Comparison: UK and US Constitutions

When comparing the Constitutions of the UK and USA it is useful to understand their history and origins. The UK constitution has evolved over time with its origins in the medieval period over 800 years ago or even earlier. The constitution of the USA began with a revolution and so has starting point.  In the UK the constitution has continued to change significantly over the last two centuries, where as the US constitution has largely remained intact since 1787.

One way of understanding the differences between the two constitutions is to compare their structure by comparing the buildings where their respective legislatures are housed. In the USA Congress is located in the capitol building in the UK parliament in the Palace of Westminster.

Over the years I have taken many groups of students on trips to London and Washington DC where they have toured Parliament and Congress. The Palace of Westminster is a useful representation of the UK's constitution.  It has parts which are 800 years old such as Westminster Hall, and while most of the building is Victorian there are also some modern additions. There is also a current debate about the need to modernise and restore the building. This is quite a useful metaphor for the constitution. The Capitol building was built between the 1800 and 1850 and although there were revisions of design and enlargements it remains a unified design in the neo classical style.  Again this unity of design might well represent the US constitution.

If I cared to, I might note that the Supreme Court was originally housed in a modest room in the Capitol but now resides in one of the grandest buildings in DC and this might also a provide a handy metaphor for the develop to the court from the writing of the constitution until today.

The differences in their origins and history resulted in quite different structures and the differences in the two cultures.  The US Constitution is a product of revolution and the enlightenment of the late eighteenth century. It is shaped by rationalism and the ideas of the enightenment. and thinkers such as John Locke.  Belief in liberty, individualism, equality, representative democracy, limited government, states’ rights and the rule of law. These form the core values of America’s political culture. The Constitution is also shaped by a society that had broken free from autocratic monarchy by revolution and was anxious to create a constitution which preserved itself from the dangers of returning to autocracy and revolutionary disorder, so  the separation of powers and checks and balances reflect these twin fears. The constitution also reflects 18th Century values that accepted  slavery, and was fearful of state-organised religion, and saw gun ownership as a fundamental liberty. The constitution was also a product of 13 colonial provinces which has a long history and distinct identities, economies and culture. By 1787 it was already clear that a profound divide existed between the slave owning south and non slave north. This was reflected in the federal system of government.

 The British Constitution, on the other hand, is different because it is the product of a different culture and history. A belief in a constitutional monarchy, a class system and an established (state)church.

The role and power of the monarchy evolved over five centuries from monarchs with near absolute power to the constitutional monarchs of today which have largely ceremonial importance.

The principle of hereditary privilege continues in the monarchy and in  the presence of hereditary peers in the House of Lords. The US Constitution rules out all titles and the republican form of government assumes no hereditary authority.

The established church results in the inclusion of the two archbishops and 24 of the bishops of the Church of England in the House of Lords as well as the monach's position as head of the church of England. The first amendment to the constitution forbids a state church and the principle of aseparation between the state and religion goes so far as to mean no prayers on schools.

The structural differences 

The USA — like the vast majority of democracies — has a codified constitution, the UK has an uncodified constitution. A codified constitution is one in which most of the rules concerning the government of the nation are drawn together in one document. The United States has a single document running to no more than 7,000 words which contains most of the country’s constitutional arrangements. The UK constitution has multiple sources generally identified as:  statute law, common law, conventions, treaties and works of authority.

The UK and USA are often described as having unwritten (UK)and written (USA) constitutions. This is misleading because even a codified constitution contains parts that are uncodified. For example, the US Constitution contains no mention at all of  primary elections, voting rules, parties, congressional committees, the president’s cabinet, or the Executive Office of the President. The Supreme Court's most significant power of Judicial Review is not mentioned in the constitution. So there are many 'unwritten' elements in the US  constitution. However, the UK Constitution contains more elements, particularly of procedure, which are unwritten. For example, the monarch will always sign bills in to law, always grant a request to prorogue parliament, always ask the leader of the largest party in parliament to form a government. That the monarch always acts this way is a matter of convention. Convention can become part of the constitution even in a codified constitution. When President George Washington declined to seek a third term of office in 1796, he put in place the convention of a two-term limit on the presidency — a convention that held for well over a century until broken by Franklin Roosevelt in 1940. It was only after Roosevelt had been elected to a fourth term that the Twenty -Second Amendment was added restricting presidents to two terms.(1951). 

Although the UK is said to have an unwritten constitution much of the UK Constitution is written ,for example, in Acts of Parliament, Common Law, and works of authority such as those by Erskine May (1815–86) and Walter Bagehot (1826–77). It is simply not collected together into a codified document called ‘a constitution’.

Another structural difference is that the UK constitution is not entrenched which means it is more flexible and easier to amend. In the USA the process for amending a constitution is difficult one since it must be supported by a super-majority in Congress and in the states. 

Under Article I of the United States Constitution, the length of terms for members of the House of Representatives and the Senate is fixed at two and six  years respectively.  To change the length of those terms of office would require an amendment. By comparison the length of terms for  members of the UK House of Commons is fixed at five years. But this is fixed by an Act of Parliament — the Fixed-Term Parliaments Act (2011). So all that would be required to change the length of that term of office would be another Act of Parliament — passed by simple majorities in both houses of Parliament. 

