In February 2020, the United Nations (UN) updated their world map to depict the Chagos Islands as part of Mauritian territory. Although this event could seem rather trivial, it was later described as a major step in the sovereignty dispute between the United Kingdom (UK) and Mauritius over these Islands by the Mauritian Prime Minister. This recent development is a good opportunity to dive back into the Chagossians’ saga.
From a British plantation colony to a US military base
The Chagos Islands are a group of 65 islands in total, located in the middle of the Indian Ocean. After having been occupied by the Dutch, then administered by the French, they were officially ceded to the UK as a dependency of Mauritius in 1814. The Islands’ main economy was coconut (copra) production.
In 1965, the UK and Mauritius signed the Lancaster House Agreement, whereby the Chagos Islands were detached from Mauritius and included in a new territory called the British Indian Ocean Territory (BIOT). Mauritius later alleged that this detachment was forced, especially due to its vulnerable position as a former British colony.
Due to the geographically strategic position of the Chagos Islands – equally situated between Indonesia, Australia, Iraq and eastern Africa – the UK and the United States (US) had long been considering it for the installation of a military base. In 1966, the UK and the US signed a deal for the implementation of such a base on the island of Diego Garcia for an indefinite period with provision for a review in 2016. The base was installed in 1971. One of the measures contained in the 1966 agreement was the resettlement of the local population. The UK retained sovereignty over the Islands after Mauritius gained its independence in 1968.
Between 1967 and 1973, the entire Chagossian population was evacuated from the Chagos Islands to Mauritius, the Seychelles and the UK. Those traveling before the evacuations were prevented from returning. The others were told that the company that owned the coconut plantations where they worked was closing down. Several ordinances were adopted by the UK between 1971 and 2004 to restrict access to the Chagos Islands without a permit. Outside of the Chagos Islands, the Chagossians suffered poverty and discrimination, as they lacked the linguistic or professional skills necessary to integrate. The Chagossians who moved to Mauritius were automatically granted Mauritian or UK citizenship, whereas those who moved to the Seychelles stayed stateless. In 1972, the UK Government allocated a sum of GBP 650,000 compensation to Mauritius to assist with the Chagossians’ resettlement. Compensation was only paid in 1977, in the form of a sum of GBP 1092 paid in cash to a total of 595 Chagossian families. Those relocated to the Seychelles received no compensation at all.
The Chagos Islands were a pivotal US naval and air base for all American military operations accomplished in Afghanistan, Iraq, and Iran between the 1970s and the 2000s. Some former US officials even allege that the base was used to detain, interrogate or torture suspects during the post-9/11 US war on terror.
Several international organizations also expressed their concerns about the detachment of the Chagos Islands for the purpose of establishing a military base and demanded that the island of Diego Garcia be returned to Mauritius, including the UN General Assembly, the Organization of African Unity (later renamed African Union) and the Movement of Non-Aligned Countries.
In 2016, the 50-year period covered by the 1966 Agreement came to an end and it was extended for a further period of twenty years, until 2036. That same year, Chagossians participated in the Micronations and Stateless Persons Football World Cup to make their cause heard worldwide.
Legal actions for the annulment of certain British orders banning access to the Chagos Islands
Legal actions were brought before UK domestic courts challenging the validity of certain ordinances which had the effect of excluding the Chagossians from the Chagos Islands. The principal issues were whether the BIOT Commissioner was allowed to adopt such ordinances and whether such ordinances were immune from judicial review.
In 1998, an action was brought (the Bancoult I case), challenging the validity of Section 4 of the 1971 BIOT (Immigration) Ordinance. In 2000, the court ruled that the Chagossians did not own any land or hold any right to permanent use of the land on the Chagos Islands, which was held by the British Crown. However, the court also held that this particular provision was invalid as it went outwith the BIOT Commissioner’s powers to act “for the peace, order and good government” of BIOT. The court found that the detention and removal of the Chagossians from the Islands were inconsistent with the letter of this provision, which implied that those powers should benefit the Chagossians. The ordinance was quashed and the UK government decided not to appeal. It also promised the publication of feasibility studies on resettlement and adopted a new Order in Council, reopening access to all the Chagos Islands, except for Diego Garcia.
In 2000, the UK started working on a feasibility study into resettlement. The second stage of this study was published in 2002 (the 2B report). It assessed that a long-term resettlement would be precarious and costly. In 2004, following the conclusions of the 2B report, the UK adopted two Orders in Council, which were challenged in court through the Bancoult II case. In 2006, the Court upheld the claim, finding that the provisions of Section 9 of the 2004 Orders were irrational on public law grounds, being mainly concerned with the interests of the UK and of the US, instead of those of the BIOT, thus the Chagossians. It also found that Orders in Council were not immune from judicial review. An appeal was formed by the UK Secretary of State for Foreign and Commonwealth Affairs.
