Brexit: UK's Supreme Court set to rule next year on EU exit challenge
The Government faces a wait until next year to find out whether it has won its historic Brexit challenge at the UK's highest court.
At the completion of four days of detailed legal argument yesterday, 11 Supreme Court justices reserved their ruling until the new year.
The Supreme Court's president Lord Neuberger said: "It bears repeating we are not being asked to overturn the result of the EU referendum.
"The ultimate question in this case concerns the process by which that result can lawfully be brought into effect.
"As we have heard, that question raises important constitutional issues and we will now take time to ensure the many arguments presented to us orally and in writing are given full and proper consideration."
Lord Neuberger added: "Having said that, we appreciate that this case should be resolved as quickly as possible, and we will do our best to achieve that."
The proceedings began on Monday amid a blaze of publicity around the world.
The hearing followed a High Court ruling against the Government in November.
Three judges ruled that Prime Minister Theresa May lacked legal power to use the royal prerogative to trigger Article 50 of the Lisbon Treaty to start the two-year process of withdrawing from the European Union.
Opponents say that an Act of Parliament is needed. But yesterday's proceedings were rounded off with a final claim by James Eadie QC, for the Government, that the use of the royal prerogative was lawful.
He said the Government was asserting that the prerogative provided "a specific power to notify Article 50 and so start the process of withdrawal notwithstanding that will result in changes to domestic law".
Gina Miller, the lead claimant in the successful High Court action before the Lord Chief Justice Lord Thomas, said after the Supreme Court hearing: "The tone of this week's proceedings from everyone involved and many parts of the media showed respect, civility and professionalism and I very much hope that this will continue throughout the process of the UK's withdrawal from the EU."
Ms Miller, an investment fund manager and philanthropist who had endured death threats during the High Court hearing, added: "As my counsel Lord Pannick said, the constitutional elephant in the room remains - to give notice under Article 50 using the prerogative is an affront to parliamentary sovereignty."
Mr Eadie told the court the EU Referendum Act 2015 had set up the June vote.
The use of the prerogative was "consistent with the legislative scheme" to give effect to the outcome of the vote to leave the EU.
Mr Eadie acknowledged that if primary legislation were required to trigger Brexit, it would have to be by way of an Act of Parliament.