 In discussing the history and nature of constitutionalism, a comparison is often drawn between Thomas Hobbes and John Locke who are thought to have defended, respectively, the notion of constitutionally unlimited sovereignty (e.g., Rex) versus that of sovereignty limited by the terms of a social contract containing substantive limitations (e.g.,  Regina).[3]  But an equally good focal point is the English legal theorist John Austin who, like Hobbes, thought that the very notion of limited sovereignty is incoherent. For Austin, all law is the command of a sovereign person or body of persons, and so the notion that the sovereign could be limited by law requires a sovereign who is self-binding, who commands him/her/itself. But no one can command himself, except in some figurative sense, so the notion of limited sovereignty is, for Austin (and Hobbes), as incoherent as the idea of a square  circle.[4]  Though at one time this feature of Austin’s theory had some surface plausibility when applied to the British system of government, where Parliament was often said to be supreme and constitutionally  unlimited,[5]  it faces obvious difficulty when applied to most other constitutional democracies such as one finds in the United States, Canada, Mexico and Germany, where it is abundantly clear that the powers of government are legally limited by a constitution. Austin’s answer to this apparent weakness in his theory was to appeal to popular sovereignty, the idea that sovereign power ultimately resides in ‘the people’, that is, the population at large. Government bodies—e.g., Parliament, the President or the judiciary—can be limited by constitutional law, but the sovereign people remain unlimited in their powers to command. Whether this appeal to popular sovereignty provides Austin with an adequate means of dealing with constitutional democracies is questionable. For Austin’s sovereign is supposed to be a determinate individual or group of individuals whose commands to the bulk of the population constitute law. But if we identify the commanders with the people themselves, then we seem inexorably led to the paradoxical result identified by H.L.A. Hart—the commanders are commanding the commanders. In short, we lapse into incoherence (Hart 1994, 73–78; Austin 1995, Lecture VI).