UK Constitutional Law Association

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Robert Brett Taylor: Constitutional Conventions, Article 50 and Brexit

Robert Brett TaylorFollowing the result of the referendum on British membership of the European Union, constitutional commentators have been embroiled in a discussion over the legal basis on which withdrawal from the EU can take place, in particular whether parliamentary approval is legally required before Article 50 of the Treaty on European Union can be triggered.  The purpose of this post is not to explore these arguments in great detail, however, but to comment upon a point raised principally by Alison Young, but also in passing by Mark Elliott, regarding the possibility of a constitutional convention – a politically-binding rule – regulating the use of Article 50.

In my view, it seems likely that the power to trigger Article 50 and withdraw from the EU remains legally with the Government under the royal prerogative, and not with Parliament.  Although it is conceded that an Act of Parliament amending or repealing the European Communities Act 1972 would eventually be needed in order to give domestic effect to EU withdrawal – thus de facto inviting Parliament to give its consent to EU withdrawal – this fact does not legally bar the Government from withdrawing the UK from its international obligations under the EU treaties prior to this.  Consequently, although parliamentary consent is preferable for democratic reasons, there is nevertheless no legal requirement for prior parliamentary deliberation or approval before Article 50 can be triggered.  The absence of any legal obligation, however, does not necessarily preclude the Government from any political obligation.  If the power to trigger Article 50 remains in the hands of the executive under the prerogative, without any legal requirement of prior parliamentary deliberation or approval, a constitutional convention would provide the only means by which Government could be compelled to consult Parliament before withdrawing.

The existence of any such convention at present, however, appears unlikely.  Indeed, as observed by Young, there is no precedent for any convention requiring prior parliamentary deliberation for the use of Article 50.  Despite this, however, Young looks to the alleged convention requiring prior parliamentary deliberation and approval for the deployment of armed forces for support of a convention regulating Article 50.  Whilst Elliott acknowledges the lack of any equivalent convention in relation to Article 50 at present, Young nevertheless argues that a convention may have arisen by analogy.  This may be the case, she argues, because the convention regulating the deployment of armed forces demonstrates that a democratic mandate is needed before a prerogative power, in particular a controversial one with huge constitutional repercussions, can be exercised.  Even if a convention cannot be established on this basis, Young nevertheless argues that the Government may yet seek to initiate one, and that a convention would be the easiest way of securing parliamentary approval.  Similarly Elliott, although conceding the absence of any recognised convention regulating the use of Article 50, argues that there is a strong normative argument for, and perhaps expectation of, parliamentary involvement which, if not currently manifested as a convention, could certainly form the basis of one in the future.

By drawing an analogy, Young suggests that the circumstances surrounding and implications of the two prerogative powers are so similar as to warrant similar treatment.  In other words, if one controversial prerogative power is subject to parliamentary deliberation if not approval, so should another equally controversial power.  On this reading, precedent for the claimed convention need not be direct but indirect, and as Young correctly notes herself, a new convention must start somewhere.  It is submitted, however, that whilst the prospect of conventions arising by analogy is an intriguing notion based upon sound reasoning, analogical precedent does not in and of itself guarantee the existence of a convention.  By definition, precedent by analogy does not show evidence of a pre-existing rule, but instead simply strengthens the normative case for the adoption of a rule.  In any event, the argument in favour of either the existence or adoption of such a rule may also be undermined by the precedent cited in support.  Whilst there is growing evidence that there is a convention requiring prior parliamentary deliberation if not approval before the deployment of armed forces, doubt nevertheless persists, and the scope of the convention remains open to debate.  It is a persuasive, but nevertheless imperfect, precedent.

It is certainly possible, however, for a convention to emerge quickly, or for it to be declared as in the case of the Sewel Convention (See A. McHarg, ‘Reforming the United Kingdom Constitution: Law, Convention, Soft Law’ (2008) 71(6) Modern Law Review 853).  Conventions, as argued by Jennings, ‘provide the flesh which clothes the dry bones of the law; they make the legal constitution work; they keep it in touch with the growth of ideas.” (Sir W. I. Jennings, The Law of the Constitution, 5th edn (London: University of London Press, 1960), pp.81-82).  In other words, conventions are designed to keep the law up-to-date with political expectations without having to change the law.  It is thus possible that a convention has arisen since the result of the referendum on 23rd June as a consequence of Article 50 now having to be triggered.  It did not and could not exist before, because Brexit was only a mere possibility, not a reality.

