Council for Civil Service Unions and Others v Minister for the Civil Service [1985] AC 374
The Prime Minister, acting in her capacity as Minister for the Civil Service, issued an oral instruction under the Civil Service Order in Council 1982 banning continued membership of trade unions at GCHQ, the government’s communications headquarters.
The government, having lost in the High Court, pleaded national security in the Court of Appeal and won.
The House of Lords upheld the decision of the Court of Appeal ruling that the courts had no jurisdiction to intervene in matters of national security.