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A Disaggregative View of Customary International Law-Making

Published online by Cambridge University Press:  29 April 2016


This article argues that some familiar principles, like the protection of reasonable expectations or fair play, can justify the normative force and binding character of some types of customary international practices. We have no reason to think that any one of those principles can justify all customary practices that are typically taken to have such force. Accordingly, instead of proposing a unifying justification for all customary international law-making, I will suggest that the impact of past international practices on the normative situation of international agents is determined not by one master principle, but by a range of different normative principles, each applicable in different situations. If this is correct, i.e., if the principles that give customary practices their normative force vary depending on the kind of principle governing the practical problem that those practices are meant to respond to, both the critique and the defence of customary law-making must proceed on what I will call a ‘disaggregative’ basis.

Copyright © Foundation of the Leiden Journal of International Law 2016 

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1 J. Bentham, A Comment on the Commentaries and a Fragment on Government (1977), 183–4.

2 Cf. Gardner, J., ‘Some Types of Law’, in Edlin, D. (ed.), Common Law Theory (2007) 51CrossRefGoogle Scholar, at 66–8; D. Bederman, Custom as a Source of Law (2010), 37–8.

3 I am using equality as a placeholder for a range of moral concerns about unjustified control, procedural unfairness, and inequitable distribution. For a similarly ‘reductive’ understanding of equality, see Scanlon, T.M., ‘The Diversity of Objections to Inequality’, in The Difficulty of Tolerance: Essays in Political Philosophy (2003), 202CrossRefGoogle Scholar.

4 Cf. Kumm, M., ‘The Legitimacy of International Law: A Constitutionalist Framework of Analysis’, (2004) 15 EJIL 907CrossRefGoogle Scholar, at 908–9.

5 Roberts, A., ‘Traditional and Modern Approaches to Customary International Law: a Reconciliation’, (2001) 95 American Journal of International Law 757CrossRefGoogle Scholar, at 767–8; Kelly, P., ‘The Twilight of Customary International Law’, (2000) 40 Virginia Journal of International Law 449Google Scholar, at 519–22; Chodosh, H., ‘Neither Treaty Nor Custom: The Emergence of Declarative International Law’, (1991) 26 Texas International Law Journal 87Google Scholar, at 102; M. Byers, Custom, Power and the Power of Rules (1999), 37.

6 McGinnis, J. and Somin, I., ‘Should International Law be Part of Our Law?’, (2007) 59 Stanford Law Review 1175Google Scholar, at 1193ff. See also Bradley, C. and Goldsmith, J., ‘Customary International Law as Federal Common Law: A Critique of the Modern Position’, (1997) 110 Harvard Law Review 815CrossRefGoogle Scholar, at 857.

7 Cf. J. Finnis, Natural Law and Natural Rights (1980), 238-45; F. Schauer, ‘Pitfalls in the Interpretation of Customary Law’, in A. Perreau-Saussine and J. Murphy, The Nature of Customary Law: Legal, Historical and Philosophical Perspectives (2008) 13, at 25–7.

8 Pogge, T., ‘Recognized and Violated by International Law: The Human Rights of the Global Poor’, (2005) 18 Leiden Journal of International Law 717CrossRefGoogle Scholar; Pogge, T., ‘The Role of International Law in Reproducing Massive Poverty’, in Besson, S. and Tasioulas, J., The Philosophy of International Law (2010), 234Google Scholar.

9 Ratner, S., ‘Is International Law Impartial?’, (2005) 11 Legal Theory 39CrossRefGoogle Scholar.

10 McGinnis, J., ‘The Comparative Disadvantage of Customary International Law’, (2007) 30 Harvard Journal of Law & Public Policy 7Google Scholar; Kontorovich, E., ‘Inefficient Customs in International Law’, (2006) 48 William & Mary Law Review 859Google Scholar.

11 On this point, see Kumm, supra note 4, at 924–6.

12 For an argument in favour of stakes-sensitive democratic decision-making, see Brighouse, H. and Fleurbaey, M., ‘Democracy and Proportionality’, (2010) 18 Journal of Political Philosophy 137CrossRefGoogle Scholar, at 138: ‘power should be distributed in proportion to people's stakes in the decision under consideration’. For a criticism of that view, see Kolodny, N., ‘Rule Over None I: What Justifies Democracy?’, (2014) 42 Philosophy & Public Affairs 195CrossRefGoogle Scholar, at 227–8.

13 For a similar view that relies on an account of state interests rather than a difference in the nature of the problems that different customary practices aim to resolve, see Stephan, P., ‘Disaggregating Customary International Law’, (2010) 21 Duke Journal of International & Comparative Law 191Google Scholar.

14 I am grateful to an anonymous reviewer for pointing out this complication to me. I believe that a similar question arises in any community that has more than one ways of making law, e.g., are some issues best left to Parliament or to courts?

15 See Section 6, text to notes 50–1 in relation to setting-off and means-testing mechanisms in international schemes of environmental protection.

