LONDON (Reuters) - Boris Johnson’s decision to suspend parliament is not a matter for judges and was not done for improper reasons, a lawyer for the prime minister said on Wednesday as he sought to persuade the British Supreme Court the five-week shutdown was lawful.

A protester, wrapped in British Union Jack flag, is seen outside the Supreme Court of the United Kingdom, in London, Britain September 18, 2019. REUTERS/Hannah McKay

Johnson asked Queen Elizabeth to prorogue, or suspend, parliament from Sept. 10 until Oct. 14, prompting accusations from opponents that he wanted to silence the legislature in the run-up to Britain’s exit from the European Union on Oct. 31.

The Supreme Court, Britain’s top judicial body, began three days of hearings on Tuesday to decide whether Johnson’s advice to the queen regarding the suspension was unlawful.

A ruling against him would be a major embarrassment for Johnson, who has no majority in parliament. It could see lawmakers, a majority of whom oppose Johnson’s promise to leave the EU even if no deal has been struck, returning early, with more time to try to influence his Brexit plans.

“We have got here the Mother of Parliaments being shut down by the father of lies,” said Aidan O’Neill, the lawyer for about 75 lawmakers who are among those challenging the suspension.

“Rather than allowing lies to triumph, listen to the angels of your better nature and rule that this prorogation is unlawful and an abuse of power,” he said in a passionate appeal to the court’s 11 judges.

They will have to decide whether it is right for them to interfere in the prorogation decision and if so, whether the decision and length of the shutdown was unlawful. Their ruling is expected on Friday at the earliest.

James Eadie, a lawyer for Johnson, said the ability to prorogue parliament was a matter of politics or “high policy” which was non-justiciable, meaning it was not something on which judges could rule.

POLITICS OR LAW?

It was a matter for parliament to hold the government to account, not the courts, Eadie said, arguing that lawmakers could take action themselves such as holding a vote of no-confidence in the government if they wished.

He rejected the accusation that the suspension was for an improper purpose and said the suggestion that Johnson “was operating on the basis that parliament was intended to be stymied” was untenable.

He referred to minutes of a cabinet meeting and memos from Johnson and one of his top aides before the suspension which indicated the reasoning was to prepare a new legislative agenda.

But lawyer O’Neill said the court should not treat the documents as “gospel” and, while a government would be expected to engage in high politics and not low, dishonest, dirty tricks, he said: “I’m not sure we can assume that of this government.”

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The court has been told it was “remarkable” Johnson had not provided a witness statement spelling out his reasons for the prorogation, an omission even the judges queried.

“No one has come forward from your side to say this is true ... the whole truth, nothing but the truth or partly true,” Judge Nicholas Wilson said to Eadie.

He replied that the memos provided were sufficient and ministers did not usually provide statements or open themselves up to cross-examination in such cases.

Eadie told the court he would produce a written document on Thursday outlining what Johnson, who has denied misleading the queen, would do if he lost. Another government lawyer, Richard Keen, said on Tuesday that in such an instance, the prime minister could recall parliament earlier than planned.