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Section IX of the ICRC Interpretive Guidance on Direct Participation in Hostilities: The End of Jus in Bello Proportionality as We Know It?

Published online by Cambridge University Press:  05 March 2012

Jann K Kleffner
PhD, LLM, Head of the International Law Centre, Associate Professor of International Law, Swedish National Defence College. The research assistance of Ana-Sofia Valderas is gratefully acknowledged. Email:
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Section IX of the ICRC Interpretive Guidance on Direct Participation in Hostilities asserts: ‘In addition to the restraints imposed by international humanitarian law on specific means and methods of warfare, and without prejudice to further restrictions that may arise under other applicable branches of international law, the kind and degree of force which is permissible against persons not entitled to protection against direct attack must not exceed what is actually necessary to accomplish a legitimate military purpose in the prevailing circumstances’. The present article scrutinises arguments that have been, or can be, advanced in favour of and against a ‘least harmful means’ requirement for the use of force in situations of armed conflict as suggested in Section IX. The principal aim of the article is to examine the question whether such an additional proportionality requirement forms part of the applicable international lex lata.

Copyright © Cambridge University Press and The Faculty of Law, The Hebrew University of Jerusalem 2012

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1 See, for example, Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I) (entered into force 7 December 1978) 1125 UNTS 3 (‘AP I’), arts 51(5)(b) and 57(2)(a)(iii).

2 cf Henckaerts, Jean-Marie and Doswald-Beck, Louise, Customary International Humanitarian Law, Vol I: Rules, (ICRC, CUP 2005)CrossRefGoogle Scholar (‘ICRC Study’) Rules 14, 46.

3 ICRC, ‘Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law’ (‘ICRC Guidance’), 77, available at (emphasis added).

4 See, for example, Melzer, Nils, Targeted Killing in International Law (OUP 2008) 297, 397–99CrossRefGoogle Scholar; Melzer, Nils, ‘Targeted Killing or Less Harmful Means? – Israel's High Court Judgment on Targeted Killing and the Restrictive Function of Military Necessity’ (2006) 9 Yearbook of International Humanitarian Law 87CrossRefGoogle Scholar (‘Melzer, YIHL’).

5 Most notably, HCJ 769/02 Public Committee Against Torture in Israel and Palestinian Society for the Protection of Human Rights and the Environment v Israel and Others ILDC 597 (IL 2006) [2006] (‘Public Committee Against Torture’) para 40.

6 ICRC Guidance (n 3) 78–82; Melzer, YIHL (n 4).

7 Fourth Expert Meeting on the Notion of ‘Direct Participation in Hostilities under IHL’, Geneva, 27–28 November 2006, Background Document, ‘Draft Interpretive Guidance on the Notion of Direct Participation in Hostilities’, 47; Fifth Expert Meeting on the Notion of ‘Direct Participation in Hostilities under IHL’, Geneva, 5–6 February 2008, Background Document, ‘Expert Comments and Elements of Response concerning the Revised Draft of the Interpretive Guidance on the Notion of Direct Participation in Hostilities’, 39; Expert Meeting on the Notion of ‘Direct Participation in Hostilities under IHL’, Report, 19. Documents available at

8 For situations of non-international armed conflict, see Sassòli, Marco and Olson, Laura M, ‘The Relationship Between International Humanitarian and Human Rights Law Where it Matters: Admissible Killing and Internment of Fighters in Non-international Armed Conflicts’ (2008) 90 International Review of the Red Cross 599, 613–14CrossRefGoogle Scholar.

9 See, among others, Schmitt, Michael N, ‘The Interpretive Guidance on the Notion of Direct Participation in Hostilities: A Critical Analysis’ (2010) 1 Harvard National Security Journal 5, 3943Google Scholar; Parks, W Hays, ‘Part IX of the ICRC “Direct Participation in Hostilities” Study: No Mandate, No Expertise, and Legally Incorrect’ (2010) 42 New York University Journal of International Law & Policy 769Google Scholar.

10 ICRC Guidance (n 3), 78–79.

11 ibid 79.

12 ibid.

13 ibid.

14 ibid 80–81.

15 Public Committee against Torture (n 5).

16 ibid.

