Prime Minister's Brexit deal crushed for second time
The House of Commons rejected her updated agreement with Brussels by 149 votes.
Theresa May's Brexit agreement has been dealt a second emphatic defeat, with the House of Commons rejecting her updated deal by a majority of 149.
The Prime Minister had earlier told MPs "this is the moment" to endorse her plan for EU withdrawal, but they voted it down by 242 votes to 391.
It is the fourth largest defeat for a sitting government in Commons history and comes seventeen days before the UK is due to leave the European Union, on March 29.
May also suffered the biggest ever parliamentary defeat back in January, when her Brexit deal was defeated for the first time by 230 votes.
Her revised deal included a new legally-binding document agreed with Brussels which committed both sides to working to find a way to avoid the controversial Irish backstop.
Opening the debate for the second so-called "meaningful vote", the Prime Minister warned MPs: "Support this deal, in which case we leave the EU with a deal, or risk no-deal or no Brexit. These are the options."
She added: "It was not this House that decided it was time for the United Kingdom to leave the European Union, it was the British people.
"It falls to us here to implement that decision... this is the moment and this is the time."
But Labour leader Jeremy Corbyn said the new version of the deal had not changed "a single word" of the Withdrawal Agreement signed off last November.
He added: "In terms of the substance, literally nothing has changed... There is no unilateral exit mechanism, there is no time limit, there are no alternative arrangements."
SNP Westminster leader Ian Blackford urged MPs to vote down May's deal to "stop the greatest act of self-harm to our economy".
"This deal isn't a new deal, it's the same deal and it's the same bad deal for Scotland," Blackford said.
Following May's first defeat, the Commons held a series of votes designed to help the PM find a "plan B" Parliament could support.
The revised version of her deal put to MPs on Tuesday built upon the existing Withdrawal Agreement with a joint UK-EU legal instrument promising to seek alternative arrangements to avoid the need for a backstop.
The UK also set out a "unilateral declaration" seeking to show how Britain could have the backstop removed if the EU acted in bad faith or did not act with "best endeavours".
But legal advice from attorney general Geoffrey Cox made clear that while the changes reduced the risk of the UK getting trapped in the backstop - as many Conservative and DUP MPs fear - it did not remove the risk.
The backstop is a term used to describe the provision of UK-wide customs arrangement with the EU post-Brexit to prevent a hard border in Ireland if needed.
Wednesday will see MPs vote on whether they oppose a no-deal Brexit, with a vote on delaying Brexit expected to be held on Thursday should no-deal be rejected.