1 The research in this article was finalized for publication in September 2021. In the literature, see, generally, the thematic issue of the International Review of the Red Cross on “Protracted Conflict”, Vol. 101, No. 912, 2019.

2 This article focuses on the obligations owed by States when withdrawing from international and non-international armed conflicts. As indicated in Section 2.C, some of the obligations discussed in this article may also apply to non-State armed groups (NSAGs), although we leave this issue for future scholarship.

3 See Section 1.A.

4 See, for example, Nathalie Weizmann, “The End of Hostilities Versus the End of Armed Conflict”, Lawfare, 28 May 2015, available at: www.lawfareblog.com/end-active-hostilities-versus-end-armed-conflict-%C2%A0/ (all internet references were accessed in November 2021); Weizmann, Nathalie, “The End of Armed Conflict, the End of Participation in Armed Conflict, and the End of Hostilities: Implications for Detention Operations under the 2001 AUMF”, Columbia Human Rights Law Review, Vol. 47, No. 3, 2016Google Scholar; Scholdan, Bettina, “‘The End of Active Hostilities:’ The Obligation to Release Conflict Internees Under International Law”, Houston Journal of International Law, Vol. 38, No. 1, 2016Google Scholar.

5 See Moellendorf, Darrel, “Two Doctrines of Jus ex Bello”, Ethics, Vol. 125, No. 3, 2015, pp. 653–659CrossRefGoogle Scholar (explaining the potential relationship between an unjustly begun armed conflict and its continued prosecution).

6 Moellendorf defines jus ex bello as “the set of considerations that govern whether a war, once begun, should be brought to an end and if so how”. Moellendorf, Darrel, “Jus ex Bello”, Journal of Political Philosophy, Vol. 16, No. 2, 2008, p. 123Google Scholar. Moellendorf and Rodin distinguish between two jus ex bello considerations, namely “whether” and “how” a conflict should be brought to an end. See ibid.; Rodin, David, “Ending War: A Response to Richard W. Miller”, Ethics & International Affairs, Vol. 25, No. 3, 2011, p. 360CrossRefGoogle Scholar. The focus of the present article, however, is only on the “how” question. See also D. Moellendorf, above note 5; Moellendorf, Darrel, “Jus ex Bello in Afghanistan”, Ethics & International Affairs, Vol. 25, No. 2, 2011CrossRefGoogle Scholar.

7 Rodin describes jus terminatio as pertaining to questions of “when it is obligatory to terminate a state of war and how this can be done in the morally best way”. D. Rodin, above note 6, pp. 359–360. See also Rodin, David, “The War Trap: Dilemmas of Jus Terminatio”, Ethics, Vol. 125, No. 3, 2013Google Scholar.

8 See Blum, Gabriella and Luban, David, “Unsatisfying Wars: Degrees of Risk and the Jus ex Bello”, Ethics, Vol. 125, No. 3, 2015CrossRefGoogle Scholar. See also Michael Walzer, “The Aftermath of War: Reflections on Jus Post Bellum”, lecture, Berkeley Center for Religion, Peace and World Affairs, 22 April 2010.

9 D. Moellendorf, above note 5, p. 670.

10 For more on jus post bellum, see, for example, Jens Iverson, Jus Post Bellum: The Rediscovery, Foundations, and Future of the Law of Transforming War into Peace, Brill, Leiden, 2021. As is relevant in the context of this article, Moellendorf distinguishes jus ex bello from jus post bellum by explaining that jus post bellum is primarily concerned with post-conflict order and responsibilities, whereas jus ex bello concerns the conditions for ending a conflict. D. Moellendorf, “Jus ex Bello”, above note 6, pp. 130–131. Rodin similarly distinguishes his term jus terminatio from jus post bellum, noting that the latter “governs conduct in the subsequent postwar state” while the former “governs the transition from a state of war back into a state of peace”. D. Rodin, above note 6, p. 360.

11 See, for example, International Committee of the Red Cross (ICRC), Commentary on the Second Geneva Convention: Convention (II) for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, 2nd ed., Geneva, 2017 (2017 Commentary on GC II), paras 231–233.

12 See Geneva Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field of 12 August 1949, 75 UNTS 31 (entered into force 21 October 1950) (GC I); Geneva Convention (II) for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea of 12 August 1949, 75 UNTS 85 (entered into force 21 October 1950) (GC II); Geneva Convention (III) Relative to the Treatment of Prisoners of War of 12 August 1949, 75 UNTS 135 (entered into force 21 October 1950) (GC III); Geneva Convention (IV) relative to the Protection of Civilian Persons in Time of War of 12 August 1949, 75 UNTS 287 (entered into force 21 October 1950) (GC IV).

13 See Protocol Additional (I) to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts, 1125 UNTS 3, 8 June 1977 (entered into force 7 December 1978) (AP I).

14 See Gabriella Venturini, “The Temporal Scope of Application of the Conventions”, in Andrew Clapham, Paola Gaeta and Marco Sassòli (eds), The 1949 Geneva Conventions: A Commentary, Oxford University Press, Oxford, 2015, p. 59.

15 ICTY, The Prosecutor v. Duško Tadić, Case No. IT-94-1-AR72, Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, 2 October 1995, para. 70. AP II Article 1 sets a similar, albeit higher, threshold.

