The prorogation judicial reviews concerned the constitutional equilibrium between government, parliament and the courts. Today, an 11 member UK Supreme Court panel affirmed its centuries-old supervisory jurisdiction over acts of government and ruled unanimously that Boris Johnson’s government failed to advance any reasonable justification for proroguing parliament. The prorogation was therefore unlawful and ‘never happened’ so parliament is back in the game.

What are the implications?

The UK Supreme Court declared that the advice given to the Queen was unlawful, and it was outside the powers of the Prime Minister to give it. Therefore the order proroguing parliament was also unlawful. The court ‘quashed’ the order, meaning it was null and of no effect. It declared that “Parliament has not been prorogued” and that “it is for Parliament to decide what to do next”. In a memorable phrase in the summary she read out today in court, Lady Hale announced that “…when the Royal Commissioners walked into the House of Lords it was as if they walked in with a blank sheet of paper.”

In other words, legally speaking, parliament is still in session and there is nothing to prevent parliamentary business from resuming immediately. That is a political decision for parliament itself, and the court invited the Speaker of the House of Commons and the Lord Speaker to decide as soon as possible upon a way forward. It appears John Bercow has already announced that the 2017-2019 session will resume tomorrow, 25 September 2019.

The court also gave guidance that, in most circumstances, the prime minister’s desire to end one parliamentary session and begin another “will normally be enough in itself to justify the short period of prorogation [for a few days] which has been normal in modern practice” (para 51). The court said it would exercise caution in second guessing any justification put forward, because the prime minister should receive a degree of deference in his area of responsibility. Might the prime minister seek to prorogue parliament afresh, albeit for only the ‘normal’ few days? It would appear extraordinary for the prime minister to do something so politically incendiary at this juncture, and it would inevitably face a further judicial review. However, the UK Supreme Court does seem to have left open the possibility of briefly proroguing in order to deliver a Queen’s Speech. Boris Johnson has said that he is returning to London shortly from New York and will respect the court’s judgment, but it does not appear he has yet ruled a further prorogation out.

The wider implications may be significant. For example, only three carry over motions were passed for eligible bills before parliament was purportedly prorogued, so a range of bills, including all five Brexit bills, were understood to have fallen. If the parliamentary session never ended, however, logically those bills are still ‘live’. Will a temporary recess need to be agreed to allow for the Conservative party conference next weekend as would happen in a typical year? Will parliament’s first act be to seize control of the order paper again, and to what end – perhaps to legislate a new statutory control mechanism for use of the prerogative? It must be rather unsatisfactory for politicians that future prorogations are clearly open to challenge and their lawfulness rests on uncertain criteria: whether it is long enough to require justification, and whether the justification is reasonable.

The UK Supreme Court has clearly tried to limit its ruling to the very extraordinary circumstances that have arisen, calling the case a “one off”. Nevertheless, the terms of its judgment, particularly around the “without reasonable justification” test, seem to invite further litigation. That potentially includes claims brought by parties who wish not only to use the courts to uphold the constitution, but also to advance political objectives – even where they have not succeeded in doing so in parliament.