The fallout from the Supreme Court’s ruling in Miller keeps coming. As the previous blog discussed, parliamentarians are seeking to clothe the Government’s bare Brexit Bill – introduced to give effect to the Supreme Court’s insistence on statutory authorisation for the triggering of notice under Article 50 – with amendments intended to enhance parliamentary oversight of the withdrawal process. This week the Bill reaches its committee stage in the House of Lords, after which it will become clear what amendments, if any, will make it onto the face of the Bill and which of these, if any, will be accepted by the Government.

The Article 50 Bill seeks to close the loop on what Parliament omitted to do with the European Referendum Act 2015: to equip the Government with the legal power to begin the withdrawal process. The Supreme Court accepted the argument that once this process began, the UK’s withdrawal from the EU would lead to a loss or variance of rights which had made available in domestic law through the European Communities Act 1972. As such, only Parliament had the authority to authorise a process which could lead to the loss or variance of these rights.

In a recent intervention by a group of leading lawyers, including Sir David Edward (former judge of the Court of Justice), Sir Francis Jacobs (former Advocate General) and Sir Jeremy Lever – collectively the ‘Three Knights’ – it is suggested that Parliament’s involvement is not limited to the triggering of a notice of withdrawal under Article 50, paragraph 2. If, as they contend, a withdrawal decision must be taken in accordance with ‘constitutional requirements’ – the wording of Article 50, paragraph 1 – and if the UK’s constitutional requirement is for Parliament to give statutory authorisation for a loss or variance of rights, as it will not be known what rights will be lost or varied until the end of the Article 50 process, Parliament must legislate to either approve a withdrawal agreement or to allow the UK to leave without such an agreement. To put is simply, fidelity to ‘constitutional requirements’ does not begin and end with the triggering of notification; it continues through to the end of the process. The authors of this Opinion view this as the necessary implication of the Supreme Court’s ruling in Miller.

There is much that may be tempting, normatively, in this enhanced level of political control over Brexit. But there are six Potential Interpretative Problems (PIPs) that emerge from the Three Knights Opinion.

Problem 1 – Chronology

The words ‘constitutional requirements’ are only used in paragraph 1 of Article 50 in terms of the taking of a decision to withdraw. No further mention is made of it in respect of the notification obligation under paragraph 2, or the final withdrawal under paragraph 3. One interpretation of the Three Knights Opinion is that it assumes that the decision to withdraw has not yet been formally taken and only happens at the end of the process and so attracts the need to comply with ‘constitutional requirements’. However, as my colleague Mark Elliott has also pointed out,  that would change the sequence and chronology of Article 50 from decision, notification, withdrawal to notification, decision, withdrawal.

Problem 2 – Gap between Law and Politics.

It is not just that the sequence of things changes, the implication is that the decision to withdraw has not yet been made legally, even though a notification of an intention to withdraw could already have been sent. While politically the decision may have been made – after all we have a minister and a government department for Exiting the European Union, – if fidelity to constitutional requirements bites when a decision is made to withdraw, it follows that this decision has not yet been made or has only been made conditionally or contingently. That may not be a problematic interpretation for lawyers but for voters and politicians, that a decision to withdraw was made in accordance with a referendum for which Parliament had enacted legislation might have been thought enough to satisfy constitutional requirements.

Problem 3 – The ‘Silence’ of Article 50(3)

What has always been striking about Article 50 is that it stipulates that a withdrawal agreement can be concluded, by a Qualified Majority Vote of the Member States (with the consent of the EP). Unlike other provisions of the treaty including the treaty amendment process under Article 48 TEU which expressly require domestic approval in accordance with constitutional requirement, this language is entirely – and one has to assume consciously – absent from the wording of Article 50, paragraph 3. To read across the wording of Article 50 into the ‘silence’ of  paragraph 3 in the way that the Supreme Court did with regards to paragraph 2, would not only further stretch the wording and structure of Article 50, it would introduce wording that appears to have been deliberately omitted.

Problem 4 – defeating the logic of Miller

The crux of the Opinion is the idea that it is only at the end of the process when it is clear whether the UK will have a withdrawal agreement or not and what rights will be protected or lost. As such, this is the point when the UK’s constitutional requirements bite. However, the more that this is true, the more that it undermines the very logic at the heart of Miller, namely the acceptance of Lord Pannick’s analogy that once Article 50 is triggered, the bullet hits the target and the loss or variance of rights becomes inevitable. If the Three Knights are right – and their Opinion also rests on an assumption that Article 50 notification is revocable – then it is less clear that the claimants in Miller ought to have succeeded in their Article 50 litigation.

Problem 5 – We Have Constitutional Requirements

If there is a concern about what constitutional provisions ought to bite at the end of the Article 50 process, as the Three Knights Opinion makes clear, we do actually have constitutional practices which have been enshrined in legislation. The most relevant are the provisions of the Constitutional Reform and Governance Act (CRAG) 2010. This Act builds on a previous convention that the Government must lay the text of a treaty before Parliament before ratification. It acknowledges the potential risk that the Executive could enter into binding commitments under international law through treaties that Parliament could fail to give effect to in national law. Thus, Parliament is given sight of the treaty before it is ratified. Under the terms of CRAG, a resolution in either House of Parliament can delay, but only the House of Commons can block if it continually resolves that the treaty not be ratified. These domestic constitutional requirements are not, however, merely interesting examples of analogous constitutional practices that are triggered once international negotiations produce an agreement. These ARE the constitutional requirements provided by domestic law. They deliberately stop short of ceding control and power to Parliament to dictate what is or is not acceptable from the point of view of the loss or variance of domestic rights before the Government finalises its negotiations. The Executive does not negotiate according to a mandate set by Parliament. Rather Parliament exercises scrutiny over negotiations and has control before ratification. This is a question of constitutional design with which one can argue, but it is what it is: the constitutional requirements that currently apply.

Problem 6 – From Description to Prescription

Article 50, paragraph 1, describes a state of affairs: the decision to withdraw from the EU. It describes a right that exists in international law. As regards the ‘constitutional requirements’ that apply to a decision, it again describes a state of affairs: it assumes that states have constitutional arrangements and that decisions are taken in accordance with them. It would be quite wrong from both a domestic and an EU law perspective to read this as prescribing particular constitutional requirements. But equally, it becomes problematic to use this description as a bootstrap for suggestions that the UK should have certain constitutional requirements in the absence of compelling domestic legal arguments explaining what these requirements are and how such requirements are triggered. What would make the Three Knights argument more compelling is actually to detach the claim for parliamentary approval from the wording of Article 50 entirely. This would rightly acknowledge that what is or is not a constitutional requirement can only be answered by the domestic legal order as indeed are the circumstances which trigger those domestic constitutional requirements. This would also avoid linking the proposal to the difficult issue of when, legally, a decision to withdraw is made.

Viewed in this way, it may well be that UK constitutional law imposes constitutional requirements right across the notification, decision and withdrawal stages. But for the reasons given, it may not be possible to argue that statutory authorisation is needed at the decision stage because it undermines the argument for statutory authorisation at the notification stage. And the argument to read in constitutional requirements at the end of the process has to be reconciled with what UK law DOES already say in terms of CRAG, as much as what Article 50 DOESN’T say about adoption of a withdrawal agreement in accordance with national constitutional requirements.

The Three Knights Opinion is a provocation to think about the design of constitutional requirements but as it stands the Three Knights Opinion has its PIPs.

This post is based on remarks made to the Law Society, Copenhagen, Denmark 27 February 2017.