International humanitarian law has evolved as an important body of conventional and customary law applicable in both international and non-international armed conflicts. Its operational and political relevance is widely accepted, notwithstanding existing implementation gaps and so many breaches. In fact, hardly any other branch of international law can benefit today from a comparable dense discourse on the global scale, from so many fora provided for this discourse, and a proliferation of expertise worldwide. The relatively broad attention for these activities is part of a progressive development that includes the introduction of principles and rules of international humanitarian law even in areas well beyond the realm of armed conflicts, i.e. beyond the specific field of application for which that body of law was originally designed. It is generally accepted today that these principles and rules must also be observed in peace operations and related activities conducted by the United Nations and by states.1
While it is fully appropriate to positively respond to such a broader perception of, and respect for, international humanitarian law, certain clarifications remain necessary to ensure a correct understanding and proper application of its rules in practice. The protection of victims of military operations is part of a balance that may require different considerations in armed conflicts than would normally be the case in peacetime. This differentiation may be difficult in practice, as quite often the dividing line between peace and armed conflict is blurred. Peace enforcement operations are a case in point. The Security Council has developed an expanded role relating to international humanitarian law. In a particularly dense practice during the last decade, it has called states and nonstate actors in many emergency situations, both during and after armed conflicts to respect its principles and rules.2 Although in principle entitled to do so under Articles 25 and 103 of the UN Charter, the Council has never authorized any substantial modification of international humanitarian law, e.g., for peace enforcement operations, but has limited itself to adapting certain obligations of Occupying Powers3 to allow for legal, economic and political reforms in a specific post-conflict situation.4 Regional organizations have actively followed this trend and have called for full compliance with principles and rules of international humanitarian law. The relevant European guidelines5 are designed to ensure that important aspects of this legal order are sufficiently present in political and military planning processes. Yet there is still a widespread lack of knowledge of existing rights and obligations, and the issue of different legal approaches by states and nonstate actors as to the interpretation and application of the law in force remains of practical and political relevance. New efforts are required to harmonize interpretation of pertinent obligations in multinational military operations. A proactive role to ensure compliance with applicable principles and rules may be key to a successful performance of military missions. It is in this broader context that the notion of direct participation in hostilities and its resulting effect for humanitarian protection should be contemplated by those engaged in planning and conducting military operations today.
I will first comment on the general relevance of the concept of direct participation in hostilities for current military operations. In a second part, I will address different opinions on this concept in academic as well as in practice-oriented discussions. In the third part, I will discuss the role of the International Committee of the Red Cross (ICRC) in the process that has lead to the new Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law,6 and consider possibilities for states and relevant international organizations as well as individual experts to participate in the ongoing discourse on this issue, which is essential to support measures to implement existing rules.
Relevance for Current Military Operations
A clear understanding of direct participation in hostilities may be considered as the decisive prerequisite to ensure legal protection of innocent victims. Article 3 common to the 1949 Geneva Conventions (GC I-IV) provides for the protection of “persons taking no active part in the hostilities” and the two 1977 Additional Protocols (AP I and II) confirm that civilians enjoy protection “… unless and for such time as they take a direct part in hostilities.”7 This rule is rightly considered part of customary international law both in international and non-international armed conflicts.8 Its practical relevance has grown considerably in recent years, due to a continuous shift of military operations away from distinct battlefields into civilian population centers and a growing involvement of civilians in activities closely related to the actual conduct of hostilities.
There are, of course, many reasons for this development. In all military operations today there is an increasing need for logistic support and the use of services from civilian sources. Even regular armed forces with well-organized logistic systems are widely dependent from commercial deliveries, transport services and communication lines. Armed opposition groups in non-international armed conflicts could not exist at all, nor could they operate effectively without civilian support.