16 AP II, Art. 1(1).

17 Emphasis added. The other Geneva Conventions are less explicit as to the end of their general applicability. See GC III, Art. 5; GC II, Art. 2; GC I, Arts 2, 5.

18 See AP I, Arts 75(6), 99(1); AP II, Arts 2(2), 25(1).

19 ICRC, Commentary on the First Geneva Convention: Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field, 2nd ed., Geneva, 2016 (2016 Commentary on GC I), paras 278–279; see also N. Weizmann, “The End of Armed Conflict”, above note 4, p. 221 (discussing the definition provided in the AP I Commentary).

20 While the 1958 Commentary on GC IV interpreted the general close of military operations as the “final end of all fighting between all those concerned”, the updated Commentary explains that “evidence that there has been a ‘general close of military operations’ is the only objective criterion to determine that an international armed conflict has ended in a general, definitive, and effective way”. See Jean Pictet (ed.), Commentary on the Geneva Conventions of 12 August 1949, Vol. 4: Geneva Convention relative to the Protection of Civilian Persons in Time of War, ICRC, Geneva, 1958 (1958 Commentary on GC IV), p. 62; 2016 Commentary on GC I, above note 19, paras 277–278. See also Milanovic, Marko, “The End of Application of International Humanitarian Law”, International Review of the Red Cross, Vol. 96, No. 893, 2015, p. 174Google Scholar. For more on the temporal applicability of IHL, see Julia Grignon, L'applicabilité temporelle du droit international humanitaire, Schulthess Éditions Romandes, Geneva, 2014, pp. 207–408.

21 See M. Milanovic, above note 20, p. 170. Milanovic notes the general rule on IHL applicability as well as a few of the exceptions to this general position.

22 2016 Commentary on GC I, above note 19, para. 275.

23 ICTY, Prosecutor v. Gotovina, Case No. IT06-90-T, Judgment (Trial Chamber), 15 April 2011, para. 1694 (emphasis added).

24 M. Milanovic, above note 20, p. 171. See also Robert Kolb and Richard Hyde, An Introduction to the International Law of Armed Conflicts, Hart, Oxford, 2008, p. 102.

25 M. Milanovic, above note 20, pp. 178–179; N. Weizmann, “The End of Armed Conflict”, above note 4, p. 223; Derejko, Nathan, “A Forever War? Rethinking the Temporal Scope of Non-International Armed Conflict”, Journal of Conflict and Security Law, Vol. 26, No. 2, 2021, p. 14CrossRefGoogle Scholar. See also Rogier Bartels, “From Jus in Bello to Just Post Bellum: When Do Non-International Armed Conflicts End?”, in Carsten Stahn, Jennifer S. Easterday and Jens Iverson (eds), Jus Post Bellum: Mapping the Normative Foundations, Oxford University Press, Oxford, 2014, pp. 303–309.

26 M. Milanovic, above note 20, p. 180.

27 ICTY, Tadić, above note 15, para. 70; International Criminal Court (ICC), Prosecutor v. Jean-Pierre Bemba Gombo, Case No. ICC-01/05-01/08, Judgment Pursuant to Article 74 of the Rome Statute (Trial Chamber), 21 March 2016, para. 141.

28 See ICRC, International Humanitarian Law and the Challenges of Contemporary Armed Conflict, October 2015, pp. 10–11. See also Dustin A. Lewis, Gabriella Blum and Naz K. Modirzadeh, “Four Theories on the End of Non-International Armed Conflict”, in Indefinite War: Unsettled International Law on the End of Armed Conflict, legal briefing, Harvard Law School Program on International Law and Armed Conflict, February 2017, Chap. 8, available at: https://pilac.law.harvard.edu/indefinite-war (discussing approaches).

29 Yves Sandoz, Christophe Swinarski and Bruno Zimmermann, Commentary on the Additional Protocols, ICRC, Geneva, 1987, paras 4491–4492 (ICRC Commentary on AP I/AP II) (emphasis added).

30 The former view, that IHL ceases to apply at the end of armed conflict, is more consistent with prevailing understandings, particularly given the absence of such language in the text of AP II, and the Commentary's note that the Protocol applies to qualifying NIACs from the “moment when the criteria laid down in [Article 1] are objectively fulfilled”, thus meaning that application of the Protocol is tethered to the existence of armed conflict. Ibid., para. 4491. For more on this issue, see J. Grignon, above note 20, pp. 334–338.

31 See, for example, Emily Crawford, “The Temporal and Geographic Reach of International Humanitarian Law”, in Ben Saul and Dapo Akande (eds), The Oxford Guide to International Humanitarian Law, Oxford University Press, Oxford, 2020, pp. 60–65; R. Kolb and R. Hyde, above note 24, pp. 73 (“[T]he LOAC [law of armed conflict] is designed to apply only in a time of armed conflict and not in peacetime”), 74 (“[T]he applicability of the LOAC depends on the existence of an armed conflict. This is true for [IACs and NIACs] even if the definition of ‘armed conflict’ is not absolutely identical in both branches of the LOAC”); Jann K. Kleffner, “Scope of Application of International Humanitarian Law”, in Dieter Fleck (ed.), The Handbook of International Humanitarian Law, Oxford University Press, Oxford, 2021, p. 69, para. 3.23; Sandesh Sivakumaran, The Law of Non-International Armed Conflict, Oxford University Press, Oxford, 2012, p. 253 (“Ultimately, the applicability of the law of non-international armed conflict turns on whether or not a non-international armed conflict continues to exist at the relevant time. … Just as the law of non-international armed conflict commences upon the existence of certain facts (an armed conflict) so too should it cease to apply upon the non-existence of certain facts (the lack of an armed conflict)”). These sources recognize exceptions to the general position on IHL termination to varying degrees.

