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 (Lord Templeman in Re M [1994] 1 AC 377 at 395).

There are distinctions between the personal and political capacities of the monarch and between the King or Queen regnant as an individual and the monarchy as a public institution providing the constitutional Head of State.