractors or Illegal Combatants? The Status of Armed Contractors in Iraq’ (2008) 62 Air Force Law Review 199, 215 (citing O’Brien, ‘Private Military Companies and African Security 1990–98’ in Musah and Fayemi, Mercenaries, 43, 46).

31  Ridlon, ‘Contractors or Illegal Combatants?’, 199, 215 (citing O’Brien, ‘Private Military Companies and African Security 1990–98’ in Musah and Fayemi, Mercenaries, 43, 46).

32  Sabelo Gumedze (ed), Private Security in Africa: Manifestation, Challenges, Regulation (Pretoria: Institute for Security Studies, 2007), 3.

33  See, generally, Richard Ned Lebow, ‘The Long Peace, the End of the Cold War, and the Failure of Realism’ (1994) 48 International Organisation 249; Jeffrey W. Legro and Andrew Moravcsik, ‘Is Anybody Still a Realist?’ (1999) 24 International Security 5; Bruce Russett, Grasping the Democratic Peace: Principles for a Post-Cold War Peace (Princeton, NJ: Princeton University Press, 1993); Paul Schroeder, ‘Historical Reality vs. Neo-Realist Theory’ (1994) 19 International Security 108; John A. Vasquez, ‘The Realist Paradigm and Degenerative vs. Progressive Research Programs: An Appraisal of Neotraditional Research on Waltz’s Balancing Proposition’ (1997) 91 American Political Science Review 899.

34  Francis Fukuyama, ‘The End of History?’ (Summer 1989) The National Interest 4.

35  David Shearer, ‘Private Armies and Military Intervention’, International Institute for Strategic Studies, Adelphi Paper 316, 1998, 13–16 and 26–7.

36  Sean Dorney, The Sandline Affair: Politics and Mercenaries and the Bougainville Crisis (Sydney: Australian Broadcasting Commission, 1998).

37  Jim Hooper, Bloodsong! An Account of Executive Outcomes in Angola (London: Harper, 2003); Roelf van Heerden and Andrew Hudson, Four Ball, One Tracer: Commanding Executive Outcomes in Angola and Sierra Leone (Solihull: Helion & Co, 2012).

38  Elizabeth Rubin, ‘An Army of One’s Own: In Africa, Nations Hire a Corporation to Wage War’ (Feb 1997) Harper’s 47; Laura Dickinson, ‘Government for Hire: Privatizing Foreign Affairs and the Problem of Accountability under International Law’ (2005) 47 William and Mary Law Review 137, 153.

39  Gaston, ‘Mercenarism 2.0?’, 225–6.

40  Virginia Newell and Benedict Sheehey, ‘Corporate Militaries and States: Actors, Interactions and Reactions’ (2006) 41 Texas International Law Journal 67, 75.

41  Newell and Sheehey, ‘Corporate Militaries and States’, 75.

42  Sandline International Website, available at <http://www.sandline.com>.

43  Aegis website, ‘Tim Spicer’, available at <http://www.aegisworld.com/index.php/tim-spicer>.

44  Kevin A. O’Brien, ‘The New Warrior Class’ in Paul B. Rich (ed), Warlords in International Relations (Basingstoke: Palgrave Macmillan, 1999), 52, 57.

45  O’Brien, ‘The New Warrior Class’ in Rich, Warlords in International Relations, 58.

46  Alison Stranger and Mark Williams, ‘Private Military Corporations: Benefits and Costs of Outsourcing Sovereignty’ (2006) 2 Yale Journal of International Affairs 8–9.

47  Ken Silverstein, ‘Privatizing War: How Affairs of State are Outsourced to Corporations Beyond Public Control’, The Nation, 28 July 1997, available at <https://www.mtholyoke.edu/acad/intrel/silver.htm>.

48  Deborah D. Avant, The Market For Force: The Consequences of Privatizing Security (Cambridge: Cambridge University Press, 2001), 104.

49  Hannah Tonkin, State Control Over Private Military and Security Companies in Armed Conflict (Cambridge: Cambridge University Press, 2011), 48–9; Avant, The Market For Force, 104.

