The UK Supreme Court has delivered a unanimous judgment confirming that the UK Courts have jurisdiction to review the advice of the UK Prime Minister to prorogue Parliament. They have held that the Prime Minister Boris Johnson’s recent advice to prorogue for an “extreme” length of time was unlawful. The decision is unprecedented and constitutionally significant for all Westminster democracies. It nevertheless involved, at least in terms of the question of whether or not the Courts had the power to rule on the issue, the application of conventional principles of judicial review.
The judgment can be obtained here: https://www.supremecourt.uk/cases/docs/uksc-2019-0192-judgment.pdf