In the UK Judicial Review is more modest. It allows the Courts to review decisions made by public bodies (the Courts will consider not the form of the person or body taking the decision, but whether the powers exercised are of a sufficiently public nature.) They cannot strike down decisions made by Parliament (particularly Laws passed! - a principle deriving from the doctrine of Parliamentary Sovereignty).
The "GCHQ case" gave up the "Diplock Criteria" - a threefold classification of grounds for Judicial Review.
- Procedural Impropriety
it is important to remember that the Courts often attach labels to the most frequent types of decision which can be challenged - so look for for (in textbooks; and in law reports) such as -
"ultra vires"; "irrelevant considerations"; "improper purpose"; "error of law"; "unauthorised delegation"; "fettering discretion"; "failure to perform a statutory duty"; "breach of natural justice"; "the rule against bias"; "the right to a fair hearing"...