Another UN Court Rules Chagos Archipelago Belongs to Mauritius

February 02, 2021

The International Tribunal for the Law of the Sea, based in Hamburg, has joined the International Court of Justice, which sits in The Hague, in determining that the Chagos Archipelago, a group of islands strategically located in the Indian Ocean, belongs to Mauritius.

In so doing, both international courts, which are part of the United Nations system, have rejected the United Kingdom’s pretensions to sovereignty over the islands, referring to the British colonial administration as a “continuing violation of international law” which “must be brought to an end as rapidly as possible” so that Mauritius can recover possession of “its territory.”

Mauritius was represented in both proceedings by an international legal team including Professors Philippe Sands, Q.C. of London and Pierre Klein of Montreal, and partners Paul Reichler, Andrew Loewenstein and Yuri Parkhomenko of Foley Hoag LLP, based in Washington, D.C. and Boston.

The ITLOS ruling, handed down on January 28, 2021 in a case between Mauritius and Maldives, rejected Maldives’ argument that the Tribunal was without jurisdiction to delimit its maritime boundary with the Chagos Archipelago because sovereignty over the Archipelago was disputed between Mauritius and the UK. The Tribunal ruled, by an 8-1 majority, that the ICJ, in an Advisory Opinion issued in February 2019, settled the legal status of the Archipelago by determining that it belonged to Mauritius. Although that Opinion was “Advisory,” the Law of the Sea Tribunal ruled that it still had “legal effects.”

The ruling was celebrated in Mauritius. Prime Minister Pravind Kumar Jugnauth said, “We are grateful to ITLOS for confirming the ICJ’s determination that the Chagos Archipelago is an integral part of Mauritian territory, and that the United Kingdom has no territorial rights or claim in respect of the Archipelago. Both of the world’s leading international courts have now ruled that Mauritius is the undisputed sovereign over the Chagos Archipelago.  ITLOS will now proceed to delimit our maritime boundary with Maldives, on the basis that the Chagos Archipelago is a part of our territory.”

Foley Hoag partner Paul Reichler, who argued for Mauritius, called the Tribunal’s decision “another major victory for Mauritius in its effort to recover the Chagos Archipelago” and “equally a major defeat for the UK in its efforts to hold on to its last colonial possession in Africa.”

Andrew Loewenstein, another Foley Hoag partner, explained that the Tribunal’s reliance on the ICJ’s Advisory Opinion has “potentially far-reaching significance.” The Tribunal held that, while an advisory opinion is non-binding, judicial determinations made in those opinions have “no less weight and authority than those in judgments because they are made with the same rigor and scrutiny by the ‘principal judicial organ’ of the United Nations with competence in matters of international law.”

Foley Hoag associate Diem Huang Ho was also part of Mauritius’ legal team.

The Tribunal will next proceed to delimit the maritime boundary between Mauritius, including the Chagos Archipelago, and Maldives. After receiving the written pleadings of the parties and hearing oral argument, the Tribunal will deliver a final judgment, which will be legally binding on the parties. It is expected next year.