Parliament Is Sovereign—So Why Does It So Often Appear Powerless?

Britain is regularly described as a sovereign country governed by a sovereign Parliament. Yet whenever a government proposes something difficult—controlling the border, developing domestic energy, deporting a foreign criminal or changing an inherited policy—we are increasingly told that it cannot be done. International law will not permit it. A treaty prevents it. Human-rights obligations stand in the way. The courts would intervene.

Both statements cannot be accepted without examination. If Parliament is sovereign, why does it so often appear unable to govern?

The short legal answer is that Parliament remains sovereign. It can make or repeal any law, and the courts cannot strike down an Act of Parliament merely because they disagree with it. No Parliament can bind every Parliament that follows it.^[1]

The practical answer is more complicated. Governments enter treaties, Parliament incorporates obligations into domestic law, courts interpret those laws, administrative systems grow around them and international relationships come to depend upon them. What began as a voluntary commitment becomes progressively more expensive—legally, politically and diplomatically—to reverse.

The historian David Starkey has framed the problem more sharply: Britain’s difficulty is not simply that Parliament lacks legal authority, but that elected governments have surrendered or dispersed much of the practical machinery required to exercise it. His argument, presented at a Popular Conservatism fringe session during the 2025 Reform UK Conference, is that restoring democratic government requires institutional repeal and reconstruction, not merely a different collection of policies.^[2]

Sovereignty survives on paper. The freedom to use it becomes conditional.

What Parliamentary Sovereignty Actually Means

The traditional doctrine is admirably direct. Parliament is the supreme law-making authority. It can legislate on any subject. The courts apply its Acts. A present Parliament cannot prevent a future Parliament from changing its mind.^[1]

That does not mean government ministers may do whatever they please. Parliament is not the government. Ministers remain subject to legislation, judicial review and the ordinary law. Nor does sovereignty mean that every decision is wise, moral or free of consequences. It means that the final domestic legal authority rests with Parliament rather than with a superior constitutional court or an external legislature.

This distinction matters because the word “sovereignty” is often used carelessly. Critics sometimes treat it as a demand that Britain should ignore every promise it has made. Supporters sometimes imply that passing an Act eliminates every practical obstacle. Neither is correct.

A sovereign Parliament can choose to accept constraints. It may delegate power, create independent institutions, recognise rights and incorporate treaty obligations into domestic law. The important constitutional point is that these arrangements obtain their domestic authority from Parliament. In principle, Parliament can amend or repeal them.^[1]

The question is therefore not simply whether Parliament remains legally sovereign. It is whether the machinery through which Britain accepts international obligations provides sufficient democratic scrutiny before those obligations become difficult to escape.

International Law Does Not Usually Write Itself into British Law

The United Kingdom operates what lawyers call a dualist system. International law and domestic law occupy separate legal planes. A treaty entered into by the government binds the United Kingdom internationally, but it does not normally become enforceable in British courts unless Parliament gives it domestic effect.^[3]

This is an important protection. A minister cannot return from an international conference having quietly changed British law simply by signing an agreement. Where domestic rights and duties must change, Parliament generally has to legislate.

But the protection is less complete than it first appears. The negotiation and signature of treaties remain largely executive functions. By the time Parliament encounters an agreement, the text may be finished, other governments may have committed themselves and withdrawal may carry a heavy political price. A parliamentary committee examining treaty scrutiny concluded that the present arrangements give the government considerable power and often present Parliament with terms that are effectively already settled.^[4]

Under the Constitutional Reform and Governance Act 2010, most treaties must be laid before Parliament for 21 sitting days before ratification. The House of Commons may object, but this is not equivalent to the detailed amendment and repeated votes attached to ordinary primary legislation. Parliament can delay or block ratification in certain circumstances; it cannot normally rewrite a negotiated treaty line by line.^[5]

The constitutional sequence is therefore peculiar. The executive negotiates the obligation. Parliament is asked to accept or reject a largely completed package. Future governments inherit the consequences. The people may discover the practical meaning years later, when a policy they support is said to conflict with the commitment.

