1 Martti Koskenniemi, ‘Fragmentation of international law: difficulties arising from the diversification and expansion of international law, Report of the Study Group of the International Law Commission’, UN Doc A/CN.4/L.682, 13 April 2006; Report of the International Law Commission (ILC), Fifty-sixth session, UN Doc A/59/10, paras. 304 ff.

2 See Marco Sassòli, ‘Le droit international humanitaire: Une lex specialis par rapport aux droits humains?’ in Andreas Auer, Alexandre Flückiger, Michel Hottelier (eds.), Les droits de l'homme et la constitution: Etudes en l'honneur du Professeur Giorgio Malinverni, Schulthess, Geneva, 2007, pp. 375–95, with further references.

3 See Marco Sassòli, ‘La Cour européenne des droits de l'homme et les conflits armés’, in Stephan Breitenmoser et al. (eds.), Human Rights, Democracy and the Rule of Law: Liber Amicorum Luzius Wildhaber, Dike, Zurich, 2007, pp. 724–5.

4 United States Supreme Court, Hamdan v. Rumsfeld (29 June 2006) 548 U.S. 557, 126 S. Ct. 2749.

5 Jean-Marie Henckaerts and Louise Doswald-Beck, Customary International Humanitarian Law, Cambridge University Press, Cambridge, 2005.

6 Laura M. Olson, ‘Practical challenges of implementing the complementarity between international humanitarian and human rights law – demonstrated by the procedural regulation of internment in non-international armed conflict’, Case Western International Law Journal, Vol. 40 (2009) (forthcoming, manuscript on file with authors).

7 Liesbeth Zegveld, Accountability of Armed Opposition Groups in International Law, Cambridge University Press, Cambridge, 2002, pp. 9–38, with further references.

8 Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, ICJ Reports 1996, para. 25; Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, ICJ Reports 2004, para. 106; ICJ, Case Concerning Armed Activities on the Territory of the Congo (DRC v. Uganda), Judgment of 19 December 2005, paras. 216–220.

9 Koskenniemi, above note 1, para. 60; Report of the ILC, above note 1, para. 305; Joost Pauwelyn, Conflict of Norms in Public International Law: How the WTO Law Relates to Other Rules of International Law, Cambridge University Press, Cambridge, 2003, p. 387.

10 Norberto Bobbio, ‘Des critères pour résoudre les antinomies’, in Chaïm Perelman (ed.), Les antinomies en droit: Etudes, Bruylant, Brussels, 1965, pp. 237–41.

11 Koskenniemi, above note 1, para. 112; Krieger, Heike, ‘A conflict of norms: the relationship between humanitarian law and human rights law in the ICRC Customary Law Study’, Journal of Conflict & Security Law, Vol. 11 (Summer 2006), pp. 269CrossRefGoogle Scholar, 271; Alston, Philip et al., ‘The competence of the UN Human Rights Council and its special procedures in relation to armed conflicts: extrajudicial executions in the “war on terror”’, European Journal of International Law, Vol. 19 (2008), p. 192CrossRefGoogle Scholar; Report of the ILC, above note 1, para. 304.

12 Lindroos, Anja, ‘Addressing norm conflicts in a fragmented system: the doctrine of lex specialis’, Nordic Journal of International Law, Vol. 74 (1) (2005), p. 42CrossRefGoogle Scholar.

13 This term was first used by Mary Ellen Walker, LL.M. student at the Geneva Academy of International Humanitarian Law and Human Rights in Marco Sassòli's 2008 international humanitarian law course.

14 Karl Larenz, Methodenlehre der Rechtswissenschaft, 6th edn, Springer Verlag, Berlin, 1991, pp. 267–8.

15 Bobbio, above note 10, p. 244.

16 See for examples Seyed Ali Sadat-Akha, Methods of Resolving Conflicts between Treaties, Nijhoff, Leyden, 2003, p. 124.

17 See, e.g., the European Court of Human Rights concerning the relationship between Articles 13 and 5(4) of the European Convention on Human Rights 1950 (hereinafter ECHR), ECtHR, Brannigan and McBride v. UK, Judgment, 26 May 1993, ECtHR, Series A, No. 258, p. 57, para. 76.

