UK: The New Constitution: U.K. Supreme Court Intervenes In Brexit Debate

Byron Shaw is a litigation partner and the co-author of Constitutional Law with Justice Patrick Monahan and Padraic Ryan.

Awi Sinha is a litigation partner specializing in Government Law & Political Risk.

Emily Leduc-Gagne is an articling student at McCarthy Tétrault.


Law, Not Politics?

The U.K. Supreme Court entered the explosive Brexit debate yesterday, ruling that Prime Minister Boris Johnson's advice to the Queen to prorogue Parliament until October 14th was unlawful. In a unanimous 11-judge decision written by Lady Hale and Lord Reed, the Court in R (on the application of Miller) v The Prime Minister, [2019] UKSC 41 held that Johnson exceeded the limits of the prerogative power. The Court expressly stated that its decision was a straightforward application of legal principles. Lady Hale and Lord Reid held that courts can and do rule on the extent of executive powers[1]; here, the Court was ostensibly defining the limits of the prorogation power, which were exceeded in this exceptional case.

According to the Court, "a decision to prorogue Parliament (or to advise the monarch to prorogue Parliament) will be unlawful if the prorogation has the effect of frustrating or preventing, without reasonable justification, the ability of Parliament to carry out its constitutional functions as a legislature and as the body responsible for the supervision of the executive. In such a situation, the court will intervene if the effect is sufficiently serious to justify such an exceptional course[2]."

The Supreme Court therefore held that the government has a positive obligation to provide a reasonable justification to prorogue, failing which, its advice (and, by extension, the Queen's decision based on that advice) is null and void[3].

In other words: this is law, not politics. Is it?

Politics, Not Law

The Court's ruling is unquestionably political in terms of the subject matter of the decision. It requires that British MPs return to Parliament and continue working in the run-up to the Brexit deadline of October 31, 2019 notwithstanding the existing government's publicly declared support for a "no deal" Brexit.

The decision is also political in the sense that it arguably expands the role of the judiciary into what has previously been an area in which the Courts have treaded delicately. The Court's ruling is difficult to reconcile with Britain's traditions of Parliamentary supremacy and the role of the judiciary in a country with no written constitution. 

The Court presented the decision as simply defining the limits of executive power, something entrusted to the courts in a constitutional democracy. It took great pains to state that it was not reviewing the "mode of exercise" of the Johnson government's decision to prorogue or its "motives"[4]. On closer examination, that is exactly what the Court did.

The Court did not know (and we will likely never know) precisely what transpired during the meeting with the Queen at Balmoral Castle on August 28, 2019. Despite that, the Court proceeded to assess the legality of that conversation based on inferences from documents surrounding the meeting, including:

  • a memo from the Director of Legislative Affairs in the Office of the PMO recommending prorogation for reasons apart from Brexit and acknowledging that "prorogation, on its own and separate of a Queen's Speech, has been portrayed as a potential tool to prevent MPs intervening from the UK's departure from the EU on 31st October[5]";
  • the Prime Minister's comments noting that the "September session is a rigmarole introduced ... [to] show the public that MPs were earning their crust[6]"; and
  • Minutes of a Cabinet meeting shortly after the prorogation decision explaining that the decision "was not driven by Brexit considerations" but was "about pursuing an exciting and dynamic legislative programme to take forward the Government's agenda[7]".

The Court said that the prorogation was unlawful because it was "not a normal prorogation in the run-up to a Queen's speech" and "prevented Parliament from carrying out its constitutional role for five out of a possible eight weeks between the end of the summer recess and exit day on the 31st October[8]." According to Lady Hale and Lord Reed, the documents discussed above disclosed no reason, "let alone a good reason" to prorogue for five weeks[9]. The Court relied on evidence from former Prime Minister Sir John Major about how long it "normally" takes to work on the Queen's Speech[10]. In addition, it concluded that the memoranda to the Prime Minister failed to offer a coherent explanation for a five week prorogation or why "it was necessary to curtail what time there would otherwise have been for Brexit related business[11]."

We are left to infer that the Court felt that the government's stated reasons to prorogue were not its true reasons and the explanation believed to have been given to the Queen was a farce. It is thus difficult to understand how the Court was doing anything other than examining the Johnson government's motives and the manner in which the prorogation power was exercised.