To ensure legal protection for those not taking a direct part in hostilities, clear terms and conditions are required. But treaty law is silent on this issue. It leaves the notion of “armed conflict” and ‘hostilities’ undefined. It does not exactly define who is a “civilian” nor does it delineate the elements of what is a “direct participation in hostilities”. There is also a lacuna as to the precise modalities according to which civilians directly participating in hostilities lose their protection under international humanitarian law. It is a difficult and complex task to achieve a clear understanding on this issue, which may be applied in any armed conflict situation. It is more difficult to agree on the application of pertinent rules for military operations other than war, including enforcement and peace enforcement operations. Yet common principles such as necessity, proportionality, and effectiveness are valid for all military operations and must be respected, even if these principles pose different challenges in different situations so that they cannot be applied throughout all situations in the same manner.9
The past decades have seen a remarkable development of military operations both within the United Nations collective security system and in other international settings. While traditional forms of military operations have been maintained and further developed, there have also been substantive developments responding to new security risks, specific requirements of international and multinational cooperation, and legal regulation. Treaty law, customary law and best practices relevant for military operations derive from various branches of international law that have to be applied in context. Cooperation between states and international organizations has brought about a progressive development of applicable rules, and a requirement for legal control both at the national and international level. At the same time, the correct interpretation of legal rules and best practices has become one of the benchmarks for the assessment of military operations. Failure to meet appropriate standards can have significant legal, as well as military and political implications. This makes the identification and application of these rules of crucial importance in the planning and conduct of all types of military operations. The absence of an all-encompassing regulation and the need to find specific solutions for tasks characterized by the interdependence of efforts to be taken and the results to be achieved have made a reassessment of this important part of international law both a timely and topical task.
As spelled out in the Interpretive Guidance, its text is concerned with international humanitarian law only, hence its conclusions “remain without prejudice to an analysis of questions related to direct participation in hostilities under other applicable branches of international law, such as human rights law or the law governing the use of interstate force (jus ad bellum).”10 This, of course, is a perfectly appropriate position for the ICRC to take. But those involved in the conduct of military operations must develop a comprehensive approach, to observe and restore the rule of law in all its aspects. All rules applicable to enforcement, peace enforcement, and peace operations, as well as other military operations including those conducted within the context of the right of self-defense must be considered in this context.11 While in different military operations applicable norms will in principle be distinct, common standards may be required under considerations of both military effectiveness and good governance. It may also be held that not only enforcement and peace enforcement operations, but peace operations in general are affected by international humanitarian law, even if this perception is not explicitly confirmed in treaty law.12 Similarly, the United States requires its forces to “comply with the law of war during all armed conflicts, however such conflicts are characterized, and in all other military operations.”13
Different Approaches and Controversies
From a theoretical perspective, many relevant issues of this debate can be approached in different ways, even without getting in conflict with fundamental principles and rules of international humanitarian law.
For a convincing legal evaluation one may look at the specific act committed in a given situation, before identifying it as direct participation in hostilities. But any such case-oriented evaluation can open a revolving door for individuals engaged in peaceful activities during the day and acting as fighters at night on a regular basis, thus misusing the legal protection of civilians for recurring intervals of participation in the hostilities.
Hence it appears convincing in a non-international armed conflict to consider whether a person has functional membership in an organized armed opposition group and to accept loss of protection for the duration of such membership rather than just for the duration of each specific act. A person so identified is of course not entitled to the combatant privilege. He or she may be prosecuted before national courts for having participated in the fighting. But what is important for the duration of the armed conflict is that such person may not be targeted differently from any combatant in an international armed conflict.
What does targeting mean in this context? Considering the method and purpose of military operations even in an armed conflict, it does not necessarily mean killing, but identifying a threat, intercepting an attack, and effectively incapacitating the attacker. How this can be achieved is a matter of military necessity. There may be no alternatives to killing, but where alternatives exist, the use of deadly force will be limited, and such limitation then derives from legal, military and political reasons.
The problem here is the lack of clear, unequivocal rules on the issue and a potential misuse by those involved in the planning and execution of operations on either side of an armed conflict. Who enjoys legal protection as a civilian and who may be considered as “functional member” of an organized armed group? Has it been sufficiently established that there is a lasting integration of the concerned individual into the organized armed force or group rather than a spontaneous, sporadic, exceptional or otherwise temporary role assumed for the duration of a particular operation? How should a commander or a soldier in combat be satisfied that a person belonging to an enemy group has a continuous combat function for that group rather than a mere logistic support function? What are the requirements for making such a decision in the course of fighting? Would it suffice legally to react at a first glance as may be necessary in the course of operations or is there a requirement for more detailed examination?
There was much debate among the government and academic experts invited by the ICRC as to the constitutive elements of direct participation in hostilities. Recall the example of the civilian truck driver transporting ammunition to the battlefield: may he or she be considered as directly participating in the hostilities, while a colleague driving a similar load of ammunition to be shipped in the next harbor would, generally speaking, not be so regarded? A dividing line must be drawn between general support for a party to the conflict and direct participation in the hostilities.