In 2007, the Court of Appeal dismissed the appeal, finding that the prerogative power of colonial governance enjoyed no generic immunity from judicial review, that the removal or exclusion of the population for reasons unconnected with their collective wellbeing could not be a legitimate purpose of colonial governance, and that the Orders’ content and circumstances of enactment constituted an abuse of power on the part of the UK government. The Court of Appeal also found that public comments made by the UK Foreign Secretary following the Bancoult I decision gave rise to a legitimate expectation on the part of the Chagossians that they would be granted a right of return.
Finally, in 2008, the House of Lords allowed the UK Secretary of State’s appeal and upheld it, holding that the Foreign Secretary was entitled to base its decisions on policy considerations such as diplomatic or security interests, and that its statements after the Bancoult I case did not amount to a clear and unambiguous promise for resettlement. Lord Bingham dissented, declaring that the UK government had no good reason to adopt such a policy, that it could not resile from the representation it made through its public comments without compelling reason and that the Queen’s power to legislate was an ‘anachronistic survival’ of British law.
Legal actions against the relocation of the Chagossian population
The Chagossians brought several legal actions against their relocation before UK and US domestic courts, as well as before international courts and tribunals. The first of these legal actions resulted in the signature of renunciation forms by Chagossians. In the later court decisions, the signature of such forms was used against the the claimants, either by refusing them victim status or by rejecting their claim altogether.
In 1975, the first legal action concerning the Chagossians’ relocation was brought before the High Court in London (the Vancatassen case). The applicants complained about intimidation, privation of liberty, forced deportation, interdiction of return to Diego Garcia, violation of their right to live there and the loss of their jobs. A settlement was reached in 1982,  when the UK agreed to pay GBP 4,000,000 to Mauritius without admitting any liability on its part. A Trust Fund was created. The recipients of the Trust Fund were asked to sign or thumbprint a document redacted in English where they renounced their rights for future claims. While only 12 Chagossians refused to sign such a resignation form, the other recipients later maintained that they were unaware that those forms amounted to such a renunciation. As a result of this settlement, some 1,344 Chagossians relocated in Mauritius received low-cost housing and payment of GBP 2,976 each.
In 2001, a complaint was filed before the US District Court for the District of Columbia against the US government and a number of high-ranking individuals and companies within the US Government seeking relief for the Chagossians’ relocation. The defendants argued that those individuals and companies could not be held responsible as they were acting within the scope of their office at the time. Thus, the complaint should only be made against the US government itself. The defendants also argued that the US government decision to remove the population to establish a military base on Diego Garcia could not be reviewed, as it was an exercise of foreign policy and national security powers. The court followed the defendants’ argument, and ruled that it could not exercise its jurisdiction over this case, as re-examination of the US government decision to establish the military base would go beyond the institutional competence of the US judiciary.
In 2002, a group litigation (the Chagos Islanders case) was brought against the Attorney General of England and Wales and the BIOT Commissioner. The applicants sought compensation for several alleged torts including misfeasance in public office and unlawful exile. They also called for damages for personal injury created by diseases linked to poor living conditions and mental illnesses which resulted from the relocations. In 2003, the High Court dismissed the action on the grounds that those claims were not reasonably arguable and time barred. It also held that it was an abuse of process for the Chagossians who had waived their right to return to the Chagos Islands when signing or thumbing forms in the Vencatassen case. In 2004, the Court of Appeal refused the applicants’ application for permission to appeal. It declared : “It may not be too late to make return possible, but such an outcome is a function of economic resources and political will, not adjudication”. Some Mauritian domestic courts had similarly held that the Trust Fund was perfectly entitled to require the signature of such a renunciation form by the Chagossians.
In 2012, the Chagossians brought an action before the European Court of Human Rights (ECtHR). The ECtHR decided that their case was inadmissible. The court found that their complaints were ill-founded and that the Chagossians could not be given victim status. On the issue of victim status, the applicants argued that they were unaware that signing the forms following the 1972 and 1982 settlements amounted to a renunciation to any future claim, that some of the applicants had refused to sign such forms, and that others were not even born at the time of the settlements. The ECtHR responded that the settlements constituted adequate and sufficient remedy. It also found that, as the existence of the proceedings was widely known at the time, the Chagossians that chose not to sign the forms and to bring any action could not be awarded victim status as they had failed to exhaust domestic remedies. Then, the court found that the applicants who were not born at the time of the settlements and never had a home on the Islands, could not be considered as victims either. The ECtHR also stated that these claims had already been definitely settled before domestic courts, meaning that all the later judicial attempts had to be regarded as ‘a campaign to bring pressure on the British government’, rather than bringing fresh demands.
In 2019, the Mauritian Prime Minister, Pravind Jugnauth, officially declared that, following Article 7(d) of the Rome Statute, he was considering bringing charges for the crime against humanity of deportation or forcible transfer of population against British officials before the International Criminal Court (ICC) for refusing to allow people to return to their former homes on the Chagos Islands. Although the expulsions (in 1967-1973) took place before the entry into force of the Rome Statute of the ICC (in 2002), the Statute remains silent in regard to crimes committed before the Rome Statute entered into force but maintained afterwards. Thus, this matter remains open for potential consideration by the ICC.
