1 M. Wood, First Report on Formation and Evidence of Customary International Law, UN Doc. A/CN.4/663 (2013) (hereafter, ‘First Report’); M. Wood, Second Report on Identification of Customary International Law, UN Doc. A/CN.4/672 (2014) (hereafter, ‘Second Report’).

2 The author would like to make clear that he is not a specialist in human rights law, and he welcomes comments or corrections from those who are.

3 With perhaps some inconsistency, the Special Rapporteur, however, argues that ‘artificially dividing international law into separate fields’ would ‘run counter to the systemic nature of international law’ (Second Report, supra note 1, 13, para. 28).

4 See First Report, supra note 1, para. 3.

5 See Henkin, L., ‘Human Rights and State “Sovereignty”’, (1995–1996) 25 Ga. J. Int'l & Comp. L. 31Google Scholar, 37; and the criticism of d'Amato, A., ‘Human Rights as Part of Customary International Law: A Plea for Change of Paradigms’, (1995–1996) 25 Ga. J. Int'l & Comp. L. 47–49Google Scholar.

6 E.g., Bleckman, A., ‘Zur originären gewohnheitsrechtlicher Menschenrechtsnormen’ in Menschenrechtschutz durch Gewohnheitsrecht: Kolloquium 26–28 September 2002 Potsdam (2002), 38Google Scholar ff.

7 E.g. Corfu Channel case (United Kingdom v. Albania), Merits, Judgment of 9 April 1949 [1949] ICJ Rep. 22.

8 First Report, supra note 1, at para. 19.

9 Second Report, supra note 1, at para. 28 (footnotes omitted), and ibid., at 66, Draft Conclusion 10, requiring the existence of opinio juris. Some doubt may however be felt about the reason given for insistence on the two elements: ‘Any other approach risks artificially dividing international law into separate fields, which would run counter to the systemic nature of international law’; ibid., at para. 28.

10 With the possible exception of the prohibition of genocide: in the Reservations to the Genocide Convention case, while the ICJ did not use the term ‘customary law’, it described the ‘underlying principles’ as ‘recognized by civilized nations as binding on States, even without any conventional obligation’ (Advisory Opinion of 28 May 1951, [1951] ICJ Rep., at 23). The Court did not, however, base this on any analysis of formation of custom, but rather on the conception of genocide as ‘contrary to moral law and to the spirit and aims of the United Nations’ (ibid.).

11 Thus, e.g., R. Jennings and A. Watts, Oppenheim's International Law (2008) discusses the international protection of human rights without mentioning possible reliance on customary law; similarly N. Rodley in M. Evans, International Law (2014) devotes a section to ‘The Basis of Obligation in International Human Rights Law’ with no mention of customary international law; A. Aust, Handbook of International Law (2010), Ch. 11; P. Malanczuk, Akehurst's Modern Introduction to International Law, Ch. 14; etc.; A. Boyle and C. Chinkin, The Making of International Law (2007), play down the role of custom generally (21–22), but it is striking that on human rights their examination of law-making processes is essentially limited to treaty bodies (145–58). Contra, Brownlie, Principles of Public International Law (2003) (6^th edition – the last edited by Brownlie himself), 537: ‘The vast majority of States and authoritative writers would now recognize that the fundamental principles of human rights form part of customary or general international law . . .’ (note the ‘or general’ however; general is not necessarily customary); and P. Dailler and A. Pellet, Droit International Public (1994), §286.

12 R. Wolfrum (ed.), Max Planck Encyclopedia of International Law (2012), Vol. IV, sub ‘Human Rights’, 1023–4, at para. 9.

13 See Second Report, supra note 1, at para. 15.

14 Ibid., 32, at para. 38.

15 First Report, supra note 1, 45–47, at para. 96.

16 For a recent contention that customary international law is ‘non-consensual’, see Guzman, A. and Hsiang, J., ‘Some Ways that Theories on Customary International Law Fail: A Reply to László Blutman’, 25 EJIL (2014), 555–6CrossRefGoogle Scholar.

