The United Kingdom constitutional law concerns the governance of the United Kingdom of Great Britain and Northern Ireland. With the oldest continuous political system on Earth, the British constitution is not contained in a single code but principles have emerged over centuries from common law statute, case law, political conventions and social consensus. In 1215, Magna Carta required the King to call "common counsel" or Parliament, hold courts in a fixed place, guarantee fair trials, guarantee free movement of people, free the church from the state, and it enshrined the rights of "common" people to use the land.Magna Carta clauses 1 ('... the English church shall be free...'), 12 and 14 (no tax 'unless by common counsel of our kingdom...'), 17 ('Common pleas shall... be held in some fixed place'), 39-40 ('To no one will we sell, to no one will we refuse or delay, right or justice'), 41 ('merchants shall have safe and secure exit from England, and entry to England') and 47-48 (land taken by the King 'shall forthwith be disafforested'). After the English Civil War and the Glorious Revolution 1688, Parliament won supremacy over the monarch, the church and the courts, and the Bill of Rights 1689 recorded that the "election of members of Parliament ought to be free". The Act of Union 1707 (more correctly the Treaty of Union between England and Scotland, enacted by both states in their Parliaments) unified England, Wales and Scotland, while Ireland was joined in 1800, but the Republic of Ireland formally separated between 1916 and 1921 through bitter armed conflict. By the Representation of the People (Equal Franchise) Act 1928, almost every adult man and woman was finally entitled to vote for Parliament. The UK was a founding member of the International Labour Organization (ILO), the United Nations, the Commonwealth, the Council of Europe, and the World Trade Organization (WTO).The ILO was formed as part of the (now defunct) League of Nations in the Versailles Treaty 1919 Part XIII. The UN was formed in 1945. The Commonwealth of Nations was formally established by the London Declaration of 1949. The Council of Europe was created in 1950. The European Union was formed by the Maastricht Treaty 1992, succeeding the European Community which the UK joined by the European Communities Act 1972. The WTO was created in 1994.
The constitutional principles of parliamentary sovereignty, the rule of law, democracy and internationalism guide the UK's modern political system. The central institutions of modern government are Parliament, the judiciary, the executive, the civil service and public bodies which implement policies, and regional and local governments. Parliament is composed of the House of Commons, elected by voter constituencies, and the House of Lords which is mostly appointed on the recommendation of cross-political party groups. 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 is headed by a twelve-member Supreme Court. Underneath are the Court of Appeal for England and Wales, the Court of Appeal in Northern Ireland, and the Court of Session for Scotland. Below these lie a system of high courts, Crown courts, or tribunals depending on the subject in the case. Courts interpret statutes, progress the common law and principles of equity, and can control the discretion of the executive. While the courts may interpret the law, they have no power to declare an Act of Parliament unconstitutional. The executive is headed by the Prime Minister, who must command a majority in the House of Commons. The Prime Minister appoints a cabinet of people who lead each department, and form His Majesty's Government. The King himself is a ceremonial figurehead, who gives royal assent to new laws. By constitutional convention, the monarch does not usurp the democratic process and has not refused royal assent since the Scottish Militia Bill in 1708. Beyond the Parliament and cabinet, a civil service and a large number of public bodies, from the Department of Education to the National Health Service, deliver public services that implement the law and fulfil political, economic and social rights.
Most constitutional litigation occurs through administrative law disputes, on the operation of public bodies and human rights. The courts have an inherent power of judicial review, to ensure that every institution under law acts according to law. Except for Parliament itself, courts may declare acts of any institution or public figure void, to ensure that discretion is only used reasonably or proportionately. Since it joined the European Convention on Human Rights in 1950, and particularly after the Human Rights Act 1998, courts are required to review whether legislation is compatible with international human rights norms. These protect everyone's rights against government or corporate power, including liberty against arbitrary arrest and detention, the right to privacy against unlawful surveillance, the right to freedom of expression, freedom of association including joining trade unions and taking strike action, and the freedom of assembly and protest. Every public body, and private bodies that affect people's rights and freedoms, are accountable under the law.
History
The history of the UK constitution, though officially beginning in 1800, traces back to a time long before the four nations of England, Scotland, Wales and Ireland were fully formed.See AW Bradley, KD Ewing and CJS Knight, Constitutional and Administrative Law (2018) ch 2, 32–48, on historic structure, and devolution. Before the Roman Empire's conquest, Britain and Ireland were populated by Celtic migrants from the European continent, but ones who left no recorded history of law.See F Pollock and FW Maitland, The history of English law before the time of Edward I (1899) Book I, ch I, 1, 'Such is the unity of all history that anyone who endeavours to tell a piece of it must feel that his first sentence tears a seamless web.' Near the end of the Roman Republic in 55 and 54 BC, the former Consul and legion commander Julius Caesar invaded Britain during the broader Gallic Wars. This did not establish permanent occupation, as Caesar returned to Rome, became dictator and was assassinated. The Republic was transformed into an Empire, when Caesar's heir Augustus took power in 27 BC. In the reign of Augustus' grandson, Claudius, Britain was conquered from 43 AD. Under Rome's uncodified constitution, Roman Britain was administered by a governor, usually member of the Senate but appointed by the Emperor for their military record. Londinium was a provincial capital of 60,000 people, and Britain a cosmopolitan society of around 3 million people. Roman law was based upon a slave economy, and highly militarised. Hadrian constructed a wall from 122 as part of the Empire's limits, but this was soon moved north by Antoninus Pius from 142. Constantine the Great was stationed in York in 306 when he left to claim his title to be Emperor. Constantine marched on Rome under the cross in 312, and issued an Edict of Milan in 313. This triggered a series of events where the Church assumed more and more power over the law.Pollock and Maitland (1899) 4–5 But under constant assault, the Empire began to collapse and Britain was abandoned in 407.cf E Gibbon, The History of the Decline and Fall of the Roman Empire (1789) arguing Christianity led to weakness that caused Rome's fall. Neither the Theodosian Code issued in 438, nor the great Corpus Juris Civilis of Justinian I in 534 entered the laws of Britain.Pollock and Maitland (1899) 5-6 In the Dark Ages, during power struggles between Anglo-Saxons, Britons, Danes and Vikings, kings convened regular councils, called the Witan, composed of lords and church leaders.FW Maitland, The constitutional history of England (1909) 6 But it was not until the Norman Invasion of 1066 that one common law was established through England under one monarch.