This is an extract from Lord Templeman's judgment in the House of Lords in the case of M v Home Office  1 AC 377. Lord Templeman explained the basis for finding that a government minister was in contempt of court and exercising coercive powers accordingly.
My Lords, Parliament makes the law, the executive carry the law into effect and the judiciary enforce the law. The expression “the Crown” has two meanings; namely the monarch and the executive. In the 17th century Parliament established its supremacy over the Crown as monarch, over the executive and over the judiciary. Parliamentary supremacy over the Crown as monarch stems from the fact that the monarch must accept the advice of a Prime Minister who is supported by a majority of Parliament. Parliamentary supremacy over the Crown as executive stems from the fact that Parliament maintains in office the Prime Minister who appoints the ministers in charge of the executive. Parliamentary supremacy over the judiciary is only exercisable by statute. The judiciary enforce the law against individuals, against institutions and against the executive. The judges cannot enforce the law against the Crown as monarch because the Crown as monarch can do no wrong but judges enforce the law against the Crown as executive and against the individuals who from time to time represent the Crown. A litigant complaining of a breach of the law by the executive can sue the Crown as executive bringing his action against the minister who is responsible for the department of state involved, in the present case the Secretary of State for Home Affairs. To enforce the law the courts have power to grant remedies including injunctions against a minister in his official capacity. If the minister has personally broken the law, the litigant can sue the minister, in this case Mr. Kenneth Baker, in his personal capacity. For the purpose of enforcing the law against all persons and institutions, including ministers in their official capacity and in their personal capacity, the courts are armed with coercive powers exercisable in proceedings for contempt of court.
In the present case, counsel for the Secretary of State argued that the judge could not enforce the law by injunction or contempt proceedings against the minister in his official capacity. Counsel also argued that in his personal capacity Mr. Kenneth Baker the Secretary of State for Home Affairs had not been guilty of contempt.
My Lords, the argument that there is no power to enforce the law by injunction or contempt proceedings against a minister in his official capacity would, if upheld, establish the proposition that the executive obey the law as a matter of grace and not as a matter of necessity, a proposition which would reverse the result of the Civil War. For the reasons given by my noble and learned friend, Lord Woolf, and on principle, I am satisfied that injunctions and contempt proceedings may be brought against the minister in his official capacity and that in the present case the Home Office for which the Secretary of State was responsible was in contempt.