Updated: Oct 28, 2020
The Constitution of the United Kingdom is the system of rules that decides the political governance of the United Kingdom of Great Britain and Northern Ireland. Unlike most countries, the UK constitution is not codified into a single document. However, the UK Supreme Court recognises that there are constitutional principles, including parliamentary sovereignty, the rule of law, democracy, and upholding international law.
The UK Supreme Court also recognises that some Acts of Parliament have special constitutional status. These include Magna Carta, which in 1215 required the King to call a "common counsel" (now called Parliament) to represent people, to hold courts in a fixed place, to guarantee fair trials, to guarantee free movement of people, to free the church from the state, and to guarantee rights of "common" people to use the land.
After the English Civil War and the Glorious Revolution, the Bill of Rights 1689 and the Claim of Right Act 1689 cemented Parliament's supremacy over the monarch, the church and the courts, and said that the "election of members of Parliament ought to be free". The Treaty of Union between England and Scotland in 1706, followed by two Acts of Union 1707, one in the Scottish, the other in the English parliament, unified England, Wales and Scotland, Ireland was joined in 1801, but the Republic of Ireland separated after the Proclamation of the Irish Republic of 1916.
After a slow process of democratic reform, the UK guarantees every adult the equal right to vote in the Representation of the People (Equal Franchise) Act 1928. After World War Two, the UK became a founding member of the Council of Europe to uphold human rights, and the United Nations to guarantee international peace and security.
The UK was a member of the European Union, whose predecessor the European Communities (the Common Market) it first joined in 1973, but left in 2020. The UK is also a founding member of the International Labour Organization and the World Trade Organization to participate in regulating the global economy.
The leading institutions in the United Kingdom's constitution are Parliament, the judiciary, the executive, and regional or local governments. Parliament is the supreme law-making body, and represents adult voters. It has two houses. The House of Commons is elected by a democratic vote in the country's 650 constituencies. The House of Lords is mostly appointed by cross-political party groups from the House of Commons.
To make a new Act of Parliament, the highest form of law, both Houses must read, amend, or approve proposed legislation three times. The judiciary interprets and develops the law found in Acts of Parliament or previous cases. The highest court is the twelve person UK Supreme Court, as it decides appeals from the Courts of Appeal in England, Wales, and Northern Ireland or the Court of Session in Scotland. UK courts cannot declare Acts of Parliament to be unconstitutional, but can declare acts of the executive invalid, or declare any law to be incompatible with the European Convention on Human Rights.
The executive manages the United Kingdom day to day. The executive is led by the Prime Minister appointed by Parliament, and the cabinet of other Ministers, who lead the civil service departments, such as Department of Health which runs the National Health Service, or the Department of Education which funds schools and universities. There is also a Queen[disambiguation needed], who inherits her position, and serves as a ceremonial figurehead to give royal assent to new laws. The monarch has not refused to sign any new law since the Scottish Militia Bill in 1708, and it is a constitutional convention that the Monarch follows the democratic will of Parliament.
Most litigation over the UK constitution takes place in judicial review applications, to decide whether public bodies have complied with the law. Every public body must also follow the law, as set down in Acts of Parliament, and subject to that also statutory instruments made by the executive. Under the Human Rights Act 1998, courts may review government action to decide whether the government has followed its international commitment to the European Convention on Human Rights. This was established in 1950, following World War Two. Human rights include everyone's rights to liberty against arbitrary arrest or detention, to a fair trial, to privacy against unlawful surveillance, to freedom of expression, to freedom of association including joining trade unions, and to freedom of assembly and protest.