1 Milanovic, M., ‘Norm Conflict in International Law: Whither Human Rights?’, (2009) 20 Duke Journal of Comparative & International Law 69Google Scholar, at 69. See also J. Pauwelyn, Conflict of Norms in Public International Law (2003), at 12–23, suggesting eight reasons for the inevitable occurrence of norm conflicts in modern international law.

2 Conclusions of the work of the Study Group on the Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of International Law, adopted by the International Law Commission at its fifty-eighth session, in 2006, and submitted to the General Assembly as a part of the Commission's report covering the work of that session (A/61/10, para. 251) (hereinafter ‘Conclusions of the Study Group on Fragmentation’), para. 1(2).

3 Hereinafter ‘ICJ’ or ‘Court’.

4 Hereinafter ‘Judgment’.

5 Judgment, paras. 92–97.

6 Dissenting Opinion of Judge Cançado Trindade, e.g., paras. 130–134, 296, 303.

7 Each system will have its own rules for resolving conflicts. Certain norms might be given prevalence as hierarchically superior (e.g., jus cogens norms in international law or obligations under the UN Charter per Art. 103: see in this last respect Questions of Interpretation and Application of the 1971 Montreal Convention Arising from the Aerial Incident at Lockerbie (Libyan Arab Jamahiriya v. United States of America), Provisional Measures, Order of 14 April 1992, [1992] ICJ Rep. 114, at paras. 42–4). Conflict of norms on the same level might be resolved for instance by preferring the more specific norm (lex specialis) or the more recent norm (lex posterior; see, e.g., Art. 30 of the 1969 Vienna Convention on the Law of Treaties, 1155 UNTS 331 (‘Vienna Convention’)). The Study Group on the Fragmentation of International Law suggests that the basic rules to resolve normative conflicts in international law are found in the Vienna Convention: Conclusions of the Study Group on Fragmentation, para. 1(2).

8 Judgment, para. 60.

9 Judgment, para. 61.

10 The Court found that state immunity could not be denied on the basis of a ‘territorial tort exception’ (Judgment, paras. 62–79) and that international law did not prevent or restrict state immunity when the state is accused of serious IHL violations (Judgment, paras. 81–91).

11 Although the Court does state in obiter that at least some IHL rules are jus cogens. See Judgment, para. 95. The Court recalls its finding in the Armed Activities case that the rule prohibiting genocide has the character of jus cogens (Armed Activities on the Territory of the Congo (New Application: 2002) (Democratic Republic of Congo v. Rwanda), Judgment of 3 February 2006, [2006] ICJ Rep. 6, para. 64). It also finds that the rules allegedly violated by the Congolese Minister of Foreign Affairs in the Arrest Warrant case (Arrest Warrant of 11 April 2000 (Democratic Republic of Congo v. Belgium), Judgment of 14 February 2002, [2002] ICJ Rep. 3) – the minister was accused of grave breaches of the Geneva Conventions and Additional Protocols, as well as of crimes against humanity – ‘undoubtedly possess the character of jus cogens’.

12 Judgment, para. 93. The relevant part of Article 41 of the International Law Commission's Articles on State Responsibility provides that ‘No State shall recognize as lawful a situation created by a serious breach within the meaning of article 40 [i.e., a serious breach of obligations under peremptory norms], nor render aid or assistance in maintaining that situation.’

13 Judgment, para. 95.

14 Ibid., para. 95, recalling that the Court held in those cases that (1) the jus cogens status of a rule does not confer upon the Court a jurisdiction which it would not otherwise possess (Armed Activities on the Territory of the Congo (New Application: 2002) (Democratic Republic of Congo v. Rwanda), Judgment of 3 February 2006, [2006] ICJ Rep. 6, paras. 64 and 125); and (2) the fact that a minister for foreign affairs was accused of breaching rules with jus cogens status did not deprive him of his immunity under international law (Arrest Warrant of 11 April 2000 (Democratic Republic of Congo v. Belgium), Judgment of 14 February 2002, [2002] ICJ Rep. 3, paras. 58 and 78).

15 Judgment, para. 94.

16 Ibid., para. 94.

17 Ibid., para. 96.

18 Ibid., para. 97.

19 Dissenting Opinion of Judge Cançado Trindade, para. 40.

20 Ibid., para. 52.

21 Ibid., para. 129.

22 Dissenting Opinion of Judge Cançado Trindade, e.g., paras. 130–134, 296, 315. Judge Cançado Trindade also argued that the rules on state immunity were never meant to apply in the case of international crimes in breach of jus cogens. See, e.g., paras. 184–213, 306, 312.