17 For example, in customary law the existence of any recognized right of transit for land-locked states for access to the sea, now embodied in UNCLOS Art. 125, was very doubtful, presumably since such a right was only favourable to one group of states, and a burden for the other group; see, e.g., L. C. Caflisch, ‘Land-locked States and their Access to and from the Sea’, (1978) 49 BYIL, 71–100. Another indication is the official attitude of the US to the customary status of the rules as to diplomatic protection; this is said to have altered markedly when that state, from being generally in a plaintiff position, found itself increasingly in a defendant position: see J. Dugard, ‘The Future of International Law: A Human Rights Perspective’, in T. Skouteris and A. Vermeer-Künzli, The Protection of the Individual in International Law (Special Issue of the Leiden Journal of International Law, 2010), 4.

18 It has thus been argued that, in respect of ‘intrastate issues such as the human rights obligations, which largely protect citizens from their own governments . . . we need to broaden our understanding of state practice to include consideration of intrastate action (not just interstate interaction)’: A. Roberts, infra. note 38, at 777, who thereby appears to imply that the argument referred to is, at present, correct.

19 That of d'Amato, A., ‘Human Rights as Part of Customary International Law: A Plea for Change of Paradigms’, (1995–1996) 25 Ga. J. Int'l & Comp. L. 47–49Google Scholar. Buergenthal distinguishes modern human rights as rights of individuals, unlike those resulting from the protection of categories of persons in the first half of the twentieth century, and adds that to this extent, ‘human rights are no longer exclusively matters within the domestic jurisdiction of States’ (Max Planck Encyclopedia of International Law, supra note 12, Vol. 4, 1023, at para. 7; but what is that extent? See also the resolution of the Institut de droit international of 13 September 1989, preamble.

20 In this sense, see A. Cassese, International Law (2001), 370–2. Christian Tams has discussed the difficulty of applying the criterion of ‘important’ rights (employed by the ICJ in the Barcelona Traction case), and has referred to ‘the inherently vague and indeterminate notion of “importance”’, See C. J. Tams, Enforcing Obligations Erga Omnes in International Law (2005).

21 Judgment of 5 February 1970, [1970] ICJ Rep. 32, at 33. The Special Rapporteur has considered the question of obligations of jus cogens (and decided to leave it aside), but has not so far touched on any question of erga omnes obligations (see the mention by the Secretariat in the First Report, supra note 1, at para. 11).

22 See the present writer's discussion of the point in The Law and Practice of the International Court of Justice: Fifty Years of Jurisprudence (2013), 1504–9.

23 See Domincé, C., ‘La contrainte entre États à l'appui des droits de l'homme’, in Hacía un Nuevo orden internacional y europeo, Estudios en homenaje al Professor Don Manuel Diez de Verlasco (1993), 261–72Google Scholar. In the case of Armed Activities on the Territory of the Congo, Judge Simma considered that the human rights treaties that had been relied on justified Uganda in claiming to protect persons not shown to have Ugandan nationality, inasmuch as those treaties established obligations erga omnes, but on this point he was a lone dissentient, the majority of the Court not accepting this view: see Democratic Republic of the Congo v. Uganda, Judgment of 19 December 2005, [2005] ICJ Rep. 348.

24 O. Schachter, International Law in Theory and Practice (1991), Ch. XV. He did however suggest that ‘practice’ (his quote-marks) and opinio juris could be looked for in international forums where human rights are discussed.

25 ECHR, van Anraat v. Netherlands, Decision on Admissibility, 6 July 2010, Application No. 65389/09, para. 88, cited in the Rapporteur's First Report, supra note 1, 37, note 178; the wording closely follows the dictum in North Sea Continental Shelf, Judgment of 20 February 1969, [1969] ICJ Rep., 41–42, at 72.

26 For example, the purposes of the UN Charter, specifically that of ‘promoting and encouraging respect for human rights’, relied on, for example by the ICJ in the Namibia case (Advisory Opinion of 21 June 1971, [1971] ICJ Rep. 57, at 131). There may be a question whether this provision could be adduced to prove an obligation on UN Members to respect human rights that have only come to be recognized in more recent years; can the Charter be read to contemplate ‘human rights’ that did not have even a theoretical existence at the time of its adoption? (See the observation of Judge Bork in Tel-Oren v. Libyan Arab Republic, 726 F2d 774 (DC Cir 1984), that the US Alien Tort Statute did not contemplate human rights, as the latter concept did not exist in 1789.) Is this a case of ‘evolving concepts’? (see Gaja, G., ‘The Protection of General Interests in the International Community’, (2014) 364 Recueil des cours 65Google Scholar, at 65–66).

