 Constitutionalism is the idea, often associated with the political theories of John Locke and the founders of the American republic, that government can and should be legally limited in its powers, and that its authority or legitimacy depends on its observing these limitations. This idea brings with it a host of vexing questions of interest not only to legal scholars, but to anyone keen to explore the legal and philosophical foundations of the state. How can a government be legally limited if law is the creation of government? Does this mean that a government can be ‘self-limiting’? Is this even possible? If not, then is there some way of avoiding this implication? If meaningful limitation is indeed to be possible, perhaps constitutional constraints must somehow be ‘entrenched’, that is, resistant to change or removal by those whose powers are constrained? Perhaps they must not only be entrenched, but enshrined in written rules. If so, how are these rules to be interpreted? In terms of their original, public meaning or the intentions of their authors, or in terms of the, possibly ever-developing, values and principles they express? How, in the end, one answers these questions depends crucially on how one conceives the nature, identity and authority of constitutions. Must a constitution establish a stable framework for the exercise of public power which is in some way fixed by factors like original public meaning or authorial intentions? Or can it be a living entity which grows and develops in tandem with changing political values and principles? These and other such questions are explored below.