1. Joseph Raz, The Authority of Law: Essays on Law and Morality (2d ed. 2009), at 104.

2. The example is Kelsen's. See Hans Kelsen, General Theory of Law and State (1999), at 118, and more generally, 117–119. Historical instances that raised the issue of legal revolutionary success in the twentieth century include Pakistan in 1958; then Rhodesia, now Zimbabwe in 1965; and Uganda in 1966. These examples bought the question of the criteria for determining successful revolutionary change before the courts and resulted in a large secondary literature, of which the more philosophically nuanced includes Eekelaar, J. M., Splitting the Grundnorm, 30 Mod. L. Rev. 156 (1967)CrossRefGoogle Scholar; Honore, A. M., Reflections on Revolutions, 2 Irish Jurist 268 (1967)Google Scholar; Dias, R. W. M., Legal Politics: Norms Behind the Grundnorm, 26 Cambridge L.J. 233 (1968)CrossRefGoogle Scholar; Brookfield, F. M., The Courts, Kelsen, and the Rhodesian Revolution, 19 U. Toronto L.J. 326 (1969)CrossRefGoogle Scholar; Harris, J. W., When and Why Does the Grundnorm Change?, 29 Cambridge L.J. 103 (1971)CrossRefGoogle Scholar.

3. A historical example of partial disintegration of this kind occurred toward the end of the Soviet Union where between 1987 and 1991 Estonia engaged in a “war of laws” with the central Soviet government, eventually reconstituting itself as a distinct legal entity.

4. H. L. A. Hart, The Concept of Law (3d ed. 2012), at 39.

5. John Austin, The Province of Jurisprudence Determined; and, the Uses of the Study of Jurisprudence (1998), at 193–194.

6. Kelsen, supra note 2, at 9, 119.

7. Id. at 119. Hart mirrors these points. See Hart, supra note 4, at 103–104.

8. Hart suggests, for example, that one of the “minimum conditions … for the existence of a legal system” is that “the rules of behavior which are valid according to the system's ultimate criteria of validity must be generally obeyed.” See Hart,supra note 4, at 2, 116; Joseph Raz, The Concept of a Legal System: An Introduction to the Theory of a Legal System (2d ed. 1980), at ch. 7; Raz, supra note 1, at 104. For Finnis's discussion of efficacy as a necessary condition of law's authority see John Finnis, Natural Law and Natural Rights (2d ed. 2011), at 246–247.

9. Notable exceptions include Eekelaar, supra note 2; Dias, supra note 2; Harris, supra note 2; Postema, Gerald J., Conformity, Custom and Congruence: Rethinking the Efficacy of Law, in The Legacy of H.L.A. Hart: Legal, Political, and Moral Philosophy 45–66 (Kramer, Matthew H. ed., 2008)Google Scholar.

10. Raz, Concept of a Legal System, supra note 8, at ch. 9.

11. See Hans Kelsen, Pure Theory of Law (Max Knight trans., 1967), at 10–11 and 211–214; Kelsen, supra note 2, at 118–122; Hart, supra note 4, at 112–117.

12. For analyses that draw radically different conclusions from this premise see Noam Chomsky, Pirates and Emperors, Old and New: International Terrorism in the Real World (new ed. 2002); Jack L. Goldsmith & Eric A. Posner, The Limits of International Law (2005). For an important corrective to Goldsmith and Posner's reductive view see Philippe Sands, Reasons to Comply, London Rev. Books, July 20, 2006.

13. For an alternate approach, one that places more emphasis on the claims made by legal actors within each system in adjudicating the issue, see Julie Dickson, How Many Legal Systems? Some Puzzles Regarding the Identity Conditions of, and Relations Between, Legal Systems in the European Union, 2 Problema 9 (2008).

14. In this and what follows I treat law and legal systems as synonymous, such that anything that is necessarily true of law is necessarily true of all legal systems.