17 ICRC Guidance (n 3) 82.

18 See, generally, Koskenniemi, Martti, From Apology to Utopia: The Structure of International Legal Argument (CUP 2006)CrossRefGoogle Scholar.

19 In this vein, see also Pilloud, Claude, Pictet, Jean, Sandoz, Yves and Swinarski, Christophe, Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949 (Martinus Nijhoff 1987)Google Scholar (‘AP I Commentary’) 393 (‘when the law of armed conflict does not provide for any prohibition, the Parties to the conflict are in principle free within the constraints of customary law and general principles’).

20 For that discussion in general see, among others: Meron, Theodor, ‘The Martens Clause, Principles of Humanity, and Dictates of Public Conscience’ (2000) 94 American Journal of International Law 78CrossRefGoogle Scholar; Cassese, Antonio, ‘The Martens Clause: Half a Loaf or Simply Pie in the Sky?’ (2000) 11 European Journal of International Law 187CrossRefGoogle Scholar; Ticehurst, Rupert, ‘The Martens Clause and the Laws of Armed Conflict’ (1997) 37 International Review of the Red Cross 125CrossRefGoogle Scholar. For the more specific discussion of the Martens Clause in connection with Section IX during the expert process that preceded the adoption of the ICRC Guidance, see Fifth Expert Meeting on the Notion of Direct Participation in Hostilities (n 7) 22.

21 cf art 31(3)(b) of the 1969 Vienna Convention on the Law of Treaties (signed 23 May 1969, entered into force 27 January 1980) 1155 UNTS 331 (‘Vienna Convention’). For the disparate submissions of a number of states on the meaning of the Martens Clause in the course of the proceedings before the International Court of Justice (ICJ) that preceded its Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons [1996] ICJ Rep 226 (‘Nuclear Weapons’), see the summary in Ticehurst (n 20).

22 As for the ICJ, nothing in its Nuclear Weapons Advisory Opinion suggests such an interpretation, which led some Judges to dissent from it and express a different opinion: see, for example, Nuclear Weapons (n 21), Dissenting Opinion of Judge Shahabuddeen, 375–428, 406–11. The International Criminal Tribunal for the Former Yugoslavia (ICTY) has applied the Martens Clause as an aid to interpret a given rule of positive international law (see, for example, ICTY, Prosecutor v Kupreškić, Judgment, IT-95-16-T, Trial Chamber, 14 January 2000, [525]) and as a justification to emphasise opinio juris over state practice when establishing a rule of customary international law (ibid [527]). Neither of these constructions suggests that the principles of humanity and dictates of public conscience, to which the Martens Clause refers, constitute independent sources of international law.

23 ICRC Guidance (n 3) 79 (emphasis added).

24 Schmitt, Michael N, ‘Military Necessity and Humanity in International Humanitarian Law: Preserving the Delicate Balance’ (2010) 50 Virginia Journal of International Law 796, 801Google Scholar.

25 McCoubrey, Hilary, ‘The Nature of the Modern Doctrine of Military Necessity’ (1991) 30 Military Law and Law of War Review 215, 219–21Google Scholar.

26 See, for example, the obligation to give advance warning as a precautionary measure ‘unless circumstances do not permit’: AP I, art 57(2)(c).

27 See, for example, as regards attacking objects indispensable to the survival of the civilian population within a state's own territory, ibid, art 54(5).

28 On the two dimensions (restrictive and permissive) of military necessity, see Melzer, YIHL (n 4) 104–11. He refers to the permissive function of military necessity as justifying ‘those measures which are indispensable for securing the ends of the war, and which are lawful according to the modern law and usages of war’ and the ‘justifying factor inherent in all rules of IHL which, in derogation from the rules applicable in peacetime, permit the resort to measures meeting the needs of the extreme circumstances prevailing in situations of armed conflict’ (104). The restrictive function of military necessity, on the other hand, manifests itself in the maxim ‘necessity is the limit of legality’, essentially prohibiting ‘the employment of any kind or degree of force in excess of what is required for the accomplishment of a legitimate military purpose in the concrete circumstances’ (108).

