The Attorney General will on Monday warn Supreme Court judges that they must not defy the “will of the electorate” or “stray into areas of political judgement” during a landmark Brexit legal challenge.
Jeremy Wright will say the judges must “resist” intervening in a matter of significant “political sensitivity” as they decide on whether Theresa May has the power to trigger Brexit negotiations without a vote by MPs.
He will say that people who voted for Britain to leave the European Union did so on the “clear understanding” that the Government had the power to implement the vote without “further approval of Parliament in yet further primary legislation”.
The Liberal Democrats are already plotting to overturn the EU referendum result by voting against legislation to trigger Brexit in Parliament if the Government loses the court case.
Ministers are privately already conceding that the Government is likely to lose the case and warning that the Supreme Court will create a “constitutional crisis” when it returns its ruling in January.
© PA Attorney General Jeremy WrightThe Telegraph understands that they are examining plans for Supreme Court judges to be forced to make public more information about the political interests of both themselves and their family members.
It comes after Lord Neuberger of Abbotsbury, President of the Supreme Court, faced calls to recuse himself from the case after it emerged that his wife had called the referendum “mad and bad” on Twitter.
Lady Hale, the court’s deputy president, also faced criticism for a speech ahead of the Brexit case where she questioned whether a new law along was enough to start Brexit negotiations.
Iain Duncan Smith, the former Work and Pensions Secretary, said: “The High Court called into question that the British people have the sovereign right to make this decision.
“If people aren’t careful we will be left with rule making by unelected judges. This is a political matter.
“It is a much more important debate than just Europe. If the judges go down this road they are placing themselves above Parliament. It will create a serious, constitutional issue.”
The Government’s appeal will be heard over four days by 11 Supreme Court judges and televised in full. However no judgment is expected until the New Year.
Mr Wright will open the hearing by highlighting the fact that 17million people voted for Britain to leave the European Union on the understanding that the Government would then use its powers, known as the Royal Prerogative, to implement the vote.
In a written submission to the court following an intervention by Nicola Sturgeon, the Scottish First Minister, in the case Mr Wright warned: “The Court is being invited by the Lord Advocate and the Counsel General to stray into areas of political judgment rather than legal adjudication. The Court should resist that invitation, particularly where the underlying issue is one of considerable political sensitivity.”
He added: “The premise of the 2015 [referendum] act was the continued existence of the Government’s prerogative powers to act on the international plane – including, specifically, to give Article 50 notice as the first step to implementing a “leave” vote. That was the clear understanding of all concerned and the basis on which people voted in the referendum.”
He also warned that the Supreme Court’s decision could lead to Parliament “micro-managing” all of the UK’s future treaty negotiations. He cited one of Britain’s most eminent constitutional experts, saying that he “afforded far more significance to the will of the electorate” and described referendums as “the people’s veto”.
An ally of Mr Wright said: “He is best placed to say to the High Court that 17million people taking part in a referendum isn’t something that can be treated as any other political event. It was a political event like no other in our lifetime. “They have been asked to rule on a narrow point. It will put the court in the position of being a constitutional court. It’s high stakes.”
Another minister said: “The British people have given a direct instruction to the Government, this is their decision. The Supreme Court has to be very careful to engage in only the matters before it.
“In the US the political views of judges are subject to considerable political scrutiny. I think the time will come soon when that level of scrutiny will be regarded as appropriate. This is easily the most important issue for half a century. The political views of judges should be taken into account”.
Mrs May has vowed to invoke Article 50 by the end of March even if the judges rule against the Government.
Nick Clegg, the former Liberal Democrat leader, on Sunday vowed to vote against the legislation unless the Government can guarantee Single Market access and a second referendum.
Jeremy Corbyn, the Labour leader, is also planning to table a series of amendments amid fears that the two parties could try to delay or even overturn the Brexit vote.
The Daily Telegraph understands that ministers are examining plans for all night sittings and clearing business from both houses to push the legislation through if they lose the case.