Yet even in an informed community of experts, positions taken on these issues may be rather controversial. While some would limit the definition of “directly participating in hostilities” to those engaged in the physical act of employing a weapon, others argue that any individual performing an indispensable function in making possible the application of force in hostilities, including construction work that directly relates to immediate combat operations, might well amount to direct participation.14 While the former opinion fails to consider the nature of modern combat with its new realities, covert actions and technological developments, the latter would severely endanger the protection of civilians, one of the fundamental pillars on which international humanitarian law is founded. Lawyers from the ICRC have always taken a more balanced position between such extreme opinions. The ICRC Commentary to the 1977 Additional Protocols explains “‘direct’ participation means acts of war which by their nature or purpose are likely to cause actual harm to the personnel and equipment of the enemy armed forces.”15
As explained in the Interpretive Guidance, even preparatory measures may amount to direct participation in hostilities, if they are “of a specific military nature and so closely linked to the subsequent execution of a specific hostile act that they already constitute an integral part of that act.”16 This is confirmed in Article 44 (3) AP I, which requires combatants to distinguish themselves from the civilian population not only while they are engaged in an attack, but also “in a military operation preparatory to an attack”. But it would certainly go too far to include activities of a more general nature, such as participation in purchasing, producing, smuggling and hiding of weapons, general recruitment and training of personnel, or financial, administrative or political support to armed actors,17 as this, indeed, “would bring the entire war effort within the concept of direct participation in hostilities and, thus, would deprive large parts of the civilian population of their protection against attack.”18 Hence a difference must be made between civilian support personnel and those directly participating in hostilities.
How should human shields be qualified in this context? Article 51 (7) AP I and customary international humanitarian law provide that movements of the civilian population or individual civilians shall not be used to render certain points or areas immune from military operations, in particular to shield military objectives from attacks or to shield, favor or impede military operations. But may civilians voluntarily shielding a military objective or denying access to a bridge used for military transport be considered as directly participating in hostilities? The Interpretive Guidance correctly distinguishes between the military objective itself and civilians voluntarily abusing their legal entitlement to protection in order to shield such an objective from attack. It acknowledges that these civilians do incur an increased risk of suffering incidental death or injury during attacks against the military objective, but they would not, “without more, entail the loss of their protection and their liability to direct attack independently of the shielded objective.”19
How should combatants act in case of doubt? Is it enough for military commanders to refer to the general rule enshrined in Article 50 (1) AP I: “In case of doubt whether a person is a civilian, that person shall be considered to be a civilian.” What does this mean in practice for a fighting soldier confronted with the dangers of the battlefield?
How exactly may the beginning and end of direct participation in hostilities be defined? What factual behavior is necessary before a person is eligible for claiming legal protection as a civilian?
Discussing these issues with the aim of identifying general elements to facilitate adequate case-by-case decisions for situations of armed conflict, the experts considered various scenarios for general definitions to be applied. In many cases, no unanimous solution could be reached. Although the general principles of the law are clear, the application of such principles in a given situation may, indeed, be controversial.
In this situation the ICRC gave considerable input. In raising the general issue, posing questions and writing reports for several meetings organized together with the T.M.C. Asser Institute, a co-sponsor of this project from its inception and excellently represented by Avril McDonald, the ICRC took a practice-oriented approach to clarify existing rules by transparent discussion on a spectrum of practical examples and their underlying legal principles. Compared to any alternative, this approach appeared to be the most successful and convincing. It helped to identify a considerable amount of common ground, remove gray areas, and narrow down controversies. In discussions with the experts the ICRC made an inventory of problems and solutions. All participants were invited to cooperate in their personal capacity and observe Chatham House rules, so that none of the opinions expressed should be attributed to states or organizations or even to the experts themselves. Comprehensive reports were written by the ICRC,20 which also took the sole responsibility for the final product, the Interpretive Guidance with Recommendations and Commentaries for consideration by states and nonstate actors.