29 According to the nineteenth-century doctrine of Kriegsraison geht vor Kriegsmanier (the necessities of war take precedence over the rules of war), violations of the law of armed conflict were justified when compliance was considered to jeopardise the conflict's ultimate aim of overcoming the enemy. The doctrine has since been abandoned and rejected in a string of cases: see, for example, United States v List (The Hostage Case), Case no 47 (19 February 1948), United Nations War Crimes Commission. Law Reports of Trials of War Criminals, vol VIII, (1949) 66–67.

30 On retreating armed forces see, for example, United States: Defense Department Report to Congress on the Conduct of the Persian Gulf War – Appendix on the Role of the Law of War (10 April 1992) 31 International Legal Materials 612, 631–32. See also United States Field Manual – Legal Support to the Operational Army, FM 27-100, 1 March 2000, para 8.2.5, available at See also Dinstein, Yoram, ‘The System of Status Groups in International Humanitarian Law’ in von Heinegg, Wolff Heintschel and Epping, Volker (eds), International Humanitarian Law Facing New Challenges: Symposium in Honour of Knut Ipsen (Springer 2007), 145–56CrossRefGoogle Scholar.

31 See AP I (n 1) art 53(b); Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of Non-International Armed Conflicts (entered into force 7 December 1978) 1125 UNTS 609 (‘AP II’), art 16.

32 ICTY, Prosecutor v Tihomir Blaškić, Judgment, IT-95-14-T, Trial Chamber, 2 March 2000, [180] (emphasis added).

33 ICTY, Prosecutor v Tihomir Blaškić, Judgment, IT-95-14-A Appeals Chamber, 29 July 2004, [109].

34 cf ICRC Study (n 2) 237, with further references to treaty provisions.

35 See above (n 7).

36 Melzer, Nils, ‘Keeping the Balance Between Military Necessity and Humanity: A Response to Four Critiques of the ICRC's Interpretive Guidance on the Notion of Direct Participation in Hostilities’ (2010) 42 New York University Journal of International Law & Politics 831, 905–6Google Scholar.

37 See Pictet, Jean, Development and Principles of International Humanitarian Law (Martinus Nijhoff 1985) 76Google Scholar; ICRC, Report on the Work of Experts relating to ‘Weapons that may Cause Unnecessary Suffering or have Indiscriminate Effects, 1973, 13: ‘if a combatant can be put out of action by taking him prisoner, he should not be injured; if he can be put out of action by injury, he should not be killed; and if he can be put out of action by light injury, grave injury should be avoided’.

38 Melzer (n 36), 905–6.

39 Nuclear Weapons (n 21), 257.

40 For an exhaustive treatment of the principle, see Boutruche, Theo, L'Interdiction des maux superflus: Contribution à l’étude des principes et règles relatifs aux moyens et méthodes de guerre en droit international humanitaire (PhD thesis, Geneva/Marseille, 2008)Google Scholar.

41 For an exploration of that argument, ibid, 34–58, especially 47–58.

42 Vienna Convention (n 21) art 31(1).

43 The negotiating history of extending the otherwise well-established prohibition beyond means of warfare (i.e. weapons, projectiles and material) to also include ‘methods’ in art 35(2) AP I reveals that states were less than certain about what was meant. See, for example, the statement of Australia, CDDH/III/SR.38, Committee III, Summary Records of the 38th meeting, 10 April 1975, para 51. It is equally telling that, while the ICRC Study includes the notion of ‘methods’ in the customary prohibition in Rule 70, the interpretive section accompanying Rule 70 and the examples provided address weapons exclusively: see ICRC Study (n 2) 237, 241–44.