18 Koskenniemi, above note 1, para. 107.

19 Krieger, above note 11, p. 280.

20 Georg Schwarzenberger, International Law as Applied by International Courts and Tribunals, Vol. 1, Stevens, London, 1969, p. 474; Bruno Simma and Dirk Pulkovski, ‘Of planets and the universe: self-contained regimes in international law’, European Journal of International Law, Vol. 17 (2006), p. 490.

21 Bobbio, above note 10, pp. 240–1. See also Wilfred Jenks, ‘The conflict of law-making treaties’, British Yearbook of International Law, Vol. 30 (1953), p. 450.

22 The lex generalis consists of other rules of international law to be taken into account under Article 31(3)(c) of the Vienna Convention on the Law of Treaties.

23 See Koskenniemi, above note 1, paras. 31, 37; Report of the ILC, above note 1, paras. 308, 311.

24 Henckaerts and Doswald-Beck, above note 5, Vol. I, pp. 299–383.

25 Marco Sassòli, Bedeutung einer Kodifikation für das allgemeine Völkerrecht – mit besonderer Betrachtung der Regeln zum Schutze der Zivilbevölkerung vor den Auswirkungen von Feindseligkeiten, Helbing & Lichtenhahn, Basel, 1990.

26 Jean S. Pictet, Development and Principles of International Humanitarian Law, Nijhoff, Dordrecht, 1985, pp. 75–6.

27 See Manual on Military Law, Part III, The Law of War on Land, UK War Office, London, 1958, para. 115.

28 See the divergences of opinion in the ICRC expert consultations on the notion of direct participation in hostilities, DPH 2005 (note 31 below) at pp. 45–6; Doswald-Beck, Louise, ‘The right to life in armed conflict: does international humanitarian law provide all the answers?’, International Review of the Red Cross, Vol. 88 (864) (2006), pp. 881–904CrossRefGoogle Scholar, at p. 902; Proulx, Vincent-Joël, ‘If the hat fits, wear it, if the turban fits, run for your life: reflections on the indefinite detention and targeted killing of suspected terrorists’, Hastings Law Journal, Vol. 56 (2005), pp. 801–900Google Scholar, at pp. 882–3.

29 Protocol Additional to the Geneva Conventions (Protocol I), Article 51(5)(b).

30 See Article 3 common to the Geneva Conventions I–IV; and the Protocol II, Article 4.

31 The ICRC, in consultation with experts, was recently engaged in a process of researching, examining and clarifying the notion of ‘direct participation in hostilities’ under IHL. This process has not yet shown definitive results, but it has clearly demonstrated deep divisions of opinion on the question of when enemy fighters may be killed in a non-international armed conflict. See reports of the 2003 meeting (hereinafter DPH 2003 Report), the 2004 meeting (DPH 2004 Report) and the 2005 meeting (DPH 2005 Report), available at www.icrc.org/web/eng/siteeng0.nsf/htmlall/participation-hostilities-ihl–311205?opendocument (last visited 21 May 2008). On the basis of those discussions, the ICRC is currently preparing a reference text, ‘Interpretative guidance on the notion of direct participation in hostilities’.

32 Yves Sandoz, Christophe Swinarski and Bruno Zimmermann, Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949, ICRC, Geneva, 1987, para. 4789.

33 Expert Meeting on the Right to Life in Armed Conflict and Situations of Occupation, 1–2 September 2005, University Centre for International Humanitarian Law, available at www.adh-geneva.ch/events/expert-meetings.php (last visited 21 May 2008) (hereinafter UCIHL Report), p. 34.

34 DPH 2005 Report, above note 31, p. 64; Kretzmer, David, ‘Targeted killing of suspected terrorists: extra-judicial executions or legitimate means of defence?’, European Journal of International Law, Vol. 16 (2) (2005), pp. 197–8CrossRefGoogle Scholar.

35 Under Common Article 3, the term armed forces includes rebel armed groups (see Sassòli, Marco, ‘Terrorism and war’, Journal of International Criminal Justice, Vol. 4 (2006), p. 977CrossRefGoogle Scholar).

36 DPH 2005 Report, above note 31, pp. 48–9.

37 Israeli Supreme Court sitting as the High Court of Justice, Public Committee against Torture in Israel v. Government of Israel et al., HCJ 769/02, 11 December 2005, para. 39 (hereinafter Public Committee against Torture).