The United States Constitution also entrenches rights and liberties, including the Second Amendment right to ‘keep and bear arms’. But in the United Kingdom, the rights of gun owners can be changed by statute law as they were after the Dunblaine school shooting where hand guns were banned in the UK.

Cultural Differences

A culture of individualism and personal liberty in the USA is much stronger than in the UK. This can be seen in the refusal of many Americans to where face masks during the Corona virus pandemic which they saw as a restriction of their liberty.

Another cultural difference is how people view government. For the most part  UK citizens view government as likley to provide answers to problems, whereas in the USA there is a general suspicion that governments may do more harm than good. Ronald Reagan said 'Government is not the answer, government is the problem'. In the USA a citizen might observe that the government have ' screwed up again!' but in the  UK it might be more common to the complaint that the government have failed to do something. UK Citizens expect government to resolve problems and while this may also be true for many Americans, particularly democrats, there is much less confidence in the ability of government. The different attitudes to social medicine and guns in the UK and USA are a product of individualism and suspicion of government. In the USA gun ownership is  seen as a potential means of resisting tyranny. As I saw on a bumper sticker in  Michigan 'I love my counntry, it's the government I'm afraid of'.

Democracy in the UK and USA is also different because of cultural differences, in particular the differing attitudes to popular sovereignty. Winston Churchill expressed British hesitancy towards popular sovereignty when he observed that 'the best argument against democracy is five minutes conversation with the average voter'. This might help tp explain why the UK extended the right to vote to 'the average voter' much later than the USA.

The US Constitution allows Americans a much greater role in the electoral processes of their nation than does the UK Constitution for people in Britain.  Between the 1780s and the 1880s, the US House of Representatives was elected on a far wider franchise than the UK House of Commons. The Senate has been directly elected since 1914 whereas Britain’s second chamber still has no elected members at all.

While  the Founding Father's own hesitancy with popular democracy led to the Electoral College the election of the US president has since evolved from an indirect to a virtually direct election and the increasing use  of direct democracy in the form of  primaries allows ordinary voters to participate in candidate selection. In the UK candidate selection is an internal process within political parties.

In the UK the use of referendums is relatively new and still quite rare compared to the  USA where, in the states initiatives, referendums and recall procedures allow a high level of direct participation. 

The US Constitution begins with 'We the People..'  and the Tenth Amendment clearly sets out where power resides — with the people.

By contrast, the UK has no codified Constitution and emphasises representative democracy and parliamentary sovereignty. British citizens are, strictly speaking, ‘subjects of the Crown’ — have far fewer opportunities for democratic participation than Americans. Think how many different types of election a UK citizen might vote in during their life compared to a US citizen. There are far more elected posts in the USA including sheriffs, prosecutors, school and library boards, in some states the dog catcher.

More Structural Differences

At first sight there are many similarities in structure between the two constitutions . Both could be described as representative democracies. Both have national governments divided into three branches — a legislature, an executive and a judiciary. Both have a bicameral legislature and both now have  a Supreme Court. There are also sub-national governments: state governments in the USA, and devolved governments for Scotland, Wales and Northern Ireland in  the UK.

But there are many structural differences..

One of the most significant is the principle of the 'Separation of Powers'  which is applied in the USA in a form which is unique among democracies. While almost all democracies have, or claim to have, an independent judiciary with a separation between the judiciary and the other branches of executive and legislature, the USA is unique in also having a separation between all three branches. In the USA their is a strict division of personnel between the legislature and the executive which will mean Kamala Harris will have to give up her Senate seat now she is Vice President. In the UK the legislature and executive are fused with the PM and Cabinet are all chosen from members of Parliament.  

 The UK and USA both have bicameral legislatures, but  in the US Congress both chambers are equal in power and both are elected.

Both the USA and UK have  a supreme court but the nature of the US constitution being, short, open to interpretation and entrenched mean that the US Supreme Court is far more powerful.

While devolution in the UK may appear simiar to  federalism in the US the relationship between London and the devolved governments in Scotland, Wales and Northern Ireland is very different to the relationship between Washington and the states.  Federalism is a divion of powers in a codified and entrenched constituion but devolution is a transfer of powers from a soveriegn parliament to inferior bodies.

Federalism and devolution are again structural differences which reflect cultural differences. The USA has a federal system of government in which political power is divided between a national government and state governments, each having its own area of substantive jurisdiction. Americans think of themselves as Floridians,Virginians, New Yorkers or whatever. Federalism is very appropriate to a country as large and diversified — in race, culture, language and economy — as the USA. It also adds yet another layer of checks and balances, and thereby furtherlimits governmental power.

For centuries, the UK could be described as a unitary system of government with all political power emanating from the central government in London. This reflected the strong sence of shared English identitity but not the identities of other nations in the UK?  This tension led to the creation of a devolved form of government in which certain powers are the prerogative of the central government while the exercise of other powers is devolved to the principalities of Scotland, Wales and Northern Ireland.  Federalism and devolution are two quite different political systems.  In the USA  the states are not subservient to the national government, they are not below the national government but alongside it, sovereign in their own areas of substantive jurisdiction.