32 See GC I, Arts 23, 26, 44, 47; GC II, Arts 44, 48; GC III, Art. 127; GC IV, Arts 14, 144.

33 See Petrig, Anna, “The War Dead and their Gravesites”, International Review of the Red Cross, Vol. 91, No. 874, 2009, pp. 363–364CrossRefGoogle Scholar.

34 Ibid.

35 2017 Commentary on GC II, above note 11, paras 221–222 (identifying various rules); ICRC, Commentary on the Third Geneva Convention: Convention (III) relative to the Treatment of Prisoners of War, 2nd ed., Geneva, 2020 (2020 Commentary on GC III), paras 232–233; 2016 Commentary on GC I, above note 19, paras 199–200.

36 2017 Commentary on GC II, above note 11, para. 221.

37 AP I, Arts 6, 18, 60, 66, 83 (concerning, for example, training qualified personnel, emblems, demilitarized zones and dissemination of IHL).

38 ICRC Commentary on AP I, above note 29, para. 149.

39 AP I, Arts 36, 56, 58, 79, 81, 82.

40 ICRC Commentary on AP I, above note 29, para. 149.

41 See E. Crawford, above note 31, pp. 63–64.

42 See also AP I, Art. 75(6).

43 See M. Milanovic, above note 20, p. 170 (recognizing exceptions to the general statement that IHL ceases to apply at the end of armed conflict); N. Derejko, above note 25, pp. 10–11 (explaining that “neither the ‘end of hostilities’ nor the ‘end of NIAC’ necessarily equate to the termination of IHL's applicability”).

44 2017 Commentary on GC II, above note 11, para. 306; 2020 Commentary on GC III, above note 35, para. 317; 2016 Commentary on GC I, above note 19, para. 284. See also 2016 Commentary on GC I, above note 19, para. 941 (noting that while “some provisions of the Conventions and Protocols may cease to be applicable at the end of a conflict”, “many continue to apply even after that time”).

45 ICRC Commentary on AP I, above note 29, para. 149.

46 Ibid., para. 153; see also J. Grignon, above note 20, pp. 245–275 (discussing the cessation of hostilities in relation to both IACs and NIACs).

47 See M. Milanovic, above note 20, pp. 172–174.

48 Ibid., pp. 173–174; N. Weizmann, “The End of Armed Conflict”, above note 4, p. 233 (explaining that the cessation of hostilities and the end of a NIAC may coincide if the test for determining the end of a NIAC is taken to be the inverse of the test for its existence). Cf. J. K. Kleffner, above note 31, pp. 70, 77–78 (commenting on the relationship between ceasefires and the end of armed conflict).

49 See N. Weizmann, “The End of Armed Conflict”, above note 4, pp. 225–226.

50 See ibid.; Raphael Van Steenberghe and Pauline Lesaffre, “The ICRC's ‘Support-Based Approach’: A Suitable but Incomplete Theory”, Questions of International Law, May 2019, available at: www.qil-qdi.org/the-icrcs-support-based-approach-a-suitable-but-incomplete-theory/.

51 N. Weizmann, “The End of Armed Conflict”, above note 4, p. 232.

52 GC III, Art. 118(1); see also Jean-Marie Henckaerts and Louise Doswald Beck (eds), Customary International Humanitarian Law, Vol. 1: Rules, Cambridge University Press, Cambridge, 2005 (ICRC Customary Law Study), Rule 128, available at: https://ihl-databases.icrc.org/customary-ihl/eng/docs/v1.

53 CCW Protocol (II) on Prohibitions or Restrictions on the Use of Mines, Booby-Traps and Other Devices, 2048 UNTS 133, Geneva, 10 October 1980 (amended 3 May 1996), Art. 10(1). See also CCW Protocol (V) on Explosive Remnants of War, UN Doc. CCW/MSP/2003/2, Geneva, 28 November 2003 (entered into force 12 November 2006), Arts 3(1–3) (imposing obligations regarding clearance, removal and destruction of explosive remnants “after the cessation of active hostilities”), 4(2).

54 For a similar take on this point, see J. Grignon, above note 20, p. 367.

55 See the references at above note 48.

56 See Parts 3 and 5 of this article. For more on a functional approach to the temporal scope of IHL rules applicable in NIAC, see N. Derejko, above note 25, pp. 11–29.

57 See, for example, GC I, Art. 47; GC III, Art. 127; GC IV, Art. 144; AP I, Art. 83.

58 See, for example, Hague Convention (IV) respecting the Laws and Customs of War on Land and Its Annex: Regulations Concerning the Laws and Customs of War on Land, 205 CTS 227, 18 October 1907 (entered into force 26 January 1910), Art. 54 (“Submarine cables connecting an occupied territory with a neutral territory shall not be seized or destroyed except in the case of absolute necessity. They must likewise be restored and compensation fixed when peace is made”).

