The paper benefited greatly from the comments of Larry May, Max Pensky, Nicole Hassoun, Kristen Hessler, Jens Ohlin, Christopher Morgan-Knapp, Melissa Zinkin, Benjamin Yost, audience members at the Binghamton University PPL International Law Conference, and an anonymous reviewer for Canadian Journal of Jurisprudence.

1. See Hart, HLA, The Concept of Law, 2nd ed by Bulloch, Penelope A & Raz, Joseph (New York: Oxford University Press, 1994) at 213-37Google Scholar; D’Amato, Anthony, “The Neo-Positivist Concept of International Law” (1965) 59 AJIL 321 CrossRefGoogle Scholar; Hoof, GJH van, Rethinking the Sources of International Law (Deventer: Kluwer, 1983)Google Scholar; Franck, Thomas, The Power of Legitimacy Among Nations (New York: Oxford University Press, 1990)Google Scholar; Boyle, Alan & Chinkin, Christine, The Making of International Law (New York: Oxford University Press, 2007)Google Scholar; Lefkowitz, David, “(Dis)Solving the Chronological Paradox in Customary International Law: A Hartian Approach” (2008) 21 Can JL & Jur 129 Google Scholar; Besson, Samantha, “Theorizing the Sources of International Law” in Besson, Samantha & Tasioulas, John, eds, The Philosophy of International Law (New York: Oxford University Press, 2011) at 163–85Google Scholar; Lefkowitz, David, “The Sources of International Law: Some Philosophical Reflections” in Besson, Samantha & Tasioulas, John, eds, The Philosophy of International Law (New York: Oxford University Press, 2011) at 187–203.Google Scholar

2. Any list here will be a very selective gesture, but prominent contributions include Walzer, Michael, Just and Unjust Wars (New York: Basic Books, 1977)Google Scholar; Beitz, Charles, Political Theory and International Relations (Princeton: Princeton University Press, 1979)Google Scholar; Rawls, John, The Law of Peoples (Cambridge: Harvard University Press, 1999)Google Scholar; May, Larry, Crimes Against Humanity: A Normative Account (New York: Cambridge University Press, 2005)Google Scholar; McMahan, Jeff, “The Morality of War and the Law of War” in Rodin, David & Shue, Henry, eds, Just and Unjust Warriors (Oxford: Clarendon Press, 2008) at 19–43 Google Scholar; Griffn, James, On Human Rights (New York: Oxford University Press, 2008)CrossRefGoogle Scholar; Altman, Andrew & Wellman, Christopher Heath, A Liberal Theory of International Justice (New York: Oxford University Press, 2009)CrossRefGoogle Scholar; Beitz, Charles R, The Idea of Human Rights (New York: Oxford University Press, 2009)CrossRefGoogle Scholar; Buchanan, Allen, Human Rights, Legitimacy, & the Use of Force (New York: Oxford University Press, 2010).Google Scholar

3. For a view skeptical that international law is a source of non-prudential reasons, see Goldsmith, Jack L & Posner, Eric A, The Limits of International Law (New York: Oxford University Press, 2005) at 185–224 Google Scholar. For a reply, see Buchanan, Allen, “Democracy and the Commitment to International Law” (2006) 34 Ga J Int’l & Comp L 305 Google Scholar. For additional treatment of the issue, see Besson, Samantha, “The Authority of International Law—Lifting the State Veil” (2009) 31 Sydney L Rev 343 Google Scholar; Tasioulas, John, “The Legitimacy of International Law” in Besson, Samantha & Tasioulas, John, eds, The Philosophy of International Law (New York: Oxford University Press, 2011) at 97–116 Google Scholar; Lefkowitz, “The Sources of International Law: Some Philosophical Reflections,” supra note 1. Tasioulas, Besson, and Lefkowitz draw largely on Raz’s theory of authority in their accounts. My approach is not inconsistent with that particular understanding of instrumental political authority, but it does not presuppose the mechanics or details of Raz’s theory. For his recent discussion of the theory, see Raz, Joseph, “The Problem of Authority: Revisiting the Service Conception” (2006) 90 Minn L Rev 1003.Google Scholar

4. Lefkowitz, David, “The Principle of Fairness and States’ Duty to Obey International Law” (2011) 24 Can JL & Jur 347 Google Scholar. Even on Lefkowitz’s account, however, the obligation would be restricted to human rights respecting democratic states whose officials have knowingly accepted the benefits of the international legal order.

5. See Reeves, Anthony R, “The Moral Authority of International Law” (2010) 10 APA Newsletter on Phil & Law 13 Google Scholar. Of course, the notion that subjects of even decently just and democratic states have a general obligation to obey the law remains controversial. See Simmons, A John, Justification and Legitimacy: Essays on Rights and Obligations (New York: Cambridge University Press, 2001).Google Scholar

6. Buchanan, Allen, “The Legitimacy of International Law” in Besson, Samantha & Tasioulas, John, eds, The Philosophy of International Law (New York: Oxford University Press, 2010) 79 at 90-94Google Scholar.

