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Cherry v AG for Scotland, Part II: "No Justification" For Prorogation?

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About The Author

Michael Lane (Guest Contributor)

Michael is a current PhD student at Birmingham City University, undertaking research that focuses on the UK’s interaction with the United Nations’ Universal Periodic Review. He is also a Visiting Lecturer in Constitutional and Administrative Law, and a writer for his blog, where he writes articles concerning constitutional law, international law, and human rights. When he's not researching or teaching, he spends much of his time with friends and family, gaming, or indulging in music.

This article was originally written for Michael Lane's blog, where you can find more articles from Michael on constitutional and international law, as well as Brexit. Part I of this series can be found here.

It arises in circumstances which have never arisen before and are unlikely ever to arise again. It is a “one off”. But our law is used to rising to such challenges and supplies us with the legal tools to enable us to reason to a solution.

Lady Hale

This is the second part of an article relating to Cherry & Others v The Advocate General for Scotland, the recent judicial review case concerning the lawfulness of the Prime Minister’s decision to prorogue (or ‘shut down’) Parliament from the 9th September to the 14th October 2019. The latest (and final) decision of the UK Supreme Court (UKSC) has confirmed the prorogation to be unlawful. The three stages of this case raise a variety of significant and meaningful questions about constitutional law, and deserve some careful reflection.

Part I considered the first instance hearing in the Outer House of the Scottish Court of Session. The petitioners failed to argue that the prorogation was justiciable, and therefore also failed to argue that it was unlawful.  

Part II will concentrate on the appeals to the Inner House of the Scottish Court of Session and subsequently to the UK Supreme Court. In particular, it will focus on how both Courts found in favour of the petitioners, deciding that the issue was justiciable (unlike the Outer House), how they reached these decisions. It will argue that, far from taking a controversial step or expanding its powers, the UKSC rightly exercised its jurisdiction over a matter that fundamentally concerned constitutional law. The Court’s finding that the prorogation was unlawful was similarly very authoritative and was based on the application of established constitutional principles. 


In contrast to Lord Doherty’s decision, discussed in Part I, both the Inner House and the UKSC unanimously found that the matter was justiciable, and that the prorogation was unlawful.

Leading the judgement in the Inner House, Lord Carloway did note that issues of high policy and political judgement were not justiciable. Unlike Lord Doherty, he did not consider this particular matter to be one of these issues. Instead, it was determined that decision to prorogue Parliament could be justiciable if it was undertaken with the purpose of avoiding parliamentary scrutiny – a “central pillar […] enshrined in the constitution” – a question of law, not politics.

The UKSC took greater steps to deal – perhaps pre-emptively – with the argument that they were entering "political territory." The Court emphasised that virtually all executive decisions "have a political hue to them" and that ministers’ accountability to Parliament did not make them "immune from legal accountability in the courts." Similar to the Inner House, the Court then concluded that determining the extent of prerogative powers involves "marking the boundary between the prerogative [and] the sovereignty of Parliament." This is an inherently legal question and must, therefore, be justiciable.

Both Courts received considerable negative press because of their involvement in this matter. Even the Prime Minister voiced disappointment with the UKSC's finding of justiciability, claiming that the courts were stepping into political territory by attempting to frustrate Brexit. Much of this appeared all too familiar to the reaction to the UKSC’s ruling in Miller [2017] UKSC 5 where High Court judges were branded "enemies of the people" for holding that Parliament’s consent was required to trigger Article 50.

However, I am very strongly inclined to agree with the both Courts’ analysis here, and I dismiss the comments that this was a politically motivated decision, or some sly means of preventing Brexit. I particularly concur with the UKSC’s suggestion that a decision’s "political hue" does not make it safe from review. In fact, this was something that I previously criticised Lord Doherty for failing to consider in the Outer House judgement:

Just because the decision to prorogue required political judgement, does not mean that it is excluded from judicial review altogether (in fact, it is difficult to think of a situation where the exercise of an executive power (prerogative or otherwise) would not involve political considerations).

As such, it is important to emphasise that there is nothing novel or new about the approach taken by the Courts. Whilst it is true that this case involved a wholly unique set of circumstances, the question of law was simple: whether there is a legal limit on the prerogative power to prorogue. This is not the same as asking whether any particular prorogation is desirable – this is a purely political question and is not for the Courts to determine. As the Courts were ruling on a purely legal question, it is tough to see how a finding of justiciability here can be considered anything other than constitutionally sound. The claims that the Courts were acting outside of their legal remit in hearing the case are frankly unscrupulous.

