H.L.A. Hart, Positivism and the Separation of Law and Morals, 71 Harv. L. Rev. 593 (1958)

The distinction between law as it is and law as it ought to be is conceptually valid, morally valuable, and essential for clear legal analysis, even though law and morality may intersect in practice—especially in interpretation and critique.

Chapter I: Holmes, the Utilitarians, and the Origins of Legal Positivism

Hart begins by complimenting Justice Oliver Wendell Holmes Jr. for his creativity and clarity. He praises Holmes because Holmes’s legal realism emphasized the practical effects of law and the role of judicial decision-making—an approach that aligns with Hart’s own view that law should be understood as a system of rules rather than mere commands. Holmes had the rare ability to question settled assumptions about law without descending into obscurity. For Hart, this combination of imaginative insight and analytical lucidity makes Holmes a model legal thinker—especially in contrast to those who conflate moral idealism with jurisprudential clarity.

Hart then raises a key question: is there an intersection between law and morality, and if so, what does it actually mean to say so? Critics of legal positivism often claim that the tradition artificially separates the two. But Hart insists the real problem is that these critics are unclear in their own claims—confusing descriptive legal theory with prescriptive moral judgment. To sort through this confusion, Hart turns to the intellectual origins of legal positivism in the work of the English utilitarians Jeremy Bentham and John Austin.

Hart discusses Bentham and Austin not just to recount historical positions but to clarify the core insight that legal positivism originally set out to defend: that law as it is should be distinguished from law as it ought to be. Both thinkers, though different in style and emphasis, argued that this distinction was necessary to preserve the integrity of legal analysis and to avoid dangerous political confusion. They believed that natural law theorists—especially figures like Blackstone—blurred this line by claiming that unjust laws are not truly laws. This conflation, Bentham and Austin argued, either licenses unlawful disobedience (by denying the legal validity of bad laws) or encourages uncritical obedience (by presuming that whatever exists as law must be morally justified).

Hart is careful to stress that Bentham and Austin were not moral skeptics or apologists for injustice. On the contrary, they were deeply committed to legal reform and to limiting the abuse of power—even by well-meaning reformers. Bentham, in particular, envisioned a legal system grounded in the principles of the Rechtsstaat (rule of law), emphasizing protections such as free speech, open governance, and due process. His utilitarianism led him to evaluate institutions not in abstract moral terms, but by their effects—such as whether they reduce suffering. His critique of slavery, for instance, bypasses metaphysical debates about human nature and instead focuses on the capacity to suffer as the morally relevant fact.

Although Austin and Bentham both insisted on separating law from morality, Hart emphasizes that Bentham’s approach was more flexible and morally engaged. Austin grounded moral principles in divine command, treating utility as a sign of God’s will, and maintained that only rules backed by sovereign command counted as law. Bentham, by contrast, rejected theological foundations entirely and framed both law and morality in terms of secular utility. This difference is crucial for Hart: while Bentham has been accused of formalism, he made powerful moral arguments—for instance, against slavery—by appealing not to abstract rights or tradition but to the suffering it caused.

Hart uses this to show that insisting on the conceptual separation of law and morality does not mean denying that moral principles can be incorporated into legal systems. Bentham recognized that constitutions or statutes can explicitly encode moral requirements, which then become part of the law. Austin, by contrast, refused to treat such provisions as law unless backed by sovereign threats—a rigidity Hart views as overly narrow. For Hart, this contrast reveals that legal positivism can preserve analytical clarity about what law is without denying the ways law and morality interact—historically, socially, or institutionally. The positivist claim, Hart insists, is not a moral thesis but a conceptual one: moral merit alone does not determine legal validity.

In the United States, legal thinkers like N. St. John Green, John Chipman Gray, and especially Holmes extended these insights into new territory. They adopted the positivist separation as a foundation for thinking about law not as a moral ideal, but as a functioning system of social control. Holmes’s famous essay “The Path of the Law” is perhaps the clearest example, asserting that the law should be understood from the perspective of a “bad man” concerned only with legal consequences, not moral imperatives. For these thinkers, the positivist distinction allowed jurisprudence to move beyond vague moralism and focus instead on law’s institutional and behavioral realities.

Hart’s historical reconstruction, then, serves a dual purpose: it defends a maligned conceptual distinction and restores the moral seriousness of those who first advanced it. Far from undermining moral reflection, the separation of law and morals, as Hart presents it, is what makes such reflection clearer, more precise, and ultimately more effective. By disentangling what the law is from what it ought to be, legal positivism creates the space in which criticism can flourish—and where reform can be made coherent.

