The UK’s highest court will today hear appeals from two separate challenges to Boris Johnson’s decision to suspend Parliament.
Those who brought the legal challenges said prorogation was in order to prevent Parliament scrutinising the UK’s exit from the European Union on October 31.
However the Prime Minister said the five-week suspension was to allow the government to set out its agenda when MPs return on October 14.
The Supreme Court will sit as a panel of 11 justices for only the second time in its 10-year history, and must reconcile contradictory rulings from the English and Scottish courts.
The High Court in London dismissed an earlier challenge to the suspension of Parliament and described it as “not a matter for the courts”.
However on the same day the Inner House of the Court of Session in Edinburgh ruled Mr Johnson’s actions were unlawful because “it was motivated by the improper purpose of stymying Parliament”.
Scotland’s most senior judge, Lord Carloway, said: “The circumstances demonstrate that the true reason for the prorogation is to reduce the time available for parliamentary scrutiny of Brexit.”
Anti-Brexit campaigner Gina Miller brought the unsuccessful English challenge, and said Mr Johnson was guilty of a “classic power-grab”.
“The precedent Mr Johnson will set - if this is allowed to stand - is terrifying: any Prime Minister trying to push through a policy that is unpopular in the House and in the country at large would from now on simply be able to resort to prorogation,” she said.
The Supreme Court will hear submissions from Tuesday to Thursday, but it is not clear when it will hand down its ruling.