Parliamentary Sovereignty

Parliamentary sovereignty is the cornerstone of the United Kingdom’s constitutional order. First systematically articulated by A. V. Dicey in his 1885 work “Introduction to the Study of the Law of the Constitution,” the doctrine holds that Parliament is the supreme legal authority and may enact or repeal any law on any subject whatsoever. No person or body, including the courts, may question the validity of an Act of Parliament. This principle distinguishes the UK constitution from those of most other democracies, where a written constitution limits legislative power and provides for judicial review of legislation. In the UK, Parliament is sovereign, meaning there is no higher legal authority that can override or set aside its enactments.

The Traditional Formulation

Dicey defined parliamentary sovereignty by two limbs. The positive limb provides that Parliament can make or unmake any law whatever. There are no legal limits on the subject matter of legislation: Parliament could, in theory, legislate to ban smoking in Paris or to require the execution of all blue-eyed babies, though such laws would raise profound political and practical questions. The negative limb provides that no person or body may override or set aside Parliament’s legislation. This means that a subsequent Parliament can repeal any act of its predecessors, and no Parliament can bind its successors by entrenched provisions. An Act of Parliament requiring a two-thirds majority for its repeal could itself be repealed by a simple majority in a later session, because the entrenchment provision would not bind the later Parliament. The enrolled bill rule, confirmed in Edinburgh & Dalkeith Railway Co v Wauchope (1842) and British Railways Board v Pickin (1974), prevents courts from inquiring into the manner in which an Act was passed. So long as a bill has received Royal Assent and is properly enrolled, its validity cannot be challenged on procedural grounds.

The Nature of Parliamentary Sovereignty

The doctrine has been refined through academic debate. Sir Ivor Jennings argued that the sovereignty of Parliament is a construct of the common law, meaning that what Parliament can do is ultimately determined by the courts. This view, known as the common law conception of sovereignty, suggests that if the courts were to recognise a higher-order constitutional principle limiting Parliament, they could do so. Professor H. L. A. Hart distinguished between ultimate rules of recognition that identify valid law and the ordinary operation of legislative power. The debate between these conceptions has significant implications for whether Parliament can be bound by procedural or substantive limits on its lawmaking power. The traditional or “continuing” view holds that each Parliament is equally sovereign and cannot be bound by its predecessors. The “self-embracing” view suggests that Parliament can redefine itself by changing the manner and form of legislation, though this remains controversial.

Challenges to the Doctrine

The traditional formulation has faced significant challenges. Membership of the European Communities, acceded to in 1973, introduced a superior legal order. In R v Secretary of State for Transport, ex parte Factortame (No 2) (1991), the House of Lords disapplied an Act of Parliament that conflicted with EU law—a direct departure from Dicey’s model that had profound constitutional implications. The Human Rights Act 1998 empowered courts to issue declarations of incompatibility where primary legislation violates Convention rights, though such declarations do not invalidate the Act and the government may choose whether to respond. Devolution legislation created legislatures in Scotland, Wales, and Northern Ireland with primary legislative competence in devolved areas. The Scotland Act 2016 and the Wales Act 2017 recognised these devolved institutions as permanent parts of the UK’s constitutional arrangements. Judicial recognition of constitutional statutes has also qualified the traditional doctrine: in Thoburn v Sunderland City Council (2002), Laws LJ distinguished between ordinary statutes and constitutional statutes, holding that the latter cannot be impliedly repealed.

Contemporary Significance

Following the European Union (Withdrawal) Act 2018, the supremacy of EU law ceased to apply in the United Kingdom. Judicial dicta in cases such as R (Jackson) v Attorney General (2005) have hinted that the courts might recognise limits on parliamentary sovereignty in extreme cases, particularly where fundamental constitutional principles are at stake. Lord Steyn in Jackson suggested that the courts might not accept a statute that sought to abolish judicial review or to remove the requirement for the consent of the House of Lords. Lord Hope stated that the rule of law enforced by the courts is the ultimate controlling principle of the UK constitution. However, the core of the doctrine remains intact: Parliament continues to hold legislative supremacy, subject to political and practical constraints rather than legal limits enforceable by the courts. The sovereignty of Parliament remains the organising principle of the UK constitution, even as its contours continue to evolve in response to modern constitutional conditions and the growing recognition of fundamental constitutional principles.