By Dora Robinson
Research Assistant, Constitutional Law Matters; PhD candidate, University of Cambridge

Parliament can make law on any subject and can change or overturn any earlier Acts of Parliament. Laws made by Parliament (called Acts of Parliament) trump all other types of law such as regulations or decisions made by courts. This is because the Westminster Parliament is sovereign. Constitutional lawyers call this ‘parliamentary sovereignty’. People who support parliamentary sovereignty believe that it upholds democracy and gives the final say to the people of the UK who elected the Members of Parliament.

What is Parliamentary Sovereignty? 

In the United Kingdom, we do not have a single written document that sets out the rules for what our government can and can’t do. This type of document is called a ‘codified constitution’ and most other countries in the world have one – the most famous of which is probably the American Constitution. Instead, we have a collection of different documents and principles that set out the rules for government. Parliamentary sovereignty is one of these principles. Because it is not written down in a codified constitution, people disagree about both whether Parliamentary sovereignty exists and whether it should exist.

Parliamentary sovereignty means that Parliament has the final say on all the law in the country. This means two things: (1) Parliament can make law that says anything at all, and (2) that the law that Parliament makes, called Acts of Parliament, is the highest law above all other law.

(1) Parliament can make any law

Parliamentary sovereignty means that Parliament has the power to make law on any topic, and can change any law it likes. Even if it means changing the basic rules about how the country works. So, if it wanted, it could give children the right to vote. Or take away the right to vote from everybody and make the UK a dictatorship.

(2) Acts of Parliament are the highest law

When a court decides whether something is legal or not, it must always apply Acts of Parliament. Courts don’t have any say about this. If there is any other law that conflicts with an Act of Parliament, it is invalid, which means that it is no longer law. This invalid law might be law made by judges in court judgments, law made by government departments such as regulations (for example the regulations governing ‘lockdown’), law made by the Scottish, Welsh or Northern Irish parliaments or even law made by the UK Parliament earlier on.

For example, if an Act of Parliament in 2020 said that everyone had to wear a pink mask when going into a shop, and in 2021 there was an Act of Parliament that said everyone had to wear a green mask when going into a shop, the law today would be that we all have to wear a green mask when we go into a shop.

How is this different from other systems of government?

Parliamentary sovereignty means that it is Parliament who has the final say on law, including law about how government works. Some countries write all their rules about government down in one place (a ‘codified constitution’), it is a written legal document interpreted by a special court that has the final say. For example, there are parts of Germany’s constitution, called the Basic Law, that cannot be changed by anybody in any situation. These guarantee human rights and democracy and were brought in after the defeat of the Nazis and Hitler. If there is any disagreement about Germany’s Basic Law, it is their ‘Constitutional Court’ that has the final say, not the German Parliament.

Is the UK Parliament really sovereign?

Parliamentary sovereignty means that Parliament has the final say about what the law is in the UK, and how the country works. In reality, there are several challenges to this and people disagree on whether it really is always Parliament that has the power, or if sometimes it is (1) the government, (2) the courts, (3) international bodies, or (4) the Welsh, Scottish and Northern Irish parliaments.

The Government

Some people believe that it is really the government, not Parliament, that has the final say about what the law is in the UK. This is because it has a lot of power and control over Parliament and Parliament’s law-making process.

Firstly, it is normally the government, not Parliament, who decides what Acts of Parliament will be made. Government decides what they will be about and what they will say. Secondly, the government has control over how Parliament spends most of its time. And thirdly, the government usually has control of over 50% of the MPs in the House of Commons, because of our system of electing governments. When it comes to making law, these MPs will vote the way that the government wants them to, either through choice, or because they have been told to do so by party disciplinary officers called ‘whips’. (This is a little bit different in the House of Lords.) So even though the highest law in the country is called Acts of Parliament, most of the time, some people believe they are really made by the government.