59 See, generally, ICRC Customary Law Study, above note 52. See also ICTY, Tadić, above note 15, para. 134; S. Sivakumaran, above note 31, pp. 101–152; Sassòli, Marco, “Taking Armed Groups Seriously: Ways to Improve Their Compliance with International Humanitarian Law”, Journal of International Humanitarian Legal Studies, Vol. 1, No. 1, 2010, pp. 16–17CrossRefGoogle Scholar; Sassòli, Marco and Tougas, Marie-Louise, “International Law Issues Raised by the Transfer of Detainees by Canadian Forces in Afghanistan”, McGill Law Review, Vol. 56, No. 4, 2011, p. 970Google Scholar.

60 ICRC Commentary on AP II, above note 29, paras 4442–4444; M. Sassòli, above note 59, p. 12.

61 See M. Sassòli, above note 59, pp. 12–14 (summarizing predominant approaches); Andrew Clapham, “Focusing on Armed Non-State Actors”, in Andrew Clapham and Paola Gaeta (eds), The Oxford Handbook of International Law in Armed Conflict, Oxford University Press, Oxford, 2014, pp. 771–782.

62 See A. Clapham, above note 61, pp. 781–782; M. Sassòli, above note 59, p. 16. See also Ezequiel Heffes, “Generating Respect for International Humanitarian Law: The Establishment of Courts by Organized Non-State Armed Groups in Light of the Principle of Equality of Belligerents”, Yearbook of International Humanitarian Law, Vol. 18, 2015 (focusing on the issue of equality of belligerents in determining NSAG IHL obligations).

63 See, for example, A. Clapham, above note 61, pp. 781–782; Jobstl, Hannes, “Bridging the Accountability Gap: Armed Non-State Actors and the Investigation and Prosecution of War Crimes”, Journal of International Criminal Justice, Vol. 18, No. 3, 2020, pp. 569–570, 590–593CrossRefGoogle Scholar.

64 As examples, see the discussion relating to release obligations and transfer duties in Sections 3.A and 3.B.

65 See also ICRC Customary Law Study, above note 52, Rule 128(B).

66 GC IV, Art. 133(1); see also GC IV, Art. 46(1).

67 AP I, Art. 85(4)(b).

68 At the same time, some prisoners, in particular certain wounded or sick prisoners, may need to be released and repatriated during hostilities. See GC III, Arts 109, 110, 114. In addition, an exception to the release rule exists for prisoners facing criminal proceedings for an indictable offence or serving a sentence. See, for example, GC III, Art. 119(5); ICRC Customary Law Study, above note 52, Rule 128.

69 ICRC Customary Law Study, above note 52, Rule 128(C).

70 See, for example, N. Weizmann, “The End of Armed Conflict”, above note 4, p. 248; ICRC Commentary on AP II, above note 29, para. 4493 (“In principle, measures restricting people's liberty, taken for reasons related to the conflict, should cease at the end of active hostilities … except in cases of penal convictions”).

71 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, No. 858, 2005, p. 382CrossRefGoogle Scholar. See also GC IV, Arts 42 (specifying that a person may only be interned if “the security of the Detaining Power makes it absolutely necessary”), 43 (regarding review of internment decisions); AP I, Art. 75(3).

72 Cf. N. Weizmann, “The End of Armed Conflict”, above note 4, p. 232.

73 Cf. Sandra Krähenmann, “Protection of Prisoners in Armed Conflict”, in D. Fleck (ed.), above note 31, pp. 445–446.

74 See the references at above note 48.

75 GC I, Art. 5; GC III, Art. 5; GC IV, Art. 6; see also 1958 Commentary on GC IV, above note 20, pp. 64, 271, 515; 2020 Commentary on GC III, above note 35, para. 1093.

76 E. Crawford, above note 31, p. 64.

77 2020 Commentary on GC III, above note 35, para. 4451; see also Marco Sassòli, “Release, Accommodation in Neutral Countries, and Repatriation”, in A. Clapham, P. Gaeta and M. Sassòli (eds), above note 14, pp. 1049–1050.

78 GC III, Art. 118; ICRC Customary Law Study, above note 52, Rule 128(A); see also GC IV, Art. 134 (regarding civilian repatriation).

79 S. Krähenmann, above note 73, pp. 445–446; M. Sassòli, above note 77, pp. 1040, 1057.

80 See 2020 Commentary on GC III, above note 35, paras 4474–4480. In NIACs, AP II Article 5(4) requires that where a State decides to release persons deprived of liberty, the State must take “necessary measures to ensure [the] safety” of these persons. See ICRC Commentary on AP II, above note 29, para. 4596 (suggesting that such safety measures should remain in place “until the released persons have reached an area where they are no longer considered as enemies, or otherwise until they are back home, as the case may be”). See, generally, Cordula Droege, “Transfers of Detainees: Legal Framework, Non-Refoulement and Contemporary Challenges”, International Review of the Red Cross, Vol. 90, No. 871, 2008, pp. 675–676.

81 S. Krähenmann, above note 73, p. 445.

82 Eritrea–Ethiopia Claims Commission, Partial Award: Prisoners of War – Eritrea's Claim 17, 1 July 2003, para. 147.

83 See Keiichiro Okimoto, “Evacuation and Transfer of Prisoners of War”, in A. Clapham, P. Gaeta and M. Sassòli (eds), above note 14, p. 968.

