Understanding Parliamentary Supremacy in the UK

If a country has no single written constitution, what stops its lawmakers from doing whatever they please? In the United Kingdom, the answer is surprisingly direct: nothing, at least in legal terms. This idea sits at the heart of the British constitutional system and is known as Parliamentary Supremacy, or Parliamentary Sovereignty. It holds that Parliament is the highest source of law in the land, capable of making or unmaking any law it wishes, with no court or authority able to overrule it. Understanding this principle is essential for anyone studying comparative politics, because it offers a sharp contrast to systems built around a supreme written constitution, including our own.

What parliamentary supremacy actually means 🔗

The classic definition comes from the nineteenth-century jurist A.V. Dicey. He described parliamentary sovereignty as the right to make or unmake any law whatever, with no person or body recognised as having the authority to override or set aside legislation. In plain terms, the UK Parliament has unlimited legal power to legislate, and once it has spoken, that is the final word in law.

It is worth being precise about what “Parliament” means here. In the UK, the supreme law-maker is the combination of the House of Commons, the House of Lords, and the Crown, often called the “Queen-in-Parliament” or “King-in-Parliament”. A law becomes valid only after both Houses pass it and the monarch grants Royal Assent. While Royal Assent is today a formality that has not been refused since the early eighteenth century, it remains a formal stage in turning a bill into an Act.

One distinction matters a great deal. Parliamentary supremacy is a statement of legal power, not political reality. Legally, Parliament can pass almost anything. Politically, a government would never survive passing laws that voters and institutions find outrageous. As one widely cited illustration puts it, a statute ordering the killing of all blue-eyed babies would still be legally valid, even though no Parliament would ever dream of enacting it. The point is to show how far legal authority stretches in theory, not what happens in practice.

Where the doctrine came from 🔗

Parliamentary supremacy was not designed in a single moment. It grew out of centuries of conflict between the monarchy and Parliament. In medieval England, kings ruled with the help of a royal council, which slowly evolved into Parliament as it gained control over taxation and law-making. The decisive turning point came in the seventeenth century.

The Glorious Revolution and the Bill of Rights 🔗

The struggle came to a head in 1688 with the Glorious Revolution, when Parliament helped depose King James II and invited William of Orange and Mary to take the throne jointly. The following year, the Bill of Rights 1689 firmly established the principles of frequent parliaments, free elections, and freedom of speech within Parliament. Crucially, it also prevented the monarch from suspending laws or raising taxes without Parliament’s consent.

This was the institutional moment when Parliament won supremacy over the monarch, the church, and the courts. After the Civil War and the Glorious Revolution, the Bill of Rights 1689 recorded Parliament’s new position at the top of the constitutional order. From then on, the monarch could govern only with Parliament’s consent, and the modern doctrine took shape.

The key features of parliamentary supremacy 🔗

Dicey’s account is usually broken down into three connected principles. Together they explain why the doctrine is so powerful and so distinctive.

1. Parliament can legislate on any subject 🔗

The first principle is that Parliament is the supreme law-making body and can pass laws on any matter it chooses. There is no subject area placed beyond its reach. It can create new laws, amend existing ones, or repeal old ones entirely. This unlimited competence is what makes the UK Parliament so different from legislatures that operate under a written constitution which fences off certain rights or powers.

2. No law is higher than an Act of Parliament 🔗

The second principle is that all Acts of Parliament have equal legal status, and no special category of “constitutional” law sits above ordinary law. The House of Commons Library notes that there is no special process for constitutional law-making in the UK, that all Acts are equal in status, and that newer Acts take precedence over older ones in cases of conflict. This contrasts sharply with countries that have codified constitutions, where amending the constitution demands a special, more demanding procedure and where judges can strike down ordinary laws that clash with it.

This feature is closely tied to the doctrine of implied repeal. If a newer Act conflicts with an older one and does not expressly repeal it, courts treat the earlier law as automatically overridden to the extent of the conflict. Cases such as Vauxhall Estates v Liverpool Corporation (1932) and Ellen Street Estates v Minister of Health (1934) established this rule. The practical consequence is that no legislation can be entrenched, meaning no law can be protected from future change.

3. No Parliament can bind its successors 🔗

The third principle follows naturally from the second. Because every Parliament must be supreme in its own time, no Parliament can pass a law that ties the hands of a future one, and no Parliament is bound by laws of the past. As one legal guide explains, where a later Act conflicts with an earlier one, the later statute is considered to have repealed the earlier one by implication, to the extent of the conflict.

This raises a famous puzzle. If Parliament is all-powerful, why can it not use that power to limit itself permanently? Scholars distinguish between “continuing” sovereignty and “self-embracing” sovereignty. Under the orthodox view defended by Sir William Wade, the UK Parliament has continuing sovereignty, which means it cannot destroy or restrict its own future power. The freedom to change any law is permanent precisely because it cannot be given away.

