Parliamentary sovereignty is a principle of constitutional law under which a legislature possesses supreme authority to enact and repeal law. In its orthodox British formulation, Parliament may legislate on any subject, courts cannot override its validly enacted primary legislation, and one Parliament cannot prevent a successor from changing its laws. It is a central feature of the United Kingdom’s constitution, which is uncodified rather than wholly unwritten: constitutional rules appear in statutes and other sources rather than a single authoritative document. (parliament.uk)
Historical development
The doctrine developed gradually through changes in the relationship between the Crown and Parliament. During the Tudor period, legislation became an important instrument for constitutional and religious change. The Reformation Parliament asserted the authority of Crown-in-Parliament: royal authority exercised through laws enacted by the monarch, Lords and Commons, rather than by the monarch acting alone. (parliament.uk)
The Glorious Revolution of 1688 and the ensuing constitutional settlement strengthened parliamentary authority. The Bill of Rights 1689 affirmed free elections, frequent parliaments, and freedom of speech in parliamentary proceedings. It also prohibited taxation without parliamentary agreement. These provisions constrained monarchical government, although the settlement did not itself present a complete modern theory of legislative sovereignty. (parliament.uk)
The influential orthodox account was articulated by A. V. Dicey in An Introduction to the Study of the Law of the Constitution, first published in 1885. Dicey treated Parliament as the monarch, House of Lords and House of Commons together. His formulation concerned this legislative institution, not the elected chamber acting alone or the government of the day. (commonslibrary.parliament.uk)
Legal meaning and successive Parliaments
The doctrine concerns legal competence rather than unrestricted practical power. Electoral pressures and political legitimacy affect Parliament’s decisions, but the orthodox account distinguishes these considerations from legal restrictions on its legislative authority. Parliamentary sovereignty is therefore not identical to democracy: it identifies the institution whose enactments possess final domestic legal authority, rather than establishing how representative that institution must be. (commonslibrary.parliament.uk)
The principle that Parliament cannot bind its successors preserves the legislative freedom of later Parliaments. An earlier statute’s declaration that it is permanent does not, under the orthodox account, prevent its subsequent repeal. Ordinary statutes may also undergo implied repeal when a later enactment conflicts with them. However, courts distinguish certain constitutional statutes, which are not subject to ordinary implied repeal. Their alteration requires sufficiently clear legislative intention; protection against implied repeal is not equivalent to complete immunity from amendment. (commonslibrary.parliament.uk)
Courts and executive authority
Parliamentary sovereignty does not eliminate judicial review. A fundamental distinction exists between Acts of the UK Parliament and delegated legislation, made under powers conferred by an Act. Courts may invalidate delegated legislation that exceeds its statutory authority or suffers from other legally recognised defects. Such review can uphold parliamentary authority by ensuring that ministers exercise only the powers Parliament granted them. (erskinemay.parliament.uk)
Courts also determine the limits of the royal prerogative. In R (Miller) v Secretary of State for Exiting the European Union, decided on January 24, 2017, the Supreme Court held that ministers could not initiate withdrawal from the European Union without parliamentary authorisation. Withdrawal would change domestic law and statutory rights, which executive prerogative powers could not accomplish independently. The judgment distinguished Parliament’s legislative authority from the government’s authority to conduct international relations. (supremecourt.uk)
Human rights and devolution
The Human Rights Act 1998 combines judicial protection of human rights with continued parliamentary legislative authority. Section 3 requires legislation to be interpreted compatibly with rights protected by the European Convention on Human Rights, so far as possible. Where compatible interpretation is impossible, specified courts may issue a declaration of incompatibility. That declaration does not invalidate the statute or prevent its continued enforcement. (lordslibrary.parliament.uk)
Devolution distributes legislative responsibilities to institutions in Scotland, Wales and Northern Ireland through UK statutes. These institutions legislate within defined areas of competence, while Westminster retains authority to legislate in devolved fields. Under the Sewel Convention, it does not normally do so without the relevant devolved legislature’s consent. This creates an important distinction between Westminster’s continuing legal power and the constitutional expectations governing its exercise. (commonslibrary.parliament.uk)
European integration and withdrawal
UK membership of the European Union affected the operation of parliamentary sovereignty. The European Communities Act 1972 provided the domestic foundation for applying European law. In the Factortame litigation, courts disapplied conflicting provisions of domestic legislation because of obligations given effect through that Act. The relationship between this arrangement and parliamentary sovereignty generated extensive legal debate. (researchbriefings.files.parliament.uk)
Parliament subsequently enacted legislation enabling withdrawal, and the UK left the EU in 2020. The constitutional significance lies in the distinction between accepting a legal framework that gives another body’s rules priority and surrendering the legislative capacity to change that framework. (parliament.uk)
Comparative context
Parliamentary sovereignty should not be inferred merely from a country’s possession of a parliament. New Zealand’s Constitution Act 1986 states that Parliament continues to have full power to make laws. Canada, by contrast, operates under constitutional supremacy: section 52(1) of the Constitution Act, 1982 makes inconsistent legislation legally ineffective to the extent of the inconsistency. These arrangements illustrate different relationships between legislative authority and higher constitutional law. (legislation.govt.nz)