Parliament should avoid ’dangerous ambiguity’ in the legal system by formally instructing courts to take account of European Court of Justice (CJEU) decisions when they are relevant post Brexit, a thinktank has warned in the run-up to the Repeal Bill. 

In Brexit and the European Court of Justice the Institute for Government says that ministers have left fundamental questions unanswered on the status of CJEU decisions after the UK leaves the European Union. While the government has said pre-Brexit decisions of the European Court will be incorporated into UK law, it has not said how British judges should treat future rulings. This would expose judges to a 'fierce political battle', the institute maintains. 

The report says parliament has three options for ending the ambiguity. 

- Telling the courts to ignore post-Brexit CJEU rulings. The report cites unnamed legal experts as describing this option as 'mad', 'absurd' and 'potty'. It states that UK courts regularly invoke the reasoning of courts around the world and that proscription of CJEU decisions would give the European court a lesser status than those other courts.

- Making post-Brexit decisions binding. The institute concedes that this option 'is unlikely to be considered compatible with the government's stated objective of ending the CJEU's jurisdiction in the UK'. 

- 'Taking account.' Under this, preferred, option parliament would in effect license courts to refer to the CJEU's reasoning in future judgments, without making them binding.  It would allow British judges to draw on helpful precedents as they do from other foreign courts, the institute states and would be 'compatible with the objectives set out in the government's white papers on Brexit and the Repeal Bill'.

Raphael Hogarth, the report's author, said it was important not to leave the matter for judges to decide: 'Parliament should protect the independence of the UK judiciary by ensuring that responsibility for setting the terms of the post-Brexit constitutional order is seen to rest firmly in Westminster, not beneath a wig.'