15. See, on these points, Hart, supra note 4, at 103; Kelsen, supra note 2, at 119.

16. For the analogy see Hart,supra note 4, at 104. This helps to explain why Ronald Dworkin was wrong to hold that questions concerning “what makes a particular structure of governance a legal system” were neither of “much practical nor much philosophical interest” while the “doctrinal question” of “what makes a statement of what the law of some jurisdiction requires or permits true” was of “enormous practical and considerable philosophical significance.” Because the existence of a functioning legal system forms part of that which is presupposed when we make individual claims of law, the institutional question is crucial to the doctrinal one. See Dworkin, Ronald, Hart and the Concepts of Law, 120 Harv. L. Rev. F. 95 (2006)Google Scholar. For further criticism of Dworkin on this point see John Gardner, Law as a Leap of Faith : Essays on Law in General (2012), at 270–272.

17. Hart, supra note 4, at 103–104.

18. Anscombe, G. E. M., On Brute Facts, 18 Analysis 69, 69 (1958)CrossRefGoogle Scholar. The point is taken up and developed by John Searle in John R. Searle, Speech Acts: An Essay in the Philosophy of Language (1969), at 33–39, 50–53 and John R. Searle, The Construction of Social Reality (1995), at 27–29. For Searle the existence of “institutional facts”—such as the fact that an individual is “in check” in a game of chess or that I am liable to pay damages under a contract—depend on systems of constitutive rules, rules that make possible the relevant acts and descriptions of such acts. The argument developed here sits tangentially to Searle's central idea: the issue is not so much that legal act descriptions—that I am liable to pay damages, for example—depend on sets of interrelated institutional rules (which is undoubtedly true), but that these rules must interact with their target population in a particular way for the system of which they form a part to be said to exist.

19. The point can be put differently by saying that we do not yet have legal institutions unless and until their rules and rulings are in force.

20. So Anscombe's claim must be interpreted figuratively, not literally.

21. It is sometimes suggested that claims about historical or fictional legal systems stand as counterexamples to this view, as such assertions can be true absent an effective legal order. But in the former case the statement will be relativized to a legal system that actually was in force and in the latter case it will be relativized to one that is conceived of as so being in the relevant fictional context. As such, the tension between the argument and the examples is in the end only apparent. On this point as applied to the historical example see Hart, supra note 4, at 104 and J. W. Harris, Law and Legal Science: An Inquiry into the Concepts Legal Rule and Legal System (1979), at 123–124.

22. Brian Z. Tamanaha, A General Jurisprudence of Law and Society (2001), at 145.

23. Id. at 145.

24. Id. at 146.

25. Id. at 146.

26. See, on this possibility, Hart, supra note 4, at 117–123.

27. Tamanaha, supra note 22, at 146.

28. Id. at 146.

29. For criticism of Tamanaha's argument along similar lines to those developed here see Postema, supra note 9, at 48–49 and for discussion of law's “Janus-faced” nature, “looking both towards obedience by ordinary citizens and to the acceptance by officials of [certain] rules as … standards of official behaviour,” see Hart, supra note 4, at 116–117.

30. On which see Leslie Green, Positivism and the Inseparability of Law and Morals, 83 N.Y.U. L. Rev. 1035, 1052–1054 (2008).

31. Tamanaha, supra note 22, at 146.

32. Kelsen, Pure Theory, supra note 11, at 212. Cf. Hart, supra note 4, 103–104.

33. For discussion of this issue in relation to the Rhodesian/Zimbabwean case see Eekelaar, supra note 2, at 173–174.

34. The vagueness inherent in the distinction puts pay to criticisms of Kelsen's theory for its failure to clearly determine whether a new legal system has come into existence in the aftermath of attempted revolutionary change. To this question there will often be no clear answer. See, for the criticism, Dias, supra note 2 (1968), at 253 and Harris, supra note 2, at 120–121. For discussion of the contrast between philosophical analysis of legal concepts and their role “within the ordering of human life in society” and lawyers’ use of language, often in such a way as to attempt to “read off a definite solution to definite problems—in the final analysis, judgment for one party rather than the other in a litigable dispute,” see Finnis, supra note 8, at 279–280.

35. See Kelsen, supra note 2, at 58–63.

36. See Hart, supra note 4, at 35–42, Joseph Raz, Practical Reason and Norms (2d ed. 1990), at 161–162.

37. See Hart, supra note 4, at 27–32.

38. Kelsen, Pure Theory, supra note 11, at 11.

39. Id. at 11.

40. There is a large literature on the psychology of why people obey the law, of which the most important work is probably Tom R. Tyler, Why People Obey the Law (rev. ed. 2006). This body of scholarship largely takes for granted or assumes an answer to the question being considered here, namely, what it means to obey duty-imposing laws. For criticism of some of the assumptions made by Tyler and others see Frederick F. Schauer, The Force of Law (2015), at 57–61.

