Canada: Can Brexit Still Be Prevented?

On 23 June, voters in the UK chose to leave the EU.

Does that make a Brexit inevitable? Or are there still ways in which it could be averted?

We previously pointed out that the outcome of the referendum was not legally binding. Now that the initial shock of that outcome has subsided, questions are being asked as to what this means. What further legal steps need to be taken to extract the UK from the EU, and is there a possibility that they will never happen?

In this alert we answer some of those questions, including whether it will be for the government or Parliament to make a decision to trigger a Brexit, whether the EU can force us to leave, and whether Scotland could really prevent that outcome.

The Position in brief

The position in brief, which we explain more fully below, is this -

  1. The referendum vote is not legally binding.
  2. This means that a relevant person or body needs to make a decision whether or not to follow the wishes of the majority of voters in the referendum.
  3. While the government appears to have operated on the assumption that this was a decision falling within the scope of its powers, the correct legal position, in our opinion, is that it is a matter for Parliament.
  4. MPs may feel politically bound to act on the wishes of the majority in the referendum. However, they are not legally bound, and indeed have a constitutional obligation to think about whether this is the right thing to do and apply their own judgment.
  5. Neither Scotland nor any other devolved legislature has the legal power, by itself, to frustrate a Brexit.

Is Brexit inevitable?

The mechanism for the UK's withdrawal from the EU is set out in Article 50 of the Treaty on European Union (the 'TEU' or Lisbon Treaty).

Although Vote Leave suggested some (legally dubious) alternative means of withdrawal during the referendum campaign, the consensus is that Article 50 is the correct route by which to effect a Brexit.

From being an obscure provision in an international treaty only weeks ago, Article 50 has now been catapulted onto centre stage. As minds turn to how the Brexit process actually works, much current discussion has focused on the first paragraph of Article 50 and the opening sentence of the second. These contain two deceptively simple statements -

  1. Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements.
  2. A Member State which decides to withdraw shall notify the European Council of its intention...

Several things are clear from these provisions. Firstly, there must be a decision by a member state to leave the EU. Secondly, that decision must be taken in accordance with the member state's own constitutional arrangements. Thirdly, once a decision has been made in accordance with those arrangements, the member state must notify it to the European Council.

Many, in the UK and also (more especially) the wider EU, appear to have jumped to the conclusion that the outcome of the referendum was a decision to leave the EU for the purposes of Article 50.

This is not the case. The result of the referendum has no effect in domestic law. This is because there is no provision in the European Union Referendum Act 2015 which says either that the result itself constitutes a decision to leave or that it is to be treated as a binding instruction to government. That position must be treated as the deliberate intention of Parliament, because it is in stark contrast to the legislation governing other referendums.

For instance, under the Parliamentary Voting System and Constituencies Act 2011, the result of the alternative voting referendum gave rise to an obligation on the relevant minister (depending on the outcome) either to make an order adopting proportional representation or to refrain from making that order.

Again, in referendums held under the European Union Act 2011 in relation to amendments to the EU Treaties, the Act provides that, where a majority of voters have rejected ratification of such amendments, this must be respected.

In both cases, the outcome of the referendum gives rise directly to legal consequences. This is not the case in relation to the outcome of the referendum on 23 June, and it is clear that Parliament did not intend it to be.

The outcome of the referendum cannot therefore constitute the UK's decision to leave the EU. Something more is required before the UK can serve an Article 50 notice 'in accordance with its own constitutional requirements'. But what?

Who decides - Government or Parliament?

Plainly, a further decision is needed to serve an Article 50 notice. However, if not the voters in the referendum, who makes that decision under the UK's 'constitutional arrangements'?

It is important for the decision to be taken by the correct person or body. An unlawful decision would not meet the test in Article 50(1) and could not, in domestic or EU law, form the basis for a notification under Article 50(2). An unlawful decision would certainly be litigated.

That question has quickly become the subject of debate among constitutional law academics, counsel specialising in public law, and former members of the judiciary. Opinions are divided, with some suggesting that the government can make the decision in law and others that it is for Parliament to decide.

Our view is that it is for Parliament to make the decision to leave the EU, and only with Parliamentary authority can an Article 50 notice be issued. We suggest that a decision by the government made without reference to Parliament would be open to a successful challenge.