84 The ICTY, in the Vukovar Hospital case, considered this article in relation to obligations arising in NIAC. In addition, some States involved in NIACs have expressly assumed transfer obligations based on special agreements or declarations applying GC III. See M. Sassòli and M Tougas, above note 59, pp. 965, 975–981; K. Okimoto, above note 83, p. 973; see also C. Droege, above note 80, p. 675 (“[T]he humanitarian principle underlying these provisions, namely that a detaining power should ensure that the ally to whom it transfers detainees treats them according to the standards of the Geneva Conventions, should also be taken into account in non-international armed conflict”). In NIACs, transfer of a detainee of a non-State party to its own party would more properly qualify as a repatriation, and different rules, for example non-refoulement, may apply. See M. Sassòli and M. Tougas, above note 59, p. 979.

85 2020 Commentary on GC III, above note 35, para. 1535; see also K. Okimoto, above note 83, pp. 968–969; M. Sassòli and M. Tougas, above note 59, pp. 980, 998.

86 2020 Commentary on GC III, above note 35, para. 1537. Canada and Afghanistan, for instance, entered into agreements in 2005 and 2007 to abide by GC III PoW obligations, but these did not “foreclose the knowledge of Canadian forces members that the transfer would lead to the commission of the crime of torture by Afghan authorities”. See M. Sassòli and M. Tougas, above note 59, p. 1008.

87 1958 Commentary on GC IV, above note 20, p. 268.

88 See Section 1.B of this article.

89 See K. Okimoto, above note 83, p. 970 (“[E]ven when an IAC between state A and state B has ended, state C, which holds POWs transferred by state A or B, must apply GC III until their final release and repatriation”). See also 2020 Commentary on GC III, above note 35, paras 1546 (temporal scope of duties for transferee State), 1550 (temporal scope of duties for transferring State).

90 See K. Okimoto, above note 83, p. 968.

91 “Eleventh Circuit Approves General Noriega's Extradition to France”, American Journal of International Law, Vol. 103, No. 3, 2009, p. 591.

92 ICTY, Prosecutor v. Mile Mrkšić and Veselin Šljivančanin (Vukovar Hospital Case), Case No. IT-95-13/1-A, Judgment (Appeals Chamber), 5 May 2009, paras 71–75. See M. Sassòli and M. Tougas, above note 59, pp. 1005–1008 (summarizing key facts). The Appeals Chamber appears to have understood the customary international law applicable in NIACs, reflected in CA 3, as including obligations in relation to transfer similar to those expressed in Article 12. See ibid., pp. 980–981.

93 ICTY, Vukovar Hospital, above note 92, para. 75 (emphasis added).

94 Ibid., paras 57–63.

95 Ibid., para. 101.

96 Ibid., paras 333–334.

97 See, generally, Jessie Ingle, “Aiding and Abetting by Omission before International Criminal Tribunals”, Journal of International Criminal Justice, Vol. 14, No. 4, 2016 (summarizing international criminal tribunal case law); International Law Commission (ILC), Draft Articles on Responsibility of States for Internationally Wrongful Acts, with Commentaries, UN Doc. A/56/10, November 2001 (Draft Articles), p. 32, para. 1 (“An internationally wrongful act of a State may consist in one or more actions or omissions or a combination of both”). Omission liability also finds roots in the Geneva Conventions. For instance, GC III Article 13(2) prohibits “any unlawful act or omission … causing death or seriously endangering the health of a prisoner of war”, and the war crime of “wilful killing” has been taken to cover omission. See Michael Duttwiler, “Liability for Omission in International Criminal Law”, International Criminal Law Review, Vol. 6, No. 1, 2006, pp. 10–11.

98 Draft Articles, above note 97, Art. 16, and Commentary on Art. 16, p. 66, paras 3–4.

99 Ryan Goodman and Miles Jackson, “State Responsibility for Assistance to Foreign Forces (aka How to Assess US-UK Support for Saudi Ops in Yemen)”, Just Security, 31 August 2016, available at: www.justsecurity.org/32628/state-responsibility-assistance-foreign-forces-a-k-a-assess-us-uk-support-saudi-military-ops-yemen/.

100 Miles Jackson, Complicity in International Law, Oxford University Press, Oxford, 2015, p. 157.

101 See International Court of Justice ICJ), Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, 9 July 2004, para. 106.

102 See, for example, J. Pejic, above note 71, pp. 378–379.

103 See ibid., p. 378 (suggesting that AP I Article 72 therefore “allows recourse to human rights law as an additional frame of reference in regulating the rights of internees”, and that the “minimum” mentioned in Article 75, read in light of Article 72, “is supplemented by other provisions of humanitarian and human rights law”).

104 AP I, Arts 75(1), 75(6).

105 See, for example, 2020 Commentary on GC III, above note 35, paras 548–551, 654, 657–658, 709, 715, 745–746.

106 The Commentary specifies that such instruments include UN human rights treaties as well as regional instruments. ICRC Commentary on AP II, above note 29, paras 4428–4430.

107 Ibid., para. 4430.

108 See, generally, Human Rights Committee, General Comment 36, “Article 6: Right to Life”, UN Doc. CCPR/C/GC/36, 30 October 2018, paras 7, 21–22 (explaining State obligations in relation to foreseeable harms caused by actors whose conduct is otherwise not attributable to the State); European Court of Human Rights, El Masri v. The Former Yugoslav Republic of Macedonia, Appl. No. 39630/09, Judgment, 12 December 2012, paras 215–223, 228.

