UK Constitutional Law Association

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Alison Young: Brexit, Article 50 and the ‘Joys’ of a Flexible, Evolving, Un-codified Constitution

young_alison-l2There has been a lot of speculation as to the meaning of the ‘constitutional requirements’ to trigger Article 50. Nature abhors a vacuum and sometimes, it seems, so do constitutions. This vacuum arises because, unlike other legislation providing for a referendum, the European Union Referendum Act 2015 makes no mention of any legal obligation triggered by the referendum result. Most, if not all, British constitutional lawyers would accept the proposition that referenda do not generate legally binding obligations upon government to implement their results, and the lack of provisions in the 2015 Act contrasts starkly with the Northern Ireland Act 1998 and the Parliamentary Voting and Constituencies Act 2011. Given the relative silence of the European Union Referendum Act 2015, one can only infer that the result of the referendum is advisory only, and does not trigger Article 50 in and of itself. If any legal obligations follow from the Referendum they are to be found elsewhere, or are to be considered to be purely political.

Given this, what are the ‘constitutional requirements’ governing a decision of the UK to withdraw from the European Union? There would appear to be a number of possibilities:

  • The Prime Minister need only inform the European Council through an exercise of prerogative powers
  • Constitutional convention requires that there is some form of parliamentary deliberation before an exercise of prerogative powers
  • There is a legal requirement of parliamentary deliberation before an exercise of prerogative powers
  • There is a legal requirement for legislation before an exercise of prerogative powers

The argument in favour of a legal requirement for legislation before an exercise of prerogative powers has been made by Nick Barber, Tom Hickman and Jeff King. Their argument turns on an interpretation of legal requirements governing the existence and the exercise of prerogative powers. It is clear that, to the extent to which the two directly conflict, statutory provisions override prerogative powers. It is also clear that, where there are clear statutory provisions governing the way in which prerogative powers is exercised, it is unlawful to exercise these powers in a manner which contradicts these statutory provisions. Barber, Hickman and King argue for a different interpretation of the nature of the relationship between statutory provisions and prerogative powers, essentially arguing that as statute always overrides the prerogative, prerogative powers cannot be exercised in a manner which would ‘turn a statute into what is in substance a dead letter’ or to ‘cut across the object and purpose of an existing statute’. They argue in addition that the European Communities Act 1972 is the means by which all EU rights and obligations are incorporated into European Union law. As such, to use the prerogative power to initiate Article 50, which will then inevitably remove these rights, would be to cut across the purpose of the European Communities Act 1972.

This is a difficult argument to accept. First, it is clear that their interpretation, though clever, is not widely accepted. Second, it is by no means clear that the triggering of Article 50 automatically means that all of the EU rights currently enjoyed by EU citizens will be removed. Unless and until a withdrawal agreement is reached between the UK and the European Union, it is impossible to predict which EU rights will and will not continue to be enjoyed by UK citizens. Even though we can point to some that definitely will be removed – the right of UK citizens to vote in EU elections, for example – it is hard to argue that the removal of one right found in existing UK legislation means that prerogative powers cannot be exercised so as to restrict that right without legislation. Third, it is hard to read Article 50 as requiring that, once commenced, the only possible outcome is a withdrawal agreement or the removal of the United Kingdom from the EU. Article 50 makes it clear that ‘the Treaties cease to apply’ to the UK ‘from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification’ unless there is an extension of the negotiation period. It is silent on whether a Member State may withdraw its decision to leave the EU before the end of that period. Admittedly, to read a power to withdraw the notification may be abused – a Member State being held in a constant state of limbo by notifying the EU of its intention to withdraw, failing to reach an agreement within 2 years and failing to obtain permission to extend the negotiation period, then withdrawing its notification only to trigger this again to obtain at least a further two years for negotiations. However, this potential for abuse can be countered by potential legal action before the European Court of Justice, not to mention the political difficulties of adopting this course of action. Fourth, a prerogative power to enter into Treaties does not in and of itself create rights and obligations in UK law, these rights and obligations need to be ratified – normally through legislation – into UK law.

It is easier to argue for a requirement of parliamentary deliberation prior to the exercise of a prerogative power. The easier argument would be to argue in favour of a convention requiring parliamentary deliberation prior to the exercise of Article 50. It is difficult to point to a specific convention to this effect. However, that is not in and of itself conclusive – new conventions have to start somewhere. If we adopt Jennings’s definition of a constitutional convention, they arise from a series of past actions, coupled with the belief of the actors that they were bound to act in this manner, and a reason for acting in this way. There is no past practice of the use of the prerogative power to initiate Article 50. Nor is there any past practice of a requirement of parliamentary deliberation prior to the use of the prerogative to leave an international Treaty. However, it may be possible to argue that a new convention has arisen by analogy with the convention, recognised in the Cabinet Manual, although subject to different interpretations, of providing the House of Commons with the ‘opportunity to debate’ before the commitment of troops to military action. Arguably, this convention has since evolved into a requirement for a parliamentary vote in favour of military action, following the failure to obtain a vote in favour of military action in Syria in 2013, the prerogative power then being exercised following a later vote in favour of military action in 2015.

