The Order of the UNCLOS Annex VII Arbitral Tribunal to Suspend Proceedings in the Case of the MOX Plant at Sellafield: How Much Jurisdictional Subsidiarity? VOLKER RÖBEN* 1. Introduction The Mixed Oxide fuel (MOX) plant at Sellafield in the United Kingdom has gained notoriety in legal circles interested in the law of sea. To date the International Tribunal for the Law of the Sea, an Arbitral Tribunal established pursuant to Annex VII of the UN Convention on the Law of the Sea, and an Arbitral Tribunal under the Convention for the Protection of the Marine Environment of the North-East Atlantic have pronounced on certain interna- tional law questions raised by the commissioning of the plant. The European Court of Justice in Luxemburg may soon enter the fray. The jurisdictional over- lap arises because the three substantive conventional regimes of the UN Convention on the Law of the Sea (UNCLOS or Convention), 1 the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) 2 and the Treaty establishing the European Community (EC) 3 each with their own compulsory dispute settlement mechanism apply to the same set of facts. This note will focus on the order of 24 June 2003 of the UNCLOS Annex VII Arbitral Tribunal. 4 Seized by Ireland with the claim that the United Kingdom had violated its obligations under UNCLOS in commissioning the Nordic Journal of International Law 73: 223–245, 2004. 223 © 2004 Koninklijke Brill NV. Printed in the Netherlands. * Dr. Iur, LLM (College of Europe, Bruges), LLM (UC Berkeley), Max Planck Institute for Comparative Public Law and International Law, Heidelberg. 1 United Nations Convention on the Law of the Sea, with Annexes, Done at Montego Bay, 10 December 1982. 2 Convention for the Protection of the Marine Environment of the North East Atlantic, 22 September 1992. 3 Treaty Establishing the European Community, 25 March 1957, as amended by the Treaties of Amsterdam, 2 October 1997, and Nice, 26 February 2001. 4 For a general analysis of the issue of overlapping jurisdictions in international law, see Y. Shany, The Competing Jurisdictions of International Courts and Tribunals (Oxford University Press, Oxford, 2003); V. Lowe, ‘Overlapping Jurisdiction in International Tribunals’, 20 Australian Yearbook of International Law (2001) p. 1; J. Pauwelyn, ‘How to Win a World Trade Organization Dispute Based in Non-World Trade Organization Law?’, 37 Journal of NORD_f3_223-245 10/17/2004 5:17PM Page 223