Legal Power and the Price of Using It

Suppose Parliament passes an Act that clearly conflicts with an earlier treaty obligation. As a matter of domestic law, the courts must apply the Act. The later statute prevails where Parliament has expressed itself clearly. Britain may then be in breach of international law, but the treaty does not ordinarily erase the Act.^[6]

That sounds decisive. It is—but only at the level of legal hierarchy.

At the international level, treaties are intended to be kept. The Vienna Convention on the Law of Treaties states that treaties in force are binding and must be performed in good faith. A state cannot normally rely upon its internal law as an excuse for failing to perform them.^[7] Breach may invite litigation, retaliation, suspension of cooperation, reputational damage or the loss of benefits obtained under the same agreement.

This is why ministers so often say that a policy “cannot” be pursued when what they really mean is that it cannot be pursued without changing domestic legislation, challenging an interpretation, renegotiating an obligation, accepting a dispute or withdrawing from an agreement.

Those are real costs. They should not be dismissed. A country that treats every promise as disposable will soon find that other countries attach little value to its promises. Trade, defence, extradition, aviation and financial markets depend upon reliable agreements.

But cost is not the same as impossibility. Politics becomes evasive when a choice is presented as an external command. If a government believes an obligation remains in the national interest, it should defend it. If it believes the cost of departure is greater than the benefit, it should explain that judgement. It should not pretend that democratic choice has ceased to exist.

The Human Rights Settlement

The Human Rights Act 1998 provides the clearest illustration. It brought rights contained in the European Convention on Human Rights (ECHR) into the work of British courts. Courts must interpret legislation compatibly with Convention rights so far as it is possible to do so. Public authorities generally may not act incompatibly with those rights.^[8]

Yet the Human Rights Act was deliberately constructed to preserve parliamentary sovereignty. A senior court may issue a declaration that primary legislation is incompatible with a Convention right, but it does not thereby invalidate the Act. Parliament remains responsible for deciding whether and how the law should change.^[9]

This is a more subtle constitutional arrangement than either side often admits. Those who say that foreign judges simply strike down Acts of Parliament misdescribe the domestic position. Those who say that the framework creates no meaningful constraint ignore its practical force.

A declaration of incompatibility carries political weight. Ministers and civil servants plan around anticipated legal challenge. Public bodies alter conduct. Parliament normally takes judicial findings seriously. Separately, while Britain remains party to the Convention, final judgments of the European Court of Human Rights in cases against the United Kingdom are binding in international law.^[10]

Once again, Parliament retains the ultimate legal capacity to act. It could amend the Human Rights Act, legislate expressly, seek reform of the Convention or withdraw from it. But every route carries consequences. The issue is not the disappearance of sovereignty. It is the accumulation of legal and political costs around its exercise.

Self-Binding Can Be Sensible

There are good reasons for governments to bind themselves. A treaty allows one country to rely upon another. Human-rights law protects individuals—including unpopular individuals—from arbitrary power. Independent courts prevent ministers from becoming judges in their own cause. Long-term commitments can stop each election from producing an abrupt reversal in defence, trade or environmental policy.

Investors understand the principle. Credible rules reduce uncertainty. Property rights, contractual enforcement and predictable regulation attract capital. A government that can confiscate, cancel or discriminate without restraint may be sovereign in the crudest sense, but it will not be trusted.

The case for restraint is therefore strong. The case for unexamined restraint is not.

The value of a constraint depends upon who created it, how clearly it was approved, whether its meaning has changed and whether a democratic route remains available to revise it. An agreement suitable for one set of circumstances may become damaging in another. Courts may develop interpretations not anticipated by the politicians who originally signed. A commitment presented as cooperation can become a substitute for political judgement.

Good constitutional government requires both stability and adaptability. If rules can be changed casually, they provide no protection. If they can never be reconsidered, democratic government becomes ceremonial.

The Ratchet Effect

International commitments tend to operate like a ratchet. Signing is celebrated as progress. Incorporation creates rights, procedures, agencies and professional interests. Judicial decisions add interpretation. Other agreements begin to refer to the first. Businesses and public bodies organise themselves around it. Reversal is then described not as a legitimate policy choice but as regression.

