Britain's Supreme Court is set to decide whether Prime Minister Boris Johnson broke the law when he suspended Parliament just weeks before the U.K. is due to leave the European Union.
Lower courts have given contradictory rulings.
England's High Court said it was a political rather than legal matter, but Scottish court judges ruled that Johnson acted illegally to avoid democratic scrutiny.
Johnson sent lawmakers home Sept.9 until Oct. 14, which is barely two weeks before the scheduled Brexit day of Oct. 31.
He says the suspension will allow his government to launch its domestic agenda with a new session of Parliament. Opponents say it's designed to prevent lawmakers interfering with his plan to leave the EU next month, deal or no deal.
The case starts Tuesday and could last three days.