Britain's attorney general Geoffrey Cox has severely undermined the chances of the latest Brexit deal being backed by Britain after saying it does not entirely remove the "risk" of the backstop trapping the UK.
In a detailed statement this morning, Mr Cox contradicted British prime minister Theresa May's Monday night claims she had won what Britain wants, saying while the new deal downplays the backstop risk it does not remove it completely.
His comments mean it is highly unlikely the DUP or hard-line Brexiteers will back Ms May's deal in a key House of Commons vote today, a situation that will push Britain towards either a crash out Brexit or a deadline extension.
"The legal risk remains unchanged that if through no such demonstrable failure of either party, but simply because of intractable differences, that situation does arise, the UK would have no internationally lawful means of exiting the Protocol's arrangements, save by agreement," Mr Cox said.
"I now consider that the legally binding provisions of the joint instrument and the content of the unilateral declaration reduce the risk that the UK could be indefinitely and involuntarily detained within the protocol's provisions at least in so far as that situation had been brought about by the bad faith or want of best endeavours of the EU.
"But as I have previously advised, that is a political judgment, which, given the mutual incentives of the parties and the available options and competing risks, I remain strongly of the view it is right to make.
"However, the legal risk remains unchanged that if through no such demonstrable failure of either party, but simply because of intractable differences, that situation does arise, the UK would have, at least while the fundamental circumstances remained the same, no internationally lawful means of exiting the protocol's arrangements, save by agreement," he said.
Ms May's chances of securing support for the latest EU-UK deal hinged on her hopes of being backed by Mr Cox in her view Britain's right to make a "unilateral" statement saying it could leave the backstop if it chooses was legally secure.
Ms May sought the plan in meetings with European Commission president Jean Claude Juncker in Strasbourg, France, on Monday night, initially demanding that the EU agreed to this position.
However, after a number of hours of talks, Ms May had to limit her position to the UK saying it would be able to release a "unilateral" statement on the backstop while the EU and Ireland noted this was the UK's position without agreeing to it.
DUP sources have said it is now highly unlikely they will support Ms May's deal in a House of Commons vote on Tuesday, while hard-line Brexiteers are almost certain to also oppose it based on Mr Cox's comments.