Virtually every society around the world has something called a “constitution.” But they differ from one another significantly. Some bind only the government of the country, some bind private actors as well. Some constitutions are written (like those of the United States, France, South Africa and India), some (like that of the United Kingdom, New Zealand and Israel) are unwritten (or “uncodified”) and some (like Canada) are hybrids of the two. Some (like Canada, the United States and South Africa) contain protections for human rights, and some (like Australia) do not.

At a basic level, however, the function of a constitution is to define and limit the institutions that govern a society. In terms of limiting governmental power, constitutions define set of fundamental principles by which future governments must abide. Otherwise, the state can operate for the short-term benefit of those in currently in government, to the detriment of those that are not. A corollary of this principle is that constitutions tend to be difficult to amend; often requiring the assent of a “supermajority” (e.g. two thirds or three fourths) of legislators (or legislatures in countries with federal arrangements).