50  Tonkin, State Control Over Private Military and Security Companies in Armed Conflict, 48–9, citing Robert Fox, ‘Fresh War Clouds Threaten Ceasefire: Secret U.S. Military Advice Helps “Cocky” Croats Push Towards Eastern Slavonia’, Sunday Telegraph, 15 Oct 1995; Samantha Power et al, ‘The Croatian Army’s Friends’, US News and World Report, 21 Aug 1995; Roger Cohen, ‘US Cooling Ties to Croatia after Winking at Its Buildup’, New York Times, 28 Oct 1995, available at <http://www.nytimes.com/1995/10/28/world/us-cooling-ties-to-croatia-after-winking-at-its-buildup.html?pagewanted=all&src=pm>; ‘Croatia: Tudjman’s New Model Army’, The Economist, 11 Nov 1995; Ken Silverstein, Private Warriors (London: Verso, 2000), 172–3; Singer, Corporate Warriors, 5.

51  Roger Cohen, ‘US Cooling Ties to Croatia after Winking at Its Buildup’, New York Times, 28 Oct 1995.

52  It is worth noting that, in addition to the points discussed, MPRI’s involvement in Croatia also led to an Alien Tort Claims Act claim against MPRI’s parent company, L-3 Communications, Genocide Victims of Krajina v. L-3 Communications, Complaint Case 1:10-cv-05197 (ND Ill, 2010). The claim alleged:

Defendant MPRI, a private military contractor subsequently acquired by Defendant L-3 Communications Inc., trained and equipped the Croatian military for Operation Storm and designed the Operation Storm battle plan. Operation Storm became the largest land offensive in Europe since World War II and resulted in the murder and inhumane treatment of thousands of ethnic Serbs, the forced displacement of approximately 200,000 ethnic Serbs from their ancestral homes in Croatian territory, and the pillaging and destruction of hundreds of millions of dollars worth of Serbian-owned property. The victims of Operation Storm and their heirs and next of kin herein claim that Defendants were complicit in genocide.

The case was effectively ended, however, by the US Supreme Court ruling in Kiobel v. Royal Dutch Petroleum, 569 US __ (2013) on 17 Apr 2013 which held that the Alien Tort Claims Act does not apply extraterritorially.

53  Alison Stranger and Mark Williams, ‘Private Military Corporations: Benefits and Costs of Outsourcing Sovereignty’ (2006) 2 Yale Journal of International Affairs 8–9.

54  Avant, The Market For Force, 104.

55  Avant, The Market For Force, 104.

56  Samantha Power et al, ‘The Croatian Army’s Friends’, US News and World Report, 21 Aug 1995; Roger Cohen, ‘US Cooling Ties to Croatia after Winking at Its Buildup’, New York Times, 28 Oct 1995, available at <http://www.nytimes.com/1995/10/28/world/us-cooling-ties-to-croatia-after-winking-at-its-buildup.html?pagewanted=all&src=pm>; ‘Croatia: Tudjman’s New Model Army’, The Economist, 11 Nov 1995; Bradley Graham, ‘U.S. Firm Exports Military Expertise; Role in Training Croatian Military Brings Publicity and Suspicions’, Washington Post, 11 Aug 1995; Charlotte Eager, ‘Invisible U.S. Army Defeats Serbs’, The Observer, 5 Nov 1995.

57  Christian J. Westra, ‘Will the “Bush Doctrine” Survive its Progenitor? An Assessment of Jus ad Bellum Norms for the Post-Westphalian Age’ (2009) 32 Boston College International and Comparative Law Review 399, 416.

58  Frank M. Walsh, ‘Rethinking the Legality of Colombia’s Attack on the FARC in Ecuador: A New Paradigm for Balancing Territorial Integrity, Self-Defense and the Duties of Sovereignty’ (2009) 21 Pace International Law Review 137, 138.

59  Walsh, ‘Rethinking the Legality’, 143–7.

60  Gabriel Marcella, ‘War Without Borders: The Ecuador-Colombia Crisis of 2008 and Inter-American Security’, Air and Space Power Journal, 1 Apr 2009, available at <http://www.airpower.au.af.mil/apjinternational/apj-s/2009/1tri09/marcellaeng.htm>.

