Parliamentary Sovereignty

According to the House of Commons Library's research briefing, 'a fundamental principle of the United Kingdom's constitution is that the UK Parliament is sovereign', meaning that Parliament has 'the right to make or unmake any law whatever' and that 'no person or body' has 'a right to override or set aside the legislation of Parliament' — the classic formulation associated with the constitutional scholar A. V. Dicey. Under Dicey's 'orthodox' account, Parliament is a tripartite body of the Monarch, the House of Lords and the House of Commons, and 'no other institution could override its primary legislation'. This principle, also called parliamentary supremacy, governs the relationship between the legislature, the executive and the courts, and provides the UK — which has no single codified constitution — with a recognised internal hierarchy of laws.

A core tenet of the doctrine is that Parliament cannot bind its successors: any Parliament may repeal or amend legislation passed by an earlier one, and 'no law was immune from repeal'. Equally, the courts do not have the power to strike down primary legislation: the Commons Library briefing notes that 'Dicey maintained that courts must implement acts of Parliament and could not strike them down', a position it describes as having 'for several centuries been consistently upheld in UK constitutional law', in contrast to secondary or delegated legislation, which the courts can nullify. The briefing also records that the principle has faced modern challenges — from the Human Rights Act 1998, devolution, and the UK's former EU membership — but that Parliament reasserted its sovereignty when it repealed the European Communities Act 1972 and triggered EU withdrawal.