38 DPH 2005 Report, above note 31, pp. 43–4.

39 Ibid., p. 64; Kretzmer, above note 34, pp. 198–9, takes a similar line.

40 Henckaerts and Doswald-Beck, above note 5, Rule 1, p. 3.

41 Ibid., Rule 6, p. 19.

42 Ibid., Rule 5, p. 17.

43 Ibid., p. 3.

44 Ibid., p. 12.

45 Ibid., p. 17.

46 Ibid., p. 21.

47 Marco Sassòli and Antoine Bouvier, How Does Law Protect in War? 2nd edn, ICRC, Geneva, 2006, p. 251.

48 Orakhelashvili, Alexander, ‘The interaction between human rights and humanitarian law: fragmentation, conflict, parallelism, or convergence?’, European Journal of International Law, Vol. 19 (1) (2008), p. 167CrossRefGoogle Scholar.

49 Bugnion, François, ‘Jus ad bellum, jus in bello and non-international armed conflict’, Yearbook of International Humanitarian Law, Vol. 6 (2003), pp. 167–98CrossRefGoogle Scholar; Marco Sassòli, ‘Ius ad bellum and ius in bello: the separation between the legality of the use of force and humanitarian rules to be respected in warfare – crucial or outdated?’, in Michael Schmitt and Jelena Pejic (eds.), International Law and Armed Conflict: Exploring the Faultlines, Essays in Honour of Yoram Dinstein, Nijhoff, Leiden/Boston, 2007, pp. 254–7.

50 ECHR, Article 2(2).

51 ECtHR, McCann v. United Kingdom, Application No. 18984/91, Judgment, 5 September 1995, Series A No. 324, paras. 200–205.

52 ECtHR, Nachova v. Bulgaria, Application No. 43577/98, Judgment, 6 July 2005, Reports 2005-VII, para. 95.

53 See e.g. Inter-American Court of Human Rights, Las Palmeras Case, Judgment, 26 November 2002, Series C No. 96 (2002).

54 See Articles 9 and 10 of the Basic Principles on the Use of Force and Firearms by Law Enforcement Officials, adopted by the 9th UN Congress on the Prevention of Crime and Treatment of Offenders, Havana, 27 August–7 September 1990, UN Doc. A/CONF.144/28/Rev.1 at 112 (1990) (hereinafter Basic Principles).

55 In the Basic Principles a footnote added to the term ‘law enforcement officials’ clarifies this by referring to the commentary on Article 1 of the Code of Conduct for Law Enforcement Officials.

56 ECHR, Article 15(2). It has been argued that this refers only to international armed conflicts (see Doswald-Beck, above note 28, p. 883). In any case, no state has ever tried to derogate on the basis of this exception.

57 Inter-American Commission on Human Rights, Abella v. Argentina (Tablada), Case No. 11.137, Report No. 55/97, 18 November 1997, para. 178.

58 Human Rights Committee, Suarez de Guerrero v. Colombia, Communication No. R.11/45, 31 March 1982, UN Doc. Supp. No. 40 (A37/40) (hereinafter Guerrero case).

59 Kedar Prasad Poudyal, ‘The role of national human rights institutions in armed conflict situations, with special reference to NHRC–Nepal’, Danish Institute for Human Rights, 2006, pp. 87–8.

60 ECtHR, Isayeva v. Russia, Application No. 57950/00, Judgment 24 February 2005, paras. 175–176.

61 See an overview by Nils Melzer, Targeted Killing under International Normative Paradigms of Law Enforcement and Hostilities, Oxford University Press, Oxford, 2008, pp. 169–73 and pp. 384–92.

62 UCIHL Report, above note 33, p. 36.

63 DPH 2005 Report, above note 31, p. 52.

64 UCIHL Report, above note 33, p. 38; according to several experts in DPH 2005 Report, above note 31, pp. 51–2.

65 Nuclear Weapons, above note 8, para. 25.

66 Alston, above note 11, pp. 183–209, 192–3.

67 If the very person targeted is under government control, both branches of law prohibit any summary execution.

68 Doswald-Beck, above note 28, p. 897; UCIHL Report, above note 33, p. 36; Kretzmer, above note 34, p. 203; Droege, Cordula, ‘The interplay between international humanitarian law and international human rights law in situations of armed conflict’, Israel Law Review, Vol. 40 (2007), p. 347CrossRefGoogle Scholar.

