Britons are about to tune into a televised courtroom drama that could end with the British Prime Minister facing a constitutional crisis.
On Monday morning in London (10:00pm AEDT), the UK’s Supreme Court will start hearing the Government’s arguments against a High Court decision
This appeal is already historic, with all 11 justices presiding for the first time in what will be the most high-profile and complex case they have faced.
The British Attorney-General will argue on behalf of the Government that the High Court judges relegated the Brexit vote to a footnote and that the referendum should not be dismissed as “merely a political event”.
He will argue the issue “cannot be resolved in a vacuum, without regard to the outcome of the referendum”.
A majority of British voters — 17.4 million — supported the UK leaving the European Union in the June 23 referendum.
How did it get here?
It ended up in court after several complainants, including businesswoman Gina Miller, said the Prime Minister did not have the right to take Britain out of the EU without parliamentary approval.
Ms May had promised she would trigger Article 50 before the end of March next year.
That would start two years of formal talks ending in divorce from the EU by early 2019.
The three High Court judges who made the original ruling were demonised in the press.
The Daily Mail ran their photos on the front page with the headline “Enemies of the People”.
The Government announced it would appeal their decision and Monday marks the start of the four-day hearing.
Are the odds against Theresa May?
Former UK Independence Party leader Nigel Farage had threatened to bring 100,000 protesters to the Supreme Court, but those plans have been cancelled.