A group of politicians has started a legal action aimed at preventing Boris Johnson shutting down parliament to force through a no-deal Brexit.
The group of parliamentarians include Liberal Democrat leader Jo Swinson, SNP MP Joanna Cherry and independent MP Heidi Allen.
They have lodged legal papers at the Court of Session in Edinburgh.
Their petition is being considered by a judge who will decide whether to allow the case to proceed.
The UK is currently due to leave the EU on 31 October, with the prime minister saying Brexit will definitely happen on that day regardless of whether or not a deal has been agreed with the EU.
Most MPs at Westminster are opposed to a no-deal Brexit, and there has been speculation that Mr Johnson could try to get around this by closing parliament in the run-up to 31 October.
This is known as proroguing, and would require the permission of the Queen.
The group of pro-Remain politicians involved in the legal action at Scotland's highest court argue that shutting down parliament in this manner would be unlawful.
They have instructed the same Good Law Project team that won a victory at the European Court of Justice last year over whether the UK could unilaterally cancel Brexit by revoking Article 50.
The legal papers, which were initially lodged last week and have now been formally published by the court, claim that proroguing parliament ahead of Brexit would be "both unlawful and unconstitutional" and would have "irreversible legal, constitutional and practical implications for the United Kingdom".
And they stress that the petition "clearly concerns a live constitutional issue on which there is a real and practical necessity to have the court's determination as a matter of urgency".
It is understood that the case has been brought in Scotland because the Court of Session continues to sit over the summer, while the equivalent court in England is on holiday.
Mr Johnson has refused to rule out proroguing parliament, arguing that all options must be left on the table in order to ensure the EU referendum result is respected and the UK leaves on the scheduled day.
Speaker of the Commons John Bercow has said the idea of the parliamentary session ending in order to force through a no-deal Brexit is "simply not going to happen" and that that was "so blindingly obvious it almost doesn't need to be stated".
Who is involved in the legal action?
According to paperwork at the Court of Session, the parliamentarians bringing the latest action are the MPs Joanna Cherry, Jo Swinson, Ian Murray, Geraint Davies, Hywel Williams, Heidi Allen, Angela Smith, Lord Hain, Baroness Jones of Moulescomb and the Right Honourable Janet Royall, the Baroness Royall of Blaisdon.
They are joined by Lord Winston, Lord Wood of Anfield, Debbie Abrahams MP, Rushanara Ali MP, Tonia Antoniazzi MP, Hannah Bardell MP and Dr Roberta Blackman Woods MP.
Other parliamentarians listed as bringing the action include Ben Bradshaw, Tom Brake, Karen Buck, Ruth Cadbury, Marsha Cordova, Ronnie Cowan and Neil Coyle MP.