Introduction
The Chagos Archipelago remains a highly contested decolonisation issue under international law. The islands were first colonised by France until the Treaty of Paris in 1814, which conceded Mauritius to the UK. In 1965, the UK split the Islands away from Mauritius and registered them as the British Indian Ocean Territory (BIOT) for the US to build a naval base on its biggest island, Diego Garcia (Minority Rights Group, 2025).
Despite being the homeland of the Chagossians, they were forcefully expelled in 1971 at the request of the US (Minority Rights Group, 2025). Since then, only military personnel have been allowed on the island. In 2019, Mauritius launched a sovereignty dispute against the UK with the International Court of Justice (ICJ), claiming the Chagos Archipelago. Similarly, the International Tribunal for the Law of the Sea (ITLOS) heard the dispute in 2021. In 2025, the UK signed the treaty transferring the Chagos Islands back to Mauritius, with a special provision allowing the leasing of Diego Garcia for 99 years (Minority Rights Group, 2025).
This article will explore the Chagos Island dispute and the legal rights of Mauritius and Chagossians. This analysis focuses on whether Chagossians hold a legal right to return to their homeland.
Background on the Chagos Island Dispute
The longstanding dispute between the UK and Mauritius on the sovereignty of the Chagos Islands was first brought to legal attention when the United Nations (UN) General Assembly (UNGA) adopted a resolution to prevent the UK from dismembering the territory of Mauritius in 1965 (Afogo, 2025). Decades later, the Permanent Representative of Mauritius to the UN submitted a request for an advisory opinion (AO) of the ICJ in 2016 (McNair Chambers, 2019). Subsequently, the UNGA referred two questions to the court:
- Was the process of decolonisation of Mauritius lawfully completed when Mauritius was granted independence in 1968?
- What are the consequences under international law arising from the continued administration by the UK of the Chagos Archipelago? (UNGA Resolution 71/292)
As such, the ICJ case, Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, addresses issues of colonialism, self-determination, and territorial integrity. The AO found that the separation of the archipelago from Mauritius was in violation of the right to self-determination, thereby the military base on Diego Garcia constituted as an internationally wrongful act (Milanovic, 2019). The right to self-determination of the Chagossians was reaffirmed by the Court, as well as the unlawful decolonisation process administered to Mauritius (ICJ, 2019). The AO thus concluded that the creation of the BIOT in 1965 violated the 1960 Declaration on the Granting of Independence to Colonial Countries and Peoples when it broke apart the archipelagos from Mauritius (Vallance, 2023).
Despite the ruling, the UK has been reluctant to sever its control over the archipelago. While negotiations between the UK and Mauritius are ongoing, Chagossians continue to be excluded from the process. They have fought for the recognition of the violations against them and the acknowledgement of their right to return after being forcefully deported (Human Rights Watch, 2022). For instance, a 2008 case before the House of Lords rejected the Chagossians’ right to return, claiming that the UK government was entitled to legislate for a colony (Campbell and Weaver, 2008). Furthermore, the UK has repeatedly prohibited their return to the Chagos Islands citing security reasons (Human Rights Watch, 2022).
In 2015, the UN arbitral tribunal for the Law of the Sea delivered its conclusion on The Matter of the Chagos Marine Protected Area Arbitration, agreeing that Mauritius has sovereign rights and jurisdiction in the territorial seas and the exclusive economic zone around the Chagos Archipelago as a coastal state (Afogo, 2025). Later, ITLOS again concluded in the case Delimitation of the Maritime Boundary between Mauritius and Maldives in the Indian Ocean, that the UK is not the coastal state and does not have a legal interest in the maritime zones of the Chagos Archipelago (Afogo, 2025). These two cases, as well as the ICJ AO, recognise Mauritian sovereignty over the archipelago.
Importantly, the interests of Mauritius and the Chagossians do not fully align. While Mauritius has reiterated a right to return to the archipelago, it also supports the continued leasing of Diego Garcia to the US as a military base that would exclude Chagossian residence (Human Rights Watch, 2023). The Chagossians are predominantly descendants of enslaved people brought over from other African states during the French and British colonial rule. Nevertheless, they have developed their own culture and language over the centuries, identifying themselves as a separate group of people from Mauritians (Human Rights Watch, 2023).
The continued forced displacement of the Chagossians and the outright refusal to right previous wrongful treatment amounts to crimes against humanity against an Indigenous people (Human Rights Watch, 2023). Although the UNGA has declared the Chagos Archipelago to be an integral part of the territory of Mauritius in Resolution 73/295, practical implementation regarding the rights of the islanders remains contested.
In 2025, the UK and Mauritius concluded their agreement recognising Mauritius sovereignty over the Chagos Archipelago, in line with decisions of international courts and tribunals.
