Most MPs are opposed to a so-called "no-deal Brexit" scenario.

Britain's Supreme Court aims to deliver its ruling early next week on whether Prime Minister Boris Johnson acted unlawfully when he suspended parliament for five weeks in the run-up to Brexit, the president of the court said on Thursday.

If the ruling goes against Johnson, he could be compelled to recall parliament ahead of schedule, giving the legislature additional time to challenge his plan to lead Britain out of the European Union on Oct. 31, with or without a divorce deal.

However, a legal document submitted to the court by Johnson's lawyer indicated that the prime minister's legal team was seeking to keep the option open for him to suspend parliament again even if the court ruled against him.

Johnson asked Queen Elizabeth to prorogue or suspend parliament from Sept. 10 to Oct. 14 on the grounds that he needed time to prepare a new legislative agenda. His opponents say the real reason was to prevent members of parliament (MPs) from thwarting his plans.

Under Britain's unwritten constitution, the power to suspend or dissolve parliament formally remains with the monarch, a politically impartial figure who acts in accordance with the advice of the prime minister.

At the end of three days of hearings, Supreme Court President Brenda Hale said the case was not about when and how Britain would leave the EU but only about the lawfulness of Johnson's advice to the queen.

"As we have heard, it is not a simple question and we will now consider carefully all the arguments that have been presented to us," she told the court. "But we also know this case must be resolved as quickly as possible and we hope to be able to publish our decision early next week."

"RIGMAROLE"

During the hearing, the court was shown a handwritten note in which Johnson had described the parliamentary session as "a rigmarole ... to show the public that MPs were earning their crust".

David Pannick, a lawyer representing one of Johnson's challengers in the court case, said that this showed the prime minister had failed to understand parliamentary sovereignty.

Pannick said he wanted a declaration from the court that the advice to the monarch was unlawful and that parliament should reconvene to decide how to proceed. If Johnson ignored any such declaration, then it would be up to the speakers of both houses of parliament to reconvene the legislature, he said.

Before the suspension, Johnson suffered one defeat after another in the House of Commons, where he now has no majority.

Most MPs are opposed to a so-called "no-deal Brexit" scenario, predicting that it would cause economic damage and severe disruption, including to food and medicine supply chains.

On Tuesday, one of Johnson's lawyers had told the court that if the prime minister lost the case, he could recall parliament earlier than scheduled. But in a more recent document submitted to the court, the prime minister's legal team appeared to say there could still be a way for him to prevent parliament from sitting, even in the event of an adverse ruling.

"Depending on the court's reasoning it would still either be open or not open to the PM to consider a further prorogation," two senior lawyers representing Johnson said in the document.

Among Johnson's opponents at the Supreme Court hearing was one of his predecessors as prime minister and Conservative Party leader, John Major, who submitted a written witness statement saying that the reason given by Johnson for the suspension was not true.

"The inescapable inference to be drawn (from the evidence) is that the prorogation is to prevent parliament from exercising its right to disagree with the government and legislate as it sees fit," Major said in the witness statement, according to an excerpt read out in court by his lawyer.