The ECJ has today ruled that an attempt by the Irish Government to bring the UK before the International Tribunal for the Law of the Sea (ITLOS) over the Sellafield nuclear plant is in breach of EU law, on the grounds that only the Union institutions have jurisdiction of such claims between its Members. The Court has apparently held that, as the UN Convention on the Law of the Sea (UNCLOS) has been incorporated into EU law, the Irish action before ITLOS - which focuses on the Mox plant, designed to import and reprocess foreign waste - is illegal, as it fails to respect the its own exclusive jurisdiction over the case.
This was not unexpected. The Arbitral Tribunal set up to hear the Mox case noted as early as 2003 (see its Order No. 3 here) that it could not proceed with an examination of the merits until the question of exclusive EU competence had been decided; and it seemed entirely prepared to leave this decision to the ECJ (see para. 26). Even though neither the UK nor Ireland had argued before it that all interpretation of the Convention falls entirely under the exclusive jurisdiction of the ECJ, the Tribunal found that "it cannot be held with certainty that this view would be rejected by the European Court of Justice" (para. 21); and both parties were in agreement that, should this happen, then the Arbitral Tribunal set up under the UNCLOS would have no jurisdiction to hear the case.
The judgment is not yet available online, and it will certainly be necessary to read it closely before drawing any hard conclusions from it. It does, however, seem significant in more general terms, for those (such as, for example, the International Law Commission) concerned with the fragmentation of international law, and in particular with the fragmentation of those judicial bodies competent to rule on it. It is clear that this ECJ judgment paves the way for the possibility that the same Convention may well be subjected to final and binding interpretations by two different bodies, with potentially differing views, depending on which states are parties to any given dispute. It is thus easily conceivable that the same words of a legal instrument could give rise to two substantively different sets of obligations, depending on not what, but who is at issue. It is difficult to see, in these terms, how this decision of the ECJ can do anything but undermine the push towards the creation and enforcement of coherent and consistent global standards; and this in perhaps one of the most important areas of this endeavour, the responsibility for transboundary nuclear pollution.