What will happen to UK references for preliminary ruling which are pending before the Court of Justice in Luxembourg if and when the UK leaves the EU? As with most Brexit questions, the short answer is that no one knows.
But this is an important practical question for many clients and their lawyers. And it is a question which they need to think about now when considering litigation, since it is not unheard of for references to take as long as two years to resolve (see the CJEU’s Annual Report on Judicial Activity (2015) p 88). Two years, of course, is also the time allowed under Article 50 TEU for negotiation of an agreement for Brexit.
References for preliminary ruling are made under Article 267 TFEU, and have been described as a “dialogue” between courts of Member States and the Court of Justice of the European Union: David Anderson and Marie Demetriou, References to the European Court (2nd ed, 2002). Where a case before a UK court/tribunal raises a question of interpretation or validity of an EU act, that court/tribunal may request that the Court of Justice give a ruling on the question if “a decision on the question is necessary to enable [the court/tribunal] to give judgment”: Article 267.
An earlier post on Brexit Law by Sarah Abram addressed the immediate effects of the EU referendum on Article 267 references. What about references which are still pending before the Court of Justice at the time of Brexit?
Perhaps this would be one of the myriad of issues that would be addressed during the two-year period after Article 50 has been triggered. So there may be special arrangements made or guidance provided. However, given the large number of complex issues which will need to be addressed, there can be no guarantee that time will be found for this. The fate of pending references is hardly likely to be high up negotiators’ agenda.
One possibility is that if the UK fully exits from the EU, and so is no longer a Member State, pending references would be declared devoid of purpose and so inadmissible. A referring court is under a duty to withdraw a preliminary reference if that reference has become pointless due to some later event (here, Brexit): see Advocate-General Warner’s Opinion at p 46 in Case 166/73 Rheinmühlen-Düsseldorf. The Court of Justice would normally contact the referring court in order to ask whether it wished to withdraw its request for a ruling. If the referring court refused to withdraw a reference that had become devoid of purpose, it would be open to the Court of Justice to decide that the case was inadmissible on the ground that the decision on the issue could no longer be considered to be necessary. As noted above, the second paragraph of Article 267 makes necessity one of the requirements for a valid reference. For example, in Case C-314/96 Djabali at  the Court of Justice recalled that the purpose of the reference procedure “is not that it enables advisory opinions on general or hypothetical questions to be delivered but rather that it is necessary for the effective resolution of a dispute”.
There are further possibilities. For example, the Court of Justice might more straightforwardly declare that it lacks jurisdiction post Brexit, since the referring court/tribunal would no longer be a court/tribunal of a Member State. However, what if transitional arrangements introduced as part of the procedure for uncoupling the UK from the EU mean that the answer to questions referred remains necessary? In those circumstances, the stage would be set for very interesting arguments about whether the case remained admissible.