SCOTLAND’S highest court has reserved the right to force Boris Johnson to seek a Brexit delay if he fails to obey the law.  

The Inner House of the Court of Session today refused to grant orders compelling the Prime Minister to ask EU leaders for a delay if no deal is agreed next week.

However it rolled the case over until later in the month to allow campaigners including SNP MP Joanna Cherry QC another chance if Mr Johnson showed "demonstrable unlawfulness". 

Ms Cherry said said the court had left "a sword of Damocles" dangling over the PM's head.

It followed Lord Pentland, in the Outer House, ruling on Monday that there was no need for such orders, as the UK Government had clearly promised to obey the relevant law.

The so-called Benn Act compels the PM to request an extension by October 19 if no deal has been agreed by MPs, something he has said he will not do.

There are reports the PM may try to circumvent the Benn Act by sending a second letter undermining the one he is required to send by the legislation.

The Prime Minister to due to address MPs on his next moves in a special Saturday sitting of the Commons on October 19, after the EU summit that will say yes or no to his proposed alternative to the Irish backstop. 

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Ms Cherry, businessman Dale Vincent and Jolyon Maugham QC, who fear the PM will try to get around the letter of the law, had asked the Court of Session to order him to obey the law before it kicked in.

Although he did not grant such an order, the Lord President, Lord Carloway, said the campaigners could return to court to address the facts as they  stood on October 21. 

Mr Maugham said he was “delighted” the case remained live, and said if Mr Johnson did try to get round the law, he would ask the court to exercise its “nobile officium” power to write a letter in Mr Johnson’s place if he acted unlawfully.

Mr Cherry tweeted: “Delighted to advise Scotland’s Supreme Court is holding off ruling on whether to force Boris Johnson to send Brexit extension Benn Act letter until 21 Oct to give PM time to fulfill the promise he made to the court. A victory for us & all our supporters.”

READ MORE: Date set for Johnson's showdown with Parliament over Brexit 

The three judges said they would not make a ruling until October 21, after the deadline.

The judges said that at this stage there is no basis on which they could grant either of the campaigners’ requests and that ordinarily they would have been refused.

Lord Carloway, Lord President of the Court of Session, said: “Until the time for sending the letter arrives the Prime Minister has not acted unlawfully.

“If October 19 comes and goes without the act having been satisfied the petitioners would be entitled to return to court asking for the Prime Minister to have to comply with the act.

“The situation remains fluid. What is known is that over the next two weeks circumstances will change.”

He added: “The Court can only intervene if there is a demonstrable unlawfulness which it requires to correct. There has been no such unlawfulness.”

Ms Cherry said later: "This decision is a victory for the petitioners and everyone who wants the Tory government to obey the law, and call for an extension, so we can avoid a devastating no-deal Brexit.

"As a result of this vital court action, the Tory government has been forced to concede the Prime Minister will comply with the law, and promise to send a letter requesting a Brexit extension. Crucially, he has also had to admit that he will not frustrate the purpose of the Benn Act.

"The Court's decision is a clear signal it will keep a watch on Boris Johnson's actions - and is holding a Sword of Damocles over him in case he breaks his promise. 

"The Tory Prime Minister must obey the law and call for an extension, or face the consequences - including the ability for Scotland's Supreme Court to force a request for an extension.

"Tory plans for an extreme Brexit would be devastating for Scotland and the UK - threatening to cause a recession, destroy 100,000 Scottish jobs, and cause lasting harm to living standards, public services and the economy. That is a price that we must not pay.

"Once an extension is secure, the opposition parties must unite to bring this Tory government down and hold an election. The SNP will put Scotland's opposition to Brexit and our right to choose our own future as an independent country at the heart of that election.”