Royal Prerogative in UK Law

The prerogative powers of the Crown remain in existence to the extent that Parliament has not expressly or by implication extinguished them. But under the principle in Attorney-General v. De Keyser's Royal Hotel Ltd. [1920] A.C. 508, if Parliament has conferred on the executive statutory powers to do a particular act, that act can only thereafter be done under the statutory powers so conferred: any pre-existing prerogative power to do the same act is pro tanto excluded.

The question is simply whether the nature and subject matter of the decision is amenable to the judicial process. Looked at in this way there must be cases in which the exercise of the Royal prerogative is reviewable in our judgment. If, for example, it was clear that the Home Secretary had refused to pardon someone solely on the grounds of their sex, race or religion, the courts would be expected to interfere and in our judgment would be entitled to do so.

Like my noble and learned friend Lord Diplock, I believe that the law relating to judicial review has now reached the stage where it can be said with confidence that, if the subject matter in respect of which prerogative power is exercised is justiciable, that is to say if it is a matter upon which the court can adjudicate, the exercise of the power is subject to review in accordance with the principles developed in respect of the review of the exercise of statutory power.

It is not easy to discover and decide the law regarding the Royal Prerogative and the consequences of its exercise. Apart from In re a Petition of Right [1915] 3 K.B. 649 and Attorney-General v. de Keyser's Royal Hotel [1920] A.C. 508, there have been no cases directly raising the matter for some centuries, and obiter dicta and the views of institutional writers and text writers are not always very helpful.

The mobilisation of the industrial and financial resources of the country could not be done without statutory emergency powers. The prerogative is really a relic of a past age, not lost by disuse, but only available for a case not covered by statute. So I would think the proper approach is a historical one: how was it used in former times and how has it been used in modern times?

What, then, do we mean by the prerogative in this connection? I say "this connection" because in our history the prerogatives of the Crown have been many and various, and it would not be possible to embrace them under a single description.