7. So one need not fully agree with my blunt assessment above to accept the argument of the paper. Here I speak to the proper motivations for developing legal theory in a certain direction.

8. Other agencies can be both subjects and, in virtue of their practice, creators of international law. Having acknowledged this, I will, for the sake of avoiding awkward locutions, simply refer to states. The argument applies with equal force to non-state subjects of international law.

9. For a general discussion of these matters for traditional customary law, see Cassese, Anthonio, International Law (York, New, Oxford University Press, 2005) at 153–69Google Scholar. Regarding treaty interpretation, see Gardiner, Richard, Treaty Interpretation (New York: Oxford University Press, 2010) at 203-49CrossRefGoogle Scholar. How exactly state practice and the opinio juris ought to be ascertained, and what role, precisely, they ought to and do play as sources of law (e.g., how far state practice must be shown before appealing to the opinio juris of states) are matters of significant controversy. This controversy is not idle, but I think we can sidestep some of the issues, at least for the issue of responsible reasoning under international law, on the approach advocated here. For a discussion of the central issues, see Weil, Prosper, “Towards Relative Normativity in International Law?” (1983) 77 AJIL 413 CrossRefGoogle Scholar; D’Amato, Anthony, “Trashing Customary International Law” (1987) 81 AJIL 101 CrossRefGoogle Scholar; Kirgis, Frederick Jr, “Custom on a Sliding Scale” (1987) 81 AJIL 146 CrossRefGoogle Scholar; Tasioulas, John, “In Defence of Relative Normativity: Communitarian Values and the Nicaragua Case” (1996) 16 Oxford J Legal Stud 85 CrossRefGoogle Scholar; Roberts, Anthea Elizabeth, “Traditional and Modern Approaches to Customary International Law: A Reconciliation” (2001) 95 AJIL 757.CrossRefGoogle Scholar

10. Waldron, Jeremy, “The Rule of International Law” (2006) 30 Harv JL & Pub Pol’y 15 at 23 Google Scholar.

11. I consider in greater detail below at the text for footnote 36 how we should think about these norms from the standpoint of legality. For a discussion of how we can accommodate developing customary international law on positivist assumptions, see Lefkowitz, “(Dis)Solving the Chronological Paradox in Customary International Law: A Hartian Approach,” supra note 1.

12. I intend “practical reason” here to be ecumenical regarding conceptions of practical reason. I pursue clarification of the proper role of legal nascency in practical reasoning without committing myself to some special view about the precise nature of practical reason. We can ask whether a norm’s legal nascency justifes an attitude regarding its mandatoriness without, e.g., saying whether mandatoriness is a matter of exclusionary reasons. See Raz, Joseph, Practical Reason and Norms (Oxford: Oxford University Press, 1975)Google Scholar. Deploying the idea of practical reason here assists the right kind of theoretical focus.

13. I am not claiming that such moral norms cannot be legal norms also. I am not entering that debate here. I am merely stipulating that N is not simply this kind of norm.

14. A point well at home in legal positivism. See, for example, Hart supra note 1 at 185-212; Lyons, David, “Moral Aspects of Legal Theory” in Moral Aspects of Legal Theory: Essays on Law, Justice, and Political Responsibility (Cambridge: Cambridge University Press, 1993) at 64-101CrossRefGoogle Scholar. However, it is a point that is conceded by many philosophers who would call themselves natural law theorists. See, for example, Murphy, Mark C, Natural Law in Jurisprudence and Politics (Cambridge: Cambridge University Press, 2006) at 1-60CrossRefGoogle Scholar. Dworkin may be an exception, but that is because legal validity is established by providing some moral political justification for the well-accepted elements of legal practice. See generally Dworkin, Ronald, Law’s Empire (Cambridge: Harvard University Press, 1986).Google Scholar

15. This way of putting the point is consistent with a Razian analysis, but again, does not require it.

16. The question of when personal interests are actually of such moral significance is not a matter of anyone’s discretion, but an issue requiring discernment.

17. Legitimate functions will likely vary, to some degree, from department to department such that, for example, there are values of special concern to international criminal law. See, e.g., May supra note 2.

