The government is wrong to have threatened parliament with a "deal or no deal" vote on the final Brexit agreement, a new report has said.
MPs have been warned repeatedly by Brexit secretary David Davis that while they will have a "meaningful" vote on the heads of terms agreed by him and his EU counterpart Michel Barnier in October, they either have to accept the deal as it is, or vote against it – meaning the UK would potentially crash out of the EU.
This threat has been used to see off any suggestion that opposition and rebel MPs could force a public vote on the terms or a second referendum.
But in a new report the Institute for Government, an influential think tank, argues things are not so black-and-white.
"The governments claim that the vote is a binary choice between deal or no deal is wrong. Parliament wont be able to amend the content of the withdrawal agreement or future framework. But if MPs and peers are unhappy with what the government has negotiated, they will almost certainly be able to amend the motion so as to put conditions on approval," the report points out.
"Even if Parliament voted the governments deal down without amendment, this could lead to a renegotiation if the government faced insurmountable political pressure to heed parliaments concerns, and the 27 member states of the EU (EU27) were willing to discuss the issues raised by parliamentarians."
The report argues that law makers should not wait until the Withdrawal and Implementation Bill to stand their ground, but should focus on the initial motion.
And parliament should be given a minimum of five days to debate the deal, and should not "try to rush the deal through".
"Five days of debate, in line with the 1971 precedent and similar to the time typically allocated for debate on budgets, should be the governments starting point," the report states.