A decision with historic resonance is set to be announced Tuesday when Britain's Supreme Court rules on the legality of Prime Minister Boris Johnson's five-week suspension of Parliament.
The case marks a rare confrontation between the prime minister, the courts, and Parliament over their rights and responsibilities, and also involves Queen Elizabeth II.
It revolves around whether Johnson acted lawfully when he advised the queen to suspend Parliament for five weeks during a crucial time frame before the Oct. 31 Brexit deadline when Britain is scheduled to leave the European Union.
Johnson, who is in New York for the United Nations General Assembly, has refused to say whether he will resign if he is found to have broken the law, or will seek to shut down Parliament again.
Britain's highest court says it will announce the decision at 10:30 a.m. (0930GMT) after holding three days of hearings last week before 11 judges.
It could decide the suspension was proper, or that the courts don't have jurisdiction in this matter _ rulings that would give Johnson a victory _ or it could find that the prime minister acted improperly.
The government says the decision to suspend Parliament until Oct. 14 was routine and not related to Brexit. It claims that under Britain's unwritten constitution, it is a matter for politicians, not courts, to decide.
The government's opponents argue that Johnson illegally shut down Parliament just weeks before the country is due to leave the 28-nation bloc for the ``improper purpose'' of dodging lawmakers' scrutiny of his Brexit plans.
They also accused Johnson of misleading the queen, whose formal approval was needed to suspend the legislature.
Johnson and Parliament have been at odds since he took power in July with the determination to take Britain out of the EU on Oct. 31 with or without a divorce deal with Europe.
Parliament has passed a law requiring him to formally seek an extension if no deal is reached by mid-October, but Johnson has said he will not do that under any circumstances, setting the stage for future confrontations.
The suspension of Parliament sparked several legal challenges, to which lower courts have given contradictory rulings. England's High Court said the move was a political rather than a legal matter, but Scottish court judges ruled that Johnson acted illegally "to avoid democratic scrutiny.''