The Tories fear that the Supreme Court is looking set to rule against Boris Johnson and the government over the suspension of parliament.
There is concern that judges will rule for the first time in history that they can rule on a decision that was once left to the politicians.
The BBC’s Laura Kuenssberg has reported that Number 10 believes that judges will rule they do have the power to stop political prorogations.
She tweets that Downing Street thinks the “Supreme Court will say prorogation is justiciable in principle” but she adds they do not think this will “unravel” the plan for a Queen’s Speech on October 14th.
“I fear this is slipping away from Boris. The judges will want to rule on this and I think they will come down quite hard,” a senior Tory told The Sun.
The Telegraph’s Gordon Rayner commented: “The government is now preparing for the possibility that the court could well overturn a High Court ruling that prorogation is ‘purely political’ and decide that courts can intervene in extreme circumstances.”
It comes as Sir John Major is expected to intervene in the case by giving written evidence to the courts.
He has argued that Boris Johnson’s claim that prorogation of parliament was necessary for a Queen’s Speech “makes no sense and cannot be the true explanation”.
He fears that if the court rules in favour of Johnson “the consequence would be that there is nothing in law to prevent a prime minister from proroguing parliament in any circumstances or for any reason.”