​ITLOS Judgments
​​​​​On 18 June 2019, Mauritius initiated arbitral proceedings against Maldives under the UN Convention on the Law of the Sea (UNCLOS) for the delimitation of the maritime boundary between the two States in the region of the Chagos Archipelago.  Mauritius and Maldives subsequently agreed to transfer the dispute to a Special Chamber of the International Tribunal for the Law of the Sea (ITLOS) composed of nine member.

Maldives raised preliminary objections to the jurisdiction of the Special Chamber.  Its main contention was that the Special Chamber could not exercise jurisdiction because the United Kingdom continues to claim sovereignty over the Chagos Archipelago and thus the Chamber would be required to determine which State possesses sovereignty, which it is not competent to do under UNCLOS.

After the exchange of written pleadings on Maldives’ preliminary objections and the hearing held from 13 to 19 October 2020, the Special Chamber of ITLOS delivered on 28 January 2021 its Judgment in which it rejected all the preliminary objections raised by Maldives, and confirmed that Mauritius has undisputed sovereignty over the Chagos Archipelago and the United Kingdom cannot claim any rights over the Chagos Archipelago.

Highlights of the Judgment with regard to the legal status of the Chagos Archipelago are as follows:​
•​​​“The ICJ thus determined that the United Kingdom’s continued administration of the Chagos Archipelago is an unlawful act of a continuing character, entailing its international responsibility, and must be brought to an end as rapidly as possible. The Special Chamber considers that these determinations, together with those previously mentioned, have unmistakable implications for the United Kingdom’s claim to sovereignty over the Chagos Archipelago. In the Special Chamber’s view, such claim is contrary to the determinations made by the ICJ that the detachment of the Chagos Archipelago was unlawful and that the United Kingdom’s continued administration of the Chagos Archipelago constitutes an unlawful act of a continuing character.” (para. 173)

​•

“In the Special Chamber’s view, determinations made by the ICJ in an advisory opinion cannot be disregarded simply because the advisory opinion is not binding. This is true of the ICJ’s determinations in the Chagos advisory opinion, inter alia, that the process of decolonization of Mauritius was not lawfully completed when that country acceded to independence in 1968, following the separation of the Chagos Archipelago, and that the United Kingdom is under an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible. The Special Chamber considers that those determinations do have legal effect.” (para. 205)

​•

“In resolution 73/295, the General Assembly affirmed, “in accordance with the advisory opinion of the Court”, that: “[t]he Chagos Archipelago forms an integral part of the territory of Mauritius”. The Special Chamber considers that this affirmation is the General Assembly’s view of the advisory opinion.

In the resolution, the General Assembly demanded that


the United Kingdom … withdraw its colonial administration from the Chagos Archipelago unconditionally within a period of no more than six months from the adoption of the present resolution, thereby enabling Mauritius to complete the decolonization of its territory as rapidly as possible.


The Special Chamber notes that this demand was made as one of the “modalities” for ensuring the completion of the decolonization of Mauritius pursuant to the advisory opinion. In the Special Chamber’s view, the fact that the time-limit set by the General Assembly has passed without the United Kingdom complying with the demand further strengthens the Special Chamber’s finding as to the United Kingdom’s claim to sovereignty over the Chagos Archipelago noted in paragraph 173 above.” (paras. 228 and 229)

​•

“the continued claim of the United Kingdom to sovereignty over the Chagos Archipelago cannot be considered anything more than “a mere assertion” (para. 243)

•​

“The determinations made by the ICJ with respect to the issues of the decolonization of Mauritius in the Chagos advisory opinion have legal effect and clear implications for the legal status of the Chagos Archipelago.  The United Kingdom’s continued claim to sovereignty over the Chagos Archipelago is contrary to those determinations.  While the process of decolonization has yet to be completed, Mauritius’ sovereignty over the Chagos Archipelago can be inferred from the ICJ’s determinations.” (para. 246)

•​
“In the Special Chamber’s view, it is inconceivable that the United Kingdom, whose administration over the Chagos Archipelago constitutes a wrongful act of a continuing character and thus must be brought to an end as rapidly as possible, and yet who has failed to do so, can have any legal interests in permanently disposing of maritime zones around the Chagos Archipelago by delimitation.” (para. 247)

​•
“The Special Chamber considers that the above findings as a whole provide it with sufficient basis to conclude that Mauritius can be regarded as the coastal State in respect of the Chagos Archipelago for the purpose of the delimitation of a maritime boundary even before the process of the decolonization of Mauritius is completed”. (para. 250)

Written Observations of Mauritius on Maldives’ preliminary objections( Volume I & Volume II​)




Following two rounds of written pleadings and a hearing held from 17 to 24 October 2022, the Special Chamber of ITLOS delivered on 28 April 2023 its Judgment on the merits of the case.  In its Judgment, the Special Chamber established a binding international maritime boundary between Mauritius and Maldives in the Chagos Archipelago region.  The Judgment which is final and binding once again confirms that the Chagos Archipelago forms an integral part of the territory of Mauritius and that Mauritius is the only State which has sovereignty over the Chagos Archipelago.