Britain's Supreme Court has begun considering legal challenges to Prime Minister Boris Johnson's controversial decision to suspend parliament for over a month, as the country's political crisis over Brexit intensifies.
The court started hearing three days of arguments over Mr Johnson's move to shutter, or prorogue, the House of Commons last week until 14 October - just two weeks before the country is scheduled to leave the European Union.
The politically-charged case, unprecedented in Britain, could lead to parliament being recalled and Mr Johnson's political hand severely weakened in the run-up to the 31 October departure date.
The appeals revolve around "whether it was lawful for the prime minister to advise Her Majesty to order prorogation," Supreme Court President Brenda Hale said as she opened proceedings.
"This is a serious and difficult question of law.
"We are not concerned with the wider political issues.
"The determination of this legal issue will not determine when and how the UK leaves the EU."
At a small demonstration outside, protesters held up placards reading "Defend Democracy".
One protester dressed as a Boris Johnson version of the Hulk. Source: AAP
One was dressed as the Incredible Hulk - a reference to an analogy made by Mr Johnson between the comic book character and Britain as it prepares to leave the EU.
It is not known when Britain's highest court will reach a decision.
Johnson told BBC television beforehand that he would "wait and see what the judges say".
Johnson chaired a cabinet meeting on Tuesday, the day after holding his first face-to-face talks with European Commission chief Jean-Claude Juncker and EU Brexit negotiator Michel Barnier.
Following the meeting in Luxembourg he insisted there remained a "good chance" of striking a new divorce deal -- if there was "movement" from the bloc.
Prime Minister Boris Johnson arriving to meet Prime Minister Xavier Bettel at the prime ministers office in Luxembourg. Source: Press Association
But Mr Juncker's office appeared more pessimistic, saying Britain must "come forward with legally operational solutions" to the existing withdrawal agreement struck by his predecessor Theresa May.
"Such proposals have not yet been made," it said.
'Entirely proper'
The Supreme Court's entry into the three-and-a-half year saga stems from Johnson's "do or die" promise to deliver Brexit on 31 October.
He suspended parliament for five weeks in what his critics say was a blatant bid to keep his pro-European opponents from trying to get it further postponed.
The government counters that parliament is usually dissolved yearly and that Mr Johnson was simply clearing the way for a new agenda following May's resignation in July.
The Supreme Court has called in the maximum 11 of its 12 judges to hear the case, so that there cannot be a tie.
They must rule on whether they even have the right to adjudicate on the politically contentious issue, before considering Mr Johnson's motivations for the move.
The High Court in England said it was not a matter for the courts to decide upon, while Scotland's highest civil court called the suspension "unlawful".
David Pannick, representing campaigners appealing against the High Court decision, opened his case by saying that Mr Johnson had asked Queen Elizabeth II to suspend parliament "to avoid what he saw as the risk that parliament, during that period, would take action to frustrate or to damage the policies of his government."
London's Queen Mary University law professor Sionaidh Douglas-Scott said the verdict could have monumental consequences not only for Brexit but also how the world's oldest parliamentary democracy functions in future.
"If parliament is prorogued (suspended) with no remedy available then the balance of power is tipped far too heavily to the executive," she told AFP.
A defeat for Mr Johnson would leave him open to charges that he has effectively lied to Queen Elizabeth and likely calls for his resignation.
If Boris Johnson loses he is likely to be accused of effectively lying to the Queen. Source: AAP
The British monarch is the head of state and is constitutionally bound to act on her prime minister's advice.
'Dead in a ditch'
Ahead of its suspension parliament rushed to pass a law forcing Mr Johnson to ask Brussels for a delay if no compromise emerges from an 17-18 October EU summit in Brussels.
But he has insisted he would rather be "dead in a ditch" than ask his European counterparts to postpone Brexit for a third time.
Mr Johnson is hoping widespread fears a chaotic "no-deal" end to Britain's 46-year involvement in the European project will push its leaders to compromise.