44 Vienna Convention (n 21) art 31(3)(b).

45 Public Committee against Torture (n 5).

46 ICRC Study (n 2) 237, 241–44.

47 See, for example, Ilascu and Others v Moldova and Russia App no 48787/99 (ECtHR, 8 July 2004), para 312, in which the European Court of Human Rights held: ‘[The presumption that jurisdiction within the meaning of art 1 of the European Convention on Human Rights] is exercised normally throughout the state's territory may be limited in exceptional circumstances, particularly where a state is prevented from exercising its authority in part of its territory. That may be as a result of military occupation by the armed forces of another state which effectively controls the territory concerned (see Loizidou v Turkey, Preliminary Objections, Judgment, 23 March 1995, Series A no 310, and Cyprus v Turkey [GC], no 25781/94, ECHR 2001/IV, paras 76–80, as cited in the above-mentioned Banković decision, paras 70–71), acts of war or rebellion, or the acts of a foreign state supporting the installation of a separatist state within the territory of the state concerned.’ See also para 330. Note, however, that the Court nevertheless held (at para 331) a State Party to have the positive obligation under art 1 of the European Convention to take the diplomatic, economic, judicial or other measures that are in a State Party's power and in accordance with international law to secure to individuals the rights guaranteed by the Convention (all emphases added). See also UN Human Rights Committee, Concluding Observations: Cyprus (1998) UN Doc CCPR/C/79/Add.88, para 3; and Concluding Observations on Lebanon (1997) UN Doc CCPR/C/79/Add.78 paras 4–5.

48 International Covenant on Civil and Political Rights (opened for signature 19 December 1966, entered into force 23 March 1976) 999 UNTS 171 (‘ICCPR’), art 2(1). Note the differing wording in the European Convention on Human Rights and Fundamental Freedoms (entered into force 3 September 1953) 213 UNTS 222 (‘European Convention’), art 1 (‘to everyone within their jurisdiction’), and the American Convention on Human Rights (opened for signature 22 November 1969, entered into force 18 July 1978) 1144 UNTS 123 (‘ACHR’), art 1(1) (‘to all persons subject to their jurisdiction’).

49 HRC General Comment no 31: Nature of the General Legal Obligation on States Parties to the Covenant, UN Doc CCPR/C/21/Rev.1/Add.13, 26 May 2004, para 10; Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion [2004] ICJ Rep 136, [108]–[112]; Case Concerning Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda), Judgment, 19 December 2005, [2005] ICJ Rep 168 [216]; Loizidou v Turkey, Preliminary Objections, 23 March 1995, ECHR (ser A) 310, para 62; Loizidou v Turkey, Merits, ECHR 1996-VI, paras 52, 56; Cyprus v Turkey ECHR 2001-IV, para 77; Ilascu (n 47); Al Skeini and Others v United Kingdom App no 55721/07 (ECtHR, 7 July 2011), paras 138–140. For an overview of domestic court judgments, see Droege, Cordula, ‘The Interplay between International Humanitarian Law and International Human Rights Law in Situations of Armed Conflict’ (2007) 40 Israel Law Review 310, 325–30CrossRefGoogle Scholar. Note that the Inter-American Commission on Human Rights (‘IACHR’) and Court employ instead the notions of ‘authority and control’: Coard and Others v United States, Case 10.951, Report no 109/99, 29 September 1999, IACHR, para 37. However, these latter notions of ‘authority and control’ overlap to a significant extent with the notion of effective control, although they are not identical.

50 See, for example, the positions taken by the Netherlands, Israel, UK and the USA before the Human Rights Committee, referred to in Droege, ibid, 326 (fn 64). For a critique of the position taken by the Human Rights Committee, see Dennis, Michael J, ‘Application of Human Rights Treaties Extraterritorially in Times of Armed Conflict and Military Occupation’ (2005) 99 American Journal of International Law 119CrossRefGoogle Scholar.

51 See, for example, UN Human Rights Committee, Delia Saldias de Lopez v Uruguay, UN Doc CCPR/C/13/D/52/1979, 29 July 1981, para 12.1; UN Human Rights Committee, Concluding Observations on Israel, UN Doc CCPR/C/79/Add.93, 18 August 1998, para 10; Concluding Observations on Israel, UN Doc CCPR/CO/78/ISR, 21 August 2003, para 11; Loizidou (n 49); Ocalan v Turkey ECHR 2005-IV, para 91; Issa and Others v Turkey, App no 31821/96 (ECtHR, 16 November 2004), para 71; IACHR, Decision on Request for Precautionary Measures (Detainees at Guantanamo Bay, Cuba), 12 March 2002, (2002) 41 International Legal Materials 532.

