1. Constitutionalism: a Minimal and a Rich Sense
In some minimal sense of the term, a "constitution" consists of a set of rules or norms creating, structuring and defining the limits of, government power or authority. Understood in this way, all states have constitutions and all states are constitutional states. Anything recognisable as a state must have some acknowledged means of constituting and specifying the limits (or lack thereof) placed upon the three basic forms of government power: legislative power (making new laws), executive power (implementing laws) and judicial power (adjudicating disputes under laws). Take the extreme case of an absolute monarch, Rex, who combines unlimited power in all three domains. If it is widely acknowledged that Rex has these powers, as well as the authority to exercise them at his pleasure, then the constitution of this state could be said to contain only one rule, which grants unlimited power to Rex. He is not legally answerable for the wisdom or morality of his decrees, nor is he bound by procedures, or any other kinds of limitations or requirements, in exercising his powers. Whatever he decrees is constitutionally valid.

When scholars talk of constitutionalism, however, they normally mean something that rules out Rex\'s case. They mean not only that there are rules creating legislative, executive and judicial powers, but that these rules impose limits on those powers.[1] Often these limitations are in the form of individual or group rights against government, rights to things like free expression, association, equality and due process of law. But constitutional limits come in a variety of forms. They can concern such things as the scope of authority (e.g. in a federal system, provincial or state governments may have authority over health care and education while the federal government\'s jurisdiction extends to national defence and transportation); the mechanisms used in exercising the relevant power (e.g. procedural requirements governing the form and manner of legislation); and of course civil rights (e.g. in a Charter or Bill of Rights). Constitutionalism in this richer sense of the term is the idea that government can/should be limited in its powers and that its authority depends on its observing these limitations. In this richer sense of the term, there is no "constitution" in Rex\'s society because the rules defining his authority impose no such limits. Compare a second state in which Regina has all the powers possessed by Rex except that she lacks authority to legislate on matters concerning religion. Suppose further that Regina also lacks authority to implement, or to adjudicate on the basis of, any law which exceeds the scope of her legislative competence. We have here the seeds of constitutionalism as that notion has come to be understood in Western legal thought.

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 a constitutionally unlimited sovereign (e.g. Rex) versus that of a sovereign limited by the terms of a social contract containing substantive limitations on her authority (e.g. Regina).[2] 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, 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.[3] Though this feature of Austin\'s theory has some plausibility when applied to the British Parliamentary system, where Parliament is often said to be "supreme" and constitutionally unlimited,[4] it faces serious difficulty when applied to most other constitutional democracies such as one finds in the United States and Germany, where it is clear that the powers of government are legally limited by a constitution. Austin\'s answer was to say that sovereignty may lie with the people, or some other person or body whose authority is unlimited. Government bodies -- e.g. Parliament or the judiciary -- can be limited by constitutional law, but the sovereign -- i.e. "the people" -- remains unlimited. Whether