As anticipated, the Supreme Court has upheld the High Court’s judgment by ruling (albeit on an 8 to 3 majority) that an Act of Parliament before UK government ministers can lawfully trigger the Article 50 notice procedure for leaving the EU.
The majority accepted the respondents’ view that, by virtue of the European Communities Act 1972, the EU became an independent source of UK law, which would be cut off at the point of exit, with the results that rights enjoyed by UK residents will change. This would represent a fundamental change to the UK’s constitutional arrangements, and that cannot be done without primary legislation.
The Supreme Court also found that withdrawal from the EU is a matter for the UK’s parliament and government. There is no legal obligation to consult devolved administrations and the Sewell convention, which concerns devolution, is a political matter that’s not justiciable before the courts.