41. Regan, Donald H., Reasons, Authority, and the Meaning of Obey: Further Thoughts on Raz and Obedience to Law, 3 Can. J. L. & Juris. 3, 15 (1990)Google Scholar. See also Schauer, supra note 40, at 48–49.

42. It is clear that Hart thought of obedience in cognitive terms, that is, as involving knowledge of the law: see Hart, supra note 4, at 112, 115 (although cf. Postema, supra note 9, at 50 & n.1 for a different interpretation). Kelsen, on the other hand, appears not to have done. Although he describes willing submission to a legal rule as “the ideal case of the validity of a legal norm” Kelsen also countenances the possibility of “obedience to [a] legal norm caused by other motives,” such as the wish to avoid “religious sanction.” See, on this, Kelsen, Pure Theory, supra note 11, at 11–12. Kelsen's failure to distinguish between behavioral coincidence with the requirements of the law and intentional compliance owes itself to his insistence on the separation of philosophical study of the law not only from ethics but also from psychology; this is the “purity” of his pure theory, the attempt to avoid “the uncritical mixture of methodologically different disciplines.” Id. at 1. Kelsen's notion of purity here goes one step too far, however. He is right that the psychological study of law is different from philosophical understanding of the subject, and that the concerns that illuminate the former will not be the same as those that illuminate the latter. But this is distinct from saying that the philosophy of law should pay no attention to psychological concepts. As Raz has argued, “it is beyond doubt part of the task of legal philosophy to explain the methods by which the existence and content of the law are ascertained [and that] they cannot be ascertained without regard to the practices and manifested attitudes of legal institutions … .” When considering the question of whether the law is in force the point applies mutatis mandis to the “practices and … attitudes” of the law's subjects. See, for the criticism, Raz, supra note 1, 294–295. For more general discussion of the notion of “purity” in Kelsen's work see Stanley L. Paulson, The Purity Thesis, 31 Ratio Juris 276 (2018).

43. For discussion of some of the theoretical issues engendered by this fact see Joseph Raz, Ethics in the Public Domain: Essays in the Morality of Law and Politics (1994), at 342–346.

44. In making this claim I depart from Fred Schauer's recent treatment of the issue according to which individuals should be classified as obeying the law only if it makes a causal difference to their behavior. “If we are interested in obedience to law,” he suggests, “we must focus on law's effects on people who, but for the law, would have done something other than what the law commands.” In making this claim Schauer confuses a sufficient condition for obedience—that one performs some action simply because the law requires it—with a necessary one. See Schauer, supra note 40, at 49.

45. I thank my anonymous reviewers for getting me to clarify my thoughts on this issue, especially in relation to the wider literature.

46. Raz, for example, takes this to be an important criticism of traditional accounts of the efficacy of law: “The principle of efficacy is concerned only with obedience and disobedience to [duty-imposing] laws. But is not the way in which people do or do not make use of powers conferred on them by [power-conferring] laws of equal importance to the existence of the legal system?” See Raz, Concept of a Legal System, supra note 8, at 204.

47. It is important to be clear that here, as per above, the question is whether the law itself plays a decisive role in the reasoning of the individual. People's moral and prudential reasons to keep to their promises, taken in isolation from the law, do not count in favor of the efficacy of the institution of contract. On the other hand, keeping to a contractual obligation because mandated to do so by law does.

48. Raz wants to go one stage further. “If” he says, the “violation of certain contracts affects the existence of the legal system, so does the fact that the population refrains from making certain types of contract.” But this does not follow. There is a difference, after all, between repeatedly moving the bishop in a straight line in a game of chess and refusing to use it at all. Only the former of these actions threatens the integrity of the game. See Raz, Concept of a Legal System, supra note 8, at 204.

49. The efficacy of these rules in turn being analyzed as above: depending on the extent to which their duty-imposing components are complied with.