The Court concludes that the decision "interrupt[ed] the process of responsible government[12]." Of course, that is true of every prorogation, which by definition stops responsible government until the next Queen's Speech. But in concluding that this particular interruption in responsible government "matter[ed]", Lady Hale and Lord Reed relied on the "exceptional circumstances" of the October 31st deadline as well as events that occurred after the prorogation decision had been made[13]. They emphasized that the "House of Commons has already demonstrated, by its motions against leaving without an agreement and by the European Union (Withdrawal) (No 2) Act 2019"—passed on September 4, 2019—"that it does not support the Prime Minister on the critical issue for his Government at this time and that it is especially important that he be ready to face the House of Commons[14]."

In other words, the government's justification to prorogue was not only deficient, said the Court, but hindsight has proven it to have been incorrect.

Implications: Prorogation Before the Courts

The U.K. Supreme Court is undoubtedly right in describing the specific circumstances of the Johnson government's decision to prorogue as a "one off" which have "never arisen before and are unlikely to ever rise again[15]." But the Court's decision is a remarkable exercise of the powers of judicial review with implications that are perhaps greater than the Court would have us believe.

The Court's rationale for reviewing a prorogation decision represents a curious application of the principle of responsible government. The Court relied on the unwritten constitutional principle that the government is "accountable to Parliament[16]." It is quite true that responsible government is a central tenet of the Westminster system, which means, among other things, that Ministers serve at the pleasure of Parliament so long as they enjoy the confidence of the House. Yet it does not follow automatically that government must explain how politically controversial prorogation advice meets a standard of reasonable justification to the judiciary. As the Lady Hale and Lord Reed concede elsewhere in their reasons, the principle of Parliamentary accountability has typically been invoked "as a justification for judicial restraint" and an "explanation for non-justiciability[17]."

It is far from clear, as the Court suggests, that the standard of "reasonable justification" for a prorogation decision is workable in practice and throws up "question[s] of fact which prevents no greater difficulty than many other questions of fact which are routinely decided by the courts[18]." The Court did state that deference should ordinarily be afforded to a decision to prorogue and the Court should approach the task of judicial review with a "degree of caution[19]". But government's justifications for prorogation are often politically controversial. Whether any decision to prorogue is reasonable involves inherently political judgments that are far different than the factual questions that the courts routinely decide.

Limitless hypotheticals to test the Supreme Court's standard can be conceived which admit of no clear answers. What if the proposed prorogation was four weeks? Three weeks? Two and a half weeks? Suppose, for instance, that Johnson's government had simply told the Queen (consistent with his public stance on the issue) that in his view, he needed to prorogue because Britain would get a better result if it left the EU—or could credibly threaten to leave the EU—without a withdrawal agreement in place? Would that justification to prorogue have been reasonable in the "exceptional circumstances" existing on August 28, 2019?

Precisely because prorogation decisions are inherently political, it is no surprise that the Canadian experience has focused on the political implications of prorogation for the Prime Minister and the exercise of discretion by the Governor General, who by convention, acts on the advice of the Prime Minister provided that he or she enjoys the confidence of the House. For instance, former Prime Minister Harper's decision to prorogue in 2008 when the Liberals, NDP and Bloc Quebecois announced that they had lost confidence in the Harper government and would introduce a non-confidence motion was politically controversial. Canadian constitutional scholars generally agree that in the unique circumstances of the request, Governor General Michaëlle Jean had a discretion to consider the advice from the Prime Minister and made the correct decision—based on independent advice from constitutional scholar Peter Hogg—to prorogue given the facts known at the time[20].

Prime Minister Harper's decision to prorogue Parliament from December 30, 2009 to March 3, 2010 (longer than the five week prorogation by the Johnson Government), was also a politically controversial event in Canadian history. It came after the Conservative government had refused to provide certain documents to a Parliamentary committee inquiring into the handover of prisoners in Afghanistan. The focus of the debate was squarely on the Prime Minister, however, who enjoyed the confidence of the House at the time, but was criticized by his political rivals for trying to put an end to the Parliamentary committee's work[21].

Of course, there was no judicial review application challenging Prime Minister Harper's advice to the Governor General in either of these situations or several other controversial prorogation decisions in Canadian history. It is not clear that Canadian Parliamentary democracy would have been better served had unelected Canadian judges been tasked with reviewing the advice given to the Governor General and determining whether it was "reasonably justified". However, the effect of the U.K. Supreme Court's decision is to encourage judicial review of prorogation and require the judiciary to examine what has previously been considered a political decision, politically made and politically judged.


