LONDON, Sept. 11 (Xinhua) -- Prime Minister Boris Johnson's suspension of the Britain Parliament is unlawful, Scotland's highest civil court ruled Wednesday.

The three judges of Scotland's Court of Session, chaired by Lord Carloway, Scotland's most senior judge, overturned an earlier ruling that the courts did not have the power to interfere in the prime minister's political decision to prorogue the parliament.

Lawyers acting for 75 opposition MPs and peers argued that Johnson's decision to suspend the parliament for five weeks was illegal and in breach of the constitution.

Scotland National Party's Joanna Cherry, one of the MPs to bring the case forward, tweeted on Wednesday: "Huge thanks to all our supporters and our fantastic legal team who have achieved the historic ruling that #prorogation is #unlawful."

A summary from Scotland's Court of Session said: "This was an egregious case of a clear failure to comply with generally accepted standards of behaviour of public authorities."

"Principal reasons for the prorogation were to prevent or impede parliament holding the executive to account and legislating with regard to Brexit, and to allow the executive to pursue a policy of a no-deal Brexit without further Parliamentary interference," it said.

"The Court will accordingly make an Order declaring that the Prime Minister's advice to HM the Queen and the prorogation which followed thereon was unlawful and is thus null and of no effect," it added.

Johnson shut down the House of Commons for five weeks in the early hours of Tuesday morning after the Queen approves his request to allow such a suspension, from a date this week until Oct. 14.

But the court's decision will not immediately affect the current suspension of the parliament as no order has been given by the court to cancel the suspension ahead of a full hearing at the Supreme Court in London which starts on Tuesday next week.

Johnson's government plans to appeal against the latest ruling to the Supreme Court.

"We are disappointed by today's decision and will appeal to the UK supreme court. The UK government needs to bring forward a strong domestic legislative agenda. Proroguing parliament is the legal and necessary way of delivering this," a British government spokesperson said.

Keir Starmer, the shadow Brexit secretary, said: "I welcome the court's judgement. No one in their right mind believed Boris Johnson's reason for shutting down parliament."

"I urge the prime minister to immediately recall parliament so we can debate this judgement and decide what happens next," Starmer said.