23 Judgment, para. 93.

24 Ibid., para. 95.

25 See, e.g., A. Nollkaemper, ‘International Adjudication of Global Public Goods: The Intersection of Substance and Procedure’, SHARES Research Paper 09 (2012), ACIL 2012-08, finalized May 2012, available online at www.sharesproject.nl and to be published in (2012) 23 EJIL, at 6–9. For example, Nollkaemper explains that the question whether a claimant state is an injured state (an admissibility question) ‘requires an assessment of whether the defaulting state owed an obligation towards the claimant state, which is a question of substantive law’ (at 7).

26 Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of International Law, Report of the Study Group of the International Law Commission, finalized by Martti Koskenniemi, A/CN.4/L.682, 13 April 2006 (hereinafter ‘Report of the Study Group on Fragmentation’), at paras. 21–22.

27 Ibid., paras. 21–23.

28 Ibid., para. 22, citing Vierdag, E. W., ‘The Time of the “Conclusion” of a Multilateral Treaty: Article 30 of the Vienna Convention on the Law of Treaties and Related Provisions’ (1988) 59 BYBIL 75Google Scholar, at 100.

29 See, e.g., Vranes, E., ‘The Definition of “Norm Conflict” in International Law and Legal Theory’, (2006) 17 EJIL 395CrossRefGoogle Scholar, at 408 (referring to the work of J. Bentham and to deontic logic).

30 Pauwelyn, supra note 1, at 165–6.

31 Vranes, supra note 29, at 409.

32 Accordingly, some early commentators argued that these situations did not amount to genuine conflicts of norms, but to mere divergences. See, e.g., Jenks, C. W., ‘The Conflict of Law-Making Treaties’, (1953) 30 BYBIL 401Google Scholar, at 425–7.

33 Pauwelyn, supra note 1, at 170–1. See also Vranes, supra note 29, at 401–5.

34 Pauwelyn, supra note 1, at 175–88; Vranes, supra note 29, at 409.

35 Vranes, supra note 29, at 409. As an example of this, the Supreme Court of Canada has recognized that a permissive norm could be in conflict with a norm imposing an obligation. In Bank of Montreal v. Hall ([1990] 1 S.C.R. 121) the Supreme Court examined whether there was a conflict between a provincial rule obliging banks to obtain a judicial authorization before seizing mortgaged property, and a federal rule which gave banks a right (permission) to seize mortgaged property without judicial authorization. Both the provincial and federal rules were found valid and applicable in the circumstances. The bank could have sought to obtain judicial authorization to seize the mortgaged property as this would not have been in violation of the federal rules. However, requiring it to do so would have frustrated the legislative intent behind the federal rule, which was to ensure that the banks could seize the property quickly. The Supreme Court found that the provincial and federal rules were in conflict. Pursuant to the paramountcy doctrine in Canadian constitutional law, the federal norm was made to prevail over the provincial norm, which was declared inoperative in the circumstances.

36 Vranes, supra note 29, at 408 (references omitted). Thus, if the prohibition of a given conduct is negated, this same conduct is permitted, and vice versa. In other words, the prohibition of a given conduct constitutes the contradictory opposite of the permission of this conduct (‘non-prohibition’, positive permission). The same is true for the permission to forbear from adopting a given conduct and the obligation to adopt this conduct: negating this obligation yields a permission of contradictory content (‘non-command’, negative permission) and vice versa. Hence there are two types of permission, the first consisting in the absence, or negation, of a prohibition, the second in the absence of an obligation. Prohibition and obligation are also logically interdefinable through negation, if the conduct which is regulated (the descriptive proposition) is negated.

37 Vranes, supra note 29, at 409 (itself referring to J. Bentham, Of Laws in General, ed. H. L. A. Hart (1970), at 93–109; K. Adomeit, Normlogik – Methodenlehre – Rechtspolitologie (1986), at 26–9 and 82–6).

38 Pauwelyn, supra note 1, at 175–6. This definition is endorsed in Milanovic, M., ‘A Norm Conflict Perspective on the Relationship between International Humanitarian Law and Human Rights Law’, (2009) 14 Journal of Conflict & Security Law 459CrossRefGoogle Scholar, at 465.

39 Vranes, supra note 29, at 415.

40 Ibid.

41 Some of the norms at issue here are customary norms, and their exact content or formulation may be subject to debate. This article does not address this question. But it is obvious that the content or formulation of a customary norm might have an impact on whether it is in conflict with another norm.

42 Judgment, para. 94.

43 See supra note 12.

44 Judgment, para. 93.

45 Ibid., para. 94.