69 For the responsibility of a state for human rights violations committed on a part of the territory of a state that is not under government control, see ECtHR, Ilascu and others v. Moldova and Russian Federation, Application No. 48787/99, Judgment, 8 July 2004, para. 333.

70 Droege, above note 68, p. 347.

71 We do not deal in this article with the law applicable to extraterritorial action.

72 UCIHL Report, above note 33, p. 37.

73 Public Committee against Torture, above note 37, para. 40; Doswald-Beck, above note 28, p. 891.

74 Public Committee against Torture, above note 37, para. 40.

75 Kretzmer, above note 34, p. 203.

76 Guerrero case, above note 58, para. 13.1–13.3; Public Committee against Torture, above note 37, para. 40; Ben-Naftali, Orna and Michaeli, Keren R., ‘“We must not make a scarecrow of the law”: A legal analysis of the Israeli policy of targeted killings’, Cornell Journal of International Law, Vol. 36 (2) (2003–4), p. 290Google Scholar.

77 Thus, for the killing of what it terms civilians directly participating in hostilities, see Public Committee against Torture, above note 37, para. 40. For human rights law, precisely in situations of non-international armed conflict, see ECtHR, Kaya v. Turkey, Application No. 22729/93, Judgment, 19 February 1998, Reports 1998-I, paras 86–91 (where it was controversial whether the killed person was or was not an armed rebel and the Court criticized the enquiry for not determining this issue); ECtHR, Ergi v. Turkey, Application No. 23818/94, Judgment, 28 July 1998, Reports 1998-IV, p. 1778, para. 85; ECtHR, Isayeva, Yusupova and Bazayeva v. Russia, Application Nos. 57947–57949/00, 24 February 2005, paras. 209–213. Philip Alston, Special Rapporteur on Extrajudicial, Summary or Arbitrary Executions, ‘Report to the Human Rights Commission’, 8 March 2006, UN Doc. E/CN.4/2006/53, paras. 25–26, even argues that such an obligation exists under humanitarian law. We would limit that obligation to possible violations. To require that an enquiry be conducted every time an enemy soldier is killed on the battlefield is unrealistic.

78 Doswald-Beck, above note 28, p. 890.

79 For an affirmative view see Andrew Clapham, Human Rights Obligations of Non-State Actors, Oxford University Press, Oxford, 2006, and for a more sceptical view see Nigel S. Rodley, ‘Can armed opposition groups violate human rights standards?’, in Kathleen E. Mahoney and Paul Mahoney (eds.), Human Rights in the Twenty-First Century, Nijhoff, The Hague, 1993, p. 297. See also para. 47 of the ‘Report of the consultative meeting on the draft Basic Principles and Guidelines on the Right to a Remedy and Reparation for Victims of Violations of International Human Rights and Humanitarian Law’, UN ESCOR, 59th Sess., UN Doc E/CN.4/2003/63 (27 December 2002).

80 Even Clapham, above note 79, p. 284, considers that human rights obligations apply to them only ‘to the extent appropriate to the context’.

81 Doswald-Beck, above note 28, p. 890; UCIHL Report, above note 33, p. 35.

82 See also ‘Report of the International Commission of Enquiry on Darfur to the UN Secretary-General’, 25 January 2005, para. 422, available at www.un.org/news/dh/sudan/com_inq_darfur.pdf (last visited 21 May 2008).

83 Nepal Human Rights Commission, ‘Minimum immediate steps for CPN-(Maoist) to respect international humanitarian law and human rights principles’, in Annual Report 2004 (ch. 8, Section 8.3), pp. 99–100.

84 The terms ‘internment’ and ‘security detention’ are used interchangeably in this article.

85 GC III, Article 21.

86 GC IV, Article 42 (for an alien in the territory of a party).

87 Ibid., Article 78(1) (in occupied territory).

88 GC III, Articles 109–117.

89 Ibid., Articles 118–119.

90 GC IV, Article 132(1). See also P I, Article 75(3).

91 GC IV, Article 133(1).

92 Ibid., Articles 43 and 78(2).

93 P I, Article 75(3).

94 GC IV, Article 147. See also Article 8(2)(a)(vii) of the Statute of the International Criminal Court and Article 2(g) of the Statute of the International Criminal Tribunal for the former Yugoslavia.

