Campaigners have launched a fresh legal challenge to force Boris Johnson to write to the European Union asking for a Brexit extension if he refuses.
And they believe that if he fails to comply with the law passed by parliament aimed at preventing a no-deal, then the court could have the power to send the letter in his absence.
The challenge has been lodged at the same Edinburgh court that ruled the prime minister's suspension of parliament was unlawful, and is being led by the same campaigners.
With the PM saying he would rather be "dead in a ditch" than ask Brussels for a delay to Brexit past the Halloween deadline, there have been fears Johnson may refuse to do so.
But he is compelled to ask for an extension to the end of January if he fails to convince MPs to back a Withdrawal Agreement or support a no-deal by October 19, after parliament passed the so-called Benn Act.
SNP MP Joanna Cherry and barrister Jolyon Maugham said they issued proceedings at Scotland's highest court, the Inner House of the Court of Session, on Thursday.
Maugham said they have selected Scotland for the case because judges there have the "nobile officium" power that could allow the court to sign the letter if the PM refuses.
"The rule of law is not a thing to be grifted - not even by the prime minister," he said.
"We expect that the Inner House will be mindful of the deadline set out in the Benn Act, and will deal with the matter speedily."
They won a case that sent political shockwaves through the UK and prompted calls for the government to bring back parliament, when three senior judges ruled that the PM had acted unlawfully.
Johnson went on to deny lying to the Queen to secure the five-week prorogation of parliament.
He insisted he sought the suspension for the government to set out a new legislative agenda in a Queen's Speech when MPs return on October 14.
The judges concluded on Wednesday that Johnson had acted with the "purpose of stymying parliament".
But the government is appealing and the case is scheduled to go to the Supreme Court on Tuesday.
The same court will also hear an appeal in a case brought by campaigner Gina Miller over the suspension.
The High Court in London rejected her case, saying the decision to prorogue is "purely political" and cannot be capable of challenge in the courts.
A Number 10 source said Downing Street had been notified of the latest legal proceedings and that a response would be issued in due course.