The UK Supreme Court rules that the Government cannot trigger Article 50 without a vote in Parliament.

Following the June 2016 referendum, the UK Government proposed to use its prerogative powers to withdraw from the EU by serving a notice in accordance with Article 50 of the Treaty on European Union, withdrawing the UK from the EU treaties.

In November 2016, the High Court ruled that the Government does not have the power under the Crown’s prerogative to give notice pursuant to Article 50, requiring a vote by Parliament to give notice. The Government appealed that judgment.

References from Northern Ireland, and interventions by the Lord Advocate for the Scottish Government and the Counsel General for Wales for the Welsh Government, raise the additional issues of whether the terms on which powers have been statutorily devolved require consultation with or the agreement of the devolved legislatures before serving a notice in accordance with Article 50, or otherwise operate to restrict the Government’s power to do so (“the devolution issues”).

The UK’s highest court, by a majority of 8 to 3, has today dismissed the Government’s appeal over whether Article 50 can lawfully be triggered without a vote by Parliament. In a joint judgment of the majority, the Supreme Court holds that an Act of Parliament is required to authorise ministers to give notice of the decision of the UK to withdraw from the EU.

On the devolution issues, the Supreme Court unanimously concludes that relations with the EU and other foreign affairs matters are reserved to UK Government and Parliament, not to devolved institutions. The Supreme Court rules that the devolved legislatures do not have a veto on the UK’s decision to withdraw from the EU.

The Supreme Court’s ruling was widely expected, and the Attorney General has confirmed that the Government will “comply with the judgment of the Court and do all that is necessary to implement it”. The bill to be published by the Government is expected to be short, but both the House of Commons and House of Lords will have to vote in favour of it.

Although the Liberal Democrats, the SNP and some Labour MPs are likely to vote against the Government’s bill, few Conservative MPs are likely to vote against it, and it is likely that the bill could pass through the House of Commons before the half-term recess in February. How smoothly the bill would pass through the House of Lords, however, is less predictable. Amid warnings that any attempt to block the EU referendum result could trigger a general election, it is likely that the House of Lords will eventually pass the bill.

The full judgment can be found here.