16 On the malleability of ‘legitimacy’ in international law, see Koskenniemi, M., ‘Miserable Comforters: International Relations as New Natural Law’, (2009) 15 European Journal of International Relations 395CrossRefGoogle Scholar; Crawford, J., ‘The Problems of Legitimacy-Speak’, (2004) 98 ASIL Proceedings 271Google Scholar; Thomas, C.A., ‘The Uses and Abuses of Legitimacy in International Law’, (2014) 34 Oxford Journal of Legal Studies 729CrossRefGoogle Scholar.

17 I have defended this view in Voyiakis, E., ‘Customary International Law and the Place of Normative Considerations’, (2010) 55 American Journal of Jurisprudence 163CrossRefGoogle Scholar.

18 J. Raz, Practical Reason and Norms (1990), 35–9. See also J. Tasioulas, ‘The Legitimacy of International Law’ and D. Lefkowitz, ‘The Sources of International Law: Some Philosophical Reflections’, in Besson and Tasioulas, supra note 8, at 97 and 187 respectively.

19 Cf. Kolodny, N., ‘Rule Over None II: Social Equality and the Justification of Democracy’, (2014) 42 Philosophy & Public Affairs 195CrossRefGoogle Scholar.

20 I am content to leave open the question of whether those ‘other international agents’ are only agents adversely affected by the defaulting agent's failure to X, or whether non-affected agents may sometimes be similarly entitled to take measures against that agent, say, because certain customary obligations have an erga omnes character.

21 Dworkin, R., ‘A New Philosophy of International Law’, (2013) 41 Philosophy & Public Affairs 2CrossRefGoogle Scholar, at 15–16, note 13.

22 Voyiakis, supra note 17, at 187ff.

23 Finnis, supra note 7, at 238–45. For a defence of a similar view, see B. Lepard, Customary International Law: A New Theory with Practical Applications (2010). See also F. Schauer, ‘Pitfalls in the Interpretation of Customary Law’, in Perreau-Saussine and Murphy, supra note 7, at 58.

24 James Surowiecki identifies mutual independence as a limiting condition of claims about the ‘wisdom of the crowds’, see J. Surowiecki, The Wisdom of Crowds (2007), 45–8.

25 S. Darwall, ‘Authority and Second-Personal Reasons for Acting’, in Morality, Authority and Law: Essays in Second-Personal Ethics I (2013), Chapter 8; Hershovitz, S., ‘The Role of Authority’, (2011) 11 Philosophers’ Imprint, 1719Google Scholar.

26 Cf. the discussion in J. Raz, The Morality of Freedom (1988), 56–67.

27 Weil, P., ‘Towards Relative Normativity in International Law?’, (1983) 77 AJIL 413CrossRefGoogle Scholar.

28 M. Shaw, International Law (2003), 70.

29 Cf. A. Buchanan, ‘The Legitimacy of International Law’, in Besson and Tasioulas, supra note 8, at 91: ‘The consent of weaker states may be less than substantially voluntary, because stronger states can make the costs of their not consenting prohibitive’ and at 92: ‘To say that such states have consented to the process by which CIL norms emerge is equally unconvincing, given the inability of states to opt out of the process or to do so without excessive costs’.

30 T.M. Scanlon, What We Owe To Each Other (1998), Chapter 6. Scanlon draws on an idea proposed by H.L.A. Hart, in ‘Legal Responsibility and Excuses’, in Punishment and Responsibility: Essays in the Philosophy of Law (2008), 44.

31 I take the concept of framing from Julius, A.J., ‘Basic Structure and the Value of Equality’, (2003) 31 Philosophy & Public AffairsCrossRefGoogle Scholar, at 328–9.

32 Cf. V. Lowe, International Law (2007), 56: ‘Persistent objectors face considerable pressures . . . [Both political and practical] factors have to be weighed in the balance when asking – as governments must – if persistent opposition to a particular rule of international law is worthwhile’.

33 See, e.g., Buchanan, supra note 29, at 92.

34 M. Bedjaoui, Towards a New International Economic Order (1979), 51–4; M. Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (reissue, 2005), 388.

35 Cf. International Law Association, Statement of Principles Applicable to the Formation of Customary International Law (M. Mendelson, Rapporteur), London Conference (2000), at 64; Sloan, B., ‘General Assembly Resolutions Revisited (Forty Years Later)’, (1987) 58 British Yearbook of International Law 39CrossRefGoogle Scholar, at 76–8.

36 I discuss some parameters of the ‘framed choice’ problem in the context of UN General Assembly Resolutions in Voyiakis, E., ‘Voting in the General Assembly as Evidence of Customary International Law?’, in Allen, S. and Xanthaki, A. (eds.), Reflections on the UN Declaration on the Rights of Indigenous Peoples (2010) 209Google Scholar.

37 International Law Association, supra note 35, at 8. See also Mendelson, M., ‘The Formation of Customary International Law’, (1998) 272 Recueil des Cours de l'Academie de Droit International 155Google Scholar, at 183–6; Byers, M., ‘Custom, Power and the Power of Rules’, (1995) 17 Michigan Journal of International Law 109Google Scholar, at 165–7; Thirlway, H., ‘The Sources of International Law’, in Evans, M. (ed.), International Law (2006), 121Google Scholar. Kelsen is credited with a similar view, on the ground that his proposed Grundnorm required that ‘States ought to behave as they have customarily behaved’, H. Kelsen, Principles of International Law (1965), 564. It is not clear to me whether Kelsen thought this norm to be intrinsically attractive, although the context of his discussion (at 556–65) leaves this interpretation open.

