Which UK structure is characterized as a unitary democracy?

The United Kingdom is characterized as a unitary democracy because it has a centralized system of government where the majority of political power resides with the national government. In a unitary system, unlike federal systems, power is not constitutionally divided between the national and constituent entities such as states or provinces.

In the case of the UK, while it has devolved administrations in Scotland, Wales, and Northern Ireland that exercise varying degrees of legislative power, the Parliament of the UK retains the authority to override or modify these devolved powers. This centralized control and overarching legislative authority is typical of a unitary democracy.

The other structures mentioned reflect different forms of governance: the European Union is a supranational entity with shared sovereignty; the United States operates as a federal system with significant powers allocated to states; and Australia also uses a federal structure, dividing powers between the national and state governments. These distinctions highlight why the UK fits the definition of a unitary democracy.