A Scottish judge refused to put further obligations on U.K. Prime Minister Boris Johnson, saying that his “unequivocal assurances” to seek an extension to the Brexit deadline were sufficient.

“There can be no doubt” that the prime minister “now accepts that he must comply with the requirements of the 2019 Act and has affirmed that he intends to do so,” Judge Peter Cullen said in his ruling Monday, the first of two court dates this week.

At the hearing in Edinburgh, Johnson’s lawyers had promised he will obey a law, known as the Benn Act, that forces him to postpone Brexit if he can’t reach a deal by Oct. 19. The claimants, a group of anti-no deal campaigners, argued that Johnson can’t be trusted and should be forced to comply with the legislation under threat of a fine or imprisonment.

The judge warned the prime minister, saying it would be “destructive of one of the core principles of constitutional propriety” for him to renege on his pledge to the court. Appeal judges will hear the second strand of the lawsuit Tuesday, where the claimants will ask the court to prepare a letter to European leaders seeking an extension on the prime minister’s behalf if he refuses to send one himself.

Johnson has appeared defiant, saying he still planned to leave the U.K. by Oct. 31, despite the court promise to the contrary. Cullen said he didn’t put any weight on statements made outside court by Johnson and his cabinet.

Securing a deal is the only obvious way to obey the law and see through Brexit at the end of the month. But the indications from the EU are that proposals Johnson made last week to resolve the impasse won’t cut it.

Jolyon Maugham, one of the challengers, said he expects a higher court will hear his appeal to the decision on Tuesday.