Both Labour members and rebel Tories are gearing up to inflict a number of defeats on Mrs May as they go over the fine print of the EU (Withdrawal) Bill.
The start of the committee stage this afternoon kicks off eight days of line-by-line scrutiny of the Brexit legislation in the run-up to Christmas.
It begins with four hours of debate on the timing of when the UK leaves the EU.
That will be followed by another marathon four-hour debate on whether the Scottish and Welsh governments should get a bigger say in the process.
Eight days have been scheduled for the committee stage, with the first two taking place today and tomorrow.
And the remaining six will see the most contentious debates, with MPs set to discuss so-called Henry VIII powers – allowing the Government to make minor amendments without parliamentary scrutiny – on Tuesday.
The Bill must then come back to the Commons for report stage and third reading, before heading to the Lords, where it is likely to face further tough scrutiny.
And without an overall majority in the Commons, the Prime Minister is vulnerable to rebellions by Tory backbenchers, some of whom have grave misgivings about the whole Brexit process.
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Plaid Cymru’s Hywel Williams says that, as the Withdrawal Bill stands, both the Welsh and Scottish devolved administrations will vote it down.
Mr Williams has tabled an amendement requiring consent of devolved administrations if Theresa May is to repeat the 1972 ECA.
Lady Hermon interjects to point out that Northern Ireland is currently without a devolved assembly due to the collapse of power-sharing at Stormont.
She asks how the views of the people of Northern Ireland will be adequately represented.
Former attorney general Dominic Grieve has said he views Brexit as a “great and historic error”.
He says he understands parliament has to implement the results of the referendum, but cannot suspend his personal views on the matter.
Mr Grieve says he is appalled by the “extraordinary painful process of national self-mutilation I’m required to facilitate”.
His backbench Remainer colleagues Nicky Morgan and Anna Soubry nodded and murmured their approval behind him.
Labour’s Yvette Cooper has also made a fiery speech, hitting back at Steve Baker’s claim her amendment requiring MPs to approve the time and date of Brexit would bring “chaos”.
She said the Government had made enough chaos of its own in recent weeks.
Dominic Grieve weighs in on the bill
Just spoke in Commons for Amdmnt 386; stops concentration of power in Ministers’ hands & requires Parliamentary vote on Bill on terms of Brexit before exit day pic.twitter.com/Ceqw4sieq3
— Yvette Cooper (@YvetteCooperMP) November 14, 2017
Leading Brexiteer Bill Cash has launched a furious tirade against the EU as the debate continues.
He claims European laws have “shackled” Britain since 1972, despite the UK initially joining the economic agreement with “the best of intentions”.
Ken Clarke asked if Brexiteers could give one good example of an EU regulation that they wanted to repeal, claiming most could not.
However Mr Cash said: “I think the EU ports regulations are a very good example.
“I fought that in the European Scrutiny Committee and indeed in the House of Commons but we were not allowed to make any difference to it.
“It was opposed by the Government, it was opposed by the opposition, it was opposed by the port employers and by the trade unions.
“What could we do about it? Absolutely nothing.”
He said his father had given his life for Britain in World War II and would want to see the country make its own destiny.
Bill Cash made a powerful speech arguing repealing EU legislation would ‘unshackle’ Britain
Lady Sylvia Hermon has made a pointed intervention on Northern Ireland.
She says a “no deal” Brexit would be catastrophic for Northern Ireland and could put border officials, police, and citizens in danger by forcing a hard border with the Republic of Ireland.
Lady Hermon has been the MP for North Down since 2001.
Labour’s Hugh Gaffney tweeted his approval for her statement, saying: “We must learn the lessons of history and realise #nodeal is NOT an option.”
In Chamber for #EUWithdrawalBill – very important intervention from Lady Hermon on Northern Ireland and a hard border. We must learn the lessons of history and realise #nodeal is NOT an option #Brexit
— Hugh Gaffney MP (@HughGaffneyMP) November 14, 2017
Tory Remainer Ken Clarke says British governments have always been pro-EU regulation.
He branded the Government’s amendments “silly” in a barnstorming speech which earned him a round of applause.
The EU has tried setting up deregulatory committees but no governments, including Britain, have ever submitted laws they would like to see abolished.
Mr Clarke, a former minister in John Major’s Government, says he is confused at the level of rejoicing about the end of regulations when Britain has never attempted to deregulate before.
Responding to a question by former environment secretary Owen Paterson, asked Clarke to admit that regulations under the common fisheries policy, for example, had been bad for the UK.
But Clarke said: “Fishermen seem to believe that if we exclude foreign ships from our waters, we can wave away all this science stuff about over fishing and we’ll no longer have quotas.”
He claims the British like high regulation and high standards.
Kenneth Clarke gave a furious speech against the Government’s position
Ken Clarke currently destroying his Government’s case for a hard Brexit in the Commons. Tory MPs all looking glum as he talks on the backbenches. Universities Minister Jo Johnson very gently nodding in agreement throughout the speech.
— Chuka Umunna (@ChukaUmunna) November 14, 2017
Listening to the great Ken Clarke speaking on Europe. I wish someone of his calibre was in Cabinet. Especially at a time like this.
— Layla Moran (@LaylaMoran) November 14, 2017
Jacob Rees-Mogg says that a transitional period for leaving the EU would defeat the entire purpose of the Withdrawal Bill.
He says the difference between a transition period, as advocated by the Labour Party, and an implementation period advocated by the Conservative Party, is crucial.
The implementation period would allow the Government to implement changes in the wake of Britain leaving the EU.
However during a transitional period Britain would still be a de facto member of the EU and it would be harder to make changes.
He was intervening in a speech by shadow Brexit minister Paul Blomfield, who said the concrete exit date would close down the possibility of a smooth transition.
Labour MP Paul Blomfield hit out at the Government during the debate
Paul Blomfield, the LabourMP for Sheffield Central, says the British people voted “to pull out, not to miss out”.
He says there should be provision for the Government to extend negotiations if they are close to a deal, but not able to finalise one by the end of the Article 50 period.
He accuses the Conservatives of “appeasing extremists in their party, not thinking of the consequences for the country” by enshrining the exit date in law.
Former Attorney General Dominic Grieve has pointed out that there is provision in Article 50 that would allow the Government to extend the EU exit date.
He expressed concerns that setting a concrete exit date could come back to hurt Britain’s negotiating team later on.
The Brexit Undersecretary Steve Baker says other MPs had asked for clarity, which has now been given by the amendment setting the exit date at 29 March 2019, at 11pm.
Peter Bone has asked whether the exit date enshrined in the bill could be changed at a later date.
Responding, Mr Baker says it could not be changed at a later date.
Steve Baker took questions during a speech on the bill’s provision of an exit date
Labour Brexiteer Frank Field has demanded Theresa May form a Brexit “war cabinet” if she really cares about the national interest.
Mr Field, the MP for Birkenhead, said he had been “disappointed” in the negotiations so far and called on Mrs May to change tactics.
He told the Commons: “I don’t believe there’s the sense of importance or drive or coherence that this issue merits.
“I’ve argued before that anyone serious about comparing this historic event to us fighting for survival in World War II would have followed the move that Churchill made once he took over from Chamberlain.
Frank Field hit out at the Government’s approach to Brexit so far
“He would have moved from the ramshackle way of existing institutions and establish a war cabinet.”
He added: “I think we need a Brexit cabinet; small, with an offer to the opposition to be on it, which in wartime Mr Attlee accepted.
“It will be a test of whether we’re intent on the best possible terms, whether we have a clear position or not, and whether we’re putting our country first.”
My Field said a cross-party solution would help to “steer this debate in the national interest.”