ABSTRACT
With the procedural aspects of judicial review proceedings in mind, attention can now be turned to the grounds on which judicial review may be sought. Two principal classes of action may be pursued: those which allege that there has been a breach of statutory requirements, and those alleging that a decision has been reached in an unreasonable manner or in disregard of the rules of natural justice. These broad headings have traditionally been divided into a number of subheadings. In Council of Civil Service Unions v Minister of State for Civil Service (1985) (the GCHQ case), the House of Lords took the opportunity to offer a rationalisation of the grounds for judicial review and ruled that the bases for judicial review could be subsumed under three principal heads, namely, illegality, irrationality and procedural impropriety. It was accepted that further grounds for review, such as ‘proportionality’ might emerge. Lord Diplock elucidated the concepts:
By ‘illegality’ as a ground for judicial review, I mean that the decision maker must understand correctly the law that regulates his decision making power and give effect to it. Whether he had or not is par excellence a justiciable question to be decided, in the event of dispute, by those persons, the judges, by whom the judicial power of the State is exercisable.