Substantive Issues

Once satisfied that the question was justiciable, both Courts then considered how the prorogation’s lawfulness could be assessed – in other words what limits, if any, exist on the power to prorogue.

The Inner House Decision

The Inner House approached this question by asking whether the prorogation was sought for a "proper purpose" – a ground of review most notably recognised in the case of Padfield [1968] AC 997. If the power was not exercised for a "proper purpose", it would be open to challenge by the Court. This subsequently required asking:

  1. What was the true purpose of this prorogation?
  2. Was that purpose inconsistent with established constitutional principles?

On the first point, the Prime Minister failed to explain to the Court what the purpose of the prorogation was, despite claiming publicly that the prorogation was simply to prepare for a Queen’s speech. As such, based on documentary evidence provided to the Court, it was inferred that the true purpose for the prorogation was to “prevent Parliamentary scrutiny of the government”.

On the second point it was then determined that this purpose was inconsistent with the constitutional role of Parliament in scrutinising executive action. The prorogation was thereby ruled to be unlawfu

The Supreme Court Decision

The UKSC took a slightly similar, though in my opinion more authoritative approach, to assessing the prorogation’s lawfulness. They applied two fundamental constitutional principles – the sovereignty of Parliament, and the Government’s accountability to Parliament.

Parliamentary sovereignty is, as famously observed by Lord Bingham in Jackson [2005] UKHL 56, the “bedrock of the British constitution”, granting Parliament limitless legislative power, and therefore freedom from being challenged by the judiciary or (more importantly) the Government. Accountability to Parliament follows naturally from Parliament’s sovereignty – Parliament is immune to challenge by the Government, but the Government is not immune to challenge by Parliament. Parliament has the role, and indeed the duty, of scrutinising the Government’s actions.

With these two principles in mind, the UKSC ruled that prorogation would be unlawful where it would have the effect of:

“frustrating or preventing, without reasonable justification, the ability of Parliament to carry out its constitutional functions”

The Court considered that if the prerogative power to prorogue Parliament was unlimited, and Parliament could theoretically be suspended indefinitely, then Parliament could never be considered sovereign, nor could it ever fulfil its role in holding the Government to account. These two central constitutional principles would subsequently be rendered meaningless. Therefore, some limit had to exist on the power to prorogue.

As to “reasonable justification”, the Prime Minister failed to give any formal statement to either Court outlining the true reason for the prorogation. This meant that not only could no reasonable justification be determined for the prorogation, but no justification whatsoever could be ascertained. It is for this reason that the Court unanimously found the prorogation to be unlawful.

Given the unique, complex, and controversial matter placed before the Court’s in this case, it is easy to think that their approach would have been equally unique or complex. However, these judgements were anything but.

The requirement for the executive to provide reasonable justification for the exercise of power is similar to the principle established in Padfield and applied by the Inner House in its judgement. That is: a power cannot be exercised with a justification that is unreasonable, just as it cannot be exercised for a purpose that is improper. Both approaches require the minister to evidence the reason for that power’s exercise, and require the Court to assess whether that reason was appropriate and thus lawful. The approach taken by the UKSC here is straightforward and hardly revolutionary. Admittedly, this case involved an unusual set of circumstances, but the UKSC’s approach was simply to apply two well-established constitutional principles – parliamentary sovereignty, and governmental accountability to Parliament.


The case of Cherry required the Inner House of the Court of Session and the UKSC to determine a serious and difficult question on the lawfulness of Parliament’s suspension. Lady Hale began her judgement in the UKSC by emphasising that a case on this matter has “never arisen before and [is] unlikely ever to arise again”. In spite of these remarkable circumstances, both Courts dealt with the issues of justiciability and unlawfulness in a manner that was consistent with established constitutional law.

This case did not require either Court to consider the merits of the prorogation or the effect that this would have on the UK’s departure from the EU. Instead, it related to the limits of executive power. This is an inherently legal, and therefore justiciable issue. Both Courts determined that the prorogation negatively impacted Parliament’s role in holding the executive to account. Though the UKSC’s “reasonable justification” test may appear to some to be a revolutionary approach, it is merely a logical extension of the principles in Padfield. Though the ramifications and importance of the UKSC’s decision should by no means be understated, its legal reasoning is beautifully simple and draws upon fundamental principles of the British constitution.

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Tagged: Brexit, Constitution, Judicial Review, Public Law

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