WHEN the Scottish Parliament was established in 1999, the UK Parliament’s sovereignty was unaffected. Still, the minister in charge of the Scotland Bill, Lord Sewel, declared that he expected a convention to develop whereby Westminster would not normally legislate in relation to devolved matters without Holyrood’s consent. The Sewel Convention is a crucially important part of the UK’s devolution arrangements, providing the major constitutional protection for the devolved institutions’ autonomy. In recognition of its constitutional significance, the Smith Commission recommended that it be placed on a statutory footing.

Brexit has tested the Sewel Convention almost to destruction. First, in the Miller (Article 50) case, the UK Supreme Court held that statutory recognition of the Convention in the Scotland Act 2016 had had no legal effect. Now, in relation to the European Union (Withdrawal) Bill, it appears Westminster will, for the first time, legislate on what is accepted to be a devolved matter without devolved consent.

The dispute over the Withdrawal Bill concerns what will happen, post-Brexit, to decision-making powers at EU level. Since EU competences straddle the division of powers between the UK and devolved levels, it was expected that the devolved legislatures would gain at least some new powers. However, when the Bill was published, it provided that all returning competences would go to the UK level, although UK ministers might re-devolve some powers at an unspecified time. For the UK Government, this was necessary to enable new “common frameworks” to be established after Brexit to ensure, for instance, that people could continue to trade freely within the UK. For the Scottish and Welsh governments, this was an unacceptable “power grab” and they refused to agree to the Bill. After lengthy negotiations, the UK Government has shifted its position considerably: amendments to the Bill provide that all returning EU competences in devolved areas will default to the devolved level, subject to a power for UK ministers to reserve, temporarily, certain powers to the UK level. This was enough for the Welsh Assembly to accept the Bill. The Scottish Parliament, by a vote of 93 to 30, has continued to object. The sticking point is consent. While powers can only be taken back to the UK level if Holyrood has made a “consent decision”, such a decision may include a refusal of consent or even a failure to consider the matter.

Usually, if devolved consent to a Bill is refused, the offending provisions would be removed. However, both Houses of Parliament have agreed to the amended clause, drawing protests from SNP MPs and the Scottish Government that the Sewel Convention has been breached. The UK Government rejects this, pointing out that the Convention provides that consent is only “normally” required, and Brexit is anything but normal.

UK ministers have not provided any serious constitutional justification for ignoring Holyrood’s view. A convention is not legally binding but it is still a constitutional rule. To make an exception to a rule, an explanation is required of why its underlying rationale either does not apply or is overridden by a competing principle. The UK Government seems simply to be saying that, so long as it tried to reach agreement with the Scottish Government, the Convention is satisfied. This is a radical re-reading of the Sewel Convention that would seriously undermine the protection it offers for devolved autonomy. Supporters of devolution should be very concerned about what happens next.