Controversies focused on a wider or narrower concept of functional membership, on the duration of loss of protection in the event of concurrent participation in hostilities, and on restraints on the use of force. On these issues the ICRC quite naturally took a more restrictive position than others, thus emphasizing the protection of civilians who are not directly or no longer involved in the hostilities. The ICRC has also convincingly insisted from the very beginning of this discussion process that it was necessary to include the question of whether and to what extent there are general constraints to be observed on the use of force in direct attack. Thus, experts were requested to re-discuss the famous statement made decades ago by Jean S. Pictet: “[i]f we can put a soldier out of action by capturing him, we should not wound him; if we can obtain the same result by wounding him, we must not kill him. If there are two means to achieve the same military advantage, we must choose the one which causes the lesser evil.”21 The argument was made and widely shared that operating forces can hardly be required to take additional risks for themselves or the civilian population in order to capture an armed adversary alive. Restraints on the use of force that may be uncontroversial in peacetime or even in times of occupation, will work out differently in a situation of conflict. Hence it appeared difficult to translate Pictet’s statement into modern rules of engagement, but the principle is valid nevertheless that “it would defy basic notions of humanity to kill an adversary or to refrain from giving him or her an opportunity to surrender where there manifestly is no necessity for the use of lethal force.”22
The discussion process revealed a wide spectrum of legal controversies on the conduct of military operations. While there is certainly a need for unified approaches, it would be less than realistic to expect consensus on all aspects of the issue quite easily. A treaty solution for this difficult and conflict-loaded problem would hardly meet enthusiasm by states. It may also be disputed whether new treaty law could sufficiently solve the issue, as each situation has to be looked at on its own merit and different conclusions may still be drawn when it comes to the application of general principles in a specific case.
It would have been possible to leave these discussions to the many individual writings in the field of international humanitarian law or to wait for jurisprudence of national or international courts, which might clarify specific situations in certain armed conflicts. Yet a broad and practice-oriented discourse could hardly be expected on this route, nor would it have led to enlarging the general understanding of or even global consensus on the issue. The approach taken is clearly to be appreciated and the ICRC deserves all support for having started a discussion process that is convincingly shaped and influenced, but certainly not ended by the publication of its Interpretive Guidance.
The Role of the ICRC, International Organizations, States, and Individuals
What is the status of this Guidance and how should it be used by states and international organizations? As a neutral and independent humanitarian organization mandated by the international community of states to promote and work for a better understanding of international humanitarian law,23 the ICRC has opened a very transparent discourse based on a wealth of experience gathered by its delegates in missions all over the world and seeking participation by practitioners from states and relevant international organizations, and by academia. Rather than engaging states in negotiating new rules on the topic, the ICRC chose to provide an inventory of problems and shape its institutional opinion on legal solutions to be achieved.
The outcome of the effort taken by the ICRC is based on well-founded arguments. Yet, it may be challenged with counter-arguments. By acting transparently as it did, the ICRC made it easy for all participants invited to express even their critical opinion. But clearly the end product, the Interpretive Guidance, provides a very solid and professional legal work that cannot be dismissed easily as long as legal arguments are considered relevant.
Experts may of course differ in their opinions; yet, it is also true that states and international organizations have an interest in unifying their approach to ensure good conduct for multinational military operations. The idea of a ‘great schism’ on the application of the law of armed conflict, which at times dominates academic debates, has never been convincing. Quite on the contrary: current practice in multinational military operations shows that problems deriving from different legal obligations are not insurmountable in reality.24 It would, indeed, be neither responsible nor fully professional to let differences of opinion in the application of international humanitarian law negatively affect the planning and execution of military operations. Too strong is the need for coordinating such operations among participating states, and too important is it for States to convince the public of the approach taken to defend or re-establish the rule of law. The Interpretive Guidance is an excellent tool that should be used for informed planning and decision-making. It may thus serve as a good foundation for any effort to develop a coalition consensus on the meaning of direct participation of hostilities.
It is for this reason that one should welcome discussions by states and international organizations with the ICRC to identify relevant legal issues and solve possible differences in the application of international humanitarian law.25 The notion of direct participation in hostilities deserves to be high on this agenda. I would encourage experts engaged in military operations including robust peace operations to participate in this process, so that an informed dialogue with the ICRC and troop-contributing states could be conducted with a view to supporting both the rule of law and the effectiveness of military operations.
This dialogue could contribute to avoid misunderstandings, further clarify relevant legal principles, and solve potential differences. It may show that the Interpretive Guidance has laid out important criteria generally reflecting a consensus view, even if not all aspects will be automatically shared in day-to-day implementation. There is a need for reconsideration of humanitarian principles and rules in the conduct of military operations and the groundwork provided by the ICRC in this context should be used in a proactive manner. To conclude, however, that its criteria for the direct targeting of nonstate actors are flawed26 fails to offer a convincing assessment. Critical discussions remain essential to ensure compliance with international humanitarian law, but they should not obscure its object and purpose, which is to provide a good balance between military necessity and requirements of humanity. It would be less than convincing for States that actually go to war to pretend that they cannot countenance a normative paradigm establishing this balance.
