The Supreme Court is meeting to consider whether Boris Johnson acted lawfully in suspending Parliament.
The 11 judges are hearing two appeals relating to the PM’s decision to prorogue Parliament to mid-October.
Edinburgh’s Court of Session found last week that the shutdown was unlawful and “of no effect”, but London’s High Court said it was not a court matter.
Lady Hale, the President of the Court, said its job was to “decide serious and difficult questions of law”.
But, in her opening statement, she said the court would not determine “wider political questions” relating to the Brexit process and its ruling would have no bearing on “when and how the UK leaves the EU”.
Ahead of the unprecedented hearing, the prime minister said he would “wait and see what the judges say” before deciding whether to recall Parliament.
For the next three days, the Supreme Court in London will hear arguments from the government and campaigners challenging the decision to suspend Parliament.
The suspension, a process known as prorogation, began a week ago.
MPs are not scheduled to return until 14 October, when there will be a Queen’s Speech outlining Mr Johnson’s legislative plans.
Scotland’s highest civil court last week found in favour of a cross-party group of politicians challenging the PM’s move and ruled that Mr Johnson’s suspension of Parliament was unlawful.
The judges were unanimous in finding Mr Johnson was motivated by the “improper purpose of stymieing Parliament”, and he had effectively misled the Queen in advising her to suspend Parliament.
The judgement came after London’s High Court heard a case brought by businesswoman and campaigner Gina Miller, who argued the shutdown of Parliament was “an unlawful abuse of power”.
The judges said they rejected her claim because the suspension of Parliament was a “purely political” move and was therefore “not a matter for the courts”. Read more