The history of law is in no small part the history of its boundaries. And the history of legal theory, or jurisprudence more narrowly,1×1. Scholars these days tend to treat “jurisprudence” and “philosophy of law” as more or less synonymous. The tendency is best resisted, however, for it mistakenly suggests that only the tools of philosophy, and in practice only the tools of contemporary analytic philosophy, are suited to examining the nature of law itself, as opposed to law in particular places, and as opposed to particular branches of law. Nevertheless, the focus of this Essay is on that form of jurisprudence commonly understood as philosophy of law, even though, as will be apparent, there will be necessary excursions into those parts of jurisprudence that are decidedly less philosophical, and to those aspects of jurisprudential inquiry often ignored by contemporary practitioners of analytic philosophy of law. is thus a history of exploring, analyzing, and debating these boundaries. Indeed, as far back as 1906, in a tribute to the then–recently deceased Christopher Columbus Langdell, Joseph Beale recalled that many of Langdell’s students complained that his teaching, which tended to focus on older decisions from England rather than on general rules from treatises or newer American cases, “was not law.”2×2. Joseph H. Beale, Jr., Professor Langdell — His Later Teaching Days, 20 Harv. L. Rev. 9, 10 (1906).
Seen through 2017 eyes, the student complaint that decisions by English judges on topics such as mortgages and specific performance of contracts were not law seems bizarre. What could be more law, we might now think, than an analysis of the holdings of English courts on the subjects just mentioned, or on, say, suretyship? But to the students who carped about Langdell’s obsession with matters ancient and English, law was something narrower. For them law was constituted by general principles as stated in authoritative treatises and perhaps by currently controlling decisions (and, presumably, statutes, and various other sources of legal doctrine) of the jurisdiction within which they lived and where they intended to practice. Everything else, we suspect, was for them mere archaeology, history, or antiquarianism, none of which had a proper place in a school of law.
The anecdote is instructive. Because law is not simply the sum total of all the rules, principles, procedures, norms, and institutions that are present throughout society at large,3×3. I intend the claim in the text to be noncontroversial, to be agnostic as between positivism and natural law, and indeed agnostic with respect to virtually any extant theory of the nature of law. I mean to suggest only that law is not congruent (is extensionally divergent, in philosophical jargon) with the totality of a society’s normative and institutional landscape. After all, even that foremost of natural law theorists, Thomas Aquinas, distinguished between natural law and human law, suggesting that human law was not coextensive with the idea of the all-things-considered right thing to do. St. Thomas Aquinas, Summa Theologiae pt. 1, 1–11 q. 91, q. 96, arts. 2, 4 (R.J. Henle trans., Univ. Notre Dame Press 1993) (1269–70); see also John Finnis, The Truth in Legal Positivism, in The Autonomy of Law: Essays on Legal Positivism 195, 203–05 (Robert P. George ed., 1996); Louis W. Hensler III, A Modest Reading of St. Thomas Aquinas on the Connection between Natural Law and Human Law, 43 Creighton L. Rev. 153, 153–54 (2009). And Ronald Dworkin, the modern legal theorist most committed to rejecting the idea that law consists only of those norms identified by some legal rule of recognition, nevertheless excluded policy considerations from law’s “empire,” Ronald Dworkin, Law’s Empire 221–24 (1986) [hereinafter Dworkin, Law’s Empire]; Ronald Dworkin, Taking Rights Seriously 84–85 (1977) [hereinafter Dworkin, Taking Rights Seriously], and still recognized that legal doctrine more narrowly understood had a certain kind of “gravitational force,” id. at 111–15. It is thus hard to disagree with Professor Joseph Raz’s conclusion that “[so] long as we allow that it is possible for a population not to be governed by law, there must be a difference between legal standards and those which are not legal, not part of law.” Joseph Raz, Incorporation by Law, 10 Legal Theory 1, 15–16 (2004). it follows that there are sources of normative guidance and factual enlightenment that legitimately exist in the wider society but that are nevertheless no part of law.4×4. Conversely, there also exist sources and arguments that are legitimate or permissible in law but which do not count as sources of legitimate or permissible guidance and enlightenment in the larger society. Although this aspect of law’s specialness — its capacity to validate that which is otherwise societally invalid — is not the primary focus of this Essay, a good example comes from Oliver Wendell Holmes’s observation about stare decisis that “[i]t is revolting to have no better reason for a rule of law than that so it was laid down in the time of Henry IV.” O.W. Holmes, The Path of the Law, 10 Harv. L. Rev. 457, 469 (1897).
Even this modest claim, however, presupposes a boundary between law and not-law, in much the same way that institutions such as law schools, law libraries, and bar examinations presuppose much the same thing. But the boundary between law and not-law is a shifting one, as our contemporary reaction to the complaints of Langdell’s students indicates. The shift has not been unidirectional, and the boundaries of law, even if generally wider now than at most times in the past, still seem at some times to expand and at other times to contract. Yet although the boundaries between law and not-law are not stable, they remain no less important in delineating the character of law, legal argument, and legal decisionmaking. To know what law is, after all, requires that one know what law is not.
It is not surprising, therefore, that most of the important debates in jurisprudence over the past 200 years have been about the boundaries of law, and about the extent to which what some have thought of as non-law is, or has become, law, and occasionally about the extent to which what some have thought of as law is not really law at all. Law is a source-based enterprise, and understanding its nature accordingly requires understanding which sources constitute the law and which do not. It is only to be expected, therefore, that jurisprudential debates about the nature of law are so often debates about which sources of decisional guidance are to be treated as law — what counts as law. Examining these debates, many of them closely connected to the Harvard Law School, will tell us much about the boundaries of law, and thus about law itself.
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* David and Mary Harrison Distinguished Professor of Law, University of Virginia. I have benefited greatly from the perceptive comments of Charles Barzun, Dan Coquillette, Bruce Kimball, Nicoletta Ladavac, John Manning, Martha Minow, Dan Ortiz, Stanley Paulson, Dan Priel, Kristen Rundle, Sophie Papaefthymiou, Adrian Vermeule, Kevin Walton, Ted White, and Kenneth Winston; from valuable snippets of information offered by numerous friends and colleagues; from the facilities and hospitality of the University of Sydney Law School; and from audience questions at L’École de Droit, Sciences Po, Paris.