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An epic clash at the UK Supreme Court over whether the British Prime Minister deliberately misled the Queen has ended – and, as Westminster awaits its ruling, the government may have cause for concern.

After three days of weighty constitutional discussion about whether Boris Johnson lied to the monarch over the real reasons for suspending the UK Parliament in the run-up to Brexit, justices spent a great deal of time discussing precisely what they should do if they ruled against the government.

The President of the Supreme Court, Lady Hale, said the court would hand down its momentous ruling early next week. The lawmaker who brought the original case that led to the hearing said Parliament should be reopened immediately if the ruling goes against the government.

But after the session, Johnson did not rule out suspending parliament again. “The best thing I can say at the moment whilst their deliberations are continuing is that obviously I agree very much with the Master of the Rolls and the Lord Chief Justice and others who found in our favor the other day,” the Prime Minister told reporters on a visit to Wiltshire, western England. “I will wait to see what transpires,” the UK’s Press Association reported.

The government’s case is that if the justices declare that Johnson’s advice to the Queen on the prorogation of Parliament was unlawful, it could simply restore the prorogation on a sounder legal basis.

At the end of the hearing on Thursday, the justices engaged the lawyer for the claimants, Lord Pannick, in a lengthy and detailed discussion on how they should frame any order in the event that they ruled the government had acted unlawfully.

The government’s lawyer, Lord Kerr, suggested that, if the prorogation is to be found unlawful, it doesn’t necessarily compel the Prime Minister to take any particular action. Lord Reed noted that the government’s case was that Parliament would still stand prorogued if the judges find the suspension unlawful. But Pannick respond it would be “implicit” that the prorogation would need to be reversed.

“The remedy we seek from the courts is a declaration that the Prime Minister’s advice to Her Majesty was unlawful,” he said – essentially pressing for a legal ruling but not attempting to encourage the justices to stray into the realm of politics by flatly instructing Johnson to re-open Parliament.

Government awaits a ruling

Supreme Court justices are notoriously difficult to read, so any prediction about what form their ruling will take must be advanced with caution.

But legal commentators seemed generally in agreement that the lawyers for Gina Miller and Joanna Cherry’s cases – those that asked for the prorogation of Parliament to be overturned – would likely be happier than the government’s with how the final day ended.

“Still too close to call, but I would be far happier as a claimant lawyer than a government lawyer with how it has gone,” law commentator David Allan Green wrote on Twitter.

“The judges are asking Pannick about the appropriate remedy. That is a very bad sign for the government,” added human rights lawyer Dinah Rose.

But a question remains over what will happen if the judges do find that Johnson’s suspension was unlawful.

The Prime Minister’s noncommittal comments after the hearing followed a similar implication in the documents submitted by Downing Street to the Supreme Court.

In one of the most notable passages, government lawyer James Eadie wrote that if the judges find prorogation unlawful, it would mean the current session would remain in effect – in other words, Parliament would be open again.

But he added: “However, depending on the court’s reasoning it would still either be open or not open to the prime minister to consider a further prorogation” for the same period of time – suggesting that Johnson could try again to suspend Parliament if the court’s ruling gives him the space to do so.

Showdown between two Conservative Prime Ministers

Earlier on Friday, the courtroom played host to a remarkable sight: that of a former British Prime Minister making a case against the incumbent in the country’s highest court.

Lord Garnier, speaking on behalf of former Prime Minister John Major, said his client made “a clear and unambiguous allegation in evidence … that the reasons (for prorogation) set out in the documents put before the court by the Prime Minister cannot be true.”

He also criticized the government for failing to provide any witness statements in support of their case. “Where an allegation of this kind has been made, it would be normal for there at least to be some kind of witness statement,” he said.

Major had previously alleged in his written case that Johnson’s decision to suspend Parliament was not simply to clear the way for a Queen’s Speech, but “in fact substantially motivated by a desire to obstruct Parliament from interfering with the Prime Minister’s plans.”

Former British Prime Minister John Major.

Lord Keen later re-emphasized Downing Street’s argument that prorogation of Parliament is not a matter for the courts, warning the justices not to step into a “political minefield.”

Keen also argued that it should be up to the government, rather than the court, to decide what to do next should the prorogation be found unlawful, but he was questioned by a judge on that point.

The hearing, and the sessions in lower courts that have preceded it, have dragged the UK’s unending Brexit saga squarely into the realm of the courts.

The ruling early next week will be keenly anticipated and could determine whether or not the issue will return to the judiciary, as the clock continues to tick down to the Brexit deadline of October 31.

CNN’s Luke Hanrahan contributed reporting.