109 See, for example, ICJ, Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Judgment, ICJ Reports 1986, paras 220, 255; de Chazournes, Laurence Boisson and Condorelli, Luigi, “Common Article 1 of the Geneva Conventions Revisited: Protecting Collective Interests”, International Review of the Red Cross, Vol. 82, No. 837, 2000, pp. 68–69Google Scholar; Clause Kreß, “The International Court of Justice and the Law of Armed Conflicts”, in Christian J. Tams and James Sloan (eds), The Development of Law by the International Court of Justice, Oxford University Press, Oxford, 2013, p. 275; ICRC Customary Law Study, above note 52, Rule 139.

110 See 2020 Commentary on GC III, above note 35, para. 187 (illustrating positive and negative aspects of CA 1 in relation to the duty to ensure respect by others). See also Knut Dörmann and Jose Serralvo, “Common Article 1 to the Geneva Conventions and the Obligation to Prevent International Humanitarian Law Violations”, International Review of the Red Cross, Vol. 96, No. 895, 2014, pp. 728–731.

111 2020 Commentary on GC III, above note 35, paras 186–206.

112 Ibid., para. 153.

113 See, e.g., Hathaway, Oona A., Chertoff, Emily, Domínguez, Lara, Manfredi, Zachary and Tzeng, Peter, “Ensuring Responsibility: Common Article 1 and State Responsibility for Non-State Actors”, Texas Law Review, Vol. 95, No. 3, 2017, pp. 540, 574Google Scholar; L. Boisson de Chazournes and L. Condorelli, above note 109; Kessler, Birgit, “The Duty to Ensure Respect under Common Article 1 of the Geneva Conventions: Its Implications on International and Non-International Armed Conflicts”, German Yearbook of International Law, Vol. 44, 2001, pp. 498, 504, 516Google Scholar.

114 See 2020 Commentary on GC III, above note 35, para. 189; K. Dörmann and J. Serralvo, above note 110, pp. 719–721.

115 See 2020 Commentary on GC III, above note 35, paras 202–206.

116 Ibid., paras 198–199.

117 Ibid., para. 200.

118 Ibid., para. 197.

119 See ICJ, Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v. Serbia and Montenegro), Judgment, ICJ Reports 2007, para. 431 (“[A] State's obligation to prevent, and the corresponding duty to act, arise at the instant that the State learns of, or should normally have learned of, the existence of a serious risk that genocide will be committed”). See also 2020 Commentary on GC III, above note 35, para. 199 (comparing the positive obligation under CA 1 to the duty to prevent genocide under Article 1 of the Genocide Convention).

120 Hans-Peter Gasser, “Ensuring Respect for the Geneva Conventions and Protocols”, in Hazel Fox and Michael A. Meyer (eds), Armed Conflict and the New Law, Vol. 2: Effecting Compliance, British Institute of International and Comparative Law, London, 1993, pp. 30–32.

121 Alexandre Devillard, “L'obligation de faire respecter le droit international humanitaire”, Revue Québécoise de Droit International, Vol. 20, No. 2, 2007, pp. 96–97. See also K. Dörmann and J. Serralvo, above note 110, pp. 729–730 (analyzing the approaches of Gasser and Devillard).

122 K. Dörmann and J. Serralvo, above note 110, pp. 729–730.

123 2020 Commentary on GC III, above note 35, para. 191; ICJ, Nicaragua, above note 109, para. 220.

124 ICJ, Nicaragua, above note 109, paras 255–256.

125 2020 Commentary on GC III, above note 35, paras 198–199.

126 ICJ, Bosnian Genocide, above note 119, paras 430, 438.

127 Ibid.

128 See, for example, K. Dörmann and J. Serralvo, above note 110, pp. 724–725. See also B. Kessler, above note 113, p. 506 (suggesting that “[t]he intensity of the treaties’ violations is another element that is important for obliging the States to take further steps to ‘ensure respect’”).

129 B. Kessler, above note 113, p. 506.

130 See Beatrice Walton and Paul Strauch, “Three Lingering Question about the Legality of Withdrawal from Syria: Parts I and II”, Opinio Juris, 7–8 January 2020, available at: http://opiniojuris.org/2020/01/07/three-lingering-questions-about-the-legality-of-withdrawal-from-syria-part-i-complicity-by-omission/; Charlie Savage, “The Kurds’ Prisons and Detention Camps for ISIS Members, Explained”, New York Times, 13 October 2019, available at: www.nytimes.com/2019/10/13/us/politics/isis-prisoners-kurds.html.

131 See, generally, O. A. Hathaway et al., above note 113 (discussing the 2016 ICRC Commentary and State obligations to prevent violations of CA 3 by non-State actors).

132 See 2020 Commentary on GC III, above note 35, paras 189, 195 (noting the reference to the duty to ensure respect in the 2013 Arms Treaty, and explaining that CA 1's negative obligation requires States “to refrain from transferring weapons if there is an expectation, based on facts or knowledge of past patterns, that such weapons would be used to violate the Conventions”). CA 1's relevance to arms transfer also has a positive dimension. See K. Dörmann and J. Serralvo, above note 110, pp. 732–734.

