No reassuring new light was cast on the Withdrawal Agreement yesterday in the House of Commons.
The backstop, which was agreed last December to appease Dublin, will be hard for the UK to exit, but almost impossible for Northern Ireland to do so.
It can of course be superseded by a deal with the European Union, but the fact that the EU has a veto means that it will only accept a deal that has a similar impact to the backstop.
If, for example, a Canada-style free trade deal is agreed, Northern Ireland will be excluded.
Theresa May’s decision last December to agree to the backstop might well be seen as one of the most damaging things to have been done to the constitutional integrity of the United Kingdom since 1921.
The prime minister has abandoned paragraph 20 from the backstop, which sought to prevent a border in the Irish Sea.
A leader who boasted of her unionist credentials when it came to the crunch was more concerned with placating Irish nationalist concerns than those a constituent part of her own nation — even when propped up by a Northern Ireland unionist party.
The Withdrawal Agreement is now likely to be defeated by MPs next week. This will lead to fresh uncertainty, but from a strictly unionist perspective, most likely outcomes after such a defeat are better than this deal, including rejoining the EU, however unpalatable that might seem. It might yet prove to be the case that the Irish government has over-played its hand if a no deal looms and the EU compromises a bit.
It is disappointing that the attorney general Geoffrey Cox has thrown his weight behind this agreement. He was reported to be one of the key government figures to be concerned about the constitutional implications for Northern Ireland in the backstop. Theresa May always insisted that she rejected the EU interpretation of the backstop, which gave unionists false reassurance until now.