International humanitarian law applies likewise to all belligerents. There are no two-tiered standards for state security forces and nonstate armed opposition groups. Nor does the obligation to respect and ensure respect of norms of international humanitarian law depend on reciprocity. What is needed is a continued discussion of humanitarian principles and the comprehension that these principles are deeply connected with good governance. It is in the interest of states to further this discussion and to strengthen the implementation of existing rules that are as relevant for the ultimate success of military operations as for any lasting peace.
Dieter Fleck, Dr. iur. (Cologne) was formerly Director of International Agreements & Policy, at the German Ministry of Defense. He serves as Honorary President for the International Society for Military Law and the Law of War, http://www.soc-mil-law.org. Dr. Fleck is a member of the Advisory Board of the Amsterdam Center for International Law (ACIL), http://www.jur.uva.nl/aciluk/home.cfm, and is a rapporteur of the Committee on Nuclear Weapons, Non-proliferation and Contemporary International Law, established by the International Law Association, http://www.ila-hq.org.
* This Article is dedicated to the memory of Avril McDonald, a colleague and friend who has passed away on 14 April 2010 amidst many activities she has pursued with admirable energy and talent.
1. Fleck (ed.), The Handbook of International Humanitarian Law, 2nd ed. (Oxford: Oxford University Press, 2008), Section 208.
2. E.g. SC Res. 1265 (1999); 1296 and 1304 (2000); 1333, 1355, 1366, 1369, 1378, and 1386 (2001); 1398, 1400, 1429, and 1439 (2002); 1466, 1468, 1479, 1472, 1484, 1493, 1495, and 1502 (2003); 1509 (2003); 1528, 1535, 1544, 1545, 1547, 1565, and 1566 (2004); 1572, 1574, 1591, 1593, 1612, 1633, 1637, 1635, 1643, and 1649 (2005); 1653, 1662, 1672, and 1674 (2006); 1779, 1782, and 1787 (2007); 1795, 1805, 1806, 1807, 1822, 1826, 1833, 1834, 1842, 1843, 1856, and 1857 (2008); 1861, 1863, 1865, 1868, 1880, 1894, and 1904 (2009); 1911 and 1917 (2010); see G. Nolte, ‘The Different Functions of the Security Council With Respect to Humanitarian Law, in: V. Lowe, A. Roberts, J. Welsh, and D. Zaum (eds.), The United Nations Security Council and War. The Evolution of Thought and Practice since 1945 (Oxford: Oxford University Press, 2008), 519-34.
3. Arts. 43 of the Hague Regulations (1907) and 64 of the Fourth Geneva Convention (1949).
4. Cf. SC Res. 1483 and 1511 (2003).
5. European Union Guidelines on promoting compliance with international humanitarian law, 2005/C 327/04, 1, Official Journal of the European Union (23 December 2005).
6. N. Melzer, Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law (Geneva: ICRC, 2009), http://www.icrc.org/web/eng/siteeng0.nsf/html/p0990?opendocument (last visited 30 April 2010).
7. Common Art. 3 GC I-IV; Art. 51 (3) AP I; Art. 13 (3) AP II.
8. J.-M. Henckaerts and L. Doswald-Beck (eds.), Customary International Humanitarian Law (Cambridge University Press, 2005), Rule 6. The same position is taken by the Supreme Court of Israel in I. Public Committee Against Torture in Israel and II. Palestinian Society for the Protection of Human Rights and the Environment v The Government of Israel, Judgment of 13 December 2006 (HCJ 769/02), para 30.
9. Fleck, ‘Law Enforcement and the Conduct of Hostilities: Two Supplementing or Mutually Excluding Legal Paradigms?’, in: A. Fischer-Lescano/H.-P. Gasser/T. Marauhn/N. Ronzitti (eds..), Frieden in Freiheit. Peace in liberty. Paix en liberté. (Baden-Baden: Nomos, Zürich: DIKE, 2008), 391-407, at 401-5.
10. See above, (n. 6), at 11.
11. See T. Gill and D. Fleck (eds.), The Handbook of the International Law of Military Operations (Oxford: Oxford University Press, forthcoming in 2010).
