Lord Carloway

Petitioners Dale Vince OBE, Joanna Cherry QC MP and Jolyon Maugham QC had asked judges to enforce legislation passed by MPs aimed at preventing a no-deal Brexit.

Under the “Benn Act”, Mr Johnson must ask EU leaders for a delay if a deal has not yet been agreed by 19 October.

But judges said they could not rule on the matter until the political debate has “played out”.

The court will convene again on 21 October when circumstances should be “significantly clearer”, judges said.

Lord Carloway wrote: “Until the time for sending the letter has arrived, the PM has not acted unlawfully, whatever he and his officials are reported to have said privately or in public.

“The situation remains fluid. Over the next two weeks, circumstances will inevitably change.”

Mr Maugham said: “These cases are about keeping the Prime Minister on the straight and narrow. We have extracted from him a promise that he will comply with the law. If he breaks that promise he will face the music – including possible contempt proceedings. And the courts are likely to make good any failure on his part, including signing the Benn Act letter.”

Elaine Motion, executive chairman of Balfour and Manson, which represents the petitioners, said: “The decision today gives the Prime Minister time and space to comply with his legal obligations in terms of the Benn Act - and not to frustrate it.

“If he fails to comply with the terms of the act and does not sign the letter to extend the Brexit date, the court will determine the matter on 21 October.

“The decision by the Inner House of the Court of Session to continue the matter until 21 October reflects the fact that the 21st is the earliest date after the deadline of 19 October for the Prime Minister to sign the letter to the European Council.

“Its decision vindicates entirely the petitioners’ actions in these cases which have resulted, for the first time, in the Prime Minister indicating in formal court documents that he will sign the letter and not seek to frustrate the Benn Act.”