This short piece, which forms part of my 1,000 words series of posts, aims to set out in an accessible way the key points of the Supreme Court’s judgment in the Cherry/Miller (No 2) case. For a more detailed and technical analysis of the judgment, see this post.

In its historic judgment in Cherry/Miller (No 2) [2019] UKSC 41, the UK Supreme Court unanimously held that the prorogation of Parliament for a period of five weeks was unlawful, void and without legal effect. Since Parliament had never lawfully been prorogued, it remained in session and resumed business the day after the judgment was given. In concluding that prorogation was unlawful, the Court had to confront two key issues. First, was the question it was being asked to consider a justiciable question — that is, one that could properly be considered by a court of law? Second, if the matter was justiciable, had the Government acted unlawfully in procuring the prorogation of Parliament?

On the first issue, the Supreme Court firmly concluded that the question before it was justiciable. In doing so, it clearly, and rightly, distinguished between questions that are themselves political in nature (and thus not for courts) and questions that are legal in nature but which may have political ramifications. The issue in this case, said the Court, fell into the latter category. This conclusion was reached on the ground that the Court was being called upon to rule only upon the scope of the prorogation power: that is, on whether the power extended to doing what had been done in this case. Questions about the scope of legal powers are, self-evidently, legal questions that are justiciable before courts of law. That the answer to that question might have implications in the political realm, and that the question arose in a febrile political context, did not detract from the essentially legal nature of the issue before the Court.

Having decided that it could consider the lawfulness of the prorogation, the Court went on to explain what legal standards should be applied. Here, the court invoked two fundamental constitutional principles, both of which were impacted by the prorogation. First, the Court relied on the sovereignty of Parliament. While the core of that principle is the rule that Acts of Parliament are the highest form of law in the UK — meaning that everyone, including the Government and the courts, must obey such law — the Supreme Court correctly observed that other implications flow from the principle. The notion of parliamentary sovereignty would be rendered a dead letter if, in the first place, Parliament could be prevented from enacting legislation by an executive capable of suspending Parliament for any reason and for any length of time. Second, the Court invoked the principle that the Government is accountable to Parliament. Plainly, Parliament’s core constitutional function of holding the Government to account cannot be discharged while Parliament is prorogued, and it would thus be inconsistent with the principle of executive accountability to Parliament if the executive could evade scrutiny whenever it pleased by having untrammelled discretion as to the prorogation of Parliament.

Once it had identified the two key constitutional principles that were in play, the Court turned to consider the implications of those principles for the scope of the prorogation power. At this point, the Court in effect applied what is known as the “principle of legality”. This principle had generally only been considered to apply when courts are interpreting legislation, meaning that when courts interpret statutes they apply a strong presumption that they do not (for instance) confer powers that would cut across fundamental constitutional norms or rights. But there is no good reason why the principle should not also apply when courts are considering the scope of the Government’s prerogative powers — that is, powers that derive from the common law rather than from statute. Applying this approach, the Court held that when the effect of prorogation is to frustrate or prevent Parliament from carrying out its constitutional functions — thus compromising the principles of parliamentary sovereignty and/or executive accountability — prorogation will be unlawful unless the Government is able to provide the court with a reasonable justification.

The effect of this approach, then, is to apply a two-stage analysis. First, it must be determined whether prorogation has the effect of frustrating or preventing the execution by Parliament of its key constitutional functions. (A mundane prorogation of a few days to make way for a Queen’s speech plainly would not have such an effect.) Second, if, and only if, prorogation produces such an effect, the court must consider whether the reasons offered by the Government in support of such a prorogation are capable of constituting reasonable justification. In Cherry/Miller (No 2), the Court concluded that the Government had not merely failed to advance a good reason for an unusually long prorogation, but that it had failed to advance any reason — the Government’s insistence that it wanted to pave the way for a Queen’s speech being incapable of serving as any sort of reason for a five-week prorogation.

The judgment has drawn criticism from some quarters, attracting claims that the Supreme Court is guilty of overreach by interfering in political matters. However, for three reasons, this charge is unwarranted. First, the crucial issue in the case was a question of law concerning the extent of the Government’s legal powers. Such questions are manifestly suitable for adjudication by courts of law. Second, had the Government offered any relevant reasons for the unusually long prorogation, the Court recognised that it would have been right to extend a great deal of latitude to the Government when assessing the adequacy of such reasons. Third, and most importantly, the judgment amounts to nothing more than an articulation and application of well-established constitution principles, albeit in politically extraordinary circumstances. The UK is a democracy founded on parliamentary sovereignty, executive accountability, and government under the law. Those basic facts of constitutional life mean that the Government cannot be afforded an unfettered power to stop Parliament from performing its constitutional role, and that it is entirely proper for courts to step in when the executive, without adequate justification, seeks to marginalise Parliament in a way that prevents it from fulfilling its constitutional duties. Far from judicial intervention in such circumstances being constitutionally improper, the Supreme Court would have been in dereliction of its constitutional duty if it had declined to intervene so as to deny the Government unfettered power to undermine fundamental constitutional principle.