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Why the ICJ’s Chagos Archipelago advisory opinion matters for global justice—and for ‘Global Britain’

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)123-136
Number of pages14
JournalTransnational Legal Theory
Issue number1
E-pub ahead of print24 Apr 2019

King's Authors


The ICJ’s advisory opinion on the legal consequences of the separation of the Chagos Archipelago from Mauritius in 1965, prior to Mauritian independence, is a significant development in a long-running transnational legal process. The UK's detachment of the Chagos Archipelago from Mauritius has resulted in multiple lawsuits brought by Mauritius or by the displaced Chagossians through domestic and international courts and tribunals. The ICJ has now clarified the dispute’s international legal context, by concluding that the Chagos Archipelago’s detachment was unlawful—meaning the decolonisation of Mauritius remains incomplete. This paper situates the advisory opinion within the context of the transnational legal process of the Chagos dispute. The paper analyses the significance of the ICJ’s focus on General Assembly resolutions in reaching its conclusions, the potential of increasing multipolarity in international relations to strengthen decolonisation norms, and the relationship between the UK's decolonisation obligations, Brexit and notions of ‘Global Britain’.

KEYWORDS: Chagos Archipelago, decolonisation, international Court of Justice, UN General Assembly, advisory jurisdiction
The International Court of Justice’s (ICJ) 25th February advisory opinion,1
1 Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Advisory Opinion, International Court of Justice, 25 February 2019.
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on the legal consequences of the separation of the Chagos Archipelago from Mauritius in 1965, is a major development in a long-running controversy—with potential significance that reaches far beyond the important matter that is its focus. This case-note will analyse the ICJ’s opinion on several levels: its conclusions regarding the lawfulness of the detachment of the Chagos Archipelago from Mauritius, and what these could mean for Mauritius, the dispossessed Chagossians and the United Kingdom (UK); the positive message that the opinion sends about the ability of international law to render just answers to long-standing injustices, using a dynamic approach to legal sources; and the nature of the interaction between the development of international law, on the one hand, and the emergence of a multipolar world on the other.

The paper is structured as follows. Part one summarises the facts of the separation of the Chagos Archipelago from Mauritius, which led to decades of domestic and international litigation and ultimately to the ICJ’s advisory opinion. Part two examines the arbitration between Mauritius and the UK under the UN Convention on the Law of the Sea (UNCLOS), in the aftermath of which the Mauritian campaign for an ICJ advisory opinion was launched. Part three analyses both the process and the substance of the advisory opinion. Part four concludes with some observations about the potential impacts of the advisory opinion.

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