Judicial Review In the United Kingdom

Introduction

Judicial review refers to the legal challenge by which a judge reviews the lawfulness of a decision made by a public body. It examines the process by which a decision was made, rather than the merits of the decision itself. It is generally used only when no other means of resolving the dispute is available.

A claim for judicial review can be brought by an individual, party, or organization that has been directly affected by a public body’s decision, provided they satisfy the conditions required to bring such a claim. The process follows a strict procedure and must satisfy specific grounds before a decision can be made. Where a decision is found to be unlawful, a remedy may be granted to those affected.

Main Body

Before a claim can proceed, it must satisfy the Pre-Action Protocol, under which the claim is first submitted to the public body to determine whether the matter can be resolved without going to court. This is usually done by way of a letter before claim. Other means of resolving the dispute include Alternative Dispute Resolution, or ADR. Where a claim does proceed to court, it must be made promptly, and in any event no later than three months after the decision was made. The court must also be satisfied that the claimant has sufficient interest, or locus standi, in the claim, as required by section 31(3) of the Senior Courts Act 1981.

Once these procedural requirements are satisfied, the court considers the substantive grounds for judicial review. There are three main grounds — illegality, irrationality, and procedural impropriety — all of which were set out by Lord Diplock in Council of Civil Service Unions v The Minister for the Civil Service [1985] or the “GCHQ case.”¹

In that case, employees of the Government Communications Headquarters (GCHQ) were banned from joining trade unions as a precaution against a perceived threat to national security, a ban enforced by an Order in Council. Affected employees brought a claim for judicial review, which proceeded all the way to the House of Lords. The five-judge bench held that the ban was valid because it concerned national security; however, the case is best remembered for reshaping how the courts approach the review of prerogative power and its subjection to judicial review.

Lord Diplock identified the three grounds of judicial review as:

• Illegality, where the public body must make a decision within its powers and in accordance with the law.
• Irrationality, where the decision must make rational sense. Also called “Wednesbury unreasonableness.”
• Procedural impropriety, where the decision-maker must act fairly toward the person or persons affected by the decision.

To determine which ground is most applicable to a given claim, the various aspects of each are considered in turn.

Illegality

A claim falling under the ground of illegality may involve a misuse of power, such as a public body basing its decision on irrelevant considerations, or failing to take relevant ones into account. Another key issue is whether the decision fell within the public body’s area of legal authority, or whether it was taken ultra vires — beyond its powers.

Irrationality

The ground of irrationality asks whether a decision makes rational sense. Lord Diplock described it as a decision so unreasonable that no sensible person could have arrived at it, a principle originating from Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948].² In practice, this is a difficult ground to satisfy, as it requires a decision so extreme that no reasonable decision-maker could have reached the same conclusion.

Procedural Impropriety

Procedural impropriety focuses on the fairness of the process by which a public authority’s decision was made. It considers, among other things, the absence of bias — the principle of nemo judex in causa sua — under which a judge or decision-maker with a personal interest in the outcome must be disqualified from influencing it. A related principle is audi alteram partem, or the right to a fair hearing, which is also reflected in Article 6 of the European Convention on Human Rights.

Remedies

When the court finds a decision or action made by a public authority to be unlawful, it may grant a remedy to those affected. These include:

• A mandatory order, which compels the public authority to act in a particular way.
• A quashing order, which quashes or nullifies the decision or action made by the public body. Once a decision has been quashed, it can be sent back to the original decision-maker so that a new decision may be made.
• A prohibiting order, which prevents the public body from making a decision or taking an action it had intended to take.
• A declaration, in which the court restates the law and its application to the decision. Unlike the three remedies above, a declaration does not carry the same binding effect; while public bodies are not compelled to follow it, they are expected to comply with the law as stated by the court.
• Damages, which may be awarded to the applicant where the court is satisfied as to the cause of action, though not all cases will result in an award of damages.
• An injunction, which is a court order compelling a public body to act, or refrain from acting, in a particular way.

Conclusion

Judicial review is the legal challenge to a decision or action taken by a public body. It does not change the decision itself, but examines the process by which the decision was made. A claim for judicial review is brought by the applicant, or the person affected by the decision, who may be an individual, a party, or an organization. The claim must satisfy at least one ground when reviewed by the court. These grounds — illegality, irrationality, and procedural impropriety — were described by Lord Diplock in the GCHQ case [1985]. Once the court is satisfied, it may issue remedies in the form of a mandatory order, quashing order, injunction, or damages, among others. It is important to note that judicial review is a remedy of last resort: a claim can only be made where no other means of resolution is available, or where all other means have already been exhausted.

Reference(S):

Cases

Council of Civil Service Unions v The Minister for the Civil Service [1985] AC 374.

Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948] 1 KB 223.

Legislation

Senior Courts Act 1981.

Secondary Sources

British Institute of Human Rights, ‘What is Judicial Review?’ [insert URL] accessed 9 July 2026.

Courts and Tribunals Judiciary, ‘Judicial Review’ (Judiciary, 2026) [insert URL] accessed 9 July 2026.

Lexis+, ‘Judicial review – overview’ (LexisNexis, 2026) [insert URL] accessed 9 July 2026.

Public Law Project, ‘Remedies in judicial review’ (Public Law Project, 2006) [insert URL] accessed 9 July 2026.

Pre-Action Protocol for Judicial Review.