The limits on the Government's powers

To understand why this is the case, we first need to explain the alternative position, which is that the decision could be made by the Prime Minister using prerogative powers.

Prerogative powers are those powers which traditionally existed in the person of the monarch and which do not derive from statute. These days those powers are exercised by Ministers in accordance with the legal principle that they are exercised on behalf of the Crown. They include a rag-bag of residual powers but, most importantly for present purposes, those relating to foreign affairs - such as the making (and unmaking) of treaties.

The UK signed up to the Treaty of Rome - the precursor of the current treaties which underpin the EU - in 1972 through exercise of prerogative powers. One argument is that the exercise of those powers could equally be used to leave the EU by taking the UK out of the EU Treaties.

There are two reasons why this view is problematic.

The first is that the Courts have held that prerogative powers cannot be used to override or frustrate the will of Parliament as expressed in statute (see R v Secretary of State for the Home Department, ex p Fire Brigades Union). Prerogative powers may have been used to sign the UK up to the Treaty of Rome. However, for European Economic Community law (as it then was) to be capable of being given full effect in the UK, Parliament needed to pass the European Communities Act 1972 (the '1972 Act').

Section 2 of the 1972 Act gave domestic legal effect to the corpus of EEC law - both as it stood when the Act came into effect and as it would be amended and added to in the future. Parliament therefore clearly intended to make EEC - now EU - laws part of the UK's domestic legal framework.

A decision to leave the EU and to issue an Article 50 notice would set in train a process of withdrawal which, once concluded, would mean that the EU Treaties and the directly effective EU legislation made under them would cease to apply to the UK. After a notice was given there would be no action that Parliament could take to prevent a Brexit.

Although (under the Constitutional Reform and Governance Act 2010) Parliament would get a chance to object to the ratification of the withdrawal agreement negotiated following the notice, that would simply be a say on the terms on which the UK left the EU - not the fact of Brexit itself. If Parliament refused to ratify the withdrawal agreement, the UK would simply leave the EU without any provision being made for any particular form of ongoing relationship between the two.

Returning to the Fire Brigades Union case, the prerogative power to issue an Article 50 notice would therefore be trumped by statute in the form of the 1972 Act. The power would otherwise frustrate the terms and purpose of that Act, which is impermissible.

There has been some debate about whether or not an Article 50 notice would indeed frustrate the will of Parliament as expressed in the 1972 Act (with views from Carl Gardner and Mark Elliott that it would not). In our view there is little doubt that in the real world this is exactly what would happen.

The Special Status of the European Communities Act 1972

There is, however, a second and much deeper set of concerns relating to the legality of using the prerogative power to withdraw from the EU. To our knowledge, these have so far escaped comment in the debates around this issue.

These concerns arise from the fact that the 1972 Act is no ordinary statute. It has been recognised by the Supreme Court as being one of a number of 'constitutional instruments' - a special category of statutes which form part of the constitution of the UK. These include Magna Carta, the Bill of Rights, the Acts of Union 1707 and the Human Rights Act 1998 (R (HS2 Action Alliance Ltd) v Secretary of State for Transport).

Constitutional instruments have a special status. They are not, for example, subject to the doctrine of implied repeal (under which, in line with the principle that Parliamentary sovereignty means that no Parliament can bind a future Parliament, a provision in an earlier statute is deemed to have been changed by an incompatible provision in a later statute). Parliament can still amend constitutional instruments but it cannot impliedly do so - there must be an express statement to that effect in the amending statute which puts beyond all doubt that this was Parliament's intention (BH & Anor v The Lord Advocate & Anor).

So, not only is the 1972 Act an expression of the will of Parliament to be bound by EU law, but that expression of will is contained in a statute which has been held by the Supreme Court to be one of those pieces of law which make up the UK's constitution. Even Parliament itself can only amend these laws by doing so in clear and express terms.

A decision by the government to leave the EU by issuing an Article 50 notice without recourse to Parliament may be, in form, an exercise of the royal prerogative in the field of foreign relations. In substance, however, it would be an amendment to the UK's constitution. This is beyond the scope of the prerogative powers.

Therefore, in addition to the fact that the use of the prerogative would be unlawful because it would frustrate an existing statute, it would also be unlawful because it would amount to an amendment of the constitution by an executive decision. Such a use of prerogative powers without prior recourse to Parliament would offend fundamental principles dating back to the Bill of Rights.

