Down Arrow Button Icon

The U.K. Parliament is not suspended and must return to work immediately, the country’s highest court ruled Tuesday morning.

In an unprecedented ruling, the Supreme Court ruled not only that it was admissible for the court to rule on Boris Johnson’s advice to the Queen that Parliament should be suspended, but that it was “unlawful” for the prime minister to prorogue Parliament in the first place.

In announcing the ruling, Lady Hale, one of the 11 justices of the Supreme Court, said the justification for advising the Queen to prorogue Parliament did not explain why it was necessary to open a new session of Parliament on October 14, when the house will resume, or why the length of the prorogation was necessary. It also did not discuss the difference between a prorogation and a recess.

While a recess in the House of Commons allows Parliamentary business to continue, a prorogation (often called a suspension), stops all legislative activity, effectively wiping the slate clean.

In August, the Queen prorogued Parliament on the advice of the prime minister, which she is historically bound to take. Johnson argued that the suspension was to prepare for a new Queen’s Speech on October 14, when Parliament was to return, laying out the domestic legislative agenda of his government.

However, the decision was quickly met with fierce criticism, including from members of prime minister’s own party, who argued that the suspension had instead been requested in order to frustrate Parliament in the lead-up to a deadline to exit the EU on October 31, and the advice to the Queen was given in bad faith in order to frustrate the democratic process.

The suspension ultimately faced multiple legal challenges, including in Scotland’s highest court, which earlier this month ruled that the suspension was unlawful.

On Tuesday, the U.K.’s highest court made it clear that it sided with the Scottish ruling.

“It is impossible for us to conclude on the evidence… that there was any reason — let alone a good reason — to advise Her Majesty to prorogue Parliament for five weeks,” said Lady Hale.

“The Court is bound to conclude, therefore, that the decision to advise Her Majesty to prorogue Parliament was unlawful because it had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions within reasonable justification,” Hale said.

“This means that the Order in Council to which it led was also unlawful, void and of no effect and should be quashed,” said Hale. “The prorogation was also void and of no effect. Parliament has not been prorogued. This is the unanimous judgment of all 11 judges.”

“It is not clear to us that any step is needed from the prime minister, but if it is, the court is pleased that his counsel have told the court that he will take all necessary steps to comply with the terms of any declaration made by this court,” she finished.

Shortly after the ruling, John Bercow, the Parliamentary speaker, said he welcomed the ruling, and that the House of Commons must “convene without delay.”

“To this end, I will now consult the party leaders as a matter of urgency,” he said.

Johnson is currently in New York for climate meetings at the United Nations. While his government has said prior to the ruling that it will respect any decision by the Court, Johnson himself has not ruled out proroguing Parliament a second time.

The ruling also raises questions about the future of Johnson’s role as prime minister. In the minutes after the ruling, the Labour Party, the Scottish National Party, and Plaid Cymru, the Welsh national party, called for him to step down.

He has previously told The Times of London that he would not resign if he was found to have misled the Queen.

‘Unlawful:’ Boris Johnson Loses Brexit Battle as Supreme Court Rules Against His Suspension of Parliament

More must-read stories from Fortune: