Downing Street has published the legal advice it was given on Theresa May's Brexit deal by the government's top law officer, Attorney General Geoffrey Cox. We asked people the question; they gave us the answer.
Theresa May has been sending ministers around the country in an attempt to sell her deal ahead of the House of Commons vote on December 11.
"Theresa May's deal is at this point little more than a hypothetical exercise, with all sides of the House of Commons determined to defeat it on Tuesday". "There is nothing to see here", Cox insisted.
However, it is unclear whether the PM can offer MPs a vote specifically on the backstop.
Mr Johnson wrote on Facebook that Mrs May's deal handed the European Union the "indefinite power to bully and blackmail this country to get whatever it wants in the future negotiations". A vote on the deal is scheduled for Tuesday.
Under the current deal the "backstop" would come into effect at the end of the Brexit transition period, which is due to last until the end of 2020 but may be extended.
But May is facing opposition from both sides of the Brexit debate.
She added that there were "pros and cons" to either option, saying that the backstop would not involve paying any more funds to the European Union, whereas extending the transition would require an additional fee, plus accepting the continuation of freedom of movement with the EU.
Mr Whittaker (Calder Valley) said: "As the deal is only about the withdrawal and implementation period, I am quite pragmatic about the agreement".
But the Attorney General said it was "extremely hard to see" the five-member panel being prepared to make such a political decision unless both sides agreed on it.
"As the day of the meaningful vote in Parliament approaches, I wanted to emphasise what the deal means specifically for the people of Northern Ireland", she said.
Health Secretary Matt Hancock confirmed that the government had already drafted plans to buy "a large collection of refrigeration units so that those drugs that can be stockpiled, we will have a stockpile of" in the event of a no-deal Brexit.
Pro-EU legislators say the amendment makes the prospect of a "no-deal" Brexit less likely, because Parliament can direct the government to take that option off the table.
DUP leader Arlene Foster has said a Commons amendment supported by backbench Tories giving Parliament a say on invoking the Irish border backstop does not go far enough, adding that domestic "tinkering" to the Withdrawal Agreement would not persuade her party's ten MPs to back the government.
The Scottish National Party's leader in Westminster, Ian Blackford, called on Mrs May to take responsibility for "concealing the facts on her Brexit deal" from MPs and the public.
He said he would be "keeping my word to my town", writing: "I appreciate me voting this way and not supporting a People's Vote, are counter to the Liberal Democrats' formal position".
"Are there things which I am uneasy about?"
This would mean the European Union could "save face" as it could claim it hadn't renegotiated the withdrawal agreement but simply "tinkered with the non-binding political declaration".
Barnier's speech to the EU's committee of the regions was followed by a debate on the deal involving politicians from across the continent.
The proposal, created to ensure there is no hard border on the island of Ireland, has sparked opposition from all sides because of concerns it would drive a wedge between Northern Ireland and the rest of the United Kingdom while leaving the country tied to the European Union indefinitely.
"The backstop is not there in order to be used, necessarily".