Brexit in the Supreme Court – here’s what it all means

The biggest case in supreme court history. PA/Paul Rogers

The UK supreme court is hearing argument in one of the most important cases to be decided by British judges.

Miller v Secretary of State for Exiting the European Union concerns the question of whether the British government can begin Brexit negotiations without the consent of parliament. This is a legal question that does not involve the judges deciding on the merits of Brexit.

The government lost the case in the high court, a decision which threatened to derail its plan to trigger Article 50 by March 2017. Now it is appealing the decision in the supreme court.

The key legal argument

The government says it doesn’t need parliament’s approval to trigger Article 50 because it can use prerogative power to withdraw from international treaties, including the EU. These powers are remnants of ancient crown powers which have been largely replaced by legal powers based on acts of parliament. It can still use the prerogative to conduct international relations, including entering into or withdrawing from treaties – but there are important limits.

The respondents in the supreme court case (who were the claimants in the original high court case) say that Article 50 would, once triggered, inevitably alter domestic law and remove peoples’ rights. They say the government can’t use prerogative power to change domestic law or nullify rights unless this is expressly permitted by an act of parliament. They argue that since this permission has not been given, the prerogative cannot be used to trigger Article 50.

Gina Miller after her high court victory. PA

In a massive blow to the government, the high court agreed with these arguments. Now, the government will argue in front of the supreme court that it was wrong to do so. It will claim that the High Court paid too little attention to the referendum result. It will also argue that parliament accepts that the executive can use prerogative power to withdraw from the EU.

At this point, we must get a bit technical. The government will argue that the high court misinterpreted the 1972 European Communities Act (ECA) and later legislation relating to the EU when it made its ruling. It will say that when parliament enacted the ECA to implement treaty rights into domestic law it did not intend to limit the government’s ability to use its prerogative power to enter into or withdraw from treaties, or to alter the UK’s treaty obligations.

Had parliament intended this, it would have been clear from the wording of the legislation, the government will argue. In fact, it says, the wording shows the reverse. The ECA gives effect to rights “existing from time to time under the treaties”. This wording recognises that treaty rights may change over time and be removed by the exercise of prerogative powers. The ECA, the argument goes, is therefore not inconsistent with the exercise of prerogative power to alter the UK’s treaty obligations by triggering Article 50.

Delaying Brexit?

It’s important to note that the government agrees with the respondents that once Article 50 has been triggered it will inevitably lead to the UK leaving the EU. Had it argued that Article 50 notice could be withdrawn at a later stage – such as if Brexit negotiations proved unsatisfactory – it would have significantly weakened the respondents’ case that using the prerogative to trigger Article 50 would inevitably affect rights.

But disagreeing on this point would have been politically unacceptable for the government. It would open up a whole new discussion about what Article 50 actually means and might, in turn, mean asking for clarification from the Court of Justice of the European Union. This could delay Brexit.

That would be bad enough, but having to seek a ruling from the European court would be deeply embarrassing for the government, given the current climate. That said, it’s still possible that the supreme court will think it necessary to ask the ECJ for a ruling on the meaning of Article 50.

It’s never easy to predict how top courts will decide. Here, there are particular challenges, not least because for the first time, due to the unusual importance of the case, all 11 serving Supreme Court Judges are sitting. That all 11 will have to decide reduces the possibility of unanimity. It also increases the likelihood that we will see different approaches, even among judges who agree about the result.

If the government loses it will probably put a bill to parliament seeking to authorise giving notice under Article 50. At that point, attention will focus on the numbers in the House of Commons who are willing to support the bill – and on the House of Lords, which can be less predictable and has the potential to delay, if not to derail the government’s Brexit project.

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