The analogy is appropriate for a number of reasons. Both would provide a democratic mandate before a prerogative power is exercised which may have large constitutional repercussions; be they the deployment of troops or a potential fundamental change in the rights and freedoms of UK nations and the potential threat to the unity of the United Kingdom. Both concern the external sovereignty of the UK. Both concern issues in which the emotions of the public run high, demonstrated through public protests against military action and the signing of the petition questioning the result of the referendum and public protests. Both concern issues on which emotions run high and there may be the risk of a snap judgment that may, or may not, be regretted upon later reflection. Both may also have originated from a perceived divergence between popular and parliamentary sovereignty, with Parliament having earlier appeared to have engaged in military action when this was not approved by the public, or where the public has voted to leave the EU when major political parties were campaigning for the UK to remain. It is hard not to see the justification of a convention that provides greater democratic scrutiny over the exercise of prerogative powers. Moreover, even if the case for a convention of parliamentary deliberation cannot be sustained, there may nevertheless be ample support for the Government to initiate this convention, a requirement of deliberation as opposed to parliamentary approval being easier to justify in the face of the referendum decision.

If we can make a case for a constitutional convention for parliamentary approval, can we argue that this convention could be legally enforced? Whether we would regard it is the crystalisation of convention into law, or the adoption of a new principle of the common law mirroring the convention, it is hard to argue that a convention requiring parliamentary consultation before the exercise of a prerogative power should be enforced by the courts. First, this may cause issues for parliamentary privilege, found in Article 9 of the Bill of Rights 1689, particularly if this required the court to evaluate the sufficiency of parliamentary deliberation, although admittedly there is some suggestion by Lord Reed in HS2 that this may be possible. It may also be non-justiciable as concerning a matter of high foreign policy Second, it is no exaggeration to classify the result of the referendum as creating a constitutional crisis. In these circumstances, the UK may be wise to learn from the experience of Canada, where the Canadian Supreme Court concluded that, whilst not illegal, it was unconstitutional to seek a constitutional amendment without consent from the Provinces of Canada. This position allowed courts to provide an informed view as to the principled reasons for the existence of the convention, whilst stopping short of requiring the Government to abide by a legal obligation. This compromise has at least the advantage of aiming to provide for further negotiation and deliberation, which may be more needed in such situations. The same may be achieved by the court recognising, though not legally enforcing, a constitutional convention. The stronger argument is that, if a convention does exist, it should not be enforced by the courts.

If there is no ability to find a legal or a conventional constitutional obligation for legislation or parliamentary consultation, there is at least a good argument, in terms of political expediency, for wider consultation by the Prime Minister before an exercise of the prerogative power to trigger Article 50. The people may have voted to leave the European Union, but there is no popular consensus as to what this entails, or the relative desirability of any particular withdrawal agreement. Parliamentary debate may help to further inform us about the benefits and burdens of EU membership – something which many commentators feel the referendum debate lacked. This may lead to further reflection on the possible aims of a withdrawal agreement, providing more democratic legitimacy for the Government charged with taking the negotiations forward. Parliamentary discussion may be particularly important given the lack of an electoral mandate to withdraw from the EU, the manifesto promise being only to hold a referendum. Moreover, the political expediency argument should extend to the need for parliamentary debate in the devolved legislatures, particularly given the even split with two of the component nations of the United Kingdom voting to leave and two voting to remain in the European Union.

Whilst the political expediency argument is the easiest to satisfy, it poses a potential danger to the constitutional stability of the United Kingdom and the European Union. ‘Political expediency’ is not a constitutional requirement. As such, if there is a long delay between the outcome of the referendum and the triggering of Article 50, the delay may prompt the Commission or another Member State to initiate an enforcement action against the UK under Article 258 TFEU, or Article 259 TFEU. By failing to notify the Council of an intention to withdraw, despite fulfilling the constitutional requirements to withdraw from the EU, the UK has arguably failed to fulfil its obligation under Article 250 TFEU – especially as ‘shall’ may well be interpreted to include a requirement of ‘within a reasonable timeframe’. The constitutional implications for the EU and the UK of such actions would be gargantuan, not to mention the impact of a further erosion of goodwill between the UK and the other 27 Member States when entering into negotiations. It would be wise, if delay is sought, to find a constitutional requirement – the easiest being a constitutional convention of parliamentary deliberation.