Applicable Legal Framework
The Chagossians who were forcefully displaced by the UK have suffered from this international crime with no compensation or reparations for decades. Displaced Chagossians in Mauritius and Seychelles continue to face extreme poverty and discrimination (Human Rights Watch, 2023). Due to harmful cultural stereotypes and stigma of Chagossians being unvaccinated, many have been forced to hide their identity to prevent further abuse once displaced. Fifty years later, Chagossians remain hopeful for their return to the island one day despite the UK blockade. Despite evidence that the return of Chagossians was feasible, the UK government has opposed this numerous times on grounds of defence interest and costs (Duncan, 2016).
As the overwhelming desire for the right to return to Chagos intensifies, the debate on sovereignty is shifting to one between Chagossians and Mauritius. The 2025 UK-Mauritius Agreement solidified the transferal of the Chagos Islands to Mauritius without consultation with Chagossians. The applicable legal framework in this case goes beyond the UN instruments. It also includes the African Charter on Human and Peoples’ Rights (ACHPR), owing to the involvement of Mauritius and the Seychelles, and the European Convention on Human Rights (ECHR) when the UK extended its application to its colonies.
International human rights law recognises the responsibility to respect individuals within a state’s territory without distinction and protect them against abuse. However, the UK has persistently rejected the application of human rights law on the BIOT because of its lack of a permanent population. The Human Rights Committee (HRC) has rejected this argument and has repeatedly asked the UK to ensure Chagossians can exercise their right to return (HRC, 2008).
Peoples
The African Commission on Human and Peoples’ Rights identifies “people” as those with a “common tradition, racial or ethnic identity, cultural homogeneity, territorial connection”. In the landmark case Endorois Case, the Commission further identifies key criteria for Indigenous peoples:
- The occupation and use of a specific territory
- The voluntary perpetuation of cultural distinctiveness
- Self-identification as a distinct collectivity
- Experience of subjugation, marginalisation, exclusion or discrimination (ACHPR, 2003).
Comparably, the UN Declaration on the Rights of Indigenous Peoples (UNDRIP) clearly stipulates that Indigenous peoples cannot be removed from their lands and all decisions must take place with free, prior, and informed consent. Additionally, the specific right to self-determination is stipulated in the declaration, further acknowledging the importance of redressing forced population transfer that dispossessed them (UN, 2007). Applying this logic, the Chagossians constitute a people. With their unique Chagossian Creole language and its Sega tambour Chagos music, they are undoubtedly different from the populations of Mauritius and Seychelles (Human Rights Watch, 2023). In the same report, Chagossians recall their shared tradition of fishing and plantations and never thought they would have to leave the island they have called home for decades (Human Rights Watch, 2023). Even those in exile continue to self-identify as Chagossians and maintain a deep desire to return to the motherland. As such, Chagossians are not only a people, but an Indigenous group that has resided on the Chagos Archipelago. There is little dispute over the recognition of the Chagossians as a people, especially with the HRC, the ICJ, and the UK government in agreement.
Self-determination
In February 2026, a group of Chagossians re-entered the islands to prevent the transfer of the Chagos Archipelago to Mauritius (Badshah, 2026). Instead, they assert their right to self-determination, since no consent or process has ever been sought by the UK concerning the homeland of Chagossians.
The principle of self-determination is recognised under Article 1(2) of the UNC, as well as under Article 1 of the International Covenant on Civil and Political Rights (ICCPR). The ICJ in the Chagos case recognised the emergence of a right to self-determination as a customary international law norm since the adoption of Resolution 1514(xv) during the height of decolonisation. Since then, the right to self-determination has been recognised as jus cogens and an obligation erga omnes.
In the context of decolonisation, the right to self-determination is closely linked to the territorial integrity of colonial territories. The disruption of territorial integrity is incompatible with the UNC and constitutes an unlawful act. Nevertheless, while many former colonies gained independence that solidified the right to self-determination, it has been less successful in cases such as Kosovo, Quebec, and Catalunya (Klabbers, 2019).
In terms of the Chagos Archipelago, it became detached from Mauritius during negotiations that led to Mauritian independence. While the UK argued that the Lancaster House negotiations achieved consent of Mauritian representatives for the detachment of the Chagos Archipelago, most international tribunals and commentators have argued for the unlawful decolonisation process (Human Rights Watch, 2023).
In 2025, the Pretoria Declarations highlighted the right to self-determination of Chagossians, and more importantly, their right to decide whether to associate themselves with another state (Chagossian Voices, 2023). In this case, Mauritius or the UK. In fact, as a non-self-governing territory, the importance of achieving external self-determination is intrinsic to the protection and application of the human rights of Chagossians and the rectification of past acts (Klabbers, 2019). Serving as the ultimum remedium of the oppression and discrimination suffered, self-determination can then materialise in their independence (Klabbers, 2019).
The problem, however, also lies in the fact that the Mauritian government does not recognise Chagossians as distinct peoples (Chagossian Voices, 2023). Mauritius argues that the islands should be returned to them because it was part of the British Dependency of Mauritius prior to decolonisation.
