The UK constitution

What are constitutions and why do they matter? 

The term ‘constitution’ refers to the principles, rules and laws that establish and underpin a political system. The constitution creates and defines the powers of different political institutions and determines how they should relate to each other. It sets out the limits of these powers and regulates the relationship between the state and its citizens. 

Constitutions place both limitations and obligations on governmental organisations in their relationship with the people, and provide opportunities for the public to influence the political process. 

What is a constitution and what are the features of the UK constitution?

Click on any of the questions below to be taken to the answer.

Is the constitution of the United Kingdom written down?

Why is the UK’s constitution different to most other modern liberal democracies? 

Is Magna Carta (1215) our constitution?

What are the sources of the UK constitution?

What key reforms have been made to the UK constitution over time?

What are the advantages of having an ‘uncodified’ constitution?

What are the disadvantages of having an ‘uncodified’ constitution?


Further reading

Is the constitution of the United Kingdom written down? 

It is often noted that the UK does not have a ‘written’ or ‘codified’ constitution. It is true that most countries have a document with special legal status that contains some of the key features of their constitution. This text is usually upheld by the courts and cannot be changed except through an especially demanding process. The UK, however, does not possess a single constitutional document of this nature. Nevertheless, it does have a constitution. The UK’s constitution is spread across a number of places. This dispersal can make it more difficult to identify and understand. It is found in places including some specific Acts of Parliament; particular understandings of how the system should operate (known as constitutional conventions); and various decisions made by judges that help determine how the system works.  

Why is the UK’s constitution different to most other modern liberal democracies? 

As described above, the UK’s constitution is different from many other countries in that its core aspects are not contained in a single legal source. This can be explained in part by UK history. Unlike France, Italy and many other places, the UK did not experience a revolution or moment of political rupture in the late eighteenth century or nineteenth century, when written constitutions were at their most popular after the American Revolutionary War. 

Unlike in the United States, where the constitution is the ‘supreme law’ the UK system has no clear concept of a ‘higher law’: there is no clear distinction between what is a constitutional law and what is a regular law. This also means there are no special procedures for changing the constitution itself in the UK. If it is determined to do so, a ‘constitutional statute’ can be repealed or amended by simple majority votes in Parliament, like any other legislation. This differs from the situation in countries such as the United States, where the constitution is ‘entrenched’ – in other words, needing to satisfy additional requirements in order for it to be amended. The UK constitution can be altered relatively easily by the government of the day, meaning it changes more frequently than many other constitutions. It is often said that the UK Parliament is ‘sovereign’. This parliamentary ‘sovereignty’ means that Parliament can make or unmake any law, without being limited by a constitutional text.

Is Magna Carta (1215) our constitution? 

Magna Carta (translated as Great Charter) was an agreement reached at Runnymede in 1215 between King John and a group of English barons who had been part of a rebellion against the King. In chapter 39 and 40 it stated that: 

39. No free man shall be seized or imprisoned or stripped of his rights or possessions, or outlawed or exiled, or deprived of his standing in any other way, nor will we proceed with force against him, or send others to do so, except by the lawful judgement of his equals or by the law of the land. 

40. To no one will we sell, to no one deny or delay right or justice. 

Magna Carta became significant in placing formal limits on the King’s power over his subjects, and in articulating the notion that the monarch should not be above the constraints of the law. In this, we can see the origins of a foundational constitutional principle: the rule of law (that everyone within a state should be bound by and entitled to the benefit of the law).  

Many look to Magna Carta in the way people in other countries might look to a ‘written’ constitution. Although the extent of what it actually secured in thirteenth-century England has often been overstated, it no doubt represents a significant point in the development of our constitutional system. Much of its impact came through inspiring and supporting future developments, such as ‘habeas corpus’: that a person may not be detained without legal reason. Furthermore, it predated the existence of the UK by five centuries, and was an English document (though written in Latin).

The British Library looks at Magna Carta.

What are the sources of the UK constitution? 

The sources of the UK constitution are various, including both law and other less formal documents, without legal force. 

Acts of the UK Parliament: certain pieces of primary legislation enacted by the UK Parliament form a major source for aspects of the UK constitution. These laws provide for: the devolution settlements; the right to vote and the holding of elections; the upholding of human rights; the prohibition of discrimination; the existence of the Supreme Court; and much else. As mentioned previously, despite the constitutional significance of these statutes, there is no clear formal means of distinguishing them from more regular laws which deal with policy areas such as education and transport. 