The U.K. Supreme Court is correct in stating that there must be an outer limit on the ability of the government to prorogue. The decision to prorogue is effectively a discretionary power enjoyed by the Prime Minister and, as with other discretionary powers, "there is no such thing as absolute and untrammelled discretion," to borrow the words of the Supreme Court of Canada in Roncarelli v Duplessis[22]. Such absolute and untrammelled discretion would itself do violence to our responsible government.

It is conceivable that judicial intervention may be required in extreme cases. Yet the standard of justification for a prorogation articulated by the U.K. Supreme Court invites unelected judges to wade into inherently political waters that, for good reason, the Courts have not entered before.

[1][2019] UKSC 41 at para 35 [R v Prime Minister].

[2]Ibid at para 50.

[3]Ibid at paras 49-50 and 69.

[4]Ibid at paras 52 and 58.

[5]Ibid at para 17.

[6]Ibid at para 18.

[7]Ibid at para 20.

[8]Ibid at para 56.

[9]Ibid at para 61.

[10]Ibid at para 59.

[11]Ibid at para 60.

[12]Ibid at para 57.

[13]Ibid at para 57.

[14]Ibid at para 57.

[15]Ibid at para 1.

[16]Ibid. at para. 46.

[17]Ibid. at para. 47, citing R v Secretary of State for the Environment, Ex p Nottinghamshire County Council [1986] AC 240 at 250; (Mohammed (Serdar) v Ministry of Defence [2017] UKSC 1; [2017] AC 649 at para 57.

[18]Ibid (R v Prime Minister) at paras 50-51.

[19]Ibid at para 51.

[20] Patrick J Monahan, Byron Shaw & Padraic Ryan, Constitutional Law, 5th ed (Toronto: Irwin Law, 2017) at 74-75 [Monahan & Shaw]; Peter Hogg, Constitutional Law of Canada, 5th ed (Toronto: Carswell, 2016) at 9-22 (online at 9.7(d.2)).

[21]Ibid (Monahan & Shaw) at 77.

[22] [1959] SCR 121 at para 41.

To view the original article click here

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on

Click to Login as an existing user or Register so you can print this article.

In association with
Related Topics
Related Articles
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Mondaq Free Registration
Gain access to Mondaq global archive of over 375,000 articles covering 200 countries with a personalised News Alert and automatic login on this device.
Mondaq News Alert (some suggested topics and region)
Select Topics
Registration (please scroll down to set your data preferences)

Mondaq Ltd requires you to register and provide information that personally identifies you, including your content preferences, for three primary purposes (full details of Mondaq’s use of your personal data can be found in our Privacy and Cookies Notice):

  • To allow you to personalize the Mondaq websites you are visiting to show content ("Content") relevant to your interests.
  • To enable features such as password reminder, news alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our content providers ("Contributors") who contribute Content for free for your use.

Mondaq hopes that our registered users will support us in maintaining our free to view business model by consenting to our use of your personal data as described below.

Mondaq has a "free to view" business model. Our services are paid for by Contributors in exchange for Mondaq providing them with access to information about who accesses their content. Once personal data is transferred to our Contributors they become a data controller of this personal data. They use it to measure the response that their articles are receiving, as a form of market research. They may also use it to provide Mondaq users with information about their products and services.

Details of each Contributor to which your personal data will be transferred is clearly stated within the Content that you access. For full details of how this Contributor will use your personal data, you should review the Contributor’s own Privacy Notice.

Please indicate your preference below:

Yes, I am happy to support Mondaq in maintaining its free to view business model by agreeing to allow Mondaq to share my personal data with Contributors whose Content I access
No, I do not want Mondaq to share my personal data with Contributors

Also please let us know whether you are happy to receive communications promoting products and services offered by Mondaq:

Yes, I am happy to received promotional communications from Mondaq
No, please do not send me promotional communications from Mondaq
Terms & Conditions (the Website) is owned and managed by Mondaq Ltd (Mondaq). Mondaq grants you a non-exclusive, revocable licence to access the Website and associated services, such as the Mondaq News Alerts (Services), subject to and in consideration of your compliance with the following terms and conditions of use (Terms). Your use of the Website and/or Services constitutes your agreement to the Terms. Mondaq may terminate your use of the Website and Services if you are in breach of these Terms or if Mondaq decides to terminate the licence granted hereunder for any reason whatsoever.

Use of

To Use you must be: eighteen (18) years old or over; legally capable of entering into binding contracts; and not in any way prohibited by the applicable law to enter into these Terms in the jurisdiction which you are currently located.

You may use the Website as an unregistered user, however, you are required to register as a user if you wish to read the full text of the Content or to receive the Services.