133 ICRC, Arms Transfer Decisions: Applying International Humanitarian Law Criteria, Geneva, May 2007, p. 9.

134 Ibid.

135 See, for example, “U.S. Military Left ‘Thousands’ of Weapons ‘Vulnerable to Loss or Theft’ During Fight Against ISIS in Syria”, Newsweek, 2 February 2020, available at: www.newsweek.com/us-military-thousands-weapons-vulnerable-loss-theft-fight-against-isis-syria-1488013; “Planes, Guns, Night-Vision Goggles: The Taliban's New U.S.-Made War Chest”, Reuters, 19 August 2021, available at: www.reuters.com/business/aerospace-defense/planes-guns-night-vision-goggles-talibans-new-us-made-war-chest-2021-08-19/.

136 See, for example, 2020 Commentary on GC III, above note 35, para. 214; Palwankar, Umesh, “Measures Available to States for Fulfilling Their Obligation to Ensure Respect for International Humanitarian Law”, International Review of the Red Cross, Vol. 34, No. 298, 1994CrossRefGoogle Scholar; B. Kessler, above note 113.

137 Indeed, CA 1 is not capable of providing a legal justification for military action. See 2020 Commentary on GC III, above note 35, para. 207.

138 Ibid., para. 198.

139 See U. Palwankar, above note 136, pp. 9, 12, 16–17; 2020 Commentary on GC III, above note 35, paras 211, 214–215.

140 2020 Commentary on GC III, above note 35, para. 214.

141 U. Palwankar, above note 126, pp. 12, 17–23; see also K. Dörmann and J. Serralvo, above note 110, p. 726.

142 See 2020 Commentary on GC III, above note 35, para. 207. The IHL rules may therefore deviate from, or at least not provide explicit support for, some jus ex bello principles debated in just war theory, where authors have expressed support for the continuation of military action in certain contexts. Cf. D. Rodin, above note 6, pp. 359–361; M. Walzer, above note 8 (suggesting that parties to a conflict may have an obligation to continue fighting in order to prevent mass murder and atrocity).

143 See, generally, “After Barkhane: What France's Military Drawdown Means for the Sahel”, European Council on Foreign Relations, 2 July 2021, available at: https://ecfr.eu/article/after-barkhane-what-frances-military-drawdown-means-for-the-sahel/.

144 See M. Milanovic, above note 20, pp. 174–175 (discussing in relation to IACs). Some have expressed doubt regarding the ability of obligations to extend past the end of a NIAC specifically. Nevertheless, other commentators emphasize a more functional approach, for instance by taking into account the triggering of the obligations during the conflict. See, for example, N. Derejko, above note 25, p. 11. Further, it is notable that the ICRC Customary Law Study rules relevant to the obligations in this section have no express temporal restriction.

145 See GC I, Art. 49; GC II, Art. 50; GC III, Art. 129; GC IV, Art. 146; AP I, Arts 86, 88.

146 ICRC Customary Law Study, above note 52, Rule 158.

147 2016 Commentary on GC I, above note 19, para. 2871 (emphasis added).

148 See, for example, ICC Office of the Prosecutor, “Informal Expert Paper: The Principle of Complementarity in Practice”, 2003, para. 1 (“The principle of complementarity is based both on respect for the primary jurisdiction of States and on considerations of efficiency and effectiveness, since States will generally have the best access to evidence and witnesses and the resources to carry out proceedings”).

149 Mark Lattimer, “The Duty to Investigate Civilian Deaths in Armed Conflict: Looking Beyond Criminal Investigations”, EJIL: Talk!, 22 October 2018, available at: www.ejiltalk.org/the-duty-to-investigate-civilian-deaths-in-armed-conflict-looking-beyond-criminal-investigations/.

150 ICRC Commentary on AP I, above note 29, para. 149 (referring to Arts 85–87).

151 2016 Commentary on GC I, above note 19, para. 2868.

152 “Colombia Tribunal Begins Mammoth Task of Investigating, Trying War Crimes”, Reuters, 15 March 2018, available at: www.reuters.com/article/us-colombia-peace-court/colombia-tribunal-begins-mammoth-task-of-investigating-trying-war-crimes-idUSKCN1GR2P6.

153 GC I, Art. 51; GC II, Art. 52; GC III, Art. 131; GC IV, Art. 148.

154 ICRC, “Amnesties and International Humanitarian Law: Purpose and Scope”, legal fact sheet, Geneva, 4 October 2017.

155 ICRC Customary Law Study, above note 52, Rule 158.

156 Ibid., Rule 160.

157 Amichai Cohen and Yuval Shany, “Beyond the Grave Breaches Regime: The Duty to Investigate Alleged Violations of International Law Governing Armed Conflicts”, Yearbook of International Humanitarian Law, Vol. 14, 2011, p. 79.

158 Ibid.

159 Amnesty International, “Somalia: U.S. Must Not Abandon Civilian Victims of its Air Strikes After Troop Withdrawal”, press release, 7 December 2020, available at: www.amnesty.org/en/latest/news/2020/12/somalia-us-must-not-abandon-civilian-victims-of-its-air-strikes-after-troop-withdrawal/.

160 ICC, Judgment on the Appeal against the Decision on the Authorisation of an Investigation into the Situation in the Islamic Republic of Afghanistan, Case No. ICC-02/17-138, Decision, 5 March 2020.

161 See, for example, “Dutch Prosecutors Asked to Check Whether Dutch Soldiers Killed Afghan Civilians”, Reuters, 23 December 2020, available at: www.reuters.com/article/us-netherlands-afghanistan-prosecutors/dutch-prosecutors-asked-to-check-whether-dutch-soldiers-killed-afghan-civilians-idUSKBN28X1E0.

