CCSU v Minister for the Civil Service (GCHQ), [1985] A.C. 374

Quick Summary

This is the famous “GCHQ case.” The government changed civil service terms using the royal prerogative and stopped union activity. The union said this was unfair because there was a past practice of consultation. The House of Lords said: prerogative decisions can be reviewed. Fairness matters, but real national security can limit consultation. The court kept the change but set clear limits on prerogative power.

Issues

• Are prerogative decisions about employment terms open to judicial review?
• Is procedural fairness (consultation) needed when terms change via prerogative?
• Can national security justify skipping consultation with trade unions?

Rules

• Prerogative decisions are reviewable when they affect rights or legitimate expectations.
• Review grounds: illegality, irrationality, and procedural impropriety (Lord Diplock).
• National security does not grant automatic immunity; the government must show a real risk.

Facts (Timeline)

Arguments

Judgment

The House of Lords confirmed that prerogative decisions can be reviewed on modern public law grounds. The court accepted that fairness normally required consultation but held that proven national security concerns could override it. The union’s legitimate expectation existed, yet in this case the security justification prevailed, so the measure stood.

Ratio

• Nature of power does not block review; its subject matter and effects invite review.
• Three grounds: illegality, irrationality, procedural impropriety.
• National security can limit procedure, but needs real, evidenced risk.

Why It Matters

This case modernised control of prerogative powers. It balanced two values: fair treatment of people affected by government action, and real security needs. Today, it anchors how courts check executive action while respecting sensitive matters.

Key Takeaways

• Prerogative is not a “no-review zone.”
• Legitimate expectation arises from consistent past practice.
• Security claims need substance, not slogans.
• Fairness can bend, but only for good reason.

Mnemonic + 3-Step Hook

Mnemonic: “P-I-P with S” — Prerogative reviewable • Illegality • Procedural impropriety (and irrationality) • with Security limits.

1. Spot a prerogative action affecting people.
2. Check Diplock’s trio: illegality, irrationality, procedure.
3. Test any security claim: is the risk real and shown?

IRAC Outline

Glossary

Royal Prerogative

Executive power based on tradition and common law, not statute.

Legitimate Expectation

A fair expectation created by government practice or promise.

Procedural Impropriety

Failure to follow fair process or required procedures.

Irrationality

A decision so unreasonable that no sensible body would make it.

FAQs

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