No judicial review of legislation 🔗

A defining consequence of all this is that British courts cannot strike down an Act of Parliament. In countries with a supreme written constitution, courts can declare a law unconstitutional and void. In India, for instance, the Supreme Court regularly tests laws against fundamental rights and can invalidate them. The UK works differently. Once both Houses pass a bill and Royal Assent is given, Acts of Parliament are not subject to judicial review, and no legislation is entrenched.

This does not mean judges are powerless. They interpret statutes, develop common law, and review the actions of the executive. But interpreting and applying a law is very different from declaring it invalid. The courts accept whatever Parliament enacts as law, which is exactly why the constitutional theorist Sir Ivor Jennings argued that supremacy is really a description of the relationship between Parliament and the courts.

Why this makes Parliament the voice of the people 🔗

At first glance, unlimited legal power for a legislature might sound dangerous. The justification rests on democratic accountability. Parliament, especially the elected House of Commons, represents the people. If the supreme law-maker is the body chosen by voters, then law-making power ultimately flows from the electorate. Sovereignty in the courts and the constitution is exercised, in theory, on behalf of the citizens who elect their representatives.

This is why the doctrine is often presented as a democratic safeguard rather than a threat. There is no unelected court or fixed document with the final say over elected lawmakers. If people dislike a law, they can vote out the government that passed it, and a new Parliament can repeal it. Power stays with the representatives of the people rather than being locked away in a document that is difficult to change.

Modern pressures on the doctrine 🔗

The orthodox theory has faced real challenges, and a good comparative politics answer should acknowledge them. Several developments have tested how absolute parliamentary supremacy really is.

European Union membership and the Factortame case 🔗

During the UK’s time in the European Union, EU law took priority in areas of EU competence. In the landmark Factortame litigation, the House of Lords disapplied provisions of the Merchant Shipping Act 1988 that conflicted with EU law, the first time an Act had been set aside in this way. Defenders of orthodoxy argued this was not a true loss of sovereignty, since Parliament had voluntarily accepted EU law through the European Communities Act 1972 and could repeal it at any time, which it eventually did through Brexit.

The Human Rights Act and devolution 🔗

The Human Rights Act 1998 allows courts to issue a “declaration of incompatibility” when a law clashes with rights protected under the European Convention. Importantly, such a declaration does not invalidate the law. It simply signals to Parliament that the law sits uneasily with those rights, leaving the final decision to amend it with Parliament itself. Devolution to Scotland, Wales, and Northern Ireland has also redistributed power in practice, though Westminster technically retains the right to legislate for the whole UK.

Even where courts have intervened, they have tended to reaffirm rather than overturn the doctrine. In the high-profile Miller case concerning Brexit, the Supreme Court placed parliamentary sovereignty at the centre of its reasoning, with analysts noting the judgment offered a strong restatement of the principle in the Dicey tradition. The doctrine has evolved, but it remains a core feature of the British constitution.

Why it matters for comparative politics 🔗

Studying parliamentary supremacy sharpens your understanding of how constitutions distribute power. The British model places ultimate authority in an elected legislature with no written constitution restraining it. Many other democracies, including India, do the opposite, making a written constitution supreme and giving courts the power to enforce it against the legislature. Comparing these two approaches reveals a deep question that every democracy must answer: should the final word belong to elected representatives, or to a fixed constitution interpreted by judges? Neither answer is obviously correct, and that tension is exactly what makes the comparison so valuable.

What do you think? Is a system where elected lawmakers have unlimited legal power more democratic than one where a written constitution and courts can overrule them? And if Parliament can theoretically pass any law at all, what really stops it from abusing that power?

References

1. https://publications.parliament.uk/pa/ld5801/ldselect/ldconst/151/15110.htm
2. https://publiclawforeveryone.com/2014/10/15/1000-words-parliamentary-sovereignty/
3. https://www.parliament.uk/about/living-heritage/evolutionofparliament/parliamentaryauthority/revolution/collections1/collections-glorious-revolution/billofrights/
4. https://en.wikipedia.org/wiki/United_Kingdom_constitutional_law
5. https://commonslibrary.parliament.uk/research-briefings/cbp-10377/
6. https://lawexplores.com/parliamentary-sovereignty/
7. https://www.lexisnexis.co.uk/legal/guidance/parliamentary-supremacy-implied-repeal
8. https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100307357
9. https://lawprof.co/definition/parliamentary-sovereignty/
10. https://www.modernlawreview.co.uk/wp-content/uploads/2019/03/Ewing-2017-The_Modern_Law_Review.pdf