Alison Young is an Associate Professor of Law and a Fellow of  Hertford College, University of Oxford.

(Suggested Citation: A.L. Young, ‘Brexit, Article 50 and the ‘Joys’ of a Flexible, Evolving, Un-codified Constitution’ U.K. Const. L. Blog (1 Jul 2016) (available at

27 comments on “Alison Young: Brexit, Article 50 and the ‘Joys’ of a Flexible, Evolving, Un-codified Constitution

  1. RL Gowers
    July 1, 2016

    “The people may have voted to leave the European Union, but there is no popular consensus as to what this entails, or the relative desirability of any particular withdrawal agreement. Parliamentary debate may help to further inform us about the benefits and burdens of EU membership – something which many commentators feel the referendum debate lacked. This may lead to further reflection on the possible aims of a withdrawal agreement, providing more democratic legitimacy for the Government charged with taking the negotiations forward.”

    This is bordering on arrogance. At worst, it’s incitement to violence and the rise of the far-right.

    The people voted Out, and as much as you or I may feel that that is a mistake, it’s essential that the democratic will of the people prevails; and they there’s no hint of a re-run or patronising “there there: are you actually sure you know what you *really* want?”

    • Nick
      July 1, 2016

      You read more into that section than I did. I read it as saying that while the people have decided that the UK should leave, there has been no decision on what our future relationship with the EU should look like: should we seek to remain members of the EEA, or EFTA, aim for a Canadian-style arrangement, or something else. A Parliament debate on the best *form* of leaving, would give a Government a mandate to seek *that particular relationship* in negotiations with the EU, something it currently lacks. I didn’t read that as arguing for Parliament to overturn the leave vote.

    • notthesunblog
      July 1, 2016

      I’m really not sure where you have inferred the arrogance or incitement to violence from. This is commentary of the reality that no specific plan was put forward by the Leave campaign.

      Surely the precise form Brexit will take should be determined, and then the electorate asked if that is what they want. Wouldn’t that be more democratic, not less, than using “the democratic will of the people” as an excuse to impose terms that no one wants?

      Take immigration/free movement of people as an example. If Brexit takes the form of EEA membership, we will still have free movement of people. Given that many people voted Leave in an attempt to gain control over EU migration, surely that would be a violation of their democratic mandate, not an enactment of it.

    • Allan D
      August 1, 2016

      Nach dem Aufstand des 17. Juni
      Ließ der Sekretär des Schriftstellerverbands
      In der Stalinallee Flugblätter verteilen
      Auf denen zu lesen war, daß das Volk
      Das Vertrauen der Regierung verscherzt habe
      Und es nur durch verdoppelte Arbeit
      zurückerobern könne. Wäre es da
      Nicht doch einfacher, die Regierung
      Löste das Volk auf und
      Wählte ein anderes? –

      “Die Lösung” – Bertolt Brecht

      [After the uprising of the 17th of June
      The Secretary of the Writers’ Union
      Had leaflets distributed in the Stalinallee
      Stating that the people
      Had forfeited the confidence of the government
      And could win it back only
      By redoubled efforts. Would it not be easier
      In that case for the government
      To dissolve the people
      And elect another? –

      “The Solution” (1953) – Bertolt Brecht]

  2. Adrian Carter
    July 1, 2016

    This is the most insightful and persuasive article I have yet read on the triggering of Art 50. I commend it to any other UK Constitution nerds.

  3. Mike Tremblay PhD
    July 1, 2016

    Alison Young wrote: “…, it is no exaggeration to classify the result of the referendum as creating a constitutional crisis. In these circumstances, the UK may be wise to learn from the experience of Canada, where the Canadian Supreme Court concluded that, whilst not illegal, it was unconstitutional to seek a constitutional amendment without consent from the Provinces of Canada.”

    Ignoring for now that the referendum act did not say what to do with the result, throwing us into this “bum’s rush” to the EU exit, the distinction between legality and constitutionality in the UK context might be worth more discussion.

    Canada has a constitution with separation (not devolution) of powers with provinces having autonomy in many areas; that Quebec is recognised as a distinct society with Canada illustrates this. One might argue that Cameron came back from discussions with the other EU states with that sort of agreement, which could be consistent with the Art 1 TEU pooled sovereignty (pooling does not dissolve sovereignty; it can produce granularity).