Chapter II: Misunderstandings and the Limits of the Command Theory

In Chapter II, Hart turns from historical exposition to the criticisms that legal positivism—particularly as shaped by Bentham and Austin—has faced. He begins by acknowledging that Bentham and Austin primarily focused on laws whose meaning was clear and uncontroversial. Their central claim was that such laws, even if morally repugnant, remained laws. But Hart notes that modern criticisms go beyond this narrow focus. Critics have argued that even if the separation of law and morals is valid in those straightforward cases, the positivist approach fails when we confront ambiguous laws, judicial interpretation, and questions about the moral minimum a legal system must meet to be recognizable as a legal system at all.

To respond to these challenges, Hart first disentangles a key confusion that has clouded the debate: Bentham and Austin’s legal positivism was not a single doctrine, but a cluster of three distinct but historically associated positions: (1) the separation of law and morality; (2) the analytical study of legal concepts; (3) the command theory of law (i.e., that laws are essentially commands backed by threats, issued by a sovereign). Hart stresses that many critics—especially early American ones—have wrongly treated these as inseparable, and assumed that flaws in the command theory automatically disprove the separation thesis. But, as Hart makes clear, one can reject the command theory while still accepting the analytical method and the law/morality distinction. The failure to recognize this has led to much unjustified criticism of legal positivism as a whole.

Hart then turns specifically to the command theory, arguing that it is not only overly simplistic but fundamentally inadequate. Austin’s view that law consists of general commands issued by a sovereign (defined as one habitually obeyed but who obeys no one else) is shown to distort the nature of modern legal systems. For example, it struggles to account for changing legislatures or constitutional constraints—since the “sovereign” is not a fixed person or group, and laws are not simply followed out of habit. More importantly, Hart points out that this view omits a crucial feature of legal systems: the acceptance of rules. Law is not merely a matter of compulsion or obedience but involves social practices in which officials and citizens recognize certain procedures and standards as authoritative. The key to jurisprudence, Hart insists, is not the command backed by threats, but rather the existence of primary and secondary rules, especially rules that define how laws are created and changed.

Hart also critiques the command theory for flattening the variety of legal rules. Not all laws function as commands. Some laws—like those enabling people to make contracts or wills—do not impose duties but confer powers and rights. These are not orders but tools for individuals to structure their own affairs within the legal system. Attempts by theorists like Kelsen to reduce these to disguised sanctions miss their distinct function. Hart argues that equating all laws to commands is like claiming that the rules of baseball are really just instructions to umpires about when to penalize players—an overly reductive and misleading view.

Critics such as Salmond and Hägerström recognized that the command theory could not account for legal rights, but they mistakenly concluded that this failure proved the necessity of a connection between law and morality. Hart disagrees. He concedes that rights-conferring rules differ from commands, but insists this does not mean they must be grounded in moral principles. After all, unjust legal rights—such as those held by slaveowners—can exist. Therefore, the concept of a legal right does not imply moral justification.

In closing, Hart acknowledges that critics rightly exposed the inadequacy of the command theory and the oversimplified notion of habit in explaining legal systems. Yet these criticisms do not undermine the core positivist claim that legal validity is distinct from moral worth. Far from being refuted, the separation of law and morals remains essential to understanding the nature of law—especially if we are to grasp both its power and its limits.

Chapter III: Realism, Penumbra, and Judicial Interpretation

In Chapter III, Hart addresses a prominent American criticism of legal positivism, particularly that advanced by the American Legal Realists of the 1930s. These critics accept that in clear cases, law can be distinguished from morality, but they challenge the separation thesis—the idea that law and morality are conceptually distinct—by focusing on how judges actually decide hard cases, especially those that fall within the penumbra of legal rules, where meaning is uncertain.

Hart illustrates this with his famous “vehicle in the park” example: a rule bans vehicles from a park—cars are clearly included, but what about bicycles, toy cars, or airplanes? These cases lie in the penumbra, where the language of the rule is vague, and so deductive reasoning cannot yield a clear answer. In such cases, judges must make choices, often by appealing to social purposes, policies, or values. To some, this reliance on what “ought to be” seems to blur the line between law and morality.

But Hart argues that this does not refute positivism. To say that judges sometimes create law in unclear cases is not to say that law and morality are the same thing. Rather, it shows that law is incomplete and sometimes requires judicial supplementation—not that its meaning is entirely moral or value-based. In fact, Bentham and Austin, often accused of promoting rigid formalism, both acknowledged that judges in borderline cases must exercise discretion. Austin even viewed such discretion as a form of judicial legislation guided by public utility.

Hart draws a key distinction between two types of formalism: (1) formalism in theory (wrongly attributed to positivist thinkers)—the mistaken belief that law is a complete system from which all judgments can be logically deduced; and (2) formalism in practice—when judges apply rules mechanically, ignoring context or consequences. Hart rejects the first as a misreading of positivism and acknowledges the second as a genuine problem, but one that does not invalidate the separation of law and morality. He then argues that if critics want to go further and say that the values judges rely on in penumbral cases are part of the law itself, they are not just observing judicial discretion—they are redefining what law is. They are claiming that law includes not only the rule and its clear applications but also the moral or policy aims latent within it. Hart resists this move, warning that it risks blurring the essential structure of law and turning every legal question into an open-ended moral or political debate.

