Unlike most other sovereign states, the United Kingdom does not possess a document expressing itself to be the nation's fundamental or highest law. Instead, the British constitution is found in a number of sources. Because of this, the British constitution is often said to be an unwritten constitution; however, many parts of the constitution are indeed in written form, so it would be more accurate to refer to the body of the British constitution as an uncodified constitution.
The British constitution is spread across a number of sources:
1. Statute law
2. Royal prerogative (executive powers usually exercised by Ministers of the Crown)
3. Constitutional conventions (accepted norms of political behaviour)
4. Common law (decisions by senior courts that are binding on lower courts)
5. EU Treaties
6. Statements made in books considered to have particular authority
Note that not all of these sources form part of the law of the land, and so the British constitution encompasses a wider variety of rules, etc. than that of (say) the United States.
Many important elements of the British constitution are to be found in Acts of Parliament. In contrast with many other countries, legislation affecting the constitution is not subject to any special procedure, and is passed using the same procedures as for ordinary legislation.
The most important statute law still in force and affecting the constitution includes the following:
- The Habeas Corpus Act 1679
- The Bill of Rights (1689)
- The Claim of Right (1689)
- The Act of Settlement (1701)
- The Acts of Union (1707)
- The Septennial Act 1715
- The Acts of Union (1800)
- The Parliament Acts (1911 and 1949)
- The Regency Act 1953
- The Life Peerages Act 1958
- The Peerage Act 1963
- The European Communities Act 1972
- The British Nationality Act 1981
- The Representation of the People Act 1983
- The Parliamentary Constituencies Act 1986
- The Human Rights Act 1998
- The Scotland Act 1998
- The Northern Ireland Act 1998
- The House of Lords Act 1999
- The Civil Contingencies Act 2004
- The Constitutional Reform Act 2005
- The Government of Wales Act 2006
2. Royal prerogative
Certain powers pre-dating the establishment of the present parliamentary system are still formally retained by the Queen. In practice almost all of these powers are exercised only on the decision of Ministers of the Crown (the Cabinet). These powers, known as the royal prerogative, include the following:
- The appointment and dismissal of government ministers
- The summoning, opening, prorogation, and dissolution of Parliament
- The assenting to legislation
- The power to declare war, and to deploy the armed forces
- The power to conduct relations with foreign states, including the recognition of states or governments, and the making of treaties
- The issuing of passports
3. Constitutional conventions
Conventions are customs that operate as rules considered to bind the actions of the Queen or the Government. Conventions are not part of the law, but nevertheless are often considered to be just as fundamental to the structure and working of the constitution as the contents of any statute. Indeed, statute law affecting the constitution is often written in such a way that the existence of certain conventions is taken for granted, and some conventions are so fundamental that many people are unaware that they are in fact "unwritten" rules.
Examples of the more important constitutional conventions include:
- The Queen does not direct government policy, and leaves all decision-making to her Cabinet
- Cabinet members are bound by the principle of collective responsibility; ministers who feel themselves unable to publicly support or defend the policy of the Government are expected to resign
- The Government is headed by a Prime Minister, appointed by the Queen from the House of Commons
- The Prime Minister is usually expected to be the leader of the political party with the most MPs (members of the House of Commons)
- When a Prime Minister's political party loses a general election (i.e. obtains less seats in the House of Commons than a rival party), he or she is expected to resign
- Government ministers are usually expected to be drawn entirely from the two Houses of Parliament, and most important office-holders are expected to be MPs
- A government that is unable to obtain the passage through Parliament of important legislation, including the annual Appropriation and Finance Acts, is expected to resign
- The (unelected) House of Lords does not obstruct the passage of legislation stated in the government party's election manifesto to be fundamental policy
- The Speaker of the House of Commons is expected to be impartial, even though originally elected as the representative of a political party
4. Common law
The common law is that part of the law which does not rest on statute. Instead, it is the accumulation of specific judicial decisions set by senior courts as precedents binding on lesser courts.
Certain parts of the common law are also what is known as trite law: examples of this include the fact that the United Kingdom is a monarchy, and the fact that brothers take precedence over sisters in the succession to the throne.
5. EU Treaties
As a member state of the European Union, the United Kingdom is bound by EU law.
6. Authoritative statements
Certain published works are usually considered to have particular authority. In the first half of the twentieth century this was the case with A V Dicey's Law of the Constitution, being cited with approval in judicial decisions. A particularly important work is Erskine May, which sets out the procedures and customs of the House of Commons. Other important sources include certain ministerial statements.
However, none of these works have legal authority; at best, they are merely persuasive.