The UK’s highest court has been told the EU referendum gave ministers the right to trigger an exit from the bloc without the approval of MPs.
The government’s attempt to trigger Article 50 is not being done on a “whim” or “out of a clear blue sky”, Attorney General Jeremy Wright told a panel of 11 justices at the Supreme Court at the start of a historic constitutional legal case.
The government’s top law officer said that process was one in which Parliament had “resolved to put a clear and decisive question about our nation’s future to the British people, and in which Parliament expected the government to act on the answer they gave”.
As protesters on both sides of the EU debate demonstrated outside, the court’s president Lord Neuberger said members of the public bringing the case had received “threats of serious violence and unpleasant abuse in emails and other electronic communications” and warned those responsible that “legal powers” existed to deal with them.
And before any arguments were heard, Lord Neuberger confirmed all parties involved had given their backing to the justices hearing the historic case.
In his opening remarks, Lord Neuberger stressed the court was aware of the “strong feelings associated with the many wider political questions surrounding the United Kingdom’s departure from the European Union” - but those questions were not the subject of the appeal.
He said: “This appeal is concerned with legal issues and, as judges, our duty is to consider those issues impartially, and to decide the case according to the law. That is what we shall do.”
Mr Wright presented opening arguments on behalf of the government urging the panel of justices to overturn a High Court ruling on 3 November.
In a decision that infuriated Brexiteers, three judges said Theresa May lacked power to use the royal prerogative to trigger Article 50 of the Lisbon Treaty and start the two-year process of negotiating Brexit without the prior authority of Parliament.
The Scottish and Welsh governments and the Attorney General for Northern Ireland are all intervening in the Supreme Court case. A ruling will not be given until the new year.
The Attorney General said starting the UK’s two-year exit using royal prerogative powers was the “logical conclusion of a process in which Parliament has been fully and consciously involved”.
He added: “None of this means, of course, that Parliament will not be closely involved in the process of the UK’s withdrawal from the EU over the coming months and years.”
Mr Wright told the justices in London that the case was of “great constitutional significance in which there is understandable and legitimate interest both inside and outside this courtroom”.
He said the High Court had reached the “wrong” decision. It was for the Government to exercise prerogative powers in the conduct of the UK’s affairs on the international plane.
The position of those who had brought the case and others had always been “that they have no interest in derailing Brexit but only in defending Parliament’s role in the process”.
Mr Wright continued: “But if this is all about standing up for Parliament, I say Parliament can stand up for itself.
“When it comes to leaving the European Union, Parliament has had full capacity and multiple opportunities to restrict the executive’s ordinary ability to begin the Article 50 process and it has not chosen to do so.”
He said: “However much they may wish it had, those who support parliamentary sovereignty should, we submit, respect this exercise of parliamentary sovereignty too.”
Mr Wright submitted that “in the context of this case the imposition of a legislative precondition by the courts which Parliament did not choose to impose itself, cannot be supportive of parliamentary sovereignty but must be positively inconsistent with it”.
He said: “In the delicate balance of our constitutional settlement this court should, we submit, resist the invitation to make such an imposition.”
James Eadie QC, also appearing for the government, said Parliament had arranged for the June 23 referendum through the 2015 EU Referendum Act on the clear understanding that the Government would implement its outcome.
Nothing in law suggested that, following victory for the Leave campaign, the government’s decision to give Article 50 notice required further legislation. It was self-evident that withdrawal from the EU would affect the rights and obligations of individuals in a serious way, said Mr Eadie.
Parliament knew that would be the effect, yet left the Government’s prerogative powers untouched.
If the intention of Parliament had been to make leaving or withdrawing subject to primary legislation “not merely could it have said so, but undoubtedly would have said so”, argued Mr Eadie.
“Its silence is consistent and compelling.”
Mrs May has made it clear she still intends to give an Article 50 notification by the end of next March to start the leave negotiations with 27 other EU countries.
Downing Street yesterday accused opponents of Brexit of trying to tie the hands of UK negotiators in the upcoming talks on withdrawal from the European Union.
Both Labour and Liberal Democrats have indicated they would seek to amend any parliamentary motion as a result of the Supreme Court ruling, with Labour leader Jeremy Corbyn saying he will try to ensure that issues of market access and protections formed part of the UK position.
Other amendments could require the government to publish a white paper on its negotiating goals or hold a second referendum on the outcome.
“While others are seeming to make clear that they want to frustrate the will of the British people by slowing down the process of leaving and trying to tie the government’s hands in negotiation, the government is getting on with respecting what the British people decided and making a success of Brexit,” the prime minister’s spokeswoman said.
“If you are backing the UK team, you want them to be able to go into the negotiation and get the best deal possible.”
Liberal Democrat leader Tim Farron said the suggestion that his party is undermining UK negotiators’ hand was “silly”.