This does not require a conspiracy. Institutions naturally defend their remit. Lawyers advise against legal risk. Civil servants favour continuity. Ministers avoid diplomatic conflict. Campaigning organisations treat an established protection as a minimum from which policy may move only in one direction.

The result is an asymmetry. Joining a regime may receive limited public attention; leaving it is treated as a constitutional emergency. The formal sovereign power remains, but the threshold for using it rises with every year.

The same pattern can occur entirely within domestic law. Tony Blair’s government did not use an international treaty to prevent new maintained grammar schools. Parliament enacted the School Standards and Framework Act 1998, under which no new maintained grammar schools may generally be opened and existing schools cannot newly introduce academic selection.^[11] A later Parliament could reverse that policy. Yet a decision made by one government has endured for decades because institutional settlement creates inertia.

The grammar-school example is useful precisely because international law is absent. Not every constraint on present government has been imposed from abroad. Governments inherit domestic statutes, devolved settlements, judicial doctrine, regulatory bodies and political conventions as well as treaties. The deeper question is whether elected politicians are willing to accept responsibility for changing them.

David Starkey’s Challenge

Starkey’s argument about rights is more radical than the historical observation that British liberties developed gradually. Drawing upon Jeremy Bentham and Edmund Burke, he rejects the idea that rights exist effectively as abstract universal propositions detached from law, history and political community. In his account, rights acquire substance because particular institutions recognise, enforce and preserve them—not merely because an international declaration proclaims them.^[12]

His historical case traces British liberty through Magna Carta, the common law, Parliament, habeas corpus and the Bill of Rights. These were not handed down as a completed theory. They emerged through conflict, compromise and accumulated experience, and their authority became rooted in national institutions and political culture.^[12]

There is force in that argument. Rights survive not merely because they are written in a treaty but because institutions, political culture and the public believe in them. A constitution detached from the history and consent of the people it governs may command legal obedience without securing lasting legitimacy.

Starkey’s argument also helps explain why Britain’s contribution to the post-war European human-rights settlement was grounded in its own constitutional inheritance. International cooperation need not displace that inheritance; at its best, it can provide an additional safeguard, including for minorities, while drawing legitimacy from national institutions and traditions.

The better conclusion is that rights require democratic ownership. If people are told that important questions are beyond their authority, support for the institutions protecting those rights may weaken. A durable rights settlement must persuade the public that it protects their freedom without cancelling their vote.

Accountability Is the Missing Ingredient

The greatest danger is not international law itself. It is the diffusion of responsibility.

A minister blames a treaty. Parliament blames the courts. The courts apply legislation passed by Parliament. Officials follow guidance approved by ministers. The government says reform would damage an international relationship, while declining to state whether it actually wants reform. Everyone exercises some power; nobody accepts ownership of the outcome.

For the voter, this is maddening. Elections are presented as choices about policy, yet the winning government explains that many of the choices cannot be implemented. Over time, confidence in representative government declines. People conclude either that politicians are impotent or that elections are theatre.

Neither conclusion is healthy. If Parliament has authority, it must accept responsibility. If it chooses to preserve an international obligation, it should explain the benefit and defend the trade-off. If it wishes to change course, it should identify the legislation, treaty or institution involved and state honestly what renegotiation or withdrawal would cost.

The phrase “international law prevents us” should therefore be the beginning of an explanation, not the end of an argument.

A More Honest Sovereignty

Britain does not need to choose between isolation and submission. It needs a more honest account of sovereignty.

Parliament remains the supreme domestic legal authority. International law matters because Britain has agreed that it should matter. Many of those agreements serve the national interest and should be maintained. Some may require reform. A few may eventually impose costs that exceed their benefits.

The proper democratic questions are straightforward:

Who made the commitment? What did Parliament approve? How has its interpretation changed? What benefit does Britain receive? What would alteration or withdrawal cost? And, finally, who is accountable for deciding?

Sovereignty is not the freedom to act without consequences. No serious country possesses that freedom. Sovereignty is the authority to weigh those consequences and make the final choice.

If Parliament possesses that authority but is permanently unwilling to use it, the constitutional doctrine becomes less important than the political reality. Britain remains sovereign, yet learns to behave as though it is not.