Charles Livingstone clarifies the Supreme Court’s stance on Sewel in the wake of the Brexit judgment.

Last month, the Supreme Court ruled 8:3 that the UK government requires an act of the UK parliament before giving notice, under Article 50 of the Treaty on European Union, to begin the Brexit process. However, given that the European Union (Notification of Withdrawal) Bill has already passed through the House of Commons, the court’s decision on the other constitutional issue it was asked to consider may turn out to be more significant.

That issue concerned the constitutional role of the Scottish Parliament and other devolved institutions in relation to the Brexit legislation. The Lord Advocate argued the constitutional convention whereby Westminster will not normally legislate on devolved matters without Holyrood’s consent (the “Sewel convention”) applied, because Brexit would have the consequence of altering Scots law in some devolved areas and expand the Scottish Parliament’s powers. While the Supreme Court declined to agree with the Lord Advocate, subsequent media reports and commentary have mischaracterised the decision.

The court did state that the Scottish Parliament has no “legal veto” on Brexit, but the Lord Advocate had conceded that point in advance. Instead, he asked the court only to declare that the Sewel convention would apply to Article 50 legislation. That would have made legislating without consent more difficult politically, but the legal validity of the UK legislation would never have been in doubt.

While the court refused to make that declaration, it did not decide that the Sewel Convention was inapplicable. It avoided that substantive question by saying that the application and scope of constitutional conventions are not matters for the courts (ie not “justiciable”).

Conventions instead belong in the political arena, where it is for other (political) institutions and ultimately the voters to enforce them. Section 28(8) of the Scotland Act 1998, which “recognised” that Westminster “will not normally” legislate on devolved matters without consent, did not affect that conclusion.

In declining to decide whether the convention applied, the Supreme Court simply put the question back into the political arena. It is therefore somewhat surprising that the Scottish government held last week’s Scottish Parliament debate on the UK Article 50 Bill without a legislative consent motion (“LCM”, the mechanism by which Holyrood consents to UK legislation). The resulting vote against the Bill would therefore seem to carry less weight (at least constitutionally) than it might have.

The Scottish government may have taken its lead from certain aspects of the court’s decision, in particular, the judgment stated that “the devolved legislatures do not have a parallel legislative competence in relation to withdrawal” from the EU. Lord Neuberger, delivering the summary from the bench, added that “relations with the EU are a matter for the UK government”. These statements seem to support the UK government’s position that the Article 50 Bill is not legislating with regard to devolved matters, notwithstanding its potentially significant consequential effects in devolved areas.

On the other hand, the court also noted that removing EU constraints on the Scottish Parliament will “enhance” and “enlarge” its competence. This could support an argument for legislative consent, as the UK parliament has not normally legislated to change devolved institutions’ competence without consent and that practice had been regarded as having convention status.

However, the Supreme Court only recognised the narrower convention (on legislating in devolved areas) notwithstanding that the Lord Advocate defined the convention as including both aspects. The court may therefore only view the practice of seeking consent for varying devolved competence as just that: a practice, not rising to the level of a convention. That would be a significant change from the constitutional position as previously understood, and casts doubt on the constitutional requirements applying to future changes in devolved competence.