38 Case concerning Right of Passage over Indian Territory (Portugal v. India), Merits, Judgment of 12 April 1960, [1960] ICJ Rep. 6.

39 Ibid., at 40. India had argued that customary practices could only be created amongst a plurality of states. The Court saw ‘no reason why long continued practice between two States accepted by them as regulating their relations should not form the basis of mutual rights and obligations between the two States’ (at 39).

40 Ibid., at 40–3.

41 See Bradley, C. and Gulati, M., ‘Withdrawing from International Custom’, (2010) 120 Yale LJ 202Google Scholar. For a criticism of that view, see Stephan, supra note 13.

42 Right of Passage case, supra note 38, at 39.

43 Hart, H.L.A., ‘Are There Any Natural Rights?’, in Waldron, J. (ed.), Theories of Rights (1984), 110Google Scholar.

44 Rawls, J., ‘Legal Obligation and the Duty of Fair Play’, in Freeman, S. (ed.), John Rawls: Collected Papers (2001), 122Google Scholar. See also Sugden, R., ‘Reciprocity: The Supply of Public Goods through Voluntary Contributions’, (1984) 94 Economic Journal 772CrossRefGoogle Scholar, at 775.

45 G. Klosko, The Principle of Fairness and Political Obligation (2003), arguing that receipt of benefits may suffice; R. Nozick, Anarchy, State and Utopia (1974), at 90–5; J. Simmons, Moral Principles and Political Obligations (1979), arguing that acceptance of benefits is necessary. R. Nozick and J. Simmons use a metaphor akin to ‘framing’ to convey the moral situation of the non-participating agent who has not accepted the benefits of the scheme. They say that the scheme has been ‘built around’ that agent.

46 This objection apparently convinced J. Rawls, who eventually rejected the idea that political obligation is an instance of the duty of fair play, see J. Rawls, A Theory of Justice (rev. ed., 1999) §18, at 97–8.

47 Art. 136 of the 1982 United Nations Convention on the Law of the Sea, 1833 UNTS 397, declares these areas the ‘common heritage of mankind’.

48 UN General Assembly Resolution 1962 (XVIII) – Declaration of Legal Principles Governing the Activities of States in the Exploration and Use of Outer Space, §1: ‘The exploration and use of outer space shall be carried on for the benefit and in the interests of all mankind’ and §3: ‘Outer space and celestial bodies are not subject to national appropriation by claim of sovereignty, by means of use of occupation or by any other means’.

49 The locus classicus for this view is Cheng, B., ‘United Nations Resolutions on Outer Space: “Instant” Customary International Law?’, (1965) 5 Indian Journal of International Law 23Google Scholar.

50 Part of the explanation would be what economists call the ‘tragedy of the commons’, see Barrett, S., ‘A Theory of Full International Cooperation’, (1999) 11 Journal of Theoretical Politics 519CrossRefGoogle Scholar, at 524–6.

51 The Montreal Protocol mechanisms for implementing what later became known as the principle of ‘common but differentiated responsibility’ are, I think, a good example of a system that could not have been created through customary practice. See 1987 Montreal Protocol to the Vienna Convention on Substances that Deplete the Ozone Layer, 1522 UNTS 29, Preamble and Arts. 1–2.

52 This marks out co-operative schemes to which the fair play principle applies as those that produce ‘step goods’, cf. Hardin, R., ‘Group Provision of Step Goods’, (1976) 21 Behavioural Science 101CrossRefGoogle Scholar; Hampton, J., ‘Free-Rider Problems in the Production of Collective Goods’, (1987) 3 Economics & Philosophy 245CrossRefGoogle Scholar.

53 This seems to me to be the idea behind Ronald Dworkin's appeal to a principle of salience, supra note 21, at 19: ‘If a significant number of states, encompassing a significant population, has developed an agreed code of practice, either by treaty or by other form of co-ordination, then other states have at least a prima facie duty to subscribe to that practice as well, with the important proviso that this duty holds only if a more general practice to that effect, expanded in that way, would improve the legitimacy of the subscribing state and the international order as a whole’.

54 Contrast the views of J. Raz, ‘Human Rights without Foundations’, in Besson and Tasioulas, supra note 8, at 321, who sees the problem as the establishment of relationships of international accountability for human rights violations; J. Griffin, ‘Human Rights and the Autonomy of International Law’, ibid., at 339, who sees it as the provision of necessary protections for personhood.

55 See International Law Commission, Second report on the identification of customary international law, by Michael Wood, Special Rapporteur, 22 May 2014, A/CN.4/672, at 11–12, §28; International Law Commission, Report on the Sixty-sixth Session (2014), A/69/10, Chapter X, at 244, §156.

56 P. Allott, Eunomia (1990), 275.