A Supreme Court judgement on whether Boris Johnson unlawfully suspended Parliament is due to be delivered tomorrow, according to reports.
The case for "R v The Prime Minister" is listed in Court One on the Supreme Court's website for 10.30am on Tuesday Morning.
It comes after a three-day hearing into the hugely controversial suspension concluded on Thursday.
At the time, Lady Hale, president of the Supreme Court, said the decision would be made "early next week".
She said in her closing remarks: "I must repeat that this case is not about when and on what terms the United Kingdom leaves the European Union.
"The result of this case will not determine that. We are solely concerned with the lawfulness of the Prime Minister's decision to advise Her Majesty to prorogue Parliament on the dates in question.
"As we have heard, it is not a simple question and we will now carefully consider all the arguments that have been presented to us."
A panel of 11 judges are considering appeals arising from two separate challenges in England and Scotland - which produced different outcomes - over Mr Johnson's advice to the Queen to suspend Parliament for five weeks until October 14.
The High Court had rejected businesswoman Gina Miller's challenge to Mr Johnson's prorogation, finding that it was "purely political" and not a matter for the courts.
But in Scotland, a cross-party group of MPs and peers won a ruling from the Inner House of the Court of Session that the suspension decision was unlawful because it was "motivated by the improper purpose of stymieing Parliament".
Mrs Miller and the Government both then appealed against those decisions, resulting in last week's hearing at the Supreme Court.
If the Government looses its appeal against the Scottish ruling, Foreign Secretary Dominic Raab said it would abide by the ruling but refused to rule out suspending Parliament for a second time.
During the hearing, former Prime Minister John Major slammed Mr Johnson's Parliament suspension, saying he believed the move was motivated by his "political interest".
Sir John is an intervener in the unprecedented case at the Supreme Court.
His QC Lord Garnier said the former prime minister is of the view the "inference was inescapable" that Mr Johnson's decision was "motivated by his political interest in ensuring that there was no activity in Parliament during the period leading up to the EU Council summit on October 17 and 18".
Aidan O'Neill QC, representing a group of around 75 MPs and peers led by SNP MP Joanna Cherry QC, also urged the judges to dismiss the Westminster Government's appeal against a ruling of the Inner House of the Court of Session.
Concluding almost two hours of lively submissions, Mr O'Neill said: "Stand up for truth, stand up for reason, stand up for diversity, stand up for Parliament, stand up for democracy by dismissing this Government appeal and upholding a constitution governed by laws, not the passing whims of men.
But the Prime Minister has argued in both cases that suspending Parliament was lawful and necessary in order to prepare a domestic legislative agenda.
