What is judicial review, explained
Not an appeal against a decision, but a challenge to how it was made - how judicial review holds public bodies to the limits of their own powers.
Judicial review is one of the more misunderstood corners of English law, largely because of what it is not. It is not a mechanism for re-arguing whether a decision was right or fair on the merits - that is what an appeal does, where one exists. Judicial review instead asks a narrower question: was the decision lawfully made?
The claimant - the person or organisation bringing the challenge - must show “sufficient interest” in the matter, and can challenge decisions of central government departments, regulators, local authorities, and other bodies exercising a public function. Private decisions by purely commercial bodies generally fall outside its scope.
Claims are heard in the Administrative Court, part of the King’s Bench Division of the High Court, and must generally be brought “promptly” and in any event within three months of the decision being challenged - considerably shorter than most ordinary civil limitation periods, and in some categories of case, such as planning, shorter still, at six weeks.
The grounds a claimant can rely on are well established rather than open-ended: illegality (the decision-maker acted beyond its legal powers, or misunderstood the law), procedural unfairness (a fair process was not followed - for instance a failure to consult, or to give someone a chance to respond), irrationality or unreasonableness (a decision so unreasonable no sensible decision-maker could have reached it, sometimes still referred to by the older label “Wednesbury unreasonableness”), and breach of the Human Rights Act 1998.
If a challenge succeeds, the court does not usually substitute its own decision for the one it has quashed. More often it sends the matter back to the original decision-maker to be reconsidered properly - a reminder that judicial review polices the process of public decision-making, not its outcome.