The main Sources
Statute law: this is law made by Parliament, and is one of the most important sources of the UK constitution, as statute law overrides other laws, due to the principle of parliamentary sovereignty. One of the distinctive features of the UK’s constitutional arrangements is that a constitutional statute looks no different from any other statute. Because Parliament is sovereign and can amend or repeal any statute, all statutes look alike and have the same status. Examples would be the European Community Act of 1972, and the Human Rights Act of 1998.
Common law: this is ‘judge-made law’- laws based on precedent and tradition. When deciding on the legality of a case, judges will use previous decisions on similar cases- these are examples of common law. For example- the powers contained in the Royal Prerogative (which are now exercised by the Prime Minister).
Conventions: these are non-legal established rules of conduct and behaviour- what is ‘expected’. For example, the monarch granting Royal Assent (royal approval) to each bill passed by Parliament, the appointment of the Prime Minister (the leader of the Commons’ largest party), and collective responsibility (all government ministers openly support all government policy).A convention is an unwritten rule that is considered binding on all members of the political community. Such conventions could be challenged in law but have so much moral force that they are rarely, if ever, disputed. Many of the powers of the prime minister are governed by such conventions. It is, for example, merely a convention that the prime minister exercises the Queen’s power to appoint and dismiss ministers, to conduct foreign policy and to grant various honours, such as peerages and knighthoods, to individuals. It is also a convention (known as the Salisbury Convention) that the House of Lords should not block any legislation that appeared in the governing party’s most recent election manifesto.
The appointment of the prime minister by the monarch
Works of authority: works written by scholars seen as experts in the constitution- they outline what is ‘correct’ for the UK constitution. For example, Bagehot’s The English Constitution (1867), Dicey’s An Introduction to the Study of the Law of the Constitution (1885).
EU laws/treaties: the UK is subject to European laws and treaties, and will remain so until formally exiting the EU. Sometimes these laws and treaties come into conflict with UK law, so questioning parliamentary sovereignty. Examples include the Treaty of Rome (1957) and the Treaty of Lisbon (2009). Brexit has removed this source