Unitary state

A Unitary state is a state or country that is governed constitutionally as one single unit, with one constitutionally created parliament. While some unitary states are governed as one unit (for example, the Republic of Ireland), others do provide for sub-parliaments or regional assemblies. However unlike federal systems, where regional assemblies have a constitutional existence and a set of constitutional functions which cannot be unilaterally changed by the central parliament, in a unitary state any sub-governmental units created can be created or abolished, and have their powers varied, by the central legislature. A system of government in which sub-government units or regional parliaments have been created but exist purely in statute or ordinary law rather than constitutional law and can be abolished or have their functions broadened or narrowed by decision of the central parliament, is known as devolution.

The United Kingdom is a particularly striking example of a unitary state with a series of parliament-created devolved assemblies, for Scotland, Wales and Northern Ireland, all of which were created in the 1990s.