95 Protocol II, Articles 5 and 6(5).

96 Henckaerts and Doswald-Beck, above note 5, pp. 344–52.

97 Henckaerts and Doswald-Beck, above note 5, Vol. I, 2007 reprint (with corrections), p. li, cited in Henckaerts, Jean-Marie, ‘Customary international humanitarian law: a response to US comments’, International Review of the Red Cross, Vol. 89 (866) (2007), p. 484CrossRefGoogle Scholar.

98 Henckaerts and Doswald-Beck, above note 5, pp. 348–51.

99 International Covenant on Civil and Political Rights (ICCPR), Article 9(1). See also ECHR, Article 5(1); American Convention on Human Rights (ACHR), Article 7; and African Charter on Human and Peoples' Rights (ACHPR), Article 6.

100 ICCPR, Article 9(1); ECHR, Article 5; ACHR, Article 7(3); and ACHPR, Article 6.

101 ECHR, Article 5(1). Of these provisions, Article 5(1)(b) and (c) appears to authorize security detention; neither provision has, however, been interpreted to do so. See D. Harris, M. O'Boyle and C. Warbrick, Law of the European Convention on Human Rights, Butterworth, London, 1995, pp. 113, 117 (citing ECtHR, Lawless v. Ireland, Application No. 332/57, Judgment, 1 July 1961, Series A No. 3, section on ‘The law’, paras. 8–15; and ECtHR, Guzzardi v. Italy, Application No. 7367/76, Judgment, 6 November 1980, Series A No. 39, paras. 101–102).

102 ICCPR, Article 9(2); ECHR, Article 5(2); ACHR, Article 7(4).

103 ICCPR, Article 9(4); ECHR, Article 5(4); ACHR, Article 7(6); and ACHPR, Article 7(1)(a).

104 Of course, such derogation must only be ‘to the extent strictly required by the exigencies of the situation’ – ICCPR, Article 4(1). See also ECHR, Article 15(1), and ACHR, Article 27(1). The ACHPR contains no derogation clause.

105 For a list of practice pointing to the non-derogability of habeas corpus, see Henckaerts and Doswald-Beck, above note 5, pp. 350–1 and accompanying footnotes (including UN Human Rights Committee General Comment 29, para. 16, UN Doc. CCPR/C/21/Rev.1/Add.11 (2001)). See also Doug Cassel, ‘Pretrial and preventative detection of suspected terrorists: options and constraints under international law’, Journal of Criminal Law and Criminology, Vol. 98 (3) (2008), pp. 811–52, at p. 829 and nn. 130–132; ‘Procedural principles and safeguards for internment/administrative detention in armed conflict and other situations of violence’, Annex 1 to ‘International humanitarian law and the challenges of contemporary armed conflicts’ (ICRC document prepared for the 30th International Conference of the Red Cross and Red Crescent, 30IC/07/8.4, at 11), available at www.icrc.org/web/eng/siteeng0.nsf/htmlall/30-international-conference-working-documents–121007/$File/30IC_IHLchallenges_Annex1_Detention_FINAL_EN.pdf (last visited 29 May 2008) (originally published as Pejic, Jelena, ‘Procedural principles and safeguards for internment/administrative detention in armed conflict and other situations of violence’, International Review of the Red Cross, Vol. 87 (858) (2005), p. 387CrossRefGoogle Scholar (2005)) (hereinafter ICRC Guidelines).

106 Meron, Theodor, ‘The humanization of humanitarian law’, American Journal of International Law, Vol. 94 (2000), p. 247CrossRefGoogle Scholar. See also Byron, Christine, ‘A blurring of the boundaries: the application of international humanitarian law by human rights bodies’, Virginia Journal of International Law, Vol. 47 (2007), pp. 839–96.Google Scholar

107 ECtHR, Ireland v. United Kingdom, Application No. 5310/71, Judgment, 18 January 1978, [1978] ECHR 5310/71, para. 11. See also e.g. Lawless v. Ireland, above note 101.

