Boris Johnson has been accused of the worst abuse of power of its kind for 50 years in a historic Supreme Court case against the Prime Minister.
The UK's highest court heard bombshell claims that the PM deliberately tried to "silence" MPs with an "exceptionally long" shutdown of Parliament.
The PM asked Her Majesty to close Parliament from September 9 to October 14 - claiming it was a standard procedure to hold a Queen's Speech.
But kicking off a three-day case today, lawyers for campaigner Gina Miller said it was an "unlawful abuse of power" to stop debate on Brexit .
Her barrister Lord Pannick QC said: "The exceptional length of the prorogation in this case is strong evidence that the Prime Minister's motive was to silence Parliament for that period.
"Because he sees Parliament as an obstacle to the furtherance of his political aims."
Lord Pannick warned it was "remarkable " that Mr Johnson refused to give a statement explaining why he advised the Queen to suspend Parliament.
And with Mr Johnson unwilling to be cross-examined, Lord Pannick suggested the 11 Supreme Court justices could draw their own conclusions about the Prime Minister.
Protesters gathered outside the Supreme Court today including one dressed as the Incredible 'Sulk' - mocking Boris Johnson's comparison of himself to the cartoon hero.
The case will run for three days and culminate with evidence from lawyers for the former Tory Prime Minister John Major.
It arose out of two conflicting challenges brought in England and Scotland over the legality of the prorogation.
While the High Court in London decided it was not a question for the courts, in Edinburgh, the Court of Session concluded Mr Johnson's decision was unlawful because it was "motivated by the improper purpose" of frustrating Parliament.
Lord Pannick said the Court of Session's decision was "supported by the Prime Minister's own public statements as to his concerns as to what Parliament may do".
He said that the lack of a Government witness statement suggested the same thing.
Lord Pannick said the appeal raises "fundamental questions of constitutional law".
And he said no Prime Minister "has abused his power in the manner in which we allege in at least the last 50 years".
He accepted the Prime Minister does have the power to advise the Queen to prorogue Parliament.
But Lord Pannick argued the length of this suspension amounts to an abuse of power in the circumstances.
Lord Pannick added: "Parliament will be silenced for a substantial part of the period leading up to the deadline of October 31 when issues of grave national importance are being addressed (or not addressed) by the Government."
As the hearing began, Supreme Court President Lady Hale emphasised that the case is only about whether the Prime Minister's advice to the Queen was lawful.
She added: "We are not concerned with the wider political issues which form the context for this legal issue.
"As will be apparent when we hear the legal arguments, the determination of this legal issue will not determine when and how the UK leaves the European Union."
Mr Johnson advised the Queen on August 28 to prorogue Parliament for five weeks and it was suspended on September 9.
The Prime Minster says the five-week suspension is to allow the Government to set out a new legislative agenda in a Queen's Speech when MPs return to Parliament on October 14.
But those challenging his decision argue that it is designed to prevent parliamentary scrutiny of Brexit.
The case continues with representations from government this afternoon.
