The mood of the House of Commons on Brexit is clear: a majority of MPs do not want the UK to leave the EU without a deal.
There has been much debate at Westminster about Labour leader Jeremy Corbyn’s plan to try to remove Boris Johnson’s government through a vote of no confidence, and replace it with a temporary administration that would seek a Brexit delay with the EU and then call a general election.
But Mr Corbyn is struggling to secure sufficient support in parliament, and MPs opposed to a no-deal Brexit are expected to focus first on whether they can pass legislation that would require the prime minister to ask the EU for a Brexit delay.
What kind of Commons manoeuvre could stop a no-deal Brexit?
With Mr Johnson insisting the UK will leave the EU with or without an agreement on October 31, MPs against a no-deal Brexit are considering several options to try to stop Britain crashing out of the bloc on Halloween.
They may seek to amend a government report due in September about efforts to restore Northern Ireland’s devolved administration at Stormont, so as to express MPs’ opposition to a hard Irish border in the event of a no-deal Brexit.
However, such an amendment, even if approved by parliament, may not be binding on the government.
The best hope for MPs opposed to a no-deal Brexit could be to try to replicate the feat of backbenchers who took control of the Commons order paper — power that usually rests with the government — to pass legislation in the spring that mandated the then prime minister Theresa May to request an extension to the Article 50 divorce process with the EU.
Will MPs’ legislation prove effective?
The so-called Cooper-Letwin bill — named after MPs Yvette Cooper and Oliver Letwin who sponsored the legislation to require Mrs May to seek an Article 50 extension — involved a tortuous parliamentary process: repeating this exercise with limited time will be difficult.
MPs opposed to Mr Johnson’s Brexit strategy could aim to use Commons Standing Order 24 to organise an emergency debate that would in turn pave the way for legislation to try to stop the UK crashing out of the EU without an agreement on October 31.
The decision on whether to proceed in this way will rest with Commons Speaker John Bercow.
Mr Bercow has made it known that he will ensure parliament has its say on Brexit and in past key decisions he has angered Eurosceptic Conservatives by siding with pro-Remain MPs.
MPs opposed to a no-deal Brexit and who want to pass legislation face another hurdle: such a bill would have to be tightly written to ensure Mr Johnson does not have any room to take a different course.
For example, he could ask for an Article 50 extension in compliance with the legislation, but then reject the terms offered by the leaders of the 27 other EU member states.
There have been discussions among EU diplomats that the bloc might offer an extension until the end of 2019 or February 2020, giving Britain time to hold an election.
In this scenario, the MPs aiming to block a no-deal Brexit on October 31 could write the favoured EU date into the bill, safe in the knowledge any extension from the bloc would be consistent with the legislation.
Can Mr Johnson ignore any law passed by backbenchers?
Attorney-general Geoffrey Cox is understood to have told Mrs May that she had no choice but to accept the will of parliament if it passed a bill aimed at forcing a Brexit delay.
But Mr Johnson has taken a tough line on the role of parliament, insisting MPs must respect the outcome of the 2016 Brexit referendum.
If he could find a way around any order by MPs, it is likely he would, but to reject outright a bill approved by parliament risks undermining the rule of law.
Catherine Haddon, a senior fellow at the Institute for Government, a think-tank, said the government would face “the same consequences as anyone else” if it attempted to ignore a piece of legislation: legal action.
“It would end up in court,” she added. “Whether or not the government argued that extending Article 50 is a prerogative power [of the executive], any legislated instruction from parliament is still the law.”
Can the PM prevail over parliament?
If the UK were plunged into a constitutional crisis between Downing Street and parliament over legislation to stop a no-deal Brexit on October 31, Mr Johnson could well resort to his aides’ mantra that he is representing “the people vs politicians” in a battle to deliver on the Brexit referendum result.
But it is very difficult for the government to ignore the will of parliament.
It could increase the chances of Mr Johnson losing a no-confidence vote in the Commons, as Conservative MPs opposed to a no-deal Brexit could find it hard to back him in these circumstances.
Riding roughshod over parliament would also create a difficult situation for the civil service, which would find itself torn between the law and the will of ministers.
Ms Haddon said that “permanent secretaries would have to ask for written ministerial direction . . . In the last instance, senior mandarins may opt to resign instead of breaking the law.”