Mr. Grieve has been the M.P. for Beaconsfield since 1997 but last week, along with 20 fellow Conservative party M.P.s, he had the whip removed when he voted with the opposition to facilitate the process of passing legislation created to block the United Kingdom leaving the European Union without a deal on October 31, 2019.
Scotland's First Minister Nicola Sturgeon reacted to the accusations made by the Downing Street source - who accused the judges of political bias - saying it was "pitiful, pathetic and desperate".
The ruling added that all three First Division judges decided that the PM's advice to the British monarch was motivated by the improper objective of stymying Parliament and that it, and what has followed from it, is unlawful.
The ruling also goes beyond simply ruling that prorogation is unlawful, arguing that rather than suspending parliament to allow a new legislative programme through a Queen's Speech, the government's decision was made for the "improper objective of stymying Parliament".
Opposition politicians, however, insisted that the government must recall Parliament.
While the Court of Session judges seemed to stop short of affirming that power, they said they can still rule on the advice's effect.
"We are disappointed by today's decision, and will appeal to the U.K. Supreme Court", the government said in a statement. The UK Government needs to bring forward a strong domestic legislative agenda.
And Jolyon Maugham QC, the head of the Good Law Project that brought the case on behalf of 78 parliamentarians, tweeted: "We believe that the effect of the decision is that Parliament is no longer prorogued".
A defeat in court after six losses in the Commons before prorogation also gives the opposition a chance to frame Johnson as a serial loser who can't win in or outside of parliament.More news: Samsung Galaxy A50s, Galaxy A30s With Triple Cameras Launched in India
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The group of more than 70 largely pro-Remain MPs and peers behind the legal challenge were headed by SNP MP Joanna Cherry, who called for Parliament to be immediately reconvened following the ruling.
"You can not break the law with impunity, Boris Johnson".
Either way - if the Supreme Court rules that the prorogation was unlawful - it is likely that Parliament will have to return very quickly.
Opponents said the real reason was to shut down debate and challenges to his Brexit plans.
Rebel ringleader Dominic Grieve said Mr Johnson must resign if he misled the Queen about his motives, while Labour's David Lammy accused him of "deceiving" the monarch. A hearing there is due to begin next Tuesday.
Mr Bebb told Radio 4's World at One: "If it transpires that by offering what is deemed to be unlawful advice to her Majesty the Queen, it transpires that the prime minister misled the Queen then I think his position is untenable".
Scottish pro-Brexit campaigner Tom Walker told Al Jazeera the Scottish court's ruling was "a risky venture of the judiciary into politics".
- When will the Supreme Court make a ruling? .
He referred the matter to the UK Supreme Court for resolution.