ITLOS rejects all preliminary objections in Mauritius v. Maldives


On 28 January 2021, a Special Chamber of the International Tribunal for the Law of the Sea (“ITLOS”) ruled on preliminary objections in the Dispute Concerning Delimitation of the Marine Boundary Between Mauritius and the Maldives in the Indian Ocean (Mauritius v. Maldives).  The ITLOS rejected all five of the Maldives’ preliminary objections and found Mauritius’ claims admissible.  The ITLOS deferred to the merits phase questions concerning the extent of its jurisdiction, including under Article 76 of the United Nations Convention on the Law of the Sea (“Convention”), as well as matters concerning Articles 74(3) and 83(3).

In June 2019, Mauritius initiated arbitral proceedings pursuant to Annex VII of the Convention, to delimit a maritime boundary in the Indian Ocean.  In September 2019, both Parties concluded a special agreement, pursuant to which they agreed that the dispute be transferred to a Special Chamber of the ITLOS.  The Maldives raised five preliminary objections in respect of jurisdiction and admissibility before the ITLOS, outlined below.

The first and second objections were inter-related, as they centred on the legal status of the Chagos Archipelago.  In particular, the Maldives argued that there was an unresolved sovereignty dispute between Mauritius and the United Kingdom over the Chagos Archipelago, which fell outside the scope of the ITLOS’s jurisdiction.  The Maldives also argued that the United Kingdom, which was not party to the proceedings, was an indispensable third party.  To address these objections, the ITLOS considered two decisions: (a) the award in the Chagos Marine Protected Area Arbitration between Mauritius and the United Kingdom (“Chagos Arbitral Award”); and (b) the advisory opinion of the International Court Justice (“ICJ”) regarding the separation of the Chagos Archipelago from Mauritius (“ICJ Chagos Advisory Opinion”).  As for the Chagos Arbitral Award, the ITLOS found that, for jurisdictional reasons, the tribunal had not recognised the United Kingdom as the coastal State with respect to the Chagos Archipelago.  Nor did the Chagos Arbitral Award have res judicata effect regarding the existence of a sovereignty dispute between Mauritius and the United Kingdom.

As for the ICJ Chagos Advisory Opinion, the ITLOS acknowledged that the UN General Assembly’s questions had related to the lawfulness of the decolonization process of Mauritius and the United Kingdom’s continued administration of the Chagos Archipelago.  Although these questions were not directly about the sovereignty dispute over the Chagos Archipelago, the ITLOS found the ICJ Advisory Opinion had considerable implications for the sovereignty dispute, as decolonization and territorial sovereignty were closely interrelated.  The ITLOS recognised that advisory opinions were nonetheless authoritative statements of international law on the questions with which they dealt, even if not legally binding.  It concluded that the ICJ’s pronouncements—that the United Kingdom’s continued administration of the Chagos Archipelago was unlawful and the territorial integrity of Mauritius should be respected—“have legal effect and clear implications for the legal status of the Chagos Archipelago”, and Mauritius’ sovereignty could “be inferred” from those determinations.  This conclusion was supported by UN General Assembly Resolution 73/295, which had demanded that the United Kingdom withdraw within six months its administration of the Chagos Archipelago.   Because it found no sovereignty dispute, the ITLOS rejected the first two objections.

The third objection argued that Mauritius and Maldives had not engaged, and could not have meaningfully engaged, in negotiations required by Articles 74 and 83 of the Convention. The ITLOS agreed that Articles 74(1) and 83(1) did impose an obligation to negotiate in good faith, with a view to reaching an agreement on delimitation.  However, the obligation did not require States concerned to reach such agreement.  Among other reasons, the ITLOS noted that, for most of the time, the Maldives had refused to negotiate with Mauritius.  The ITLOS concluded that, in a situation where the Parties “cannot meaningfully engage”, it was clear that no delimitation agreement could be reached “within a reasonable period of time”, for purposes of Articles 74 and 83.  The ITLOS considered that, in such situations where no agreement could be reached, “to resort to the procedures of Part XV of the Convention […] is not only justified but also an obligation of the States concerned”.  Accordingly, the ITLOS rejected the third objection.

In its fourth objection, the Maldives argued that there had been no dispute over maritime delimitation between the two States, on the grounds that Mauritius was not a State with an opposite coast to the Maldives, for purposes of Articles 74 and 83 of the Convention. The ITLOS disagreed, finding that Mauritius qualified as an opposite or adjacent coast, as it enjoyed sovereignty over the Chagos Archipelago.  The Maldives also argued that the two States had not held positively opposed claims to their respective maritime zones.  The ITLOS found that, in light of national legislation and diplomatic exchanges, there was clearly an overlap of maritime claims between the two States.  Therefore, the ITLOS dismissed the fourth objection.

In its fifth and final objection, the Maldives argued that Mauritius’ use of maritime boundary proceedings to obtain a ruling on the territorial dispute with the United Kingdom constituted an abuse of process.  The ITLOS found that Mauritius’ claims concerned a disputed maritime boundary, not territory.  Because those maritime claims remained unresolved through negotiations and were limited to Articles 74 and 83 of the Convention, Mauritius’ claims did not constitute an abuse of process.  Accordingly, the ITLOS rejected the fifth objection.

As a result, the ITLOS upheld its jurisdiction to adjudicate upon the maritime boundary dispute and found Mauritius’s claims admissible.

In his dissenting opinion, judge ad hoc Oxman found that Mauritius’ request for judicial determination of a permanent maritime boundary was “not yet admissible”.  He found that there had been a dispute between Mauritius and the United Kingdom regarding the legal implications of the ICJ Chagos Advisory Opinion and UN General Assembly Resolution 73/295, which were closely related to a territorial dispute over the Chagos Archipelago.  Citing established jurisprudence, he considered that the ITLOS should refrain from exercising its jurisdiction.  He stressed that the Maldives’ reluctance to negotiate a maritime boundary had been based on its desire to avoid being drawn into the territorial dispute between Mauritius in the UK.  The Maldives had also indicated its willingness to proceed with delimitation negotiations once the territorial dispute was resolved.  Therefore, judge ad hoc Oxman found that “a reasonable period of time”, as stipulated by Articles 74(2) and 83(2), had not yet elapsed, with the result that the Maldives was not compelled to participate in the dispute settlement procedures of Part XV of the Convention.

The ITLOS’s judgment on preliminary objections is available here.

The joint declaration of Judges ad hoc Oxman and Schrijver is here.

The separate and dissenting opinion of Judge ad hoc Oxman is here.