27 Restatement (Third) of Foreign Relations Law of the United States (1987), para. 22.

28 Second Report, supra note 1, 54–57.

29 Ibid., at 55.

30 This is not of course to say that there may not exist a customary rule parallel to, and identical with, that stated in the treaty, as in the Military and Paramilitary Activities case (Nicaragua v. USA), Jurisdiction and Admissibility, Judgment of 26 November 1984, [1984] ICJ Rep. 424, at 73, and Merits, Judgment of 27 June 1986, [1986] ICJ Rep. 93, at 174).

31 A. Boyle and C. Chinkin, The Making of International Law (2007), 157.

32 Ibid., at 160. It should however be added that the authors indicate that ‘certain topics may be inherently unsuited to a consensus negotiation process’, because ‘these do not readily lend themselves to the package deal approach’, and these topics include ‘human rights and humanitarian treaties’ (ibid., 159).

33 Restatement (Third), supra note 27, §701, note 2: and see below, para. 22.

34 Pronto, A. N., ‘“Human-rightism” and the Development of General International Law’, in Skouteris, T. and Vermeer-Künzli, A., The Protection of the Individual in International Law (Special Issue of the LJIL, 2010)Google Scholar.

35 A particularly striking, and perhaps unexpected, form of custom-forming practice in the human rights field may be when such rights are invoked by a state as a defence to a claim, as in the case of claims for breach of an investment treaty: see, e.g., Suez, Sociedad General de Aguas de Barcelona SA v. Argentina, ICSID Case No. ARB/03/19, cited in E. de Brabandere, Investment Treaty Arbitration as Public International Law, (2014), 142–3.

36 First Report, supra note 1, paras. 98–100.

37 O. de Schutter, International Human Rights Law (2010), 52.

38 Roberts, A., ‘Traditional and Modern Approaches to International Customary Law: A Reconciliation’, (2001) 95 AJIL 757CrossRefGoogle Scholar, at 757, 758. Modern customary law is also said to be based on rational choice theory, as was (in the view of Posner and Goldsmith) traditional customary law also: ‘Understanding the Resemblance between Modern and Traditional Customary International Law’, (1999) 40 Virginia Journal of International Law 639Google Scholar.

39 In the special context of human rights, in particular, there is a whiff of circularity here: a statement may contribute to the appearance of a custom if it is authoritative, and it may be authoritative because it states what one wants to believe is the law.

40 Restatement (Third), supra note 27, 1987.

41 See the explanations and examples in the Special Rapporteur's Second Report, supra note 1, at paras. 37–41.

42 ‘Claims may be made in the widest of general terms; but the occasion of an act of State practice contributing to the formation of custom must always be some specific dispute or potential dispute’: H. Thirlway, International Customary Law and Codification (1972), 58; for the Special Rapporteur's dissent, see the Second Report, supra note 1, 18, at para. 37, where the sentence preceding the one just quoted is reproduced. This may have led to a misunderstanding: it was not, and is not here, suggested that, for example, a firm diplomatic note, addressed to the specific dispute, would not amount to state practice, even if matters remained on that level.

43 See section 3 above.

44 ‘What I tell you three times is true’: L. Carroll, The Hunting of the Snark, Fit The First, l, 8.

45 As recently confirmed by the ICJ in a case involving humanitarian law: Jurisdictional Immunities of the State (Germany v. Italy; Greece intervening), Judgment of 3 February 2012, [2012] ICJ Rep. 99.

46 630 F.2d 876, 878 (2d Cir. 1980). The US court had jurisdiction under the Alien Torts Statute, which requires that the action be for a tort ‘committed in violation of the law of nations’. In fact however the court did not cite any ‘usage’ of the traditional kind, but relied on the UN Charter, the 1975 UN Declaration, and ‘numerous treaties and accords’. The Filartiga decision thus did not in fact invoke practice, but may itself be considered an act of state practice! See also Kadic v. Karadzic, 70 F.3d 232, 236–37 (2d Cir. 1995).

47 R. v. Bartle and Commissioner of Police for the Metropolis (Ex Parte Pinochet), 24 March 1999, [1999] UKHL 17.

48 A. Boyle and C. Chinkin, supra note 31, 159. It should however be added that the authors indicate that ‘certain topics may be inherently unsuited to a consensus negotiation process’, and these include ‘human rights and humanitarian treaties’ (ibid.)

49 Ibid., at 160.