The Courts

There are two related ways in which courts may limit the final say that Parliament has about law in the UK. The first is through the ‘interpretation’ of law made by Parliament. Sometimes, judges in court cases must decide what an Act of Parliament actually means – and there are a few things they must think about. The first one is thinking about what Parliament intended when making the law. But the intention of Parliament is a complicated thing. A second thing courts normally do is make sure that Acts of Parliament are in line with the most important principles of the constitution such as the rule of law and rights protected by the common law. And a third thing they must do is choose the interpretation of an Act of Parliament that means that it is in line with human rights protected by the European Convention on Human Rights, as far as it is possible to do so (see the Human Rights Act 1998). So, a court’s interpretation of an Act of Parliament may be different from some of the intentions within Parliament.

The second way that courts might limit Parliament’s final say is if, as some people argue, there are special Acts of Parliament which do bind later Parliaments – unless that later Parliament explicitly states otherwise. We call these ‘constitutional’ Acts of Parliament. One example is the Act of Parliament that made EU law supreme over UK law (called the European Communities Act 1972). If there was a conflict between an earlier constitutional Act of Parliament and a later normal Act of Parliament and Parliament had not explicitly said that special one should be ignored or replaced, then a court might choose to prioritise the earlier constitutional Act of Parliament.

International Bodies

Parliamentary sovereignty means that Parliament can make any law it wants. But does this include law that goes against a promise that the UK has made to other countries? This could include rules that come from being part of the European Union, part of the European Court of Human Rights, or just normal treaties between countries about all sorts of things from trade, the environment to weapons. The idea that being part of the EU meant that the UK Parliament couldn’t make any law it wanted was one reason why some people wanted to leave the EU.

Normally this isn’t a problem because Parliament does not usually want to break international law. Occasionally though, Parliament has chosen to go against international law. In 2011, Parliament refused to give the right to vote to prisoners after the European Court of Human Rights said that the UK’s blanket ban was illegal. And more recently, in 2020, the government asked Parliament to make law (in the UK Internal Market Bill) that would have enabled the Government to break international law set out in a part of the Brexit withdrawal treaty with the EU. This provision was later removed and is not included in the UK Internal Market Act 2020.

Other Parliaments in the United Kingdom

It is only the UK Parliament (the Westminster Parliament) that is sovereign. The Scottish Parliament, Welsh Parliament and the Northern Irish Assembly only have the power to make law when it has been granted to them by the Westminster Parliament. The Westminster Parliament can also still make laws for the UK even when it has given the power to make law on that topic to Scotland, Wales or Northern Ireland. It normally first seeks their consent – although this is not always the case and there is no legal duty to do so.

Is Parliamentary sovereignty a good thing? Should Parliament be sovereign?


  • MPs should have the final say about what the law should be, because they are elected and represent the will of the people. This protects democracy.
  • There are still limits on what laws Parliament would make. It’s just they are political and moral rather than legal. If MPs voted, for example, to take away the right to vote from people under six-foot, public opinion would be against them and they would not get re-elected.
  • Parliamentary sovereignty means that it is much easier to change the law to keep up to date with a changing world. Otherwise, the highest law of the country would become out of date, like the US Constitution from 1787.
  • Parliaments make better law than governments or courts because there is a whole process of examining and debating the Act of Parliament in both the House of Commons and the House of Lords.


  • In practice, it doesn’t represent the will of the people because Parliament is controlled by the government. Instead, it just gives the government too much power.
  • There should be limits on what laws Parliament can make to protect the rights of the people. Parliament is elected by a majority of voters and so MPs might not care about protecting the rights of people who do not affect their election – such as minorities or people without the right to vote like children or asylum seekers.
  • A written constitution can still be changed, when necessary, but it is just a bit harder than changing normal law to make sure that people are protected from the impulses of powerful governments.
  • In practice, MPs do not have the time, expertise, knowledge or independence to properly examine and criticise all Acts of Parliament. Some people think this was a particular problem with some of the law about Covid-19 lockdowns and other restrictions.