Constitutions: Codified, Uncodified and Changing

A constitution is the set of fundamental rules that creates government institutions, divides power among them and defines the relationship between government and citizens. Most countries have a codified constitution, a single document with higher legal status than ordinary law and a special procedure for amendment. A few, notably the United Kingdom, New Zealand and Israel, have uncodified constitutions spread across statutes, court rulings, conventions and historic documents.

Constitutions also differ in rigidity: the US Constitution is hard to amend, while others can be changed by a parliamentary supermajority. Yet a written text never tells the whole story. Conventions, court interpretations and political habits shape how constitutions work, and many authoritarian states have impressive written constitutions that are ignored in practice. Comparing constitutions therefore means comparing both the text and the real behaviour of institutions.