Five Judgments That Frame the 2026 Constitution — and What They Actually Decide
Photo: This image was produced by me, David Castor (user:dcastor). The pictures I submit to the Wikipedia Project are released to the public domain. This gives you the right to use them in any way you like, without any kind of notification. This said, I w
Constitutional cases are often used as political shorthand. A minister mentions Anisminic; an opposition lawyer cites Miller; a campaign group invokes UNISON. The references are usually sincere but rarely precise. That matters, because the authority of a judgment depends on what it actually decided, not on the use to which it has been put. These five cases frame many of the arguments now being had about judicial review, executive power and parliamentary sovereignty. Each is worth reading before it is next cited.
1. Entick v Carrington (1765): the executive needs legal authority
The facts. King's messengers entered John Entick's house under a general warrant issued by the Secretary of State and seized his papers. The warrant did not specify the person or the papers. Entick sued in trespass.
The ruling. The Court of Common Pleas held that the entry and seizure were unlawful. The executive could point to no statute or common law authority for the general warrant. The principle was stated plainly: if the executive acts without legal authority, it acts unlawfully, however good its motives.
The lesson for 2026. Entick is the foundation of the legality principle. It is not a policy preference for small government. It is a rule about legal authority. When ministers claim an implied power, or when officials act on guidance rather than statute, the first question is always Entick's question: where is the legal authority? That is a legitimate judicial check, not a judicial veto on policy.
2. Anisminic v Foreign Compensation Commission (1969): the ouster clause that did not oust
The facts. The Foreign Compensation Commission rejected a claim on grounds that were later said to have misconstrued the relevant nationality provisions. The statute provided that the Commission's determinations 'shall not be called in question in any court of law'.
The ruling. The House of Lords held that the Commission had made an error of law that went to its jurisdiction, so its decision was a nullity. The ouster clause did not protect a decision that was, in law, no decision at all.
The lesson for 2026. Anisminic is often cited for the proposition that ouster clauses never work. That is too strong. It is better read as a warning: if Parliament wants to restrict judicial review, it must do so clearly and with attention to constitutional consequences. The case explains why modern ouster clauses are drafted with such care — and why courts scrutinise them so closely. It is a case about statutory interpretation, not judicial hostility to Parliament.
3. R (Miller) v Secretary of State for Exiting the European Union (2017): prerogative cannot change domestic law
The facts. After the 2016 referendum, the Government argued that it could use the royal prerogative to notify the European Union of the United Kingdom's intention to withdraw under Article 50. The claimants argued that an Act of Parliament was required.
The ruling. The Supreme Court held that the prerogative could not be used to remove rights or alter domestic law. Notification would change the domestic legal landscape, so Parliament had to authorise it. The Court was not deciding whether Brexit was a good idea. It was deciding who had the legal power to start the process.
The lesson for 2026. Miller is a parliamentary sovereignty case. It says that the executive cannot bypass Parliament when it proposes to change domestic law. That is a conservative proposition as much as a liberal one. In 2026, the same logic applies to the use of prerogative powers in treaty-making, sanctions and other areas where ministers may be tempted to act first and legislate later.
4. R (Miller) v The Prime Minister (2019): prorogation is justiciable
The facts. The Prime Minister advised the monarch to prorogue Parliament for five weeks in the run-up to Brexit. The Supreme Court was asked whether the advice was lawful.
The ruling. The Court held that the prorogation was unlawful. It frustrated Parliament's ability to perform its constitutional functions without reasonable justification. The advice to the monarch was justiciable, and the prorogation was void.
The lesson for 2026. This is the most politically contested case on the list, and it deserves to be read closely. The Court did not say that prorogation is always unlawful, or that judges should decide political questions. It said that the prerogative power to prorogue is limited by the constitutional principle that Parliament must be able to sit and legislate. That is a narrow holding with broad implications. It is a legitimate judicial check on the scope of a prerogative power, not a general licence for courts to review political tactics.
5. R (UNISON) v Lord Chancellor (2017): fees must not block access to justice
The facts. The Lord Chancellor introduced fees for employment tribunal claims. UNISON argued that the fees made it practically impossible for many workers to bring claims.
The ruling. The Supreme Court held that the fees were unlawful. The constitutional right of access to justice meant that fees could not be set at a level that effectively prevented people from enforcing their rights. The order was ultra vires.
The lesson for 2026. UNISON does not say that all court and tribunal fees are unlawful. It says that fees must not operate as a practical barrier to justice. That distinction matters as ministers look for savings in the courts and tribunals system. A policy disagreement about fee levels is not the same as a constitutional objection. But a fee regime that prices people out of the system is a constitutional problem, and the courts will say so.
Reading cases before citing them
The common thread is not judicial activism. It is legal reasoning. Entick asks whether the executive has authority. Anisminic asks what Parliament meant by an ouster clause. Miller asks who can change domestic law. The second Miller asks what limits the prerogative. UNISON asks whether access to justice has been rendered illusory. Each case separates a legitimate constitutional check from a policy disagreement. That is a distinction worth preserving in 2026, when constitutional arguments are likely to be noisy and the temptation to cite a judgment as a slogan will be strong.
