Council of Civil Service Unions v Minister for Civil Service (GCHQ Case)

• GCHQ employees had historically been consulted on changes to employment conditions
• PM (Minister for Civil Service) issued instruction banning trade union membership at GCHQ citing national security
• No prior consultation with trade unions: departure from established practice
• Unions challenged on grounds that prerogative power is not reviewable and that legitimate expectation of consultation was defeated

1. Is a prerogative power subject to judicial review?
2. What are the grounds on which administrative decisions may be judicially reviewed?
3. Did the workers have a legitimate expectation of prior consultation?

• Prerogative powers ARE subject to judicial review: the source of power (statute vs. prerogative) is irrelevant; what matters is the nature of the power
• Lord Diplock classified grounds of review: (a) Illegality: authority misunderstood the law governing the decision; (b) Irrationality: decision so outrageous in defiance of logic that no sensible person could have arrived at it; (c) Procedural impropriety: failure to comply with procedural rules or common law fairness
• Employees had legitimate expectation of consultation (based on established practice)
• BUT national security overrode the expectation on the facts: government's security assessment not reviewable
• Challenge failed on merits but legal principles established are landmark

Judicial review examines all exercises of public power regardless of source (statutory or prerogative). The three grounds provide a comprehensive framework: (1) Illegality: the decision-maker must understand the law governing the decision and act within it; (2) Irrationality (Wednesbury unreasonableness): a decision so outrageous that no sensible person could have arrived at it; (3) Procedural impropriety: failure to comply with procedural rules or common law fairness. Legitimate expectation (from past practice or promise) creates procedural right to consultation before change; however, overriding considerations (national security) can defeat the expectation.