A Right to Return?
The right of return is set out in Article 13(2) of the Universal Declaration of Human Rights (UDHR). It recognises the freedom to leave and return to one’s country, and has been further adopted in Article 12(4) of the ICCPR, Article 5(d)(ii) of the International Convention on the Elimination of All Forms of Racial Discrimination (ICERD), and Article 12(2) of the African Charter on Human and Peoples’ Rights (ACHPR). While this framework has predominantly been applied to refugees that seek repatriation, it is applicable in this situation. In essence, it implies a prohibition of transferring and expulsing a population (HRC, 1999).
The strongest legal argument supporting the right to return for the Chagossian people derives from the right to self-determination and remedial justice. The displacement of Chagossians is inseparable from the unlawful detachment and decolonisation process. Following the reasoning adopted by the ICJ in Chagos, the forced displacement of Chagossians can be understood as a continuing consequence of an internationally wrongful colonial act. If the UK’s administration of the Chagos Archipelago was unlawful because of the unlawful decolonisation process of Mauritius, then the expulsion of Chagossians would similarly lack legal legitimacy.
The right to return stems from the links of descendants with the territory, regardless of changes in control or sovereignty (Human Rights Watch, n.d.). Even where sovereignty remains contested, the rights of displaced communities should not be extinguished. In this sense, the right to return serves not only as an individual human right for the Chagossians but also as a form of restorative justice aimed at remedying the consequences of colonial displacement.
Recent legal developments further reinforce this position. In 2026, the BIOT Supreme Court overturned the 2004 position denying a right to return. This significantly shifted the recognition of Chagossian claims. Similarly, the 2025 decision of CERD recognised Chagossians as a distinct ethnocultural group whose displacement generated discriminatory effects. The Committee further expressed concern that the UK-Mauritius Agreement remained inconsistent with the UNGA Resolution 73/295, as it continued to prohibit return to Diego Garcia. Therefore, it called upon the suspension of ratification by both parties until meaningful consultation with Chagossians occurred (Tranchez, 2025). These developments underscore the UK’s obligation under international law to ensure that remedial measures incorporate the rights of the Chagossians.
On the other hand, the biggest argument against the return of Chagossians has been on grounds of security and the importance of the military base on Diego Garcia. As the UK and US play important roles in regional and global operations, they argue that unrestricted resettlement would interfere with the operational output on the island. Regardless, a feasibility study conducted by KPMG clearly concludes that the resettlement of Chagossians on the island is possible (Jere, 2019).
Thus, while the current agreement between the UK and Mauritius is an important step toward achieving the right to return for the Chagossians, both countries still incur responsibilities under international law to ensure that the other rights of the Chagossians are respected. The forced exile of the Chagossians arguably violated Article 12 of the ICCPR and Article 6 of the International Covenant on Economic, Social and Cultural Rights (ICESCR) by denying them the right to choose their place of residence. Furthermore, the dispossession of Chagossian lands and resources may constitute a violation under Article 8(2) of UNDRIP.
In addition, the International Law Commission’s Draft Articles on Responsibility of States for Internationally Wrongful Acts reinforce the obligation to provide remedies for unlawful acts. Article 34 recognises restitution, compensation, and satisfaction as forms of reparation. In this context, reparations should encompass monetary compensation for the decades Chagossians were displaced and forced to live in poverty, as well as restorative measures to address the enduring consequences of their exile. Therefore, this must include the possibility of return.
Recent political developments further illustrate the continued tension between legal principles and strategic interests in the Chagos dispute. In June 2026, US President Trump proposed the possibility of purchasing Diego Garcia to secure control and ownership of the military base (Kass, 2026). This new development comes after the US continues to stall the UK-Mauritius Agreement, citing complications of military operations and security concerns. These discussions demonstrate the significance of strategic political choices in the future of the archipelago (Reuters, 2026). It also further highlights how geopolitical priorities can impede the realisation of the Chagossians’ self-determination and their right to return.
Conclusion
The Chagos dispute represents one of the clearest examples of the enduring legal and political consequences of decolonisation in contemporary international law. The detachment of the Chagos Archipelago and subsequent forced displacement of Chagossians are intrinsically linked to the colonial framework prior to Mauritian independence.
The 2019 AO demonstrated an important foundation for the Chagossians’ right to self-determination and the unlawful decolonisation process by the UK. The combination of self-determination, territorial integrity, and remedial justice creates a solid ground for a substantial legal claim for the return of the Chagossians.
Despite recent judicial developments further strengthening the rights of Chagossians, the strategic military interest of Diego Garcia continues to be an obstacle. The legal trajectory of the dispute must extend beyond sovereignty transfer, but include the participation of the Chagossian people concerning the governance of the islands. Ultimately, it serves as a reminder that there is a legal and moral obligation within the international legal order, and Chagossians must be the centre of this debate.
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