The only relevant question now left for the UK about the Art 50 notification is what needs to be done before it is given. It is politically inevitable that the referendum result will be accepted and the notification given, perhaps in January next year.

There has been a lively discussion, to which I have contributed, in response to the post by Nick Barber, Tom Hickman and Jeff King arguing that there is a legal obligation to get Parliamentary approval first. Their argument is interesting and well presented; but it is for Parliament itself, not the courts, to ensure that the Government allows it to exercise the influence it should have, and to decide what that is. I hope and expect that the courts will exercise restraint and not arrogate to themselves the task of defining, and so limiting, the nature of Parliament’s proper relationship with Government.

However, although I believe it would be legal for the Art 50 notification to be given without Parliamentary approval, there are other reasons for not adopting that course. There is also a good case for getting more from Parliament before the notification is given than just an acceptance of the referendum result. I shall outline at greater length than has been possible as part of the discussion on the Barber, Hickman and King argument.

Alison Young and Mark Eliot and, now, Robert Brett-Taylor have discussed the role of constitutional convention in identifying the UK’s constitutional requirements for the purposes of Article 50; but there is more to whether there is a relevant, non-legal, constitutional requirement than an analysis based on a relatively rigid, legalistic definition of constitutional conventions. The traditional, lawyer’s approach to conventions, which wants to crystallise them into rules with defined exceptions and flexibilities, cannot easily accommodate the practical reality of UK constitutionalism: that constitutional implications for an issue mean that in practice decisions engaging that issue require stronger justifications and wider political support than more run-of-the-mill political decisions. Moreover, there are already existing constitutional principles about the anticipation of legislative decision- making with executive action that are applicable in this case, are more relevant than the military action precedents and were discussed in a 2013 report of the House of Lords Constitution Committee.

I am another of those who (as I argued in evidence to the Political and Constitutional Reform Select Committee in 2015) believes that the UK’s unwritten constitution is best analysed in terms of politics, and that that is a good thing. In that analysis, a constitutional issue arises whenever the political objections to something, or to a way of doing it, are likely to include a significant consensus that the proposed course of conduct is incompatible with the premises of our constitutional system, or generally with “our way of doing things”. It is good sense, both politically and practically, to avoid unnecessary engagement with constitutional issues of that sort. If engagement is unavoidable, there needs to be a strong, politically sound justification that can outweigh and hopefully mitigate any price that the engagement requires to be paid in terms of the loss of political capital, the use of more Parliamentary time or the disruption of the stability and predictability of the system.

The real constitutional issue here is about the pre-emption of the Parliamentary consideration of the legislative issues involved in Brexit.

The termination of UK membership of the EU will cause legal chaos unless Parliament has first passed a Bill that can come into force on exit. An Article 50 notification sets a deadline for the passing of the Bill and potentially affects what it should say. Those matters are put substantially outside UK control — unless the notification is in fact revocable; and it is politically impossible for the UK to ask if it is, or for the question to be answered authoritatively.

It would be constitutionally irresponsible for the Government to take an irrevocable step to begin a process without being wholly confident that it will, in practice, be able to secure the legislation to complete it in an orderly way and on time. The accepted constitutional responsibilities of the Government in the unwritten, political constitution certainly include avoiding the creation of chaos in the UK legal system. Nor should the UK put itself in a position where it might be forced to make concessions in the negotiations to secure more time for an orderly implementation.

Legal chaos would result if an Art 50 notification expired without new UK legislation in place because directly applicable law would cease to apply in the UK immediately on the exit that follows automatically on the expiry of the notification. Directly applicable law only applies in EU member States. Furthermore, there is a strong legal argument that implementing UK regulations under s. 2(2) of the 1972 Act would also cease to have effect in relation to times after exit. The power to make those regulations is contingent on the existence of the obligation on the UK, as a member State, to maintain laws giving effect to the relevant EU rules. Once the obligation expires with the termination of membership, it is as if the power to make the regulations is repealed. The effect of repealing a power under which regulations are made is that the regulations cease to have effect for the future. Section 16 of the Interpretation Act 1978 saves the operation of the regulations in relation to pre-repeal cases, but not their continuing effect. Only a Bill passed before exit could prevent that default rule from applying.