52 Against: Banković and Others v Belgium and Others, Decision on Admissibility, App no 52207/99 (ECtHR, 12 December 2001), paras 75–80; Pro: IACHR, Armando Alejandre Jr and Others v Cuba (‘Brothers to the Rescue’), Report no 86/99, Case no 11.589, 29 September 1999, para 25, available at

53 ICCPR (n 48) art 4(1); ECHR (n 48) art 15; ACHR (n 48) art 27.

54 On these requirements, see Eighth United Nations Congress on the Prevention of Crime and the Treatment of Offenders, Havana, Cuba, ‘UN Basic Principles on the Use of Force and Firearms by Law Enforcement Officials’ (1990), Principles 4, 5, and 9. For a succinct account of relevant jurisprudence of the Human Rights Committee, the European Court of Human Rights and the Inter-American Commission and Court of Human Rights, see University Centre for International Humanitarian Law, Expert Meeting on the Right to Life in Armed Conflicts and Situations of Occupation (2005), 8–14, available at

55 cf Nuclear Weapons (n 21) [25]; Legal Consequences of the Construction of a Wall (n 49) [106]; Armed Activities on the Territory of the Congo (n 49) [216].

56 Nuclear Weapons, ibid.

57 Legal Consequences of the Construction of a Wall (n 49) [106].

58 University Centre for International Humanitarian Law (n 54) 23–24. Whether and to what extent human rights law also governs the use of force in calm situations of occupation for other purposes is subject to divergent opinions amongst experts: ibid.

59 Sassòli and Olson (n 8) 613–14.

60 ibid.

61 Public Committee against Torture (n 5).

62 ibid para 40.

63 ibid.

64 See generally on that precept, Meyrowitz, Henri, Le principe de l’égalité des belligérants devant de droit de la guerre (Pedone 1970)Google Scholar; Bugnion, Francois, ‘Jus ad Bellum, Jus in Bello and Non-International Armed Conflicts’ (2003) 6 Yearbook of International Humanitarian Law 167, 174CrossRefGoogle Scholar.

65 That customary process consists, among others, of instances in which UN organs and other bodies have addressed organised armed groups in monitoring human rights and/or condemning human rights violations. See, for example, Report of the United Nations High Commissioner for Human Rights and Follow-up to the World Conference on Human Rights: Situation of Human Rights in the Darfur Region of the Sudan’ Commission on Human Rights, UN Doc E/CN.4/2005/3, 7 May 2004, para 47, in which the Human Rights Commission stated that ‘[t]he rebel forces also appear to violate human rights and humanitarian law’; Report of the Special Rapporteur, Philip Alston, Addendum, ‘Mission to Sri Lanka’ (28 November to 6 December 2005), UN Doc E/CN.4/2006/53/Add.5, 27 March 2006, especially paras 24–27 and accompanying footnotes. For the Security Council, see, for example, UNSC Res 1814(2008) on the situation in Somalia, 15 May 2008, para 16, addressed to ‘all parties in Somalia’; UNSC Res 1778(2007) on the situation in Chad, the Central African Republic and the subregion, 25 September 2007, Preamble (‘activities of armed groups and other attacks in eastern Chad, the north-eastern Central African Republic and western Sudan which threaten the security of the civilian population, the conduct of humanitarian operations in those areas and the stability of those countries, and which result in serious violations of human rights and international humanitarian law’). For further relevant resolutions of the Security Council and the General Assembly pertaining to violations of human rights (as well as humanitarian law) committed in the Former Yugoslavia, Afghanistan, the Sudan, Sierra Leone, Ivory Coast, the Congo, Angola, Liberia and Somalia, and further discussion, see Tomuschat, Christian, ‘The Applicability of Human Rights Law to Insurgent Movements’ in Fischer, Horst and others, (eds), Krisensicherung und Humanitärer Schutz – Crisis Management and Humanitarian Protection, Festschrift für Dieter Fleck (BWV, Berlin 2004) 577–85Google Scholar.

66 For contrary practice that supports this conclusion, see Zegveld, Liesbeth, Accountability of Armed Opposition Groups in International Law (CUP, 2002) 3946CrossRefGoogle Scholar.

67 Armando Alejandre Jr (n 52) para 23.

68 See nn 49–52 and accompanying text.

69 Banković (n 52) para 75.

70 Al Skeini and Others v United Kingdom (n 49) para 137.