Excluded Categories of Prerogative Power: An Idea that Never Was

Abstract

For commentators critical of the Supreme Court’s decision in Miller II, one of the judgment’s central failings was that, in contrast to the Divisional Court, the Supreme Court ignored clear precedent on the justiciability of prerogative powers. According to these commentators, these precedents provided for an excluded category of prerogative powers which are not justiciable because they address matters of politics and high policy. The power to prorogue Parliament fell into this excluded category. John Finnis, for example, criticized the “Supreme Court’s attempts to refute the Divisional Court’s well-reasoned findings that the case was not justiciable because of matters of high politics”. This article interrogates and de-bunks this excluded-categories idea. It shows that the idea’s foundational judgment, Council of Civil Service Unions v Minister for the Civil Service (CCSU), does not in any authoritative sense provide for it, and that when the idea is applied it fails the most basic tests of legal coherence and consistency. The article explores how a legal idea that never really was became an established doctrine. The answer, the article argues, is found first, in the limited attention given to the distinctive nature of prerogative power as an inherent power and to how grounds of judicial review necessarily must be adjusted to this distinct nature, and second, in the transformation in the nature and meaning of irrationality review since CCSU. The article does not take issue with this transformation of irrationality review, it merely points out that when we control for it then the stronger reading of the majority position in CCSU is one that exposes all prerogative powers to all grounds of judicial review, regardless of the subject matter addressed by those powers. This majority position, had it been taken seriously, would have provided the Supreme Court with a different approach; one that may have alleviated the pressure to cross the constitutional principles Rubicon so forthrightly.