Alternatively, the rule requiring parliamentary deliberation or approval could be an example of what I call a ‘latent convention’ (see R.B. Taylor, ‘Foundational and Regulatory Conventions: Exploring the Constitutional Significance of Britain’s dependency upon Conventions (2015) Public Law (Oct) 614-632).  Latent conventions are rules, mostly concerning matters of constitutional principle such as human rights, which exist under the constitution, but which do not fully emerge as conventions if and until someone tries to act contrary to them.  Had the referendum result on 23rd June been different, however, we may never have considered the question of how and when Article 50 can be triggered under our existing constitutional rules.  It is thus unlikely that a latent convention exists under the constitution regulating the use of a specific treaty provision, the triggering of which may never even have arisen had the referendum result been different.  Despite this, the use of Article 50 clearly raises issues of democratic legitimacy and accountability over the unilateral use of the prerogative by the Government.  A better argument for subjecting the use of Article 50 to prior parliamentary deliberation or approval, therefore, may be to say that there exists a principle under the constitution, embodied by a latent convention, which stipulates that all exercises of the prerogative, or at least the most controversial ones, should be subject to parliamentary deliberation and approval.  Attempts to subvert the rule may then allow the latent convention to manifest and receive explicit recognition by political actors.

Despite these possibilities, however, it is important to stress that the existence of any convention is dependent upon those to whom they purport to bind believing themselves to be bound by it in any precedents.  For our purposes, this means Her Majesty’s Government, in particular the Prime Minister.  Even in the absence of any precedents, it is submitted that this remains an important factor in determining the likelihood of any convention emerging.  Should the Government not believe itself to be bound by a convention, there cannot be one.  Should the Government not want to be bound by a rule, it will not introduce one.

Despite the strength of the arguments in favour of a new convention, therefore, it remains unclear whether the Government would intentionally chose to limit itself, irrespective of the democratic arguments.  Ideally, the Government’s adherence to a convention should be motivated by threat of political sanction emanating from both Parliament and the wider public.  Whilst the Government’s majority within the House of Commons may normally minimise any threat of political sanctions, such as a vote of no confidence for instance, the Conservative Party’s slim majority, as well as the divisive nature of the referendum result, particularly among MPs, may make prior parliamentary deliberation or approval more likely.  Whether or not prior parliamentary deliberation or approval will actually occur, however, will depend upon several factors: the extent to which the new Conservative Prime Minister Theresa May can maintain party discipline; the outcome of the recent challenges to the leadership of the Labour Party; whether an early election will be called; the EU’s response to Brexit; as well as the ever-changing economic climate, to name but a few.

The existence of any convention regulating the Government’s use of Article 50, therefore, is dependent upon its acceptance by the Government, which itself will turn upon the political events of the coming weeks and months.  In the aftermath of the referendum result, therefore, it is clear that the British constitution at present remains a primarily political one governed, not by clear constitutional laws, but by everyday politics conducted, admittedly, during extraordinary times. Consequently, in line with British constitutional traditional, the rules governing British withdrawal from the EU will simply not be known if and until withdrawal occurs.  As argued by Roger Masterman and Colin Murray, however, the result of the referendum on 23rd June has brought into question the desirability and validity of the UK’s current constitutional arrangements which, they say, may not survive the coming political and legal battles.

Dr Robert Brett Taylor is a Lecturer in Law at the University of Aberdeen.

(Suggested citation: R.B. Taylor, ‘Constitutional Conventions, Article 50 and Brexit’, U.K. Const. L. Blog (15th Jul 2016) (available at

5 comments on “Robert Brett Taylor: Constitutional Conventions, Article 50 and Brexit

  1. Laypersonlaw
    July 15, 2016

    Under the terms of Article 50 only a country that has “decided” to leave can invoke the process it defines.
    The referendum is not legally binding because Parliament did not include provisions in the relevant Act that would make it so.
    Therefore, before the matter of invocation arises the matter of turning the referendum “opinion” into a legal “decision” must first be resolved.
    Having reserved such a matter for itself, Parliament has to be the arena for such a decision. Prerogative powers cannot be used to turn the outcome of a referendum Parliament designed to be advisory into a legally binding decision.
    No decision, article 50 does not – yet – even apply to the UK. So no right to invoke it, yet.
    Parliament has to debate and make the referendum opinion into a decision therefore.

  2. Iain Jamieson
    July 15, 2016

    In considering whether Parliamentary approval is required, as a matter of law,convention or expediency, before triggering Article 50 which will result in the withdrawal of the UK from the EU, is it not relevant to take into account the fact that parliamentary approval was given in October 1971 to the UK joining the EC and the terms on which it should do so BEFORE Sir Edward Heath signed Treaty of Accession in January 1972? Is it not therefore likely that there will be a parliamentary vote taken, in due course, before Article 50 is triggered and,even on the broad terms on which the Government would be seeking to negotiate our withdrawal from the EU?

  3. spinninghugo
    July 15, 2016

    There is a Convention against wearing a hat in church.

    Does that mean there is also a Convention against wearing a tie, “by analogy”?


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