Chaos is the inevitable result if extensive parts of UK law suddenly stop working without being replaced. Most EU rules are integrated into our system and interact with the operation of domestic law. In many cases EU rules do a job that would need to be done, one way or another, by UK law if it was not already done for EU purposes. Some EU laws will need to be kept in place to comply with the terms of exit, or to enable us to take advantage of them. Other problems need statutory solutions if legal confusion is to be avoided. If EU provisions need to be saved, how do they work if eg they have effect in relation to connections with “other member States”? How far should UK law originally deriving from EU law, so far as it survives, continue to be construed in its EU context? What relevance should ECJ judgments, past and future, continue to have on the construction of law with an EU inspiration?

A single Bill could apply a transitory patch – keeping most things in place, with general transitional modifications – until later primary or secondary legislation can produce more comprehensive solutions. But there will undoubtedly be demands for more of the detail to be settled early. It will be difficult, in practice to prevent a consideration of the issues involved in any later legislation from arising during the passage of a paving, patching Bill; but, if the legislation is not to become totally unwieldy, some matters are bound to have to be postponed and so patched in the meantime.

Whatever course is adopted, the difficulty for the Government is whether it can be sure to have the Bill in place for the earliest time when exit may occur. It is not going to be possible to know all the detail that will be needed before the terms of exit are settled; and unless the other EU states acquiesce in a delay (which cannot be relied on), there is unlikely to be enough time to get a Bill through both Houses after the exit negotiations are completed, even assuming no need to factor in the possibility of having to use the Parliament Acts.

So the exit legislation will have to begin its progress before exit terms are agreed. But the less that is known about the terms while the legislation is passing, the more permutations have to be covered and the wider the debate on them will be able to range. The legislation, even if it goes beyond a simple patch, will probably still need to include very wide powers to make subordinate legislation: to allow for different potential outcomes from the negotiations, and generally for the widespread nature of the required changes. The wider the powers the greater the potential for controversy during the Bill’s passage.

Complicating the process of getting an Act in place by engaging the constitutional issue whether it is a constitutionally inappropriate pre-emption of Parliament for an Art 50 notification to have been given in advance of a Parliamentary commitment to the necessary legislation is only going to make it that process more difficult The House of Lords, rightly or wrongly, claims a right to be more interventionist when constitutional issues are engaged, and its Constitution Committee has already taken a position on the use of executive powers to begin the implementation of policies before the passage of the legislation needed to complete their implementation. In that context something more than a mere commitment from Parliament to respect the referendum result would more securely guarantee a timely passage of the necessary legislation.

It is not that it is never possible or justifiable to pre-empt Parliament with executive action. Sometimes it is sensible or unavoidable. But a clear and politically convincing and practical justification is needed, as well as some reliable indication that Parliament accepts the necessity of taking the executive action. The best justification would be to show that as much as can reasonably be expected in the circumstances has been done to avoid pre-empting Parliament’s role in the implementing legislation. On that basis, the earliest an Art 50 notification should be given would, perhaps, be after some form of workable paving Bill for implementation has received at least a second reading in the Commons.

The practicalities suggest that getting such a Bill through would be facilitated by persuading other EU states to open negotiations before the giving of the Art 50 notification (on the grounds that that would hasten, rather than delay, the process) and, in the meantime, not committing irrevocably to a particular date for giving the notification. It needs to be made clear that our “constitutional requirements” for giving the notification go beyond matters of law and that there are significant obstacles to satisfying the constitutional pre-conditions for doing so, and a significantly greater risk of delay, while a refusal to negotiate requires Parliament to be kept in the dark about what is possible in terms of an exit deal.

Stephen Laws was the First Parliamentary Counsel 2006-2012 and is an  Honorary Senior Research Associate, University College London, and Senior Associate Research Fellow, Institute of Advanced Legal Studies.

(Suggested citation: S. Laws, ‘Article 50 and the Political Constitution’ U.K. Const. L. Blog (18th July 2016) (available at: https://ukconstitutionallaw.org/)).