50. Raz, Concept of a Legal System, supra note 8, at 204.

51. Kelsen, Pure Theory, supra note 11, at 11.

52. Hart, supra note 4, at 112.

53. The mirror of this argument also puts pay to Jim Harris's suggestion that the aspect of Kelsen's theory having to do with obedience should be dropped in favor of an account focused only on enforcement. To hold, as he does, that “the first criterion (obedience) should be eliminated” from our understanding of the effectiveness of law fails to accommodate the fact that a legal system that achieves widespread submission makes good on its primary function of controlling behavior. As Hart notes, “it is of course very important, if we are to understand the law, to see how the courts administer it when they come to apply its sanctions. But this should not lead us to think that all there is to understand is what happens in courts. The principal functions of the law as a means of social control … [are] to be seen in the diverse ways in which the law is used to control, to guide, and to plan life out of court.” See Harris, supra note 2, at 120–121. For Hart's criticism of theories focused only on law's secondary or ancillary functions see Hart, supra note 4, at 40.

54. As enforcement is here understood to count as an “in the alternative” way of securing the efficacy of law so the argument I am making stops short of suggesting that coercive enforcement is itself an essential property of law. For arguments against the conclusion that it is see Raz, supra note 36, at 157–162 and Scott Shapiro, Legality (2011), at 154–170. For discussion of the practical and philosophical import of these claims see Schauer, supra note 40, at 93–98 and, on Schauer, Green, Leslie, The Forces of Law: Duty, Coercion, and Power, 29 Ratio Juris 164 (2016)CrossRefGoogle Scholar.

55. Kelsen, Pure Theory, supra note 11, at 11.

56. See, on this, id. at 11–12.

57. As Donald Regan notes, “obedience and disobedience … are not contradictories. They are merely contraries.” See Regan, supra note 41, at 15.

58. This observation helps to explain Leslie Green's somewhat cryptic remark that “it is a feature of our concept of law that it is coercive if necessary, though not necessarily coercive.” The property of law that makes it in the last place dependent on coercion is the fact that if all else fails it must turn to this mechanism to secure its existence. See Green, supra note 54, at 167.

59. Part of the reason why such a system is highly unlikely to come to pass has to do with the costs associated with enforcement. The less the state can get by on the goodwill of its subjects, the more its resources will be eaten up through the imposition of punishments, liabilities, etc. The point at which this would become practically unsustainable for the existence of the institution will usually be reached long before we arrive at the hypothetical situation we are considering.

60. Waldron, Jeremy, All We Like Sheep, 12 Can. J. L. & Juris. 169, 176 (1999)Google Scholar.

61. Id. at 176.

62. Id. at 176.

63. Id. at 176. The point is not that an occupying army cannot use enforcement mechanisms—and indeed they may, for example in upholding martial law—but that their use of force is not necessarily of this type. I thank one of my anonymous reviewers for forcing me to clarify the above remarks.

64. Id. at 176.

65. Although note Oona Hathaway and Scott Shapiro's recent work that suggests that international law in fact secures relatively broad enforcement, albeit by methods that depart from those associated with the modern statist paradigm. See Hathaway, Oona & Shapiro, Scott J., Outcasting: Enforcement in Domestic and International Law, 121 Yale L.J. 252 (2011)Google Scholar.

66. On the question of whether international law is really law there is a long and in some ways dispiriting literature. Most modern discussion of the topic begins with Hart, supra note 4, at 213–237 (although cf. Waldron, Jeremy, International Law: ‘A Relatively Small and Unimportant’ Part of Jurisprudence?, in Reading HLA Hart's The Concept of Law (d'Almeida, Luís Duarte et al. eds., 2013)Google Scholar. For a recent positive answer to the question see Samantha Besson & John Tasioulas, The Philosophy of International Law (2010), at 6–13.

67. Notice that this argument differs from Ken Himma's recent suggestion that law, of necessity, authorizes the deployment of coercive enforcement mechanisms. For Himma the (relative) absence of such mechanisms in international law calls into question its normative status as law. By way of contrast the argument that efficacy is necessary to law (and may in the alternative be secured through enforcement), does not, just so long as the system in question is able to secure widespread obedience. See Himma, Kenneth Einar, The Authorisation of Coercive Enforcement Mechanisms as a Conceptually Necessary Feature of Law, 7 Juris. 593 (2016)CrossRefGoogle Scholar, and especially 615–618 for discussion of the international case.