The United Kingdom Constitution

Unlike countries such as France and the US, the UK is often said to have an ‘unwritten constitution’ in that it doesn’t have a single codifying document setting out how the state works and the fundamental laws that apply to it. More than half of the British constitution is written down in some form, however, mainly in statutes, case law and international treaties. Other aspects of the constitution are found in non-binding conventions, parliamentary rules, and the royal prerogative. These various sources make it difficult to pinpoint specifics of the constitution, but do allow the constitution to be easily amended, giving it a flexible nature. Traditionally, the UK constitution is said to be founded on two principles: the doctrine of parliamentary supremacy and the rule of law.

Parliamentary supremacy

Parliament is the supreme law-making body. This means that it has complete sovereignty to make or unmake any law that it wishes to. This contrasts with other jurisdictions, such as the US, whose laws may often be challenged as being unconstitutional. Consequently, Parliament is not bound or subject to any other government or state authority, including the courts. However, this position changed after the UK joined the European Union in 1972, and, until Brexit becomes final and the UK withdraws from the EU, European law takes precedence over that of the UK where there is a conflict between the two (Factortame (No. 2) (1991)).

The rule of law

Although the concept of the rule of law differs from one jurisdiction to the next, it basically means that the law is above every citizen and is applied to every citizen equally. Although no precise definition of ‘the rule of law’ exists, certain elements are seen as essential, such as that laws should be published, and that the judiciary should be independent. Of particular importance in the concept of the rule of law is that the government itself should be restrained in its governance and government officials held accountable for their actions. Of course, dictatorships or military juntas may look upon the rule of law in a different light.

Parliamentary democracy and the royal prerogative

The UK is a parliamentary monarchy, meaning that Government members are almost always also members of one of the two Houses of Parliament (the House of Commons and the House of Lords). The Government is directly accountable to Parliament – the party in Government is only in power because it holds a majority in the House of Commons – at any time the Government can be dismissed by the Commons through a vote of ‘no confidence’.

The UK’s head of state is a monarch, although nowadays, the monarch’s role is largely ceremonial and reserved to duties such as the state opening of Parliament and outlining the Government’s planned agenda in the Queen’s Speech. The day-to-day running of the country is left to the prime minister and the heads of the various ministries of state. The monarch does retain some powers, known as the royal prerogative – a body of customary authority, privilege and immunity – although these are generally exercised in the UK upon the advice of the prime minister or other ministers. One of the most important of these is the power to appoint or dismiss prime ministers. The last time this power was used was in 1974 when Queen Elizabeth II appointed Harold Wilson as prime minister, even though he did not command a majority in the House of Commons. The appointment was made upon advice from the Privy Council. Other powers under the royal prerogative include the power to make war and peace, the power to issue passports, and the power to appoint bishops and archbishops of the Church of England.

Sources of constitutional law

As mentioned, the constitution in the UK is derived from several sources, including international treaties and (for now) EU law. One of the most important are Acts of Parliament. The Parliament Acts of 1911 and 1949 allow the House of Commons, in certain limited circumstances, to pass legislation without the consent of the House of Lords, and consequently to act in a manner which would otherwise be unconstitutional. This is very rare, however, and has happened less than five times in the last 60 years. The threat of using the Parliament Acts may be sufficient to pass legislation which is unpopular in the House of Lords.

Case law also forms an important part of the constitution. The decisions of the judiciary have occasionally imposed limits on executive power – particularly where human rights are affected. Constitutional conventions, although not legally binding, also play an important role in the UK’s legal fabric. By convention, the monarch appoints as prime minister the person who commands a majority in the House of Commons after a general election. By law, however, there is nothing to stop the monarch from appointing his or her head gardener as prime minister. Convention dictates that this would not happen, of course, but in strict legal theory remains a possibility.


The UK has a unitary system of government, meaning power is held in the centre (Westminster). Some powers, however, have been devolved to Scotland, Wales and Northern Ireland following the creation of the Welsh Assembly, the Scottish Parliament and the Northern Ireland Assembly. The main powers that have been delegated include those regarding health, transport and education. Other more serious powers, such as those on foreign affairs, defence, social security, macro-economic management and trade, remain the sole preserve of Westminster.

Article written by...
Nicola Laver LLB
Nicola Laver LLB

Nicola on LinkedInNicola on Twitter

A non-practising solicitor, Nicola is also a fully qualified journalist. For the past 20 years, she has worked as a legal journalist, editor and author.