You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these Terms or with the prior written consent of Mondaq. You may not use electronic or other means to extract details or information from the Content. Nor shall you extract information about users or Contributors in order to offer them any services or products.

In your use of the Website and/or Services you shall: comply with all applicable laws, regulations, directives and legislations which apply to your Use of the Website and/or Services in whatever country you are physically located including without limitation any and all consumer law, export control laws and regulations; provide to us true, correct and accurate information and promptly inform us in the event that any information that you have provided to us changes or becomes inaccurate; notify Mondaq immediately of any circumstances where you have reason to believe that any Intellectual Property Rights or any other rights of any third party may have been infringed; co-operate with reasonable security or other checks or requests for information made by Mondaq from time to time; and at all times be fully liable for the breach of any of these Terms by a third party using your login details to access the Website and/or Services

however, you shall not: do anything likely to impair, interfere with or damage or cause harm or distress to any persons, or the network; do anything that will infringe any Intellectual Property Rights or other rights of Mondaq or any third party; or use the Website, Services and/or Content otherwise than in accordance with these Terms; use any trade marks or service marks of Mondaq or the Contributors, or do anything which may be seen to take unfair advantage of the reputation and goodwill of Mondaq or the Contributors, or the Website, Services and/or Content.

Mondaq reserves the right, in its sole discretion, to take any action that it deems necessary and appropriate in the event it considers that there is a breach or threatened breach of the Terms.

Mondaq’s Rights and Obligations

Unless otherwise expressly set out to the contrary, nothing in these Terms shall serve to transfer from Mondaq to you, any Intellectual Property Rights owned by and/or licensed to Mondaq and all rights, title and interest in and to such Intellectual Property Rights will remain exclusively with Mondaq and/or its licensors.

Mondaq shall use its reasonable endeavours to make the Website and Services available to you at all times, but we cannot guarantee an uninterrupted and fault free service.

Mondaq reserves the right to make changes to the services and/or the Website or part thereof, from time to time, and we may add, remove, modify and/or vary any elements of features and functionalities of the Website or the services.

Mondaq also reserves the right from time to time to monitor your Use of the Website and/or services.


The Content is general information only. It is not intended to constitute legal advice or seek to be the complete and comprehensive statement of the law, nor is it intended to address your specific requirements or provide advice on which reliance should be placed. Mondaq and/or its Contributors and other suppliers make no representations about the suitability of the information contained in the Content for any purpose. All Content provided "as is" without warranty of any kind. Mondaq and/or its Contributors and other suppliers hereby exclude and disclaim all representations, warranties or guarantees with regard to the Content, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. To the maximum extent permitted by law, Mondaq expressly excludes all representations, warranties, obligations, and liabilities arising out of or in connection with all Content. In no event shall Mondaq and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use of the Content or performance of Mondaq’s Services.


Mondaq may alter or amend these Terms by amending them on the Website. By continuing to Use the Services and/or the Website after such amendment, you will be deemed to have accepted any amendment to these Terms.

These Terms shall be governed by and construed in accordance with the laws of England and Wales and you irrevocably submit to the exclusive jurisdiction of the courts of England and Wales to settle any dispute which may arise out of or in connection with these Terms. If you live outside the United Kingdom, English law shall apply only to the extent that English law shall not deprive you of any legal protection accorded in accordance with the law of the place where you are habitually resident ("Local Law"). In the event English law deprives you of any legal protection which is accorded to you under Local Law, then these terms shall be governed by Local Law and any dispute or claim arising out of or in connection with these Terms shall be subject to the non-exclusive jurisdiction of the courts where you are habitually resident.

You may print and keep a copy of these Terms, which form the entire agreement between you and Mondaq and supersede any other communications or advertising in respect of the Service and/or the Website.

No delay in exercising or non-exercise by you and/or Mondaq of any of its rights under or in connection with these Terms shall operate as a waiver or release of each of your or Mondaq’s right. Rather, any such waiver or release must be specifically granted in writing signed by the party granting it.

If any part of these Terms is held unenforceable, that part shall be enforced to the maximum extent permissible so as to give effect to the intent of the parties, and the Terms shall continue in full force and effect.

Mondaq shall not incur any liability to you on account of any loss or damage resulting from any delay or failure to perform all or any part of these Terms if such delay or failure is caused, in whole or in part, by events, occurrences, or causes beyond the control of Mondaq. Such events, occurrences or causes will include, without limitation, acts of God, strikes, lockouts, server and network failure, riots, acts of war, earthquakes, fire and explosions.

By clicking Register you state you have read and agree to our Terms and Conditions