    When folks in the UK speak of the countries of the UK, they do so with a degree of pride and as evidence of the sophistication of the UK’s structure. However, the referendum result, that two of these countries voted to remain and two to leave, produced a split vote based on the constitutional make-up of the UK. We now have significant risk to the constitutional structure of the UK. It would be pointless for legality to allow a decision (trigger Art 50) which in the end destroys the UK and with it the authority of Parliament.

    One country, one vote, produces a very different situation which does avoid the English tail wagging the UK dog. It would seem appropriate for the UK Parliament to acknowledge the referendum results in the constitutional context of the countries rather than the whole before proceeding to do anything to leave the EU. In this respect the constitutional approach is more compelling.

  4. Steve Gwynne
    July 1, 2016

    The referendum result has produced a mandate under popular sovereignty which was provided through parliamentary sovereignty. Consequently, since the UK constitution is based on accumulative law, the referendum result forms a constitutionally sound basis on which an elected party can activate article 50.

    This is interesting since traditionally our British constitution has put sovereign power in the monarch in parliament and more recently sovereign power in parliament with monarch approval. This referendum however has constitutionally included sovereign power in the people which sets a constitutional precedence.

    So it might be the case that our supreme court may favour my argument over and above others since these other arguments not only deny the precedence of popular sovereignty but are also trying to deny that parliament has the sovereignty power to evolve the British constitution.

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  6. Mike Fearon
    July 1, 2016

    Maybe it is time to recognise that Barber et al are simply starting from a false premise. Notification of an intention to withdraw does not cut across a statute or render it nugatory. It notifies an intention to do so. To put that intention into effect requires due parliamentary process. An Act or Acts to repeal and/or amend legislation which conflicts with that intention has to proceed successfully through both Houses and gain Royal Assent. If that cannot be achieved, the intention changes, and the EU must be notified that it has changed. A General Election might well precede this.

    The horse and the cart perform better in the right order. Barber et al presume otherwise, but in terms of constitutional law they are wrong.

  7. Anthony Arnull
    July 1, 2016

    The triggering of Article 50 TEU would not in itself have any effect on the rights of EU citizens under the Treaties. Their rights would only be affected when the Treaties ceased to apply to the withdrawing State pursuant to Article 50(3). If resident in a Member State other than their own, they would continue to enjoy until that point, for example, the right ‘to vote and to stand as candidates in elections to the European Parliament and in municipal elections in their Member State of residence, under the same conditions as nationals of that State’ (Article 20(2)(b) TFEU).
    The possibility of proceedings under Articles 258 or 259 TFEU against a Member State which failed to invoke Article 50 TEU promptly can in my view be ruled out. A Member State decides whether or not it wishes to withdraw in accordance with its own constitutional requirements. It is for the State concerned to decide whether or not those requirements have been met. Failure to trigger Article 50 is a sign that they have not. In any event, a ruling against the State concerned would be futile. What would be the point of requiring it to take the steps necessary to comply with the judgment of the ECJ? Are we to imagine the Commission going back to the ECJ and asking for a financial penalty to be imposed?
    Nor can Article 7 TEU be deployed, at least not in the case of the UK, for contemplating withdrawal does not involve any breach of the values set out in Article 2 TEU.

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  15. Allan Draycott
    July 13, 2016

    Let us conduct a simple thought-experiment. Suppose, instead of the result of the referendum, which had been part of the Conservative Party manifesto in the 2015 General Election, had been 52-48% in favour of the UK remaining within the European Union instead of leaving and suppose also that a majority of MPs were in favour of leaving the European Union would Ms Young and her colleagues have still been arguing that the result of the referendum was “non-binding” and created a “constitutional crisis” that could only be resolved by a Parliamentary convention? I think not.

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  22. Sean Feeney
    October 14, 2016

    Like most UKCLA commentators, Alison Young simply ignores, or is ignorant of, legal authority of potentially very high relevance to statutory construction of the 2015 Act, namely Pepper v Hart [1993] AC 593.

    The potential relevance of this very well-known authority is increased by the fact that the defendant’s skeleton argument, published after this blog post, quotes from Hansard, giving clear statements from Government proposers that the intention of the Bill was to provide for a “decision”; and by the fact that the contention that the referendum was “advisory” is in issue in the proceedings.

    Other litigation parties rely on Parliamentary materials such as a Commons Briefing Paper and a report of the House of Lord’s Constitutional Committee to evidence their submission that the referendum was “advisory”.

    The Pepper v Hart test on admissibility was applied,by the Supreme Court, and therefore reaffirmed, in Assange (Appellant) v The Swedish Prosecution Authority (Respondent) [2012] 2 AC 471.

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