MOX Plant Case

The MOX Plant case (Ireland v. United Kingdom) was an UNCLOS Annex VII arbitration over a mixed-oxide nuclear fuel facility at Sellafield and its effect on the Irish Sea. On 3 December 2001, ITLOS issued an Order on provisional measures (Case No. 10) directing Ireland and the United Kingdom to cooperate, exchange information, and monitor risks, while declining the broader suspension Ireland sought. The Annex VII tribunal later suspended its proceedings because the dispute touched EU law, and the European Court of Justice held in 2006 that Ireland had breached EU law by bringing the claim outside the EU judicial system. The case is a leading example of competing jurisdictions over a single dispute.