CCSU v Minister for the Civil Service [1985] AC 374

Key points

  • The royal prerogative is subject to irrationality review; however, it is likely to be excluded due to the policy judgement involved
  • This case established the three traditional grounds of judicial review under common law: illegality, irrationality and procedural impropriety


  • Margaret Thatcher, holding the office of Minister for the Civil Service, decided that employees of the British Intelligence Agency (GCHQ) would not be permitted to join trade unions on the grounds of national security
  • Thatcher relied on the royal prerogative power to regulate the terms of service, issuing the new rule through an Order in Council
  • CCSU applied for judicial review of the decision
  • In the Court of Appeal, the appeal was dismissed on the grounds that it would be inappropriate for the courts to intervene on matters of national security 


  • Was the decision to exercise prerogative power justiciable by courts?
  • Was it lawful to prevent GCHQ employees from joining trade unions?

Held (House of Lords)

  • Appeal dismissed; while the decision was justiciable, it was reasonable to prevent British Intelligence employees from joining trade unions in the interests of national security 

Lord Diplock 

Justiciability of prerogative

  • To qualify as a subject for judicial review, a decision must affect a person either by:
    1. altering rights or obligations which are enforceable for or against him in private law; or
    2. depriving him of a benefit or advantage which he had i) previously had or ii) legitimately expected to have: p. 408
  • There is no reason why because a decision-making (prerogative) power is derived from a common law and not a statutory source, it should for that reason only be immune from judicial review: p. 410

Ground of judicial review

  • Judicial review of the executive is made on three separate grounds: “illegality,” “irrationality” and “procedural impropriety”: p. 415
  • The first ground of illegality is refers to ‘where the authority concerned has been guilty of an error of law in its action as for example purporting to exercise a power which in law it does not possess’: p. 414
  • The second ground of irrationality refers to ‘where it exercises a power in so unreasonable a manner that the exercise becomes open to review upon what are called, in lawyers’ shorthand, Wednesbury principles’: p. 414
  • The third ground of procedural impropriety refers to ‘where it has acted contrary to what are often called “principles of natural justice.”‘: p. 414

Current case

  • Prima facie, the civil servants who were part of national trade unions had a legitimate expectation that they would continue to enjoy the benefits of membership and representation by the unions and would thus have a right to be consulted before a decision to withdraw that benefit under the head of ‘procedural impropriety’: p. 412
  • However, the decision is based on national security, which is for the executive government to assess and not the courts as the judicial process is inept to deal with these problems: p. 412
  • The government decided not to consult the civil servants as advance notice to the national unions of the executive government’s intention would attract the very disruptive action prejudicial to the national security: p. 413

Lord Roskill

Justiciability of prerogative

  • The justiciability of an exercise of prerogative on the three grounds of judicial review Lord Diplock described, is not unqualified as it depends on the subject matter of the prerogative power which is exercised: p. 418
  • ‘Prerogative powers such as those relating to the making of treaties, the defence of the realm, the prerogative of mercy, the grant of honours, the dissolution of Parliament and the appointment of ministers as well as others are not, I think susceptible to judicial review because their nature and subject matter are such as not to be amenable to the judicial process’: p. 418
  • The exercise of prerogative in the current case does not fall into the ‘excluded categories’: p. 418


  • The theoretical prospect of judicial review of prerogative power is countered by the unlikelihood of a successful judicial review claim since prerogative powers are often exercised in areas of national security or fall into the excluded category listed by Lord Roskill
  • Furthermore, Lord Diplock’s judgment reveals the reluctance of the courts to intervene when they are ill-equipped to assess executive decisions
  • At p. 410, Lord Diplock foresaw the present debate on the adoption of proportionality into common law: ‘I have in mind particularly the possible adoption in the future of the principle of “proportionality” which is recognised in the administrative law of several of our fellow members of the European Economic Community; but to dispose of the instant case the three already well-established heads that I have mentioned will suffice.’
Irrationality Review cases Separation of Powers Cases
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