Campaigners have won their High Court battle over Theresa May’s decision to use the royal prerogative in her Brexit strategy.
In one of the most important constitutional cases in generations, three senior judges ruled the Prime Minister does not have power to use the prerogative to trigger Article 50 of the Lisbon Treaty to start the UK’s exit from the European Union – without the prior authority of Parliament.
The ruling against the Government was made by Lord Chief Justice Lord Thomas, sitting with two other senior judges in London.
Unless overturned on appeal at the Supreme Court, the ruling threatens to plunge the Government’s plans for Brexit into disarray as the process will have to be subject to full parliamentary control.
Government lawyers had argued that prerogative powers were a legitimate way to give effect “to the will of the people” who voted by a clear majority to leave the European Union in the June referendum.
But the Lord Chief Justice declared: “The Government does not have power under the Crown’s prerogative to give notice pursuant to Article 50 for the UK to withdraw from the European Union.”
The Government has been given the go-ahead to appeal against the ruling at the Supreme Court but made no immediate announcement about whether it will.
International Trade Secretary Liam Fox told the House of Commons that the Government was “disappointed” at the High Court ruling, but remained “determined to respect the result of the referendum”.
The ruling was welcomed by opponents of a “hard Brexit”.
Liberal Democrat leader Tim Farron said the Government must now lay out its negotiating position in Parliament, while Scottish First Minister Nicola Sturgeon described the finding as “significant indeed”.
But Ukip leader Nigel Farage said he feared that “a betrayal may now be near at hand”, warning he had “a distinct feeling” that the political classes “do not accept the June 23 referendum result”.
“I now fear that every attempt will be made to block or delay the triggering of Article 50,” said Mr Farage. “If this is so, they have no idea of the level of public anger they will provoke.”
The judge – sitting with the Master of the Rolls, Sir Terence Etherton, and Lord Justice Sales – emphasised to a packed court that he was deciding “a pure question of law”.
He added: “The court is not concerned with and does not express any view about the merits of leaving the European Union: that is a political issue.”
Mrs May announced at the Conservative Party conference that she intends giving an Article 50 notification by the end of March 2017.
Her opponents were “concerned citizens” drawn from all walks of life, with the lead challenge brought by investment fund manager and philanthropist Gina Miller.
Outside the Royal Courts of Justice Ms Miller was greeted by rounds of applause. She said she hoped the Government would now “make the wise decision of not appealing”.
Pound rises on news
The pound rose sharply following the High Court decision.
The ruling saw sterling shoot past $1.24, up nearly 1% on the day.
Neil Wilson, markets analyst at ETX Capital, said: “Most MPs are natural Remainers, although they would face intense pressure from constituents to deliver the referendum mandate.”