108 ECHR, Article 15(1).

109 Human Rights Chamber for Bosnia and Herzegovina, Boudellaa and others v. Bosnia and Herzegovina and the Federation of Bosnia and Herzegovina (Case nos. CH/02/8679, CH/02/8689, CH/02/8690, CH/02/8691), 13 BHRC 297 (2002), paras. 233 and 237.

110 Inter-Am. C.H.R., Coard et al. v. US, Case No. 10.951, Report No. 109/99, 9 BHRC 150 (29 Sept. 1999), para. 57.

111 Ibid., para. 58.

112 Inter-American Commission on Human Rights, Detainees in Guantanamo Bay, Cuba, Request for Precautionary Measures (13 March 2002).

113 Droege, above note 68, p. 350.

114 Article 5(2) of GC IV allows for derogations in occupied territories from the communication rights of a person ‘under definite suspicion of activity hostile to the security of the Occupying Power’, while paragraph 1 of that article allows for derogations from ‘rights and privileges’ of enemy civilians on the own territory of a party to the conflict who are ‘definitely suspected of or engaged in activities hostile to the security of the State’.

115 GC III, Article 5.

116 See Henckaerts and Doswald-Beck, above note 5, pp. 344–52.

117 As encouraged by Article 3(3) common to GC I–IV.

118 Somer, Jonathan, ‘Jungle justice: passing sentence on the equality of belligerents in non-international armed conflict’, International Review of the Red Cross, Vol. 89 (867) (2007), pp. 655–90CrossRefGoogle Scholar.

119 Ibid., p. 687.

120 Article 8(2)(e)(x) of the Statute of the International Criminal Court. See also Henckaerts and Doswald-Beck, above note 5, p. 161.

121 O'Donnell, Daniel, ‘International treaties against terrorism and the use of terrorism during armed conflict and by armed forces’, International Review of the Red Cross, Vol. 88 (864) (2006), p. 876CrossRefGoogle Scholar (explaining similar reasoning for proposals to exclude acts legal under IHL from the acts prohibited in the draft comprehensive convention against terrorism).

122 See ICRC Guidelines, above note 105, p. 377.

123 Sassòli and Bouvier, above note 47, p. 258: ‘[T]he law of non-international armed conflict does not protect according to the status of a person but according to his or her actual activities.’

124 See e.g. ICTY decision in Prosecutor v. Ramush Haradinaj, Idriz Balaj and Lahi Brahimaj, Judgment, April 3, 2008, Case No. IT-04-84-T, paras. 60 and 89.

125 Henckaerts and Doswald-Beck, above note 5, p. 352.

126 Lindsay Moir, The Law of Internal Armed Conflict, Cambridge University Press, Cambridge, 2002, p. 41.

127 Henckaerts and Doswald-Beck, above note 5, p. 352.

128 See notes 36–39 above, and in particular DPH 2005 Report, above note 31, p. 43.

129 Except e.g. Article 75 of P I.

130 DPH 2005 Report, above note 31, pp. 41–58.

131 GC III, Article 5.

132 For a standpoint rejecting such an analogy, see UN Commission on Human Rights, ‘Situation of the detainees at Guantánamo’, report of the Chairperson-Rapporteur of the Working Group on Arbitrary Detention, Leila Zerrougui; the Special Rapporteur on the independence of judges and lawyers, Leandro Despouy; the Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment, Manfred Nowak; the Special Rapporteur on freedom of religion or belief, Asma Jahangir; and the Special Rapporteur on the right of everyone to the enjoyment of the highest attainable standard of physical and mental health, Paul Hunt, UN Doc E/CN.4/2006/120 (27 February 2006), para. 24.

133 ICRC Guidelines, above note 105, pp. 377–8.

134 Olson, above note 6 (citation omitted).

135 As the prohibition of arbitrary deprivation of liberty is a customary IHL rule applicable during armed conflict (Henckaerts and Doswald-Beck, above note 5, p. 344), it seems logical that it would also be a customary rule in less exigent peacetime situations; however, disagreement may remain as to the rule's content.

136 ICRC Guidelines, above note 105, p. 377.

137 Except under Article 5 of GC IV (see note 114).

138 Olson, above note 6.