Where Power Lies or Where Power Lied?

Tomorrow, on Tuesday 17 September, the UK Supreme Court will be asked to consider appeals from the Court of Session in Scotland, and the High Court in England on the question of whether prime minister Boris Johnson’s advice to the Queen to prorogue parliament was lawful. Such a question will oblige the court to consider foundational questions of the separation of powers and the division between law and politics. It will also have to decide whether the motives of executive decision-making can be judged against principles of parliamentary sovereignty, democracy and the rule of law. If the Supreme Court finds the advice was unlawful, an even more difficult question arises in what sort of order may be given to remedy such a legal wrong: can the court order Parliament to return to a session which has ended, or the Queen to ‘un-prorogue’?