Judge set to rule on whether Boris Johnson’s plans can be stopped by courts

They are now seeking an interim interdict, which would stop the prime minister taking the option of suspension until a final decision has been made on the case.

Judge Lord Doherty heard arguments from a lawyer for the campaigners – led by SNP MP Joanna Cherry QC and Liberal Democrat leader Jo Swinson and aided by Jo Maugham of the Good Law Project – and from a legal representative for the UK government at a hearing at the Court of Session in Edinburgh on Thursday.

The hearing came a day after the Queen approved Johnson’s request for parliament to be suspended for five weeks from September 10.

The judge is due to appear at the same court on Friday morning to make a decision on the case.

Aidan O’Neill QC, representing the petitioners, had urged the court to step in and stop the suspension of parliament, arguing it would prevent an “abusive” and “unconstitutional” use of government powers.

He said the “government, based on a parliamentary majority of one, is abusively seeking to entrench its power … by suspending parliament”.

He added: “The political accountability of the government is being eroded by proroguing Parliament. That’s their intention, that’s their aim, that is unconstitutional and this court should stop it.”

O’Neill argued Johnson’s letter to MPs outlining prorogation reasons has “got it wrong on the law” as it assumes the government can allow a no-deal Brexit without the authorisation of primary legislation.

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He said the Queen should be obliged to recall the prorogation order if it turned out to be based on an error of law, as she is “not above the law”, and said prorogation could be subject to review in the courts.

However, Roddy Dunlop QC, representing the UK government, called on the judge to reject the request, as the Queen has already prorogued parliament and there is “no reason” to have an interim decision on such an important matter.

He said the petitioners are asking the judge to take actions which are “wholly unprecedented and go beyond any interference which the courts have ever been permitted”.

“It is this sort of approach … that would be unconstitutional,” he added.

“It is either not justiciable because it is reserved for Her Majesty and is such a matter with which the courts will not interfere or it is a matter which involves such questions of policy that the courts should not intrude because they are ill-equipped to do so.”

Reacting to the news SNP MP Joanna Cherry QC said: “My solicitors have lodged an affidavit for me, setting out my views in sworn testimony about the circumstances surrounding this prorogation.

“The petitioner’s senior counsel has suggested that the prime minister should likewise lodge a sworn affidavit setting out his reasons for the prorogation and make himself available for cross-examination before the Court if necessary, which of course is a very interesting suggestion particularly in light of the comments that were caught off-camera from the defence minister in the British government yesterday.”

She was referring to defence secretary Ben Wallace’s off-guard comments suggesting prorogation was motivated by Brexit, which Downing Street has distanced itself from.