Positive law

• 1. Introduction

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  Positive law goes by a Latin name - ius positum - and the etymology tells you almost everything you need to know. The word comes from the verb to posit: to lay down, to set in place, to declare. What is law, then, if not a declaration? When a legislature passes a statute, or a court issues a ruling that binds future cases, something has been posited. Someone, or some body, with recognized authority has said: this is the rule. That act of saying is what makes positive law what it is.

  But the concept carries a tension that philosophers have been arguing over for centuries. Positive law stands in contrast to natural law, which holds that certain rights exist independent of any human decision - conferred, as one traditional formulation puts it, by "God, nature, or reason". If natural law is what we discover, positive law is what we make. And if we make it, who gets to make it? A sovereign? A divine authority? Both? Neither?

  Those questions lead from a thinker like Thomas Aquinas, who had no trouble accommodating divine and human law alike, into sharper territory with Thomas Hobbes and John Austin, who wanted one undivided sovereign and found the idea of divine positive law philosophically impossible. They lead, too, into the twentieth century, where Hans Kelsen and H. L. A. Hart became the foremost defenders of legal positivism as a distinct school of thought.

• 2. The Latin Distinction

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  Thomas Aquinas conflated two terms that later thinkers would pull apart. The Latin lex humana means human-made law; lex posita, or ius positivum, means positive law. Aquinas treated them as effectively the same thing, but there is a real difference in emphasis. Lex humana asks who made the law - it locates authority in the maker. Lex posita asks whether the law is legitimate - it locates authority in the act of positing itself.

  That distinction matters because it opens the door to divine positive law. If what makes law positive is the act of being posited by a recognized authority, then God can posit law just as a legislature can. In the Summa contra Gentiles, Aquinas writes directly of this: "Si autem lex sit divinitus posita, auctoritate divina dispensatio fieri potest" - if the law be divinely given, dispensation can be granted by divine authority. A second passage states simply, "Lex autem a Deo posita est" - the Law was established by God.

  Aquinas was not alone. Martin Luther acknowledged the idea of divine positive law. So did Juan de Torquemada. The tradition was broad enough that Thomas Mackenzie, writing later, organized the entire domain of law around four categories: divine positive law, natural law, the positive law of independent states, and the law of nations. For Mackenzie, divine positive law concerned the duties of religion and derived from revelation, while divine natural law was recognized by reason alone, without any revelation needed.

• 3. Sovereignty and Its Limits

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  Thomas Hobbes and John Austin both held a position that the Thomist tradition did not: that sovereignty must be singular and undivided. For Hobbes and Austin, law required an ultimate sovereign, and that sovereign could not be split between spiritual and temporal authority. The framework that worked for Aquinas and Mackenzie - God sovereign over divine positive law, the state sovereign over human positive law - struck Hobbes and Austin as philosophically incoherent.

  The problem they identified is real. If humans are subject to divine positive law, then a temporal sovereign is not truly sovereign; someone above them can overrule. But if divine positive law applies only to some humans and not others, then God is not sovereign either. The only exit from this bind, in the Hobbesian and Austinian framework, is to deny the existence of divine positive law altogether. God governs through divine natural law - law that reason can perceive - but it falls to the temporal authority to translate that natural law into enacted human positive law.

  James Bernard Murphy captured the broader difficulty with the term itself. He wrote that "although our philosophers often seek to use the term positive to demarcate specifically human law, the term and concept are not well suited to do so. All of divine law is positive in source, and much of it is positive in content." The word that was supposed to mark the boundary between human and divine kept blurring it.

• 4. Legal Positivism as Philosophy

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  The term positive law is sometimes used to name a whole school of legal philosophy: legal positivism, distinct from both natural law theory and legal realism. The three schools represent genuinely different answers to the question of what law fundamentally is.

  The Brno school, which developed a normative theory of law, gave pre-eminence to positive law specifically because of its rational nature. That was not the dominant position among classical liberals and libertarians, who generally favored natural law over legal positivism. Jean-Jacques Rousseau, approaching from a different angle, understood positive law as freedom from internal obstacles - a strikingly different framing from the emphasis on state authority that runs through Hobbes and Austin.

  In the twentieth century, Hans Kelsen became one of the foremost proponents of legal positivism. His work spanned two distinct phases: his European years prior to 1940, and his American years that continued until his death in 1973. H. L. A. Hart, the British philosopher, stood alongside Kelsen as a major voice for legal positivism in that same century. Together, their work gave the positivist tradition its most rigorous modern form, and Hart's death left the debate over the relationship between law as it is and law as it ought to be very much unresolved.