61  Eva Golinger, ‘The Assassinations Next Door: Blackwater in Colombia’, Progresso Weekly, 15 Dec 2009, available at <http://progreso-weekly.com/2/index.php?option=com_content&view=article&id=1362:the-assassins-next-door-blackwater-in-colombia&catid=40:lastest-news&Itemid=59>.

62  Eva Golinger, ‘Blackwater in Colombia’, Pravda, 14 Dec 2009, available at <http://english.pravda.ru/hotspots/14-12-2009/111133-columbiaarticle-0/>.

63  Case concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. US), Merits, Judgment, ICJ Rep 1986, 14, para 115.

64  CACI website, ‘Profile’, available at <http://www.caci.com/about/profile.shtml>.

65  L-3 Communications website, ‘Working at L-3 Communications’, available at <http://lsgcareers.l-3 com.com/careers/>.

66  Ryan P. Logan, ‘The Detainee Treatment Act of 2005: Embodying U.S. Values to Eliminate Detainee Abuse By Civilian Contractors and Bounty Hunters in Afghanistan and Iraq’ (2006) 39 Vanderbilt Journal of Transnational Law 1605, 1622.

67  Major General Antonio Taguba, Article 15-6 Investigation of the 800th Military Police Brigade, at ‘Regarding Part Two of the Investigation, I Make The Following Specific Findings of Fact’ (2004), para 30.

68  Taguba, Article 15-6 Investigation of the 800th Military Police Brigade, para 30.

69  Taguba, Article 15-6 Investigation of the 800th Military Police Brigade, paras 11 and 30.

70  Taguba, Article 15-6 Investigation of the 800th Military Police Brigade, paras 11 and 30.

71  Taguba, Article 15-6 Investigation of the 800th Military Police Brigade, paras 11 and 30. It should be noted, however, that in 2007 the Uniform Code of Military Justice was extended by the Military Extraterritorial Jurisdiction Act to cover this sort of conduct under US law.

72  See eg Ibrahim v. Titan Corp, 391 FSupp 2d 10 (DDC, 2005); Saleh v. Titan Corp, 436 FSupp 2d 55 (DDC, 2006); Saleh v. Titan Corp, 580 F3d 1, 9 (DC Cir, 2009).

73  Yoram Dinstein, War, Aggression and Self-Defence (5th edn, Cambridge: Cambridge University Press, 2011), 85.

74  Dinstein, War, Aggression and Self-Defence, 85.

75  UN Charter, Art 2(4).

76  UN Charter, Art 51.

77  Declaration on Principles of International Law Concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, GA Res 2625, Annex, 25 UN GAOR, Supp No 28, A/5217 (1970), 121.

78  Indeed, allegations regarding Russia’s use of PMCs in order to be able to deny the involvement of ‘troops’ in Crimea and Eastern Ukraine in early 2014 underscore the problems that would arise, but furthermore suggest that such activity is not completely outside the realm of possibility. See eg Josh Rogin, ‘Russian “Blackwater” Takes Over Ukraine Airport’, Daily Beast, 28 Feb 2014, available at <http://www.thedailybeast.com/articles/2014/02/28/exclusive-russian-blackwater-takes-over-ukraine-airport.html>.

79  See generally, Tonkin, State Control Over Private Military and Security Companies in Armed Conflict; Carsten Hoppe, ‘Passing the Buck: State Responsibility for Private Military Companies’ (2008) 19 European Journal of International Law 989.

80  Hoppe, ‘Passing the Buck’, 990–1.

81  Hoppe, ‘Passing the Buck’, 991.

82  Tonkin, State Control Over Private Military and Security Companies in Armed Conflict, 58.

83  Draft Articles on Responsibility of States for Internationally Wrongful Acts, with commentaries in Report of the International Law Commission on the Work of its Fifty-Third Session, UN GAOR, 56th Sess, Supp No 10, 43, A/56/10 (2001), Art 4, available at <http://www.un.org/law/ilc>; Annex to GA Res 56/83 (12 Dec 2001).

