SCOTTISH judges have said the European Court of Justice should be asked for a ruling on whether the UK can cancel Brexit unilaterally – in a judgment that is sure to infuriate Brexiteers everywhere.

Scotland’s most senior judges in the Court of Session allowed an appeal by Andy Wightman MSP, Ross Greer MSP, Cathy Stihler MEP, David Martin MEP, Alyn Smith MEP, and Joanna Cherry MP – two Greens, two Labour and two SNP members respectively – and Jolyon Maugham QC against an earlier court decision that the case could not be taken to the European Court.

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The anti-Brexit politicians argue that Article 50 can be revoked if MPs vote to do so. The UK Government had earlier told the court that the matter was hypothetical because it had no intention of cancelling the Article 50 process.

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Delivering the appeal court’s verdict, the Lord President, Lord Carloway, stated that authoritative guidance on whether it is legally possible to revoke Article 50 unilaterally “may have the capacity to influence Members of Parliament in deciding what steps to take in advance of, and at the time of, a debate and vote on the European Union (Withdrawal) Bill.”

He added: “After all, if Parliament is to be regarded as sovereign, the Government’s position on the legality of revoking the notice may not be decisive.”

Ruling that the petition was competent, the crucial paragraphs in Lord Carloway’s written judgment stated: “It is clear, in terms of the European Union (Withdrawal) Act 2018, that MPs will be required to vote on whether to ratify any agreement between the UK Government and the EU Council.

“If no other proposal is proffered, a vote against ratification will result in the UK’s departure from the EU on 29 March 2019; a date which is looming up. It seems neither academic nor premature to ask whether it is legally competent to revoke the notification and thus to remain in the EU.

“The matter is uncertain in that it is the subject of a dispute; as this litigation perhaps demonstrates. The answer will have the effect of clarifying the options open to MPs in the lead up to what is now an inevitable vote.

“Whatever the interest of MSPs and MEPs, MPs have an interest in seeing the matter resolved. On that basis the petition is competent at least at the instance of an MP.”

That sole MP is Joanna Cherry QC, SNP member for Edinburgh South West.

She said: “I’m delighted that Scotland’s Supreme Court has unanimously agreed with myself and my fellow petitioners that it’s vital for MPs to know whether Article 50 is unilaterally revocable before they are asked to ratify any agreement between the U.K. and the EU Council.

“Given Theresa May’s humiliation in Salzburg yesterday the answer to this question is particularly important.

“I look forward to the Court of Justice of the European Union’s ruling.”

Alyn Smyth tweeted: “Scotland’s Court of Session has agreed to refer our case to the European Court of Justice in Luxembourg for a ruling on how to revoke Article 50. Brexit is not inevitable, there is still time to change course.”

Elaine Motion, executive chairman of law firm Balfour+Manson, which has acted directly for the petitioners, said: “This is the most significant legal development in the Brexit process since the High Court ruled that Parliament had to legislate before the Government could invoke Article 50.

“This latest decision means the UK Parliament will get clear guidance from the European Court of Justice about the precise powers open to it when it is asked to vote on the Brexit deal. The decision will also provide helpful guidance to the European Parliament and to the devolved governments of the UK.”

The UK Government said it was “disappointed” by the appeal court decision and would be considering its response.