Britain's Supreme Court has ruled Prime Minister Boris Johnson's prorogation of Parliament was "unlawful void and of no effect."
The decision was made by the maximum of 11 justices on Tuesday after it heard two appeals, one from the government and one from businesswoman Gina Miller.
Lady Hale, who has been President of the Supreme Court since September 2017 said it was "not a normal prorogation in the run up to a queen's speech" in a calmly delivered but brutal judgement that ripped the government's argument to shreds.
"The prolonged suspension of parliamentary democracy took place in quite exceptional circumstances," she said.
"The effect on the fundamentals of our democracy remains extreme," she said, adding that the government did not explain why it needed five weeks to prepare for a Queen's speech rather than the typical 4-6 days.
"The court is bound to conclude that the decision to advise the Queen ... was unlawful because it had the effect of frustrating or preventing the ability of parliament to carry out its functions."
Boris Johnson will not resign as prime minister in wake of Supreme Court ruling, Downing St. says.
Johnson says he strongly disagrees with the Supreme Court ruling that Parliament's suspension was illegal.
He says the government will respect the decision but indicated he could try to suspend it again.
"I strongly disagree with what the justices have found. I don't think that it's right but we will go ahead and of course parliament will come back."
He added: "I do think there's a good case for getting on with a queen's speech anyway and we will do that."
The queen's speech outlines the government's plan for the coming session of Parliament.
The speaker of Britain's House of Commons says Parliament will resume its deliberations Wednesday at 11:30 a.m (local time).
John Bercow said Tuesday there will be full scope for emergency debates following the Supreme Court's ruling. He said the ruling means the suspension never took effect.
He says there will not be a Prime Minister's Questions session Wednesday. Johnson is in New York for the United Nations General Assembly.
Bercow welcomed the Supreme Court's unanimous decision and said British citizens deserve to have Parliament in session to scrutinize ministers and perform its other core functions.
Protesters outside the court changed "Johnson out" and the Plaid Cymru leader said "Johnson must resign".
The case marks a rare confrontation between the prime minister, the courts, and parliament over their rights and responsibilities, and also involves Queen Elizabeth II.
It revolves around whether Johnson acted lawfully when he advised the queen to suspend parliament for five weeks during a crucial time frame before the Oct. 31 Brexit deadline when Britain is scheduled to leave the European Union.
Johnson, who is in New York for the United Nations General Assembly, has refused to say whether he will resign if he is found to have broken the law, or will seek to shut down parliament again.
Britain's highest court announced is decision after holding three days of hearings last week before 11 judges.
The government said the decision to suspend parliament until Oct. 14 was routine and not related to Brexit. It claimed that under Britain's unwritten constitution, it is a matter for politicians, not courts, to decide.
The government's opponents argued that Johnson illegally shut down parliament just weeks before the country is due to leave the 28-nation bloc for the "improper purpose" of dodging politicians' scrutiny of his Brexit plans. They also accused Johnson of misleading the queen, whose formal approval was needed to suspend the legislature.
Johnson and parliament have been at odds since he took power in July with the determination to take Britain out of the EU on Oct. 31 with or without a divorce deal with Europe.
Parliament has passed a law requiring him to formally seek an extension if no deal is reached by mid-October, but Johnson has said he will not do that under any circumstances, setting the stage for future confrontations.
The suspension of parliament sparked several legal challenges, to which lower courts have given contradictory rulings. England's High Court said the move was a political rather than a legal matter, but Scottish court judges ruled that Johnson acted illegally "to avoid democratic scrutiny."
There were four possible outcomes for the PM with the best case scenario for him being that he won and the Commons remains shut as he decided until October 14.
Judges could also choose to find against him but do nothing - or find against him and demand the Queen's Speech is brought forward by days or weeks.
The worst case scenario was that judges would find he deliberately lied to Her Majesty, broke the law and MPs would return to Parliament this week because his prorogation was "void".
The Prime Minister has insisted said that he would comply with the Supreme Court's ruling.
- additional reporting Daily Mail