162 See GC I, Art. 16; GC II, Art. 19; GC III, Arts 122–123; GC IV, Arts 136–140. Further, although neither CA 3 nor AP II contain explicit rules regarding missing persons, many obligations relating to missing persons and the dead have been understood to apply in NIACs by virtue of customary law. See Anna Petrig, “Search for Missing Persons”, in A. Clapham, P. Gaeta and M. Sassòli (eds), above note 14, p. 272; ICRC Customary Law Study, above note 52, Rule 117. Obligations to search for and collect the dead are also understood to be customary in nature and applicable in NIACs. See ICRC Customary Law Study, above note 52, Rule 112; A. Petrig, above note 33, pp. 343–344.

163 Emphasis added. Notably, the UN General Assembly in Resolution 3220 (XXIX) called upon conflict parties to provide information about missing persons and undertake related obligations “during and after the end of hostilities”. See UNGA Res. 3220 (XXIX), 6 November 1974 (emphasis added). In addition, Article 33(2) of AP I suggests an obligation to search for persons “if they have died in other circumstances [than detention] as a result of hostilities or occupation”.

164 ICRC Customary Law Study, above note 52, Rule 117.

165 A. Petrig, above note 162, p. 269.

166 ICRC Commentary on AP I, above note 29, para. 1239; A. Petrig, above note 162, p. 269. The AP I Commentary identifies Article 33 as being among those articles “whose application in relation to a conflict may continue beyond the termination of this conflict”. ICRC Commentary on AP I, above note 29, para. 149.

167 ICRC Commentary on AP I, above note 29, paras 1235, 1237.

168 See also A. Petrig, above note 162, p. 270. GC III Article 119 also calls for agreements to be made for the purpose of searching for dispersed PoWs. See also GC I, Art. 15 (calling for the arrangement of “an armistice or a suspension of fire … to permit the removal, exchange and transport of the wounded left on the battlefield”).

169 ICRC Commentary on AP I, above note 29, para. 149. GC IV Article 26, similarly pertaining to facilitating enquiries made by members of dispersed families, arguably also continues to apply after the conclusion of armed conflict.

170 AP II, Art. 8; see also GC I, Art. 15; GC II, Art. 18. Somewhat less certain is the extent to which obligations pertaining to searching for the wounded and sick also continue to apply after the end of armed conflict. See, for example, GC I, Art. 15; GC II, Art. 18; AP II, Art. 8. The Geneva Conventions stress that the obligation to search for the wounded arises after each engagement, and that searches in relation to this obligation must be undertaken “without delay”. See also 2016 Commentary on GC I, above note 19, paras 1487 (“The obligation to act without delay is strict, but the action to be taken is limited to what is feasible, in particular in the light of security considerations”), 1486 (“[W]henever there is an indication that there may be wounded or sick people in an area, and circumstances permit, a reasonable commander should commence search and rescue activities”). Notably, under GC I Article 15, States must “[a]t all times … take all possible measures to search for and collect the wounded and sick” (emphasis added), whereas GC IV Article 16(2) provides that States should search for the dead and wounded “[a]s far as military considerations allow”. According to the Commentary on GC II, it was a conscious decision by the drafters to omit the phrasing “at all times” found in GC I Article 15 from GC II Article 18 on account of the challenging conditions of warfare at sea. See 2017 Commentary on GC II, above note 11, para. 1653. As such, while “the obligations of Article 18(1) remain applicable and are to be continued for as long as there is a reasonable chance of such persons being found”, even after one search operation has been conducted (ibid., para. 1657), the Commentary suggests that the obligation only exists during “conflict”.

171 See also GC III, Art. 120(4) (stating that PoW graves must be “suitably maintained and marked so as to be found at any time”). It has been noted that the duty to conclude agreements regarding gravesite access and maintenance may not apply in NIACs, out of concern that the conclusion of such agreements in the form of a treaty could be interpreted as affording recognition to an NSAG. A. Petrig, above note 33, p. 359.

172 See A. Petrig, above note 33, p. 360, citing Jean Pictet (ed.), Commentary on the Geneva Conventions of 12 August 1949, Vol. 3: Geneva Convention relative to the Treatment of Prisoners of War, ICRC, Geneva, 1960, p. 566. An alternative is that the obligation is not ad infinitum but instead follows the approach of AP I Article 34, which provides a system in the event that the parties are unable to enter into agreements on the maintenance of gravesites. Ibid.

173 See, for example, ICRC, “Nagorny Karabakh: ICRC Submits Updated List of Missing Persons”, news release, Geneva, 15 December 2015, available at: www.icrc.org/en/document/nagorny-karabakh-icrc-submits-updated-list-missing-persons.

174 See International Commission on Missing Persons, “EU and Western Balkan Countries Sign Joint Declaration Citing Efforts to Account for Missing Persons from 1990s”, press release, 10 July 2018, available at: www.icmp.int/press-releases/eu-and-western-balkan-countries-sign-joint-declaration-citing-efforts-to-account-for-missing-persons-from-1990s/; Joint Declaration on Missing Persons in the Framework of the Berlin Process, Western Balkans Summit, London, July 2018, available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/724294/180710_WBS_Joint_Declarations.pdf.