84  Articles on State Responsibility, Art 5.

85  Articles on State Responsibility, Art 7.

86  Hoppe, ‘Passing the Buck’, 991.

87  Hoppe, ‘Passing the Buck’, 991–2.

88  Articles on State Responsibility, Art 8.

89  Prosecutor v. Tadić, Judgment of 15 July 1999, IT-94-1-A, Appeals Chamber, para 120; Tonkin, State Control Over Private Military and Security Companies in Armed Conflict, 87.

90  Case concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. US), Merits, Judgment, ICJ Rep 1986, 14, para 115.

91  Albrecht Randelzhofer, ‘Article 2(4)’ in Bruno Simma et al (eds), The Charter of the United Nations: A Commentary (2nd edn, Oxford: Oxford University Press, 2002), vol I, 112, 123.

92  Richard Morgan, ‘Professional Military Firms Under International Law’ (2008) 9 Chicago Journal of International Law 213, 227 (citing Lassa Oppenheim, 2 International Law: Disputes, War and Neutrality 255 (ed H. Lauterpacht, 7th edn, London: Longmans Green, 1952)).

93  Tonkin, State Control Over Private Military and Security Companies in Armed Conflict, 173.

94  Hoppe, ‘Passing the Buck’, 991.

95  ICRC, ‘Interpretive Guidance on the Notion of Direct Participation in Hostilities Under International Humanitarian Law’, 2009, 39, available at <http://www.icrc.org/eng/resources/documents/feature/direct-participation-ihl-feature-020609.htm>.

96  ICRC, ‘Interpretive Guidance’, 34.

97  The lawsuit against MPRI for complicity to commit genocide, discussed at n 52, further supports this notion.

98  Martin Dixon, Textbook on International Law (6th edn, Oxford: Oxford University Press, 2007), 322.

99  Mark Mazzetti, ‘C.I.A. Sought Blackwater’s Help to Kill Jihadists’, New York Times, 19 Aug 2009, available at <http://www.nytimes.com/2009/08/20/us/20intel.html?_r=1&hp>.

100  Response of the Secretary of State for Foreign and Commonwealth Affairs to the Ninth Report of the Foreign Affairs Committee, ‘Private Military Companies’ (2001–2002, Cm 5642), para (h) (2002).

101  International Convention against the Recruitment, Use, Financing and Training of Mercenaries, GA Res 44/34, A/RES/44/34 (4 Dec 1989), Art 1 (‘The Mercenary Convention’).

102  Millard, ‘Overcoming Post-Colonial Myopia’, 61–2.

103  The Mercenary Convention, Art 1.2(a)(1).

104  The Mercenary Convention, Art 1.2(b).

105  The Mercenary Convention, Art 1.2(d).

106  The Mercenary Convention, Art 1.2(c).

107  The Mercenary Convention, Art 1.2(e).

108  Nikolas Stürchler, The Threat of Force in International Law (Cambridge: Cambridge University Press, 2007), 1–2.

109  Stürchler, The Threat of Force in International Law, 254.

110  Stürchler, The Threat of Force in International Law, 259.

111  Stürchler, The Threat of Force in International Law, 258.

112  Stürchler, The Threat of Force in International Law, 260.

113  Stürchler, The Threat of Force in International Law, 260.

114  Stürchler, The Threat of Force in International Law, 261.

115  Stürchler, The Threat of Force in International Law, 262.

116  UN Charter, Art 42.

117  UN Charter, Art 39.

118  Anne-Marie Buzatu and Benjamin Buckland, ‘Private Military & Security Companies: Future Challenges in Security Governance’, DCAF Horizon 2015 Working Paper No 3, 2010, 15–16.

119  Cedric Ryngaert, ‘Litigating Abuses Committed by Private Military Companies’ (2008) 19 European Journal of International Law 1035, 1039–40.

120  See, generally, Malcolm Patterson, ‘A Corporate Alternative to United Nations Ad Hoc Military Deployments’ (2008) 13 Journal of Conflict and Security Law 215; W. Hays Parks, ‘Evolution of Policy and Law Concerning the Role of Civilians and Civilian Contractors Accompanying the Armed Forces’, 2005, 5–6, available at <http://www.icrc.org/eng/assets/files/other/2005-07-expert-paper-icrc.pdf>; Singer, Corporate Warriors, 53–7 and 183.

