Constitution of the United Kingdom is the framework of the government and laws of the United Kingdom. The constitution is not stated in a single document but is made up of separate charters, acts of Parliament, judicial decisions, and customs. By law, Parliament is supreme and can change any constitutional provision. But, by tradition, there are certain things that Parliament cannot change. For example, citizens are protected from unlawful imprisonment by the writ of habeas corpus, which dates from the 1200's (see Habeas corpus).