But in a devolved system such as exists in the UK, the national government is sovereign. All devolved governmental power exists only with the agreement of the national government. It may cede more powers to the devolved government. Equally, it may reclaim them. In 1972, the UK government suspended the Northern Ireland Parliament at Stormont and replaced it by direct rule from the Westminster Parliament.

However, both federalism in the USA and devolution in the UK seek to serve the same purpose — to give power and legitimacy to local communities in the nation and to give voice to growing regional or, as in the case of Scotland,nationalist pressures. They are both mechanisms for answering calls for government to be ‘nearer to the people’ and to attempt to overcome a tendency for power to become distant and disconnected.

While both  systems also can be seen to limit the power of government  the  motivation for devolution was far more rational since it was seen as a means of steming the rise of nationalism in Wales and Scotland.

Using the rational model: Both constitutions exhibit similarities in their practical operation, such as the presence of political parties and the impact of pressure groups. 

For example

The executive plays a significant role in drawing up policies and setting the political agenda. Whether it is ‘Make America Great Again’ or ‘Get Brexit Done’, the president and the prime minister both seek to set the political tone. Presidents and PMs try to lead the policy agenda.

However: In the UK, a prime minister with a healthy majority can normally get their agenda through parliament without major incident. This is more difficult for US presidents, who have to negotiate carefully and bargain with congressional leaders, even those from their own party. Johnson could push through Brexit legislation in 2020, whereas Donald Trump found it far harder to secure the billions of dollars required for his proposed Mexican border wall.

Federalism and Devolution Compared


The UK and the USA systems share the liberal aim of dispersing power and taking decision-making closer to the people, in order to prevent tyranny.

•They recognise national and regional differences, e.g. the Welsh language or the contrasting attitudes to the role of the state or religion in different parts of the USA.

•They allow for the central government to carry out some functions, e.g. foreign policy, and the state/regional/ national governments to carry out others, e.g. healthcare.

•The states and the nations both receive funding from the central government.

•They have both led to some policy divergence, e.g. in Wales, 16- and 17-year-olds are able to vote, and in some states in the USA it is no longer possible to access abortions.

•Both could arguably be seen as a threat to national unity and potentially could lead to the break-up of the nations, e.g. the Scottish independence referendum.

•The US states and the UK devolved governments each have elections to their own legislatures and each have their own executives.

•In both countries, federalism/devolution has changed over time in terms of powers.


The Westminster Parliament remains sovereign, so the devolved powers are not equal to it. In theory, but probably not in practice, powers could be returned to Westminster. The UK state therefore remains unitary, rather than federal like the USA.

•The UK constitution is uncodified, so it does not explicitly protect devolution or state its relationship with the central government.

•Federalism is deeply rooted in the American system of government, as part of the codified Constitution. It is not possible that federalism could be ended and replaced with a centralised system.

•Devolution has created an asymmetrical system: some nations have more powers than others, e.g. there is no English Parliament. This is not the case in the USA: the states all have the same powers as each other.

•Devolution is a ‘top-down’ system, where Westminster can choose to give more power away, or not. Federalism is a partnership of equals. This can be described as ‘dual sovereignty’.

•The US states use the Supreme Court to challenge the authority of the federal government. This power does not exist for the UK nations.

Structural: devolution is a new part of the UK constitution. It is designed to recognise national differences and can still be seen as a ‘work in progress’. Federalism is a central aspect of the codified and rigid US codified Constitution – a way to disperse power widely and prevent dictatorship. 

Cultural: liberalism is the ideological inspiration behind the US Constitution. Its aim is to avoid tyranny, which is why federalism is so entrenched. 

Rational: leaders in devolved or federal governments compete, as rational actors, with leaders of the central government to achieve their goals, e.g. in relation to Covid-19 or, in the UK, to Brexit. 

The structural constitutional differences between the USA and the UK reflect cultural differences between the two nations as they developed. One way to understand the differences might be to say that the US Constitution was written to protect the rights of the governed while the UK Constitution evolved to protect the powers of the government. Although the right of the governed meant white men.

Checks and balances were the means by which the rights and freedoms of white men would be protected. They would limit the power of government. The end result is division of power and the creation of llimited government. The price the founders were wiling to pay was weak ederal government and the necessity to compromise if grid lock was to be avoided.

Under the UK Constitution, things are quite different. The prime minister  dominates the legislative agenda and leads a party which dominates ( most of the time) parliament. The price we pay is the likelyhood of ' elective dictatorship' and government that is careless of the rights of citizens.

Rational comaparisons are useful in understanding constitutional reforms or the lack of reforms. The failure to reform the Electoral College, or do something about gerrymandering refects the self interest of parties or politicians. Persistance with First Past the Post or Lords reform may also be seen as accepatnce by the main parties of constitutional arrangements which suit thier interests. The Conservatives and Labour both expect to govern alone and unhindered by the second chamber of Parliament.