12. Fleck (ed.), op. cit. (n. 1), Sections 208, 263, 1301-52.
13. Department of Defense, Law of War Program (DoD Directive 2311.01E, 9 May 2006), at para. 4.1; US Navy, US Marine Corps, US Coast Guard, The Commander’s Handbook on the Law of Naval Operations (NWP 1-14M, MCWP 5-12.1, COMDTPUB P5800.7A), para. 6.1.2, (June 2007); Rule of Law Handbook. A Practitioner’s Guide for Judge Advocates (Charlottesville, Va.: The Judge Advocate General’s Legal Center and School, U.S. Army Center for Law and Military Operations, 2009), at 77.
14. M. Schmitt, ‘“Direct Participation in Hostilities” and 21st Century Armed Conflict’, in H. Fischer, U. Froissart, W. Heintschel v. Heinegg, C. Raap (eds.), Krisensicherung und Humanitärer Schutz – Crisis Management and Humanitarian Protection (Berlin: BWV, 2004), 505-29; same author, ‘Humanitarian Law and Direct Participation in Hostilities by Private Contractors or Civilian Employees’, in 5 Chicago Journal of International Law (2005), 511-546.
15. C. Pilloud and J.S.Pictet in Y. Sandoz, C. Swinarski and B. Zimmermann (eds.), Commentary to the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949 (Geneva: ICRC, 1987), Art. 51 AP I, para 1944.
16. See above (n. 6), 65-66.
17. See above (n. 6), 66-67.
18. See above (n. 6), 52.
19. See above (n. 6), 57.
20. These reports are available at http://www.icrc.org/web/eng/siteeng0.nsf/htmlall/direct-participation-ihl-feature-020609 (last visited 30 April 2010).
21. J. Pictet, Development and Principles of International Humanitarian Law (Dordrecht: Nijhoff, 1985), 75.
22. Cf. above (n. 6), 82. See N. Melzer, Targeted Killing in International Law (Oxford: Oxford University Press, 2008), 289.
23. See, e.g., Art. 5 (2) (c) and (g) Statutes o the International Red Cross and Red Crescent Movement.
24. As mentioned by L. C. Green, The Contemporary Law of Armed Conflict, 2nd edn. (Manchester/New York: Manchester University Press, 2000), xv, during the 1991 war in the Gulf, which was fought by the United States alongside a coalition of 26 States in which no common legal obligations as to AP I did exist, White House press releases on aerial bombardments extensively used language of Art. 51 (5) of that Protocol (one of the most controversial provisions in the perception of the U.S. Administration which had been used as one of its arguments against ratification), to describe how precision strikes in Iraq had been planned and executed. The Chairman of the U.S. Joint Chiefs of Staff , General Colin Powell, in his Report to Congress on Coalition operations in the Gulf, had gone even further in stating that the provisions of AP I were, for the main part, applied as if they constituted customary law, see Department of Defense, ‘Conduct of the Persian Gulf War: final report to Congress’ (1992), 696, 700–703.
25. For an excellent critical review see e.g. D. Akande, ‘Clearing the Fog of War? The ICRC’s Interpretive Guidance on Direct Participation in Hostilities’, 59:1 International and Comparative Law Quarterly (January 2010), 180-192. A restrictive and less than comprehensive use of the Interpretive Guidance is made in the Commentary on the HPCR Manual on International Law Applicable to Air and Missile Warfare (Harvard: Program on Humanitarian Policy and Conflict Research, 2010), Rules 28-29 (pp. 117-23).
26. Cf. M. Schmitt, ‘The Interpretive Guidance on the Notion of Direct Participation in Hostilities: A Critical Analysis’, 1 Harvard National Security Journal (May 2010), http://www.harvardnsj.com/volumes/vol1/schmitt/). See also the contributions by K. Watkin, M. Schmitt, W. Boothby, and W. H. Parks, setting forth various concerns with the Interpretive Guidance, as well as the detailed response by N. Melzer, in 42:3 New York University Journal of International Law and Politics (forthcoming in 2010, http://www.law.nyu.edu/journals/jilp/issues/index.htm).
 C. Greenwood , R. Wolfrum, and Fleck, in Fleck (ed.), op. cit. (n. 1), Sections 102 (para. 2), 206, 1201 (para. 3b), 1219, 1402 (paras. 3-4), and 1404 (para. 1); Henckaerts and Doswald-Beck (eds.), op. cit. (n. 8), Rule 140.