In conclusion, Hart accepts that legal rules have a core of clear application and a penumbra of uncertainty, and that deciding penumbral cases often requires reference to values or purposes. But this does not mean that law and morality are indistinguishable. It means that law is sometimes incomplete, and judges must exercise creative judgment. Hart cautions, however, that just as formalism once overemphasized mechanical rule application, excessive preoccupation with penumbral reasoning can obscure the real structure of law. The challenge is to recognize both the limits and the authority of legal rules—without collapsing law into morality or politics.

Chapter IV: Radbruch and the Moral Reckoning After Nazi Law

In Chapter IV, Hart confronts the most emotionally and morally powerful criticism of the positivist separation of law and morals—one that emerged from the ruins of Nazi Germany. This criticism is not just an academic objection or philosophical argument; it is a moral outcry, a passionate plea informed by lived experience, particularly from jurists like Gustav Radbruch, who had once accepted legal positivism but later rejected it in the face of Nazi atrocities.

Radbruch’s criticism carries unique weight because it is not just theoretical but confessional—a recantation born from horror. Under Hitler’s regime, laws were used to carry out profoundly immoral acts, and German lawyers and judges often followed these laws dutifully, believing that legality and morality were distinct domains. In retrospect, Radbruch blamed this very belief—the positivist principle that law can exist without moral merit—for enabling such complicity. He came to argue that there must be fundamental moral principles (rooted in humanitarianism) within the very concept of law—that grossly immoral statutes should not count as law at all.

Hart approaches this critique with a mixture of sympathy and skepticism. He recognizes Radbruch’s moral urgency and the failure of German legal culture to resist tyranny. But he also sees a naïveté in the idea that mere belief in the separation of law and morals caused this failure. After all, thinkers like Bentham and Austin, who emphasized that separation, were also committed liberals, deeply concerned with justice, reform, and resistance to unjust power. In their view, recognizing that wicked laws are laws does not mean one must obey them—it simply clarifies that legal validity and moral obligation are different kinds of judgment.

To evaluate Radbruch’s alternative, Hart turns to a concrete legal case from postwar Germany. In this case, a woman had denounced her husband to Nazi authorities for anti-Hitler remarks, which led to his imprisonment. After the war, she was prosecuted under the old (still-valid) German Criminal Code for unlawfully depriving him of liberty. Her defense was that her actions were legal under Nazi statutes at the time. The court rejected this defense, declaring the Nazi law invalid because it violated “the sense of justice of all decent human beings.” Many hailed this as a triumph of natural law over positivism. Hart is not so quick to celebrate. While he sympathizes with the desire to punish the woman, he sees in the court’s reasoning a dangerous evasion. Instead of facing the moral dilemma directly—that punishing her would require violating the principle against retrospective punishment—the court disguised the dilemma by claiming the Nazi law was never law at all. This, Hart argues, is both philosophically dubious and morally less honest than simply acknowledging the choice between two evils: either let the woman go free or punish her in violation of legal principles. Declaring that “evil laws are not law,” as Radbruch suggests, raises several philosophical issues that are difficult to resolve.

This leads Hart to a broader philosophical point. The moral condemnation of wicked laws is clearest and most powerful when we speak plainly: such laws are law, but they are too evil to be obeyed. By contrast, denying their legal status turns moral protest into a contested philosophical claim, one that requires justification and raises complex questions about the nature of law. In short, Hart believes that the clarity of moral critique is lost when we conflate legality with moral goodness. Hart also emphasizes the value of candor in law and morality. In moments of moral conflict, we must not disguise the hard choices we make. If we violate legal principles to do justice, let us say so. Pretending that morality and law always align, or that immoral laws are not “really” laws, risks promoting the illusion that no moral compromises ever need to be made—a form of romantic optimism that ignores the real tensions between different moral and legal values.

Thus, far from weakening the positivist distinction, Hart argues, the Nazi experience reveals its continuing importance. The challenge is not to deny that evil laws can exist, but to insist that recognizing their legal status need not mean moral acceptance. Law and morality are separate so that each can play its distinct role: law can organize social life, and morality can judge law without being absorbed by it.

Chapter V: The Minimum Moral Content of Law

In Chapter V, Hart turns from responses to specific critiques of legal positivism toward a deeper reflection on whether the separation of law and morals remains convincing when applied not just to individual laws but to entire legal systems. Could it be, his critics ask, that even if we can separate law and morality at the level of particular rules, this becomes misleading or untenable at the systemic level?

