Theresa May is facing a constitutional crisis after six opposition parties joined forces to accuse the government of contempt of Parliament over its failure to publish its full Brexit legal advice.
The Commons Speaker, John Bercow, said there was "an arguable case" that the government had committed contempt, after he was asked by Labour, the SNP, the Liberal Democrats, Plaid Cymru, the Green Party and the DUP to begin proceedings.
Earlier, Attorney general Geoffrey Cox admitted the UK could be locked into a customs backstop under the prime minister’s Brexit blueprint.
Mr Cox confirmed that neither the UK nor EU would be able to unilaterally end the Northern Irish backstop arrangement if it came into force, in an address to MPs.
It also comes as The Independent’s petition calling for a Final Say referendum on Brexit was delivered to Downing Street, after more than a million people backed the campaign.
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We're wrapping up our live politics coverage for today. Thanks for reading.
Here are the key points from a day which has left Theresa May facing a full-blown constitutional crisis:
Opposition parties write joint letter calling for government to be held in contempt
'Arguable case' that government committed contempt, says Speaker
'I will still have my job after MPs vote on Brexit deal', prime minister insists
Campaigners deliver Final Say petition with 1.5m signatures to Downing Street
PM's Brexit adviser says backstop is 'slightly uncomfortable necessity'
Theresa May told 'no legal guarantee' UK could withdraw from backstop
Commons Speaker John Bercow has told MPs he believes there is an "arguable case that a contempt has been committed" by the government over its failure to publish its full Brexit legal advice.
Nicola Sturgeon, who held talks with Theresa May today, has urged the prime minister to change course to avoid an "utterly disastrous" no-deal Brexit.
The Scottish first minister said a "workable alternative" will be urgently needed if "the PM's deal is defeated in the Commons, as is widely expected".
She added the SNP would join other parties in calling for an extension Article 50 process and would propose an amendment to the meaningful vote later this week".
Downing Street said the prime minister had spoken to Ms Sturgeon about support for the government's Brexit deal from "from fishermen, farmers and business leaders".
Ms May "urged the first minister to listen to these voices in their support of the deal as opposed to risking a no-deal Brexit or going back to square one of negotiations", a spokesman added.
John Bercow says he has only just seen the letter calling for the government to be held in contempt and intends to come to "rapid decision", possibly tonight or "at the earliest opportunity".
Cox says he will also write to the speaker tonight with submissions from the government.
Geoffrey Cox says the government was wrong not to oppose a motion last month which called for publication of his final and full Brexit legal advice.
Asked if he was consulted about whether to opposite it, he says he was not.
Here's the opposition parties' letter, calling for the government to be held in contempt, in full:
Labour's Chris Byrant says he has even less sympathy Geoffrey Cox after today's proceedings. Surely the government has to "bow the knee to Parliament" sometimes, he suggests.
Cox says the House has no power to demand documents which are not official.
Labour's Chris Williamson says the attorney general could be expelled from Parliament if found in contempt. Is he happy to take that risk?
Geoffrey Cox says he understands MPs' concerns and is "truly sorry" but says it would be against the public interest to publish the advice while Brexit negotiations are ongoing.
Theresa May is facing a full-blown constitutional crisis after opposition parties joined forces to accuse the government of contempt of Parliament, writes The Independent's political correspondent Ben Kentish.
Here's his full story:
Six opposition parties have written a joint letter to the speaker asking him to launch contempt proceedings against the government over its failure to publish its Brexit legal device.
The letter is signed jointly by MPs from Labour, the SNP, the Lib Dems, the DUP, Plaid Cymru, and the Greens.
Shadow Brexit secretary, Labour's Keir Starmer, said: "The government has failed to publish the Attorney General's full and final legal advice on the Brexit deal, as was ordered by Parliament.
"We have been left with no option but to write to the Speaker of the House of Commons to ask him to launch proceedings of contempt."
Mr Davis said: “The legal summary document is worse than we feared: the backstop customs union is indefinite, the UK would be a rule taker and the European Court is in charge of our destiny, rather than the sovereign UK Parliament. This is not Brexit.
“This only reinforces what I’ve been saying for weeks: the legal advice must be published in full so that the House of Commons can debate this properly.”
Ms Braverman said: "With very little time until the historic vote on the deal, it is only proper that MPs are fully aware of the legally implications of what they are deciding upon.
"The duty that we owe our constituents and the country demands that we should go into this vote with our eyes wide open. Withholding the advice will keep parliament in the dark and this can't be right."
After Labour veteran Harriet Harman raised concerns, Mr Cox said he could not take a step which he "firmly and truly believes would be contrary to the public interest".
He went on: "I ask the House to understand that it is only that consideration that is motivating me and this government in declining at this stage to break the convention that applies to both sides of the House when they are in government.
"There is nothing to see here."
Mr Cox responded: "I make no bones about it - I would have preferred to have seen a unilateral right of termination in this backstop.
"I would have preferred to have seen a clause to exit if negotiations had irretrievably broken down.
"But I'm prepared to lend my support to this agreement because I do not believe that we're likely to be entrapped in it permanently."
Geoffrey Cox agreed there was nothing in law to stop this but such an agreement based on Article 50 would be "highly vulnerable to legal challenge" and therefore, in his legal opinion, unlikely.
He said: "If negotiations irretrievably broke down it would de facto become permanent and it would therefore fall to be seriously challenge-able in the Court of Justice of the European Union for being invalid.
"That legal certainty by itself is sufficient to promote the EU to do a deal with us."
