An amendment, tabled by former attorney general Dominic Grieve, has been backed by a number of rebel Tory MPs as well as the opposition parties.
While the Brexit bill, in clause 9, gives ministers powers to implement the Brexit withdrawal agreement by order, the amendment says these power could only be exercised if they were “subject to the prior enactment of a statute by parliament approving the final terms of withdrawal of the United Kingdom from the European Union.”
Therefore if the amendment is passed, parliament would have to approve the government’s final Brexit deal by passing a separate written law once the terms of the withdrawal agreement are known.
This could, in theory, allow MPs to send May back to the negotiating table if they do not like the deal.
Mr Grieve, the Tory MP for Beaconsfield, told Sky News this morning that the amendment was not designed to “sabotage” but instead ensure parliament was allowed to do its duty by holding the Government to account.
He said: “My impression of the last few days, when I’ve been talking to the government, is it seems to be a bit of a dialogue of the deaf. They’ve sort of turned this into a battle of wills.
“This is a completely pointless exercise. They need to listen to the point that’s being made and they need to respond to it.”
Labour’s shadow Brexit secretary, Sir Keir Starmer, tweeted to confirm the party will back Mr Grieve’s amendment because “the terms of our future are not for the government alone to determine.”
Fears about a potential defeat this evening prompted Brexit Secretary David Davis to write to Tory MPs at 5.30am this morning to try to win any rebels over.
He wrote: “There will be a number of votes for Parliament on the final deal we strike with the EU.
“Our entire approach has been to listen to MPs where they say they can improve the Bill.
He also tabled a statement saying that both Houses of Parliament will have a vote on the final deal “as soon as possible after the negotiations have concluded” which will cover both our exit from the EU and the terms for our future relationship.
Mr Davis added that “the Government will not implement any parts of the Withdrawal Agreement… until after this vote has taken place”.
MPs are set to debate the issue after PMQs today, with votes set to be cast at 7pm and then at 9pm this evening.
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1.20pm: The debate begins
Yvette Cooper, the Labour chair of the Commons home affairs committee, opens the debate.
Her amendment, new clause 3 (NC3), would require the government to implement the Brexit withdrawal agreement through separate primary and secondary legislation rather than through the EU withdrawal bill.
She admits it would achieve the same aim as Dominic Grieve’s amendment.
In response, Brexit-backing MP Bernard Jenkin says Cooper and her allies are trying to “reverse Brexit” – to which Cooper accuses Jenkin of talking “rubbish”.
1.15pm: In case you missed it…
Theresa May rebuffed Anna Soubry’s bid to force the Government to accept the Dominic Grieve’s EU Withdrawal Bill amendment during PMQs this lunchtime, because it would delay key Brexit legislation.
Anna Soubry said: “[Dominic Grieve] is a respected, seasoned parliamentarian and like many on these benches has been for many decades loyal to his party. Nobody wants to be disloyal or to bring about more disunity.
“The prime minister says she wants a meaningful vote on Brexit before we leave the European Union, even at this last moment, would she be so good as to accept [Grieve’s] amendment seven in the spirit of unity for everybody here and in the country?”
In response, the Prime Minister said Ms Soubry makes an “important point” but hinted the Government has no plans to agree the amendment.
She said: “We will ensure that there is a meaningful vote on this in this House, there will then of course be an opportunity for parliament to look at the withdrawal agreement and implementation bill.
“The fact that there will be that meaningful vote has been set out and confirmed by [David Davis] in a written ministerial statement today.
“We were very clear that we won’t commence any statutory instruments until that meaningful vote has taken place.
“But as currently drafted, what the amendment says, is that we shouldn’t put any of those arrangements, any of those statutory instruments, into place until the withdrawal agreement and implementation bill has reached the statute book.
“That could be at a very late stage in the proceedings, which could mean that we are not able to have the orderly and smooth exit from the European Union that we wish to have.”