Council of Civil Service Unions v Minister for the Civil Service

Council of Civil Service Unions v Minister for the Civil Service [1985] AC 374, commonly known as the GCHQ case was an English administrative law which held that the Royal Prerogative was subject to judicial review. In 1984 the British government under Margaret Thatcher decided that employees of the Government Communications Headquarters (GCHQ) would not be allowed to join a trade union for national security reasons. This was enforced through an Order-in-Council, an exercise of the Royal Prerogative. The Council of Civil Service Unions chose to bring this matter to court through judicial review, first to the High Court of Justice, which ruled the Order-in-Council was invalid. The case then went to the Court of Appeal, which decided that the national security issues trumped any problems of propriety.
From there the case went to the House of Lords, where it was decided on 22 November 1984. In their decision, the Lords found that exercises of the Royal Prerogative were generally subject to judicial review, with certain exceptions such as matters of national security. This was a significant break from the previous law, which held that prerogative powers were not in any way subject to judicial review. The GCHQ case served to identify that the application of judicial review would be dependent on the nature of the government's powers, not their source