Conventions: are understandings about how the constitution functions. They can be hard to define precisely and in a way that commands wide agreement; and they lack hard legal force. But conventions are the source of some of the most important features of the UK system of government. For instance, that the Prime Minister should be a member of the House of Commons able to command the confidence of that institution is only a convention. Traditionally, conventions tended not to be written down in official documents. But, increasingly in recent decades, accounts of them have come to be included in texts published by bodies such as the UK government. These include the Cabinet Manual and the Ministerial Code.

Common law: the UK has what’s known as a ‘common law’ system, meaning that judges declare the law as derived from custom and precedent. Although it is the role of the courts to interpret the rules, not to make them; in practice, through identifying what the law is, judges can create it. In doing so, they have established important features of the UK constitution, such as individual rights and the idea that public authorities are subject to limitations and do not possess arbitrary power.

Authoritative works: in the UK system, as we have seen, the constitution is spread over a number of documents and sources, which can make it particularly hard to decipher. Given this, the interpretations of experts seeking to make sense of the system can become particularly important and influential. In fact, they can become so influential to perceptions of the system that they seem to become part of it. The views of the late nineteenth/early twentieth century legal scholar, Albert Venn Dicey, for instance, came to underpin the widely accepted doctrine known as ‘parliamentary sovereignty’. The political journalist, Walter Bagehot, writing in the nineteenth century, helped shape the conception and operation of a constitutional monarchy. Although knowledge of these works has declined since the twentieth century, they continue to be important today, having shaped the ideas even of those who do not know what their source is. 

What key reforms have been made to the UK constitution over time? 

Although they do not provide a comprehensive picture, we can get a sense of the changing UK constitution through a number of key Acts of Parliament. 

1536/1543: two laws now known as the ‘Acts of Union’ between Wales and England legally incorporated Wales into England. Among other measures, the 1536 law prevented the use of the Welsh language in court proceedings; while the 1543 Act provided more detail to the general settlement set out in the earlier law.

The Bill of Rights 1689: the Catholic King James II was defeated in the revolution of 1688-89 and replaced by Mary II and William III (the Prince of Orange), ruling jointly. The Bill of Rights in essence established the terms of his ascension to the throne, and was the outcome of negotiation between William and contemporary political leaders. It was a statute of particular constitutional importance in firmly establishing the authority and independence of Parliament in relation to the monarch. Laws could no longer be suspended or got rid of without the consent of Parliament. It also contained provisions to further protect the liberty and security of the individual. 

The Act of Settlement 1701: prevented Catholics from taking the English throne and provided for the ascension of the House of Hanover. In doing so, it established Parliament’s right to decide on the line of succession, further enhancing its power. It also contained important constitutional provisions relating to the independence of the judiciary. The Act protected the salaries and positions of judges, aiming to give them the security to enforce the law without fear of retribution. 

The Treaty and Acts of Union of 1706-1707: provided for the union of Scotland and England. Two Acts were passed, one by the English Parliament and one by the Scottish Parliament, implementing the Treaty of Union. Whilst England and Scotland had the same monarch since 1603, they retained separate legislatures. After the Acts of Union, they united to form a single legislature: the Parliament of Great Britain, and a single state. Nonetheless, Scotland retained its own legal system, arrangements for education, local government, and religion.

Act of Union 1800: brought about a Union of Ireland and Great Britain. This arrangement began on a controversial footing because it was not accompanied by measures to remove political discrimination against Catholics.

The Parliament Acts 1911 and 1949: established in law the primacy of the House of Commons and reduced the power of the House of Lords. The Acts meant that the Lords could in most cases no longer veto legislation if the Commons was determined to pass it. Bills could be presented for Royal Assent without the approval of the second chamber, as long a certain amount of time had elapsed and certain other conditions were met. The Lords no longer had any power at all to reject bills certified as relating to financial matters, giving the Commons clear control over money. 

Professor Vernon Bogdanor explains the 1911 Parliament Act .

The European Communities Act 1972: provided for the UK’s ascension to the three European Communities (the European Economic Community, the European Atomic Energy Community, and the European Coal and Steel Community). Constitutionally, the most significant aspect of the Act was that European Community Law (later EU law) became incorporated and binding within UK domestic law. Furthermore, it stipulated that Community Law was ‘supreme’ within a member state, with potential conflicts between domestic law and EU legislation overseen by the European Court of Justice. It eventually became established that an Act of Parliament could be ‘disapplied’ in as far as it contradicted European law – a new departure for the UK constitution.

