Doctrine defined by A V Dicey (1835–1922), in his book Law of the Constitution (1885), as the doctrine that Parliament has ‘the right to make or unmake any law whatever… and… no person or body is recognized by the Law of England as having the right to override or set aside the legislation of Parliament’.
Parliament in this context consists of the sovereign, the House of Lords, and the House of Commons. Any act of Parliament properly passed by both Houses of Parliament (or by the House of Commons under the terms of the Parliament Acts 1911 and 1949), and which receives royal assent, is legally binding on all people and property which comes within the jurisdiction (legal power) of the UK.
This principle applies equally to delegated legislation properly promulgated under an act of Parliament. No court may question the validity or constitutionality of an act of Parliament, although this does not preclude the court from interpreting the act, nor does it prevent a court from declaring that delegated legislation is ultra vires (beyond the authority of) the enabling act of Parliament. Parliamentary sovereignty also means that legally no act of Parliament has any special status relative to other acts and that no special procedure in Parliament or elsewhere is required to amend or repeal an act other than the passing of another act of Parliament by the normal procedures. Thus those acts of Parliament which are commonly regarded as part of constitutional law, such as the Parliament Acts 1911 and 1949, or the Representation of the People Act 1969, have no special status and require no special amending procedure.
The ultimate consequence of parliamentary sovereignty is that no Parliament may bind its successors in law. In practice, however, parliamentary sovereignty is limited by political reality, since it becomes a fiction if Parliament passes laws which cannot be enforced. Parliamentary sovereignty is therefore limited by the self-imposed limitations accepted by politicians, by public opinion, by the operation of pressure groups, and by international law.
Moreover, Parliament may in practice limit its own sovereignty: (1) by passing acts such as the Parliament Act 1911, which limits the duration of a Parliament to a maximum of five years and the Statutory Instruments Act 1946, which lays down procedures regarding delegated legislation; (2) by the European Communities Act 1972, which gave effect to British entry to the then EEC; and (3) by the Statute of Westminster 1931, which gave the dominions autonomy over their external affairs.
The UK's closer integration within the European Union has meant that, during recent decades, there has been some cession of parliamentary sovereignty, as EU regulations, policed by the European Court of Justice, take precedence over national laws. Further sovereignty has been ceded since 1997 by the New Labour government, which has given the Bank of England full control over the setting of interest rates and has devolved certain powers to new assemblies in Scotland, Wales, and Northern Ireland.
With the granting of dominion status to Canada, Australia, and New Zealand the convention developed that acts passed by the UK Parliament should not apply to self-governing dominions unless expressly requested and consented to by the dominion concerned. The Statute of Westminster gave this convention legal status and a similar provision has been included in most of the legislation granting independence to former British colonies since 1947. Nonetheless, in theory parliamentary sovereignty remains intact and in the case of the Canadian constitution (the British North America Act 1867) the amendment of certain sections can only be effected by the UK Parliament passing an amending act. This, however, is an anomaly and no British government would act unless requested to do so by the Canadian government. Parliamentary sovereignty is thus limited by the reality of political independence.