The attorney general should “consider his position” after it emerged he advised Boris Johnson that proroguing parliament was legal, Sir Keir Starmer has said.
Geoffrey Cox reportedly told the prime minister and the cabinet that any accusation of unlawfulness was “motivated by political considerations”, according to previously redacted court papers.
However the Supreme Court unanimously found that Mr Johnson’s suspension of parliament was “void and of no effect”, in a bombshell ruling on Wednesday.
Mr Cox’s advice was contained in redacted cabinet papers released by a Scottish court in August, which also contained a handwritten note by Mr Johnson, where he described David Cameron as a “girly swot”.
A redacted section, leaked to Sky News, said: “The attorney general said that his advice on the question of the law is that this was lawful and within the constitution.
“Any accusations of unlawfulness or constitutional outrage were motivated by political considerations. The proposal was compatible with the provisions of the NIEF (Northern Ireland Executive Formation Act) 2019.”
Sir Keir, a former director of public prosecutions, raised concerns about the revelations and demanded the publication of the full legal advice.
He said: “We would need to look into it but I think the attorney is going to have to consider his position because he’s now had a unanimous decision of the Supreme Court completely the other way, indicating the prime minister has acted unlawfully.
“At the very least, I think the attorney general needs to be making a statement to parliament tomorrow and I think it’s very important that we now see the full legal advice on this.”
Labour is planning to use an archaic Commons mechanism to force the government to release its legal advice on prorogation, if the attorney general refuses to release it.
The procedure, known as a humble address, was used successfully by Labour to force Theresa May to produce the government’s legal advice on the Brexit deal.
Amber Rudd, who quit the cabinet in protest at the prime minister’s handling of Brexit, said senior ministers were not given the papers.
She tweeted: “Despite personal assurances from the PM, the cabinet was not shown the legal advice around this prorogation.”
Mr Johnson, who has been forced to return early from a trip to the UN general assembly in New York, told reporters he did not think the judges had come to the “right decision”.
A spokesperson from the Attorney General’s Office said: “The government acted in good faith and in the belief that its approach was both lawful and constitutional.
“These are complex matters on which senior and distinguished lawyers have disagreed.
“The Divisional Court led by the Lord Chief Justice agreed unanimously with the government’s legal position, as did the Outer House in Scotland.
“We are disappointed that in the end the Supreme Court took a different view. We respect the judgment of the Supreme Court.”
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