The risk of the UK being tied to EU rules after Brexit “remains unchanged” despite the latest changes to the PM’s deal, the attorney general has said.
However, Geoffrey Cox said the new agreements reinforced the legal rights available to the UK if subsequent talks broke down due to “bad faith”.
His updated legal advice is seen as vital to determining whether Tory Brexiteers and the DUP back the deal.
Mr Cox is now answering MPs’ questions in the Commons.
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In his advice, Geoffrey Cox said there remained no “internationally lawful means” of leaving the Irish backstop without the EU’s agreement.
But he says the extra assurances won by Mrs May “reduce the risk that the United Kingdom could be indefinitely and involuntarily detained” in the backstop if talks on the two sides future relationship broke down due to “bad faith” by the EU.
He adds: “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.”
He repeats his view, first expressed in December, that deciding whether to back the deal or not was a political rather than a legal judgement, and he was “strongly of the view” that MPs should back it.
Reaction from MPs
Mrs May has addressed a meeting of Conservative MPs, in an effort to change the minds of those opposed to her deal.
But early reaction to the latest legal advice has not been favourable, with one former Brexit-backing former cabinet minister calling it “pretty terminal”.
Labour’s Shadow Brexit Secretary Sir Keir Starmer said: “The government’s strategy is now in tatters.”
The last time Mrs May’s withdrawal agreement was put to Parliament in January, it was voted down by a margin of 230.
The BBC’s political editor Laura Kuenssberg said it would be a “political miracle of historic proportions” if Mrs May could overturn such a heavy defeat.
What was agreed with the EU?
Documents were agreed after Mrs May flew to the European Parliament with Brexit Secretary Steve Barclay for last-minute talks with Mr Juncker and EU chief Brexit negotiator Michel Barnier.
A “joint legally binding instrument” on the withdrawal agreement which the UK could use to start a “formal dispute” against the EU if it tried to keep the UK tied into the backstop indefinitely.
A joint statement about the UK and EU’s future relationship which commits to replacing the backstop with an alternative by December 2020.
A “unilateral declaration”. stating there is nothing to stop the UK from leaving the backstop if discussions on a future relationship with the EU break down and there is no prospect of an agreement.
Many MPs fear the backstop, initially agreed by the UK government in December 2017, would keep the country in a customs arrangement with the EU indefinitely.
The PM has claimed the new documents addresses this issue and urged MPs to back the “improved deal”.
Reaction to the new legal advice
The Democratic Unionist Party, whose support Mrs May relies on in the Commons, said it would be “scrutinising the text line by line” before deciding whether to give the PM their support.
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Jacob Rees-Mogg, who chairs the influential European Research Group of MPs, said Mr Cox’s views and those of the group’s own lawyers were critical but essentially it was a political judgement for MPs.
“Does this deliver enough of Brexit to make this worth accepting?” he told the BBC.
Brexit-backing Tory MP Andrew Bridgen left the meeting Mrs May is addressing after five minutes, saying “nothing has changed”.