The only possible answer to this, floated by the Cambridge academic Kenneth Armstrong, is that in some way the referendum as an exercise in direct democracy trumps representative democracy - that the government had got its constitutional authorisation from the people without the need for the people's will to be mediated through Parliament. The flaw in this argument is that the UK's constitution is that of a representative democracy with sovereignty residing in 'the Queen in Parliament'. This is in contrast to Switzerland, or certain states in America, where elements of direct democracy through referendums have constitutional force.

The UK's referendum cannot therefore be seen as an exercise in direct democracy but as a way for Parliament to test public opinion on the issue of the UK's continuing membership of the EU. If it was intended to be anything else, the European Union Referendum Act 2015 would have had to make it so, and it did not. The argument returns full circle to the fact that the referendum is not legally binding.

Having tested the opinion of the people, the correct course is for Parliament to take the next step and to consider whether to leave the EU and authorise the issue of an Article 50 notice.

Could MPs vote against Brexit?

So what happens when MPs are confronted with the question of pulling the trigger on Brexit - could they choose not to despite the result of the referendum? As a matter of law, they could.

In the case of Moohan v Lord Advocate, which concerned the right of convicted prisoners to vote in the Scottish independence referendum in 2014, Lord Hodge touched upon the effect of the outcome of that referendum -

'If there had been a "yes" vote, Scotland would not have achieved independence unless and until the UK Parliament had voted in favour, and, whatever the main parties had promised, Members of Parliament would have been free, indeed constitutionally bound, to vote as they saw fit.' (emphasis added)

This is a striking statement by the Supreme Court. It encapsulates the notion of MPs, not as mere delegates of their constituency sent to Parliament to act on the wishes of voters, but as trustees whose duty is to do what they think best in any particular situation.

This (essentially Burkean) view has long had a place in political theory and practice, but according to Lord Hodge it goes beyond that and is actually a matter of constitutional obligation on MPs.

As a matter of practical politics, however, there are considerations which impact on the way that an MP votes. The first is the system of 'whipping', whereby MPs are encouraged with greater or lesser degrees of severity to 'toe the party line' by voting in a certain way. An MP may be disciplined by his or her party for not doing so. It is doubtful that either of the two largest parties would do anything other than require their MPs to vote in favour.

The second practical consideration is the fact that most MPs will be concerned about their ability to be re-elected at the next general election. An MP from a constituency which voted to leave the EU, as the majority did, would be taking a brave stance in voting against issuing an Article 50 notice, even if to do so would accord better with his or her view of the best interests of the country.

That calculation could of course be altered by a significant shift in the complex factual matrix that surrounds the Brexit negotiations, if such a shift swings public opinion in favour of remaining in the EU.

For example, the EU Trade Commissioner has recently stated that in her opinion, talks on the UK's ongoing trading relationship with the EU would only take place after the Article 50 process had been completed and the UK had left the EU. That would mean that there was a period between leaving the EU and a new trade deal being in place during which UK - EU trade would be governed simply by the World Trade Organisation's rules, giving rise to high tariffs in various sectors. (And that period could potentially be lengthy; the EU's trade deal with Canada has taken seven years to negotiate and is still not formally commenced.)

For the record, we consider that the Trade Commissioner's approach does not accord with Article 50. However, legal accuracy aside, such comments from a senior EU official illustrate that it is far from inevitable that MPs as a whole will take a view that leaving the EU is in the UK's best interests.

If the only terms on which a Brexit is possible look to be damaging to the interests of the country, MPs have a constitutional duty to engage in certain rational calculations. Brexit could be delayed for a time, or indefinitely. Parliament could seek the cover of a second referendum.

If the period since the referendum has proved anything, it is the truth of Harold Wilson's dictum that 'a week is a long time in politics'. In the matter of what happens next, there is a considerable amount still to play for.

Can the EU force the UK to leave?

As temperatures ran high the day after the referendum, President of the European Parliament, Martin Schulz, told the Guardian that EU lawyers were studying whether it was possible to speed up the triggering of Article 50, adding that he doubted that the timing of Article 50 was down to the UK alone.

