So much for last-minute negotiations on the Continent. Theresa May announced late yesterday that she had scored a breakthrough in talks with Claude Juncker and the EU on the backstop, allowing the UK greater control over its commitment to stay in the customs union to prevent a hard border in Ireland. This morning, however, the Attorney General announced that the risks had not changed with the new memo of understanding, putting May’s deal back to its status quo ante:

In my letter of 13 November 2018, I advised that the protocol [ie, the backstop] would endure indefinitely in international law and could not be brought to an end in the absence of a subsequent agreement. This would remain the case even if parties were still negotiating many years later, and even if the parties believed that talks have clearly broken down and there was no prospect of a future relationship agreement.

I also advised that in the specific case that situation was due to the EU’s want of good faith and best endeavours, because of the difficulties of proof and the egregious nature of the conduct that would be required to establish a breach by the EU of those obligations, it would be highly unlikely that the United Kingdom could take advantage of the remedies available to it for such a breach under the withdrawal agreement.

I now consider that the legally binding provisions of the joint instrument and the content of the unilateral declaration reduce the risk that the United Kingdom 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.

It may be thought that if both parties deploy a sincere desire to reach agreement and the necessary diligence, flexibility and goodwill implied by the amplified duties set out in the joint instrument, it is highly unlikely that a satisfactory subsequent agreement to replace the protocol will not be concluded. 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 United Kingdom would have, at least while the fundamental circumstances remained the same, no internationally lawful means of exiting the Protocol’s arrangements, save by agreement.

Game over? Not quite, Cox told Parliament later in the day. The new agreement does reduce the risk of getting trapped in the backstop, even if it doesn’t eliminate it. The agreement requires both sides to accelerate efforts to find a solution after twelve months once the backstop gets invoked, and a lack of accelerated efforts by the EU would qualify as “bad faith” under the terms of the May-Juncker agreement. That, however, would still require arbitration to iron out, leaving the UK without sovereign leverage on the issue.

Others do see this as “game over,” including May’s allies in Northern Ireland:

A DUP source says they do not see how the party can support the deal following Cox legal advice.

Game over, it would seem.

— Hugh O'Connell (@oconnellhugh) March 12, 2019

DUP sources: “The party cannot support the Prime Minister’s deal in tonight’s vote.” #Brexit

— David Blevins (@skydavidblevins) March 12, 2019

That would be a key loss for May. The DUP provides May with her parliamentary majority, which has hamstrung May’s attempts to deal with the Northern Ireland question. Without their “yes” votes, it seems unlikely that May will have enough votes to pass the Brexit plan in today’s motion, even if all ten DUP MPs abstain rather than vote no.

At the moment, it appears that it won’t even be close. The European Research Group (ERG), a pro-Brexit caucus, has rejected May’s latest diplomatic efforts as insufficient. Their “star chamber” concluded that the agreement leaves the UK without any control over the final exit mechanism, and that the changes announced last night “do not deliver ‘legally binding changes’ to the WA or to the protocol.”

The vote may take place within the next couple of hours, or could be delayed while May maneuvers and negotiates. It’s not entirely certain that the bill will fail; with the clock running and no stomach in Parliament for a crash-out, it’s still possible that enough MPs from both parties see the current bill as the least-worst of all possible outcomes at the moment. For now, though, it looks like May’s heading for another massive loss, and with it the end of her political career.

Update: The DUP will not merely abstain in today’s vote, its leader announced on Twitter:

Latest ⬇️ pic.twitter.com/YLmnPcEI24

— Arlene Foster #WeWillMeetAgain (@DUPleader) March 12, 2019

The DUP will “support the right deal,” but that would be one that the EU simply will not offer nor embrace.