18. See Rawls, Griffn, Beitz, Buchanan supra note 2. Other prominent contributions, representing the theoretical pluralism, include Shue, Henry, Basic Rights (Princeton: Princeton University Press, 1980)Google Scholar; Nussbaum, Martha C, Women and Human Development: The Capabilities Approach (New York: Cambridge University Press, 2001)Google Scholar; Nickel, James, Making Sense of Human Rights, 2nd ed (Malden: Blackwell, 2007)Google Scholar; Raz, Joseph, “Human Rights Without Foundations” in Besson, Samantha & Tasioulas, John, eds, The Philosophy of International Law (New York: Oxford University Press, 2010) at 321-37Google Scholar; Forst, Rainer, “The Justification of Human Rights and the Basic Right to Justification: A Refexive Approach” (2010) 120 Ethics 711 CrossRefGoogle Scholar; Wellman, Carl, The Moral Dimensions of Human Rights (New York: Oxford University Press, 2011).Google Scholar

19. It might be doubted that I can leave matters so formal at this point, i.e., that I can avoid specifying more conclusively what counts as a morally mandatory end for subjects of international law. I present the argument as adaptable to variety of understandings of international morality, but the replacement/addition I am suggesting here might be thought unacceptable. The plausibility that international law should promote human rights, for instance, depends upon which conception of human rights is affirmed. I will consider this worry more fully below at the text for footnote 43, but as an initial reply, I do think relying upon interchangeability is appropriate here. A division of labor in normative theorizing is frequently acceptable and helpful in making progress in specialized topics. Sometimes we are interested in the substance of the legitimate aims of a social order, and other times in the character of legal authority. The analysis here focuses on the latter, and (attractively, I think) can adapt to various theoretical outcomes on the former. The benefit of dividing theoretical labor (given that we cannot say everything at once) is the potential advancement of our understanding of nascent legal authority in particular, and the precise way in which it relates to the substantive aims of the legal order.

20. See generally Buchanan, Allen, Justice, Legitimacy, and Self-Determination: Moral Foundations for International Law (New York: Oxford University Press, 2004).Google Scholar

21. Ibid at 468.

22. I will say more about nascent law’s status as law, and why it is correct to treat the law-making properties as reasons in cases where it binds, below at the text for footnote 37.

23. The relevant sense of ethically superior here will be settled by the mandatory ends at stake, e.g., which norm better protects human rights, or what ends are ethically more Pressing as a matter of substantive political morality.

24. Case Concerning Military and Paramilitary Activities In and Against Nicaragua, [1986] ICJ Rep 14 [Nicaragua v US].Google Scholar

25. The issue of responsible adjudication in international courts and responsible state reasoning under international law are, I think, closely related. However, I will not argue for that here.

26. For a discussion of some of the doctrinal issues regarding collective self-defense in the case, see Modabber, Zia, “Collective Self-Defense: Nicaragua v. United States ” (1988) 10 Loy LA Int’l & Comp L Rev 449.Google Scholar

27. Nicaragua v US, supra note 24 at para 193.

28. Ibid at para 194.

29. GA Res 3314, UNGAOR, 29th Sess, Supp No 31 142, UN Doc A/9631 (1974), art 3.

30. Ibid at art 4.

31. Nicaragua v US, supra note 24 at para 195.

32. Ibid at para 201.

33. Freeman, Mark & Pensky, Maxim, “The Amnesty Controversy in International Law” in Payne, Leigh A & Lessa, Francesca, eds, Amnesty in the Age of Human Rights Accountability: Comparative and International Perspectives (New York: Cambridge University Press, 2012) 42 at 64CrossRefGoogle Scholar.

34. Ibid at 42-65.

35. With the minor difference that sanctions from the international community might be attached to non-compliance. Set this prudential consideration aside since we are considering here how the fact of an international legal norm can render non-compliance irresponsible.

36. Waldron, Jeremy, “Vagueness in Law and Language: Some Philosophical Issues” (1994) 82 Cal L Rev 509 at 513 CrossRefGoogle Scholar.

37. The degree to and way in which the criteria of legality are vague will vary from legal system to legal system (insofar as systems have qualitatively different criteria).

38. Vagueness does not always imply nascency. Turquoise is not nascently blue. “Nascency” seems applicable in cases where a vague predicate is questionably (because of its vagueness) predicable of an object that is in the early part of a process that will, under felicitous conditions, lead to the predicate being unquestionably predicable of the object.

39. I offer an illustration in terms of customary international law, but the same point would hold for other domains of international law that contain nascent doctrine.

40. In addition, there will be vagueness regarding the extent of opinio juris required. Moreover, the rule of recognition may stipulate more complex and extensive criteria for customary law, but that does not affect the theoretical point here: vagueness in the criteria of legality ground the possibility of nascent law such that it is sensible to speak of nascent law as binding in virtue of its legal status.

41. For an excellent discussion of Bentham’s critique of the common law, see Postema, Gerald, Bentham and the Common Law Tradition (Oxford: Clarendon Press, 1986).Google Scholar

42. Besson, supra note 1 at 180-85.

43. I am grateful to the anonymous reviewer for Pressing this issue.

44. In contrast to a form that would employ, for instance, transactions of some sort to establish its binding force.

45. My examples in text at footnote 24 provide some evidence that nascent legal norms are capable, in principle, of serving important ends of global governance under certain conditions.

46. Supra notes 1, 2, 3, 9, and 18.