The suggestion that the EU could somehow force the UK to issue an Article 50 notice carries no legal weight. This is because, as discussed above, an Article 50 notice can only follow a decision by the UK, in accordance with its constitutional arrangements, to leave the EU. No such decision has yet been made, and none appears imminent.

However, once it has made that decision, the UK will be under an obligation to provide notification of its intention to withdraw ('A Member State which decides to withdraw shall notify the European Council of its intention'). If a decision were made but no Article 50 notice followed, the EU could theoretically bring infringement proceedings against the UK under Article 258 of the Treaty on the Functioning of the EU (the 'TFEU').

Even should such proceedings be brought, they could result only in a declaration of breach, although failure to then issue an Article 50 notice could lead to proceedings under Article 260 TFEU for failure to comply with the Court of Justice of the European Union's (CJEU) judgement. That could result in the absurd position of the UK being fined by the EU for not leaving. The realistic prospects of such a scenario are incredibly remote.

The reality is that there is no legally effective mechanism for forcing the UK to leave the EU. At this stage, these matters arise only in the sphere of politics.

Can Scotland (or Northern Ireland) block Brexit?

The demographics of the referendum were such that although overall the UK voted to leave the EU, a majority of voters in both Scotland (62%) and Northern Ireland (55.8%) voted to remain.

On the Sunday following the Brexit vote, Scotland's First Minister, Nicola Sturgeon, told the BBC that the Scottish Parliament could attempt to block a Brexit by refusing to consent to any changes that would need to be made to the legislation that underpins devolution to Scotland.

The threat is a reference to the Sewel Convention under which the Westminster Parliament will not normally legislate with respect to devolved matters, or amend the powers of the devolved legislatures, without the consent of the devolved legislature in question.

The convention is embodied in a Memorandum of Understanding between the UK government and the devolved executives. In relation to Scotland, the Sewel Convention is also referred to in an amendment to the 1998 Act by the Scotland Act 2016, which states 'it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament' (a similar provision with respect to Wales is found in the current Wales Bill).

The argument is that, as the Scotland Act 1998 defines the legislative competence of the Scottish Parliament by reference to compliance with EU law, a Brexit will require an amendment to that Act and the Scottish Parliament can withhold consent to that amendment.

The 2016 Act merely recognises the existence of one element of the Sewel Convention. It refers to devolved matters but not the powers of the Scottish Parliament and it is those powers which are at issue here. The Scottish Parliament would therefore be required to rely on the Sewel Convention.

There is an interesting piece to be written on whether the Sewel Convention could be used to challenge a decision by the UK Parliament to press on with legislation following a refusal of consent by the Scottish Parliament. For present purposes that question is, however, a red herring. This is because any amendment to the 1998 Act will be made after the UK has withdrawn from the EU. The Sewel Convention cannot be used to prevent the Brexit that would render such an amendment necessary. This means that even if the Sewel Convention could be used to block amendments to the 1998 Act, the UK will still have left the EU: the only effect will be the retention of a redundant provision in that Act.

The same would apply to the withholding of legislative consent by the Northern Ireland Assembly to a similar amendment to the Northern Ireland Act 1998.

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
Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:
  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.
  • Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.
    If you do not want us to provide your name and email address you may opt out by clicking here
    If you do not wish to receive any future announcements of products and services offered by Mondaq you may opt out by clicking here

    Terms & Conditions and Privacy Statement (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

    Use of

    You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). 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 & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.


    Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd 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 or performance of information available from this server.

    The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.


    Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

    • To allow you to personalize the Mondaq websites you are visiting.
    • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
    • To produce demographic feedback for our information providers who provide information free for your use.

    Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

    Information Collection and Use

    We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

    We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to with “no disclosure” in the subject heading

    Mondaq News Alerts

    In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.


    A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

    Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

    Log Files

    We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.


    This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

    Surveys & Contests

    From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.


    If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.


    From time to time Mondaq may send you emails promoting Mondaq services including new services. You may opt out of receiving such emails by clicking below.

    *** If you do not wish to receive any future announcements of services offered by Mondaq you may opt out by clicking here .


    This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to

    Correcting/Updating Personal Information

    If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to

    Notification of Changes

    If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

    How to contact Mondaq

    You can contact us with comments or queries at

    If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at and we will use commercially reasonable efforts to determine and correct the problem promptly.

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