A DATE has been set for a court battle to stop Boris Johnson forcing through a no-deal Brexit by proroguing parliament.

More than 70 MPs and peers want Scotland's Court of Session to rule that suspending parliament to ensure the UK leaves the EU without a deal is "unlawful and unconstitutional".

During an preliminary hearing in Edinburgh, Lord Raymond Doherty agreed to an accelerated timetable, with a substantive hearing scheduled for September 6.

He said all documents in relation to the case must be lodged by Friday, August 30, while a procedural hearing has been pencilled in for September 4.

Expenses for both sides will be capped at £30,000, after the UK Government argued against efforts by the petitioners to limit their own expenses to £5,000.

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Andrew Webster QC, representing the government, said the politicians involved had a combined parliamentary salary of £5.5 million before tax, while a crowdfunding campaign had also raised more than £100,000. 

He said: "It may be thought to be remarkable that a petitioner that has an income of £5.5 million, and a fighting fund of £100,000, could present themselves as in fincancial need of a protective expenses order."

The latest challenge is supported by the same legal team that secured a victory at the European Court of Justice last year over whether the UK could unilaterally cancel Brexit by revoking Article 50.

This includes Jolyon Maugham QC, director of the Good Law Project, while the SNP's justice and home affairs spokeswoman Joanna Cherry is among those leading the drive.

They want the court to declare that the Prime Minister cannot advise the Queen to suspend parliament to stop it voting on a no-deal exit.

Mr Johnson has previously insisted the UK will leave the EU on October 31 "come what may", and has refused to rule out proroguing parliament.

David Welsh, the lawyer representing the cross-party group, insisted the issue was of "substantial importance" to the constitutional law of the UK.

And he argued there was "ample reason to suspect" the government will attempt to slow down and delay the proceedings as much as possible. 

He said the case needed to be heard "swiftly" because any judgment that came after October 31 "would be rendered academic by the passing of time".

He added: "We are facing consequences of such extreme and severe nature that it's important for the court to fulfil its role in ruling on the law and how it should be applied."

However, Lord Doherty rejected the campaigners' attempts to have the whole hearing before one court to speed up the process.

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He said: "It's a case that requires expedition but there is a requirement for fairness to both sides."

Speaking afterwards, Ian Murray, Labour MP for Edinburgh South and one of those named in the petitition, said: “The courts are there to enhance our democracy by giving the public the ability to hold the government to account. 

“It’s great progress to have a full hearing in September before the Prime Minister can consider closing down parliament to force through a no deal Brexit. Congratulations thus far to the legal team.”

The legal papers, submitted by the Good Law Project acting on behalf of the politicians, state: "Seeking to use the power to prorogue parliament to avoid further parliamentary participation in the withdrawal of the UK from the EU is both unlawful and unconstitutional."

Warning that "the exercise of the power of prorogation would have irreversible legal, constitutional and practical implications for the United Kingdom", the challenge calls for the court to declare that proroguing parliament before October 31 would be both unconstitutional and unlawful by denying MPs and the Lords the chance to debate and approve the decision.