The Human Rights Act 1998: gave direct effect in domestic law to the rights contained within the European Convention on Human Rights, which was adopted in 1950 after the Second World War. The 1998 Act meant that human rights cases could be heard in UK courts, rather than individuals having to take their case to the European Court of Human Rights. Additionally, it stipulates that as far as possible judges must interpret Acts of Parliament so they are compatible with the rights in the Convention. If this is not possible, they may issue a declaration stating that the legislation is incompatible. However, this does not affect the validity of the primary legislation and the law remains the same unless it is altered by Parliament.  

The House of Lords Act 1999: reduced the size of the House of Lords and largely removed hereditary peerages (where an individual could inherit a seat in the Lords through their family). It reduced the number of peers from 1330 to 669. 

The European Union (Withdrawal) Act 2018: repealed the European Communities Act 1972 (see above), thus removing the provision that EU legislation automatically takes effect as domestic law in the UK. It was introduced by the Theresa May government in 2018 as part of the process of the UK’s exit from the European Union. It transferred all EU law onto the UK statute book and gave ministers powers to make changes to this ‘retained EU law’ in the future. 

Dr Andrew Blick talks to Professor Vernon Bogdanor about the UK constitution.

What are the advantages of having an ‘uncodified’ constitution? 

Some praise the UK’s uncodified constitution for its flexibility. As the timeline above indicates, the constitution has been modified frequently over many years in response to changing circumstances. Its proponents argue this allows for a pragmatic approach, where different things can be tried, tested and developed, with an optimal arrangement being honed over time. They point to other countries with hard to change codified constitutions that have been unable to update their political systems in line with changing attitudes and political realities. The issue of gun ownership in the United States provides one often cited example of this, where controls have been hard to implement because of the 2nd Amendment.  

Many also believe that having an uncodified constitution is more democratic. Rather than being bound by the decisions of past generations, it allows for each successive generation to influence the constitution through the representatives they elect. If a party with a constitutional reform agenda is elected, they are able to carry out what the people have voted for. The new Labour government of 1997 had a wide-ranging constitutional programme, including devolution and human rights, that might have been difficult to implement otherwise. In an uncodified constitution, its supporters argue, it is elected politicians, rather than unelected judges, who have the final say.

This video gives some of the arguments for and against a codified constitution.

What are the disadvantages of having an ‘uncodified’ constitution? 

Critics of the uncodified constitution argue that it leaves the political system open to abuse. In the UK system, there are few checks on the power of a government with a majority in the House of Commons, which could alter the rules for its own advantage. In theory, a powerful government could abolish the devolved legislatures and repeal the Human Rights Act. There are also few barriers against a government rushing through poorly thought-out changes to the constitution. 

For some the UK’s constitution is pragmatic, for others it is piecemeal. In other words, changes often happen in stops and starts and through gradual, sporadic tweaks. When the constitution isn’t considered as a whole, they say, it can lead to unintended negative consequences. 

Finally, many argue that the UK’s uncodified constitution is confusing and ambiguous. This makes it more difficult for citizens to fully understand, and therefore to know when a government is abusing its position. This lack of clarity can also be exploited by those in power to get away with things that would be more difficult if the rules were clearer. It also can make the business of governing harder, as there will be doubts surrounding the roles and responsibilities of different political institutions. Proponents of a codified constitution argue that stating clearly all in one place how the political system operates would enable the government to better serve the public and the public to better engage with government.

Channel 4 News examines whether Brexit caused a constitutional crisis in the UK.


Click here for a PowerPoint on the basics of the UK constitution, that condenses the information above. The PowerPoint is primarily designed for teachers covering the topic.

Further reading: 

Vernon Bogdanor, Brexit and our unprotected constitution

Andrew Blick, Populism and the UK Constitution  

Nat le Roux, ‘Unconstitutional Democracy?’

Nat le Roux, Is there a tension between Parliamentary Democracy and referendums?

From the UK Parliament website:

Human Rights Act Review: Do not risk UK’s constitutional settlement and enforcement of rights by amending Act, urge MPs and Peers

The Parliament Acts explained by the UK Parliament website