121  Proceedings of the Bruges Colloquium, ‘Armed Conflicts and Parties to Armed Conflicts Under IHL: Confronting Legal Categories to Contemporary Realities’ (22–3 Oct 2009), 10th Bruges Colloquium No 40 Autumn 2010, 109–10, available at <http://www.coleurop.be/file/content/publications/pdf/Collegium40.pdf>.

122  Proceedings of the Bruges Colloquium, 109–110.

123  Simon Chesterman, ‘Lawyers, Guns and Money: The Governance of Business Activities in Conflict Zones’ (2011) 11 Chicago Journal of International Law 321, 334.

124  Press Release, ‘The Montreux Document on Private Military and Security Companies’, Swiss Federal Department of Foreign Affairs, available at <http://www.eda.admin.ch/psc>.

125  Report, ‘The Montreux Document on Private Military and Security Companies’, ICRC, available at <http://www.icrc.org/web/eng/siteeng0.nsf/html/montreux-document-170908>.

126  Press Release, the Montreux Document.

127  See generally, the Montreux Document on Pertinent International Legal Obligations and Good Practices for States related to Operations of Private Military and Security Companies during Armed Conflict, A/63/467–S/2008/636 (2008).

128  The Montreux Document, Preface, para 2.

129  The Montreux Document, Preface, para 3.

130  The Montreux Document, Preface, para 8.

131  The Montreux Document, Preface, para 7.

132  According to the publicity surrounding the Montreux Process, ‘The Montreux Document is the first international document to describe international law as it applies to the activities of private military and security companies (PMSCs) whenever these are present in the context of an armed conflict.’ Press Release, the Montreux Document.

133  Keiichiro Okimoto, The Distinction and Relationship Between Jus ad Bellum and Jus in Bello (Oxford: Hart, 2011).

134  The Montreux Document, Part One, para 1.

135  The Montreux Document, Part One, para 2.

136  The Montreux Document, Part One, para 7.

137  The Montreux Document, Part Two, para 1.

138  See eg Lindsay Moir, Reappraising the Resort to Force: International Law, Jus ad Bellum and the War on Terror (Oxford: Hart, 2010); Christian Henderson, The Persistent Advocate and the Use of Force: The Impact of the United States upon the Jus ad Bellum in the Post-Cold War Era (Farnham: Ashgate, 2010); Noam Lubell, Extraterritorial Use of Force Against Non-State Actors (Oxford: Oxford University Press, 2010).

139  See eg Ian Ralby, ‘Private Military and Security Companies in the Uncharted Spaces of the Law’, unpublished dissertation, Cambridge University Library, 2011; Tonkin, State Control Over Private Military and Security Companies in Armed Conflict, 48–9; Hin-Yan Liu, ‘Leashing the Corporate Dogs of War: The Legal Implications of the Modern Private Military Company’ (2010) 15 Journal of Conflict and Security Law 141; Adam Ebrahim, Note, ‘Going to War with the Army You Can Afford: The United States, International Law, and the Private Military Industry’ (2010) 28 Boston University International Law Journal 181; Amol Mehra, ‘Bridging the Accountability Gaps—The Proliferation of Private Military and Security Companies and Ensuring Accountability for Human Rights Violations’ (2010) 22 Pacific McGeorge Global Business and Development Law Journal 323; Charles Tiefer, ‘No More Nisour Squares: Legal Control of Private Security Contractors in Iraq and After’ (2009) 88 Oregon Law Review 745; Craig S. Jordan, ‘Who Will Guard the Guards? The Accountability of Private Military Contractors in Areas of Armed Conflict’ (2009) 35 New England Journal on Criminal and Civil Confinement 309; Hoppe, ‘Passing the Buck’, 989; Ridlon, ‘Contractors or Illegal Combatants?’; Chia Lehnardt, ‘Individual Liability of Private Military Personnel Under International Criminal Law’ (2008) 19 European Journal of International Law 1015; Gaston, ‘Mercenarism 2.0?’; Antenor Hallo de Wolf, ‘Modern Condottieri in Iraq: Privatizing War from the Perspective of International and Human Rights Law’ (2006) 13 Indiana Journal of Global Legal Studies 315.

140  Lubell, Extraterritorial Use of Force Against Non-State Actors, 32.