Prime Minister Boris Johnson is facing a fresh legal attack over his planned suspension of Parliament.
A hearing in a case against him at the High Court in London on Thursday comes the day after he fought off a similar action in Scotland.
The bid to challenge the legality of the prorogation of Parliament will be heard by the Lord Chief Justice Lord Burnett and two other leading judges.
An urgent application for a judicial review was launched against the Prime Minister by businesswoman Gina Miller, who successfully challenged the Government at the High Court in 2016 over the triggering of the Article 50 process to start the Brexit countdown.
Former prime minister Sir John Major and three other parties have been given the go-ahead to join her legal action.
The High Court has granted permission to Sir John to intervene in the case in writing.
Lord Advocate James Wolffe QC, who is Scotland’s senior law officer, the Welsh Government and shadow attorney general Shami Chakrabarti have also been given permission to intervene in writing.
The Lord Chief Justice, sitting with the Master of the Rolls Sir Terence Etherton and the President of the Queen’s Bench Division Dame Victoria Sharp, will initially consider whether the case can proceed – if they rule that it can, then a full airing of the issue will follow immediately.
A spokeswoman for the judiciary said on Wednesday: “The court will consider the request for the case to be heard, and if it agrees, a full hearing will follow the same day. The hearing is listed for a full day.”
She said: “There will be no witnesses and submissions will be made by legal representatives.”
Explaining the procedure, she said: “Judicial review is a type of court proceeding in which a judge reviews the lawfulness of a decision or action made by a public body and is a challenge to the way in which a decision has been made, rather than the rights and wrongs of the conclusion reached.”
A judge at the Court of Session in Edinburgh ruled on Wednesday that the planned prorogation was lawful.
Lord Doherty said choosing when to prorogue Parliament was for politicians and not the courts, but an appeal against his decision is being heard on Thursday.
He ruled: “The power to prorogue is a prerogative power and the Prime Minister had the vires (powers) to advise the sovereign as to its exercise.”
That challenge was brought by a cross-party group of 75 MPs and peers.
A campaigner is bringing a case in Belfast arguing that no-deal could jeopardise the Northern Ireland peace process.
Whatever the outcome of the challenges against the decision to prorogue Parliament, it is likely that the dispute will end up at the UK’s highest court.
A spokeswoman for the Supreme Court in London has said that “should any parties choose to appeal to the UK Supreme Court following the prorogation appeal hearings in the lower courts”, the court has set aside September 17 “as a date to hear such an appeal”.
After the ruling in Scotland, a UK Government spokesman said: “We welcome the court’s decision and hope that those seeking to use the judiciary to frustrate the Government take note and withdraw their cases.”
– The Queen met the Privy Council on August 28 to approve an order from the Prime Minister for Parliament to be suspended from the second week in September until October 14.