Hart acknowledges that this is a serious and worthwhile question. Critics argue that, just as a legal system must include some coercive sanctions or be generally effective to count as law at all, perhaps it must also contain some moral content—such as principles of justice or fairness. The claim is not that every law must be moral, but that a legal system, to be a legal system, must incorporate some minimal alignment with morality.

This line of thought is not foreign to the tradition of legal positivism itself. Even Austin, Hart reminds us, recognized that developed legal systems rest on certain “necessary” principles tied to human nature. Hart engages with this claim through what he calls a “philosophical fantasy.” Drawing an analogy to science fiction, he asks us to imagine a radically different world—where, for example, humans are invulnerable to violence or can feed themselves directly from the air. In such a world, laws against violence or theft might not be necessary. But given the human condition as we know it, rules protecting life and property are essential—not arbitrarily so, but due to our shared biological and social reality. Therefore, Hart concedes that there is a natural necessity—rooted in our condition as vulnerable, interdependent beings—for legal systems to include certain basic protections. These rules, which overlap with basic moral principles, are necessary not because of moral philosophy but because without them, no functioning legal system could exist. Hart refers to this as a “minimum content of natural law,” echoing themes from classical natural law theory but reinterpreting them in secular, practical terms.

In addition, Hart points out that law’s general and rule-based nature introduces a kind of procedural justice. Since legal rules must apply to classes of people and types of actions, the very idea of law requires some form of consistency or impartiality—that like cases be treated alike. While this doesn’t guarantee just outcomes, it does mean that law is not completely morally indifferent in structure. But Hart draws an important limit to this argument. The overlap between law and morality—both in basic protections and procedural fairness—does not erase the distinction between the two. A legal system can be morally abhorrent and still meet these basic criteria. A system that rigorously enforces oppressive laws with procedural fairness—for example, a slave-owning regime that protects its own elite but denies rights to others—might be hideously unjust, yet still legally coherent.

The problem with denying such a system the status of law, Hart argues, is that it obscures moral criticism. To say it is not law is to raise a philosophical debate about the definition of law, whereas to say it is law, but ought not to be obeyed, delivers a direct moral condemnation that is both clearer and stronger. The danger is not in recognizing immoral law as law, but in allowing that recognition to dull our critical response to it.

In closing, Hart affirms that legal systems must, by practical necessity, include a minimal moral content. But this does not undermine the positivist claim that legal validity and moral value are conceptually distinct. What law is remains separate from what law ought to be—even if, in practice, human survival and the rule of law require some overlap between the two.

Chapter VI: Moral Objectivity and the Limits of Interpretive Fusion

In the final chapter of his essay, Hart addresses a deeper philosophical concern behind many objections to legal positivism: the fear that separating law from morality depends on a skeptical or relativistic view of moral values. Critics often assume that if positivists insist law and morality are distinct, they must believe moral judgments are just personal feelings or preferences, not rational or objective claims.

Hart rejects this assumption. He clarifies that while some 20th-century positivists like Kelsen supported non-cognitivist views of morality, the classical utilitarians—Bentham and Austin—did not. They believed moral principles could be known and debated, whether through divine command or utility. Hart himself believes that moral judgments, like factual judgments, can be supported by rational argument and are not merely expressions of emotion or choice.

However, Hart insists that even if morality is objective and rational, this does not mean we should collapse the distinction between what law is and what it ought to be. A law can still be morally wrong and yet valid as law. Likewise, a morally good rule does not count as law unless it is formally adopted in a legal system. The existence and moral value of a rule are conceptually separate issues.

Hart then turns to the critique made by Lon Fuller, who argues that in legal interpretation, the boundary between law and morality often blurs. Drawing on an example from Wittgenstein, Fuller suggests that when we apply a rule to a new case, we may not be inventing or extending the rule, but simply recognizing that the new case naturally fits within the rule’s purpose. In this view, interpretation involves discovering what the rule “really means,” not choosing to give it a new meaning.

Hart acknowledges that this account captures something real in the experience of judges and lawyers—sometimes a case seems to fall under a rule not by choice, but by recognition. However, he offers two important cautions. First, the sense of “ought” involved in interpretation is not necessarily moral. Even judges applying the rules of an immoral regime can feel a decision is “right” in terms of internal coherence, not ethics. Second, such moments of clarity are rare. Most legal interpretation involves difficult choices between competing, reasonable interpretations. In these cases, talk of “fusion” between law and morality is misleading—it disguises the creative, discretionary role judges often play.

In conclusion, Hart argues that while Fuller’s description of legal interpretation is insightful in some cases, it cannot justify abandoning the distinction between law and morality. Most legal decisions require judges to weigh alternatives and make judgments, not simply to discover hidden truths in the law. Describing law as if it naturally fuses with morality paints an overly romantic picture that hides the realities of legal reasoning. Hart closes by reaffirming the positivist message: law is not the same as morality, and recognizing this helps us to better understand, criticize, and improve both.