Yesterday, Matrix hosted a panel discussion on last week’s Supreme Court decision in R (Miller) v Secretary of State for Existing the European Union  UKSC 5. The panel consisted of three members of Matrix who appeared in the case: Helen Mountfield QC, Jessica Simor QC and Rhodri Thompson QC.
The discussion centred on three related issues:
- the impact of the decision on the royal prerogative and devolution in the UK;
- what the judgment means;
- whether a notification of withdrawal under Article 50 could be revoked.
Impact of the judgment on devolution
Rhodri discussed the impact of the judgment, including its implications for the future exercise of the royal prerogative. He expressed the view that the Court’s judgment reinforces the rule of law and the independence of the judiciary. On devolution aspects, it is important to point out that the Court ruled that there was no legal requirement to consult, let alone seek the consent of, devolved institutions. According to Rhodri, the judgment leaves unanswered questions on devolution issues which could lead to the government having more freedom in the Brexit negotiations. There was agreement on the fact that leaving the EU will change the competences of the devolved institutions.
What the judgment means
Helen identified three key principles from the reasoning of the Supreme Court’s decision:
- The Supreme Court emphasised and expanded on the Divisional Court’s conclusion that there is a clear dividing line between (a) the power of ministers who exercise the foreign policy prerogative of the Crown to make international treaties, and (b) the power to suspend or change domestic law, which has been vested in Parliament. This means that there is no prerogative power to change the content of domestic law even, if the domestic law in question has been made through a treaty.
- There must be some statutory authority to allow the Prime Minister (or Secretary of State) to withdraw from the EU. On this point, the majority of the Court concluded that section II of the 1972 Act was a “conduit pipe” by which EU law becomes a source of domestic law. Thus the continued existence of the conduit pipe, the Court considered, can be changed only if Parliament changes the law.
- The Court made it clear that EU law is a source of substantive individual rights, and that withdrawal from the EU is such a significant constitutional change that it cannot take place through the exercise of the prerogative alone.
The revocability of an Article 50 notification
After the Miller case, a key question for the next two years is whether the notification of intention to withdraw from the EU can be revoked. This question was not answered by the Supreme Court, very probably because the Miller case proceeded on the assumption that once the notification had been made it could not be revoked.
Jessica pointed out that that was a prudent approach by the claimants. The question is why the government did not argue that the notification is revocable, considering that this was the government’s strongest argument. The reasons are unknown but, as Jessica pointed out, one possible reason is that the case would have taken more time, given that the issue was not put forward before the Divisional Court, or that it would have been politically unacceptable for the Supreme Court to take a position on the issue or refer it to the European Court of Justice (the only court which could authoritatively decide whether the notification was revocable under EU law).
Whatever the reasons for not arguing the revocability of the notification, the fact is that the question remains open. Some prominent academics and commentators, including Lord Kerr, the UK official who drafted Article 50, take the view that the notification could be unilaterally revoked before the UK’s exit process is completed.
From an international law perspective that is, in my opinion, the correct approach. Article 68 of the Vienna Convention provides that a notification to withdraw from a treaty may be revoked at “any time before it takes effect”. So the question is not so much whether the notice of intention to withdraw is revocable from a legal perspective; the point is whether it is politically realistic for the UK to revoke the notification, given the position of the government and the vote of Parliament “to deliver on the decision taken by the people of the United Kingdom”. In my opinion, it appears highly unlikely from a political perspective that the notice could be revoked, event if the result of the Brexit negotiations results in a cliff-edge scenario.