The Supreme Court has ruled that Boris Johnson’s suspension of Parliament was unlawful in an historic judgement.
It means MPs could return to the House of Commons immediately.
The court first heard the ruling that the issue of prorogation was justiciable – meaning that it is capable of being challenged by the courts outside of Parliament.
The 11 justices decided unanimously that advising the Queen to prorogue Parliament was “unlawful because it had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions.”
Lady Hale, who delivered the ruling this morning, said the prorogation was "void and of no effect", adding: "Parliament has not been prorogued."
She told the court: “This was not a normal prorogation in the run up to a Queen’s Speech.
“This prolonged suspension of parliamentary democracy took place in quite exceptional circumstances, the fundamental change which was due to take place in the constitution of the United Kingdom on October 31.
“Parliament and in particular the House of Commons, as the elected representatives of the people has a right to a voice in how that change comes about.
“The effect on the fundamentals of our democracy was extreme.
“No justification for taking action with such extreme effect was put before the court.”
Protesters outside the court cheered as the judgement was delivered
Lady Hale continued that the speakers of the Houses of Commons and Lords "can take immediate steps to enable each house to meet as soon as possible".
Speaker John Bercow said he welcomed the decision and that the House of Commons must now “convene without delay”.
“To this end, I will now consult the party leaders as a matter of urgency,” he added.
Labour leader Jeremy Corbyn has called for the Prime Minister to "consider his position" whil addressing the Labour Party conference in Brighton.
He said the Prime Minister's action "demonstrates contempt for democracy and an abuse of power by him".
"I will be in touch immediately to demand that Parliament is recalled... I invite Boris Johnson in the historic words to consider his position."
Liberal Democrat leader Jo Swinson said it confirms that Boris Johnson "isn't fit to be Prime Minister".
"I'm on my way to resume my duties in the Commons and stop Brexit altogether," she tweeted.