Legislative consent is a fundamental part of the United Kingdom’s territorial constitutional arrangements. The self-denying ordinance of the UK Parliament that it will “not normally” legislate with regard to devolved matters without the consent of the relevant devolved legislature is a non-legal constitutional constraint.
This “Sewel Convention” applies when the UK Parliament wants to legislate with regard to the powers of the devolved legislatures or executives of Scotland, Wales and Northern Ireland. Under the terms of the Convention, the UK Parliament will not normally do so without the relevant devolved legislature having passed a legislative consent motion.
Although the Convention originally arose in relation to devolution for Scotland in the late 1990s (it was named after the then Scottish Office Minister Lord Sewel, who first described it), the rule and principle it embodied was neither new nor confined to the relationship between the Scottish Parliament and Westminster. In Northern Ireland between 1921-72, a similar convention was in place, which later applied to the Northern Ireland Assembly after 1999, as it did to the then National Assembly for Wales.
The Sewel Convention is precisely that, a convention. Although a statement of that Convention was included in the Scotland Act 2016 and the Wales Act 2017, it is not considered to be legally binding, something confirmed by the Supreme Court in its Miller judgement. Until recently, the Convention was relatively uncontroversial, but following the 2016 Brexit vote it became more contested. The Scottish Parliament withheld consent for the European Union (Withdrawal) Act 2018, and all three devolved legislatures withheld consent for the European Union (Withdrawal Agreement) Act 2020. Both were nevertheless passed by the UK Parliament.
The Convention has, therefore, attracted a measure of criticism, mostly from the Scottish and Welsh Governments, who argue that the UK Government has breached both its letter and spirit. This briefing paper explores the origins of the Sewel Convention, its development under the three devolution settlements, its application to Brexit legislation and proposals for reform.
[CG1]URL and/or footnote citation [2017] UKSC 5