Legal actions against the establishment of an MPA around the Chagos Islands by the UK
In 2010, the UK Foreign Secretary proclaimed the establishment of a Marine Protected Area (MPA) around the Chagos Islands, saying that it would protect marine biodiversity.
That same year, a challenge was brought against this decision. The applicants argued that it was based on improper motive (namely to prevent any resettlement), violated Article 4(3) of the Treaty on European Union (TEU), and that the consultation process that the UK conducted prior to the implementation of the MPA was invalid (due to the absence of any mention of Mauritian fishing rights in those waters). The applicants produced a document revealed by Wikileaks and published by The Guardian and The Telegraph in court. In this document, US officials argued that such an MPA would be an effective long-term way to prevent any Chagossians’ relocation on the Chagos Islands, and that it would not preclude any environmental damage caused by military use. On the other hand, the UK argued that this Wikileaks document was protected by diplomatic immunity.
In 2013, the court dismissed the claim, holding that such a document could not be considered as admissible evidence and that the creation of the MPA did not infringe European law. However, the court ruled that there was no offence under the Official Secrets Act 1989, as the document had already been disclosed by two newspapers beforehand. An appeal was formed and rejected in 2014.
In 2014, the Court of Appeal ruled that it was not certain that the admission of this piece of evidence could have made the court rule differently in 2013. As regard the consultation process preceding the establishment of the MPA, the court found that “being employed as crew members on Mauritian (or other) flagged vessels, which had licences to fish the BIOT waters, -couldn’t- be equated with the exercise of “traditional fishing rights” by the Chagossians” which would need to be protected.
In 2018, the appeal formed by the Chagossians before the Supreme Court was rejected. The Supreme Court ruled that the Court of Appeal had been correct to conclude that admission or rejection of the diplomatic cable as evidence had no material effect on the outcome of the proceedings. Lord Kerr and Lady Hale dissented by arguing that the correct test to be applied was what might have happened if the cable was admitted in evidence, and not what would have happened. In regard the diplomatic cable, the Supreme Court held that it should have been admitted into evidence, as the document had lost its inviolability by entering the public domain.
That same year, Mauritius instituted arbitral proceedings under the auspices of the Permanent Court of Arbitration (PCA) against the UK to challenge the establishment of the MPA. Mauritius claimed that the UK was not entitled to declare such an MPA as it was not the ‘coastal state’ in respect of the Chagos Islands within the meaning of the United Nations Convention on the Law of the Sea (UNCLOS), and as it violated Mauritius’ fishing rights under Article 2(3), 56(2) and 194(4) of UNCLOS. In 2015, the Arbitral Tribunal rendered its decision. It declined jurisdiction to consider whether the UK was the ‘coastal state’, considering that such question was only one aspect of a larger land sovereignty dispute. However, it decided in favour of the claimant as for the merits, holding that Mauritius had legally binding rights to fish in those waters, that the UK was bound to return the Chagos Islands to Mauritius once it no longer needed the Islands for defence purposes, and that the UK had to preserve the benefits of any minerals or oil discovered in the area for Mauritius. In their dissenting opinions, Judges James Kateka and Rüdiger Wolfrum expressed the view that the PCA should have exercised its jurisdiction concerning the identity of the ‘coastal state’ and should have found that the detachment was contrary to the principles of decolonisation and self-determination.
Legal actions for the annulment of UK courts’ decisions due to new evidence and material non-disclosure on the part of the UK
In 2014, an action was brought before the UK Supreme Court to set aside the decision rendered in 2008 in the Bancoult II case, due to new evidence and material non-disclosure on the part of the UK, which lead to an unfair procedure following English case law. Thus, certain documents (the Rashid documents) relating to the 2002 study on resettlement had been disclosed as part of separate litigation conducted against the establishment of the MPA.
In 2016, the Supreme Court dismissed the claim,  stating that there was no probability, likelihood, prospect or real possibility that the court would have ruled differently in the Bancoult II case. However, the court noted that it would be open to Mr Bancoult to challenge in subsequent proceedings any future refusal of the UK government to permit or support resettlement as irrational, unreasonable or disproportionate. In 2015, the UK had published a new feasibility study, which concluded that the MPA did not preclude resettlement. The court found that this new study rendered the applicants’ request moot. It added that it was now open to any Chagossian to start a fresh challenge to the failure to abrogate the 2004 Orders in the light of the 2015 study’s findings. In his dissenting opinion, Lord Kerr expressed the view that, to set aside the 2008 decision, it was enough for there to be a real possibility that a different outcome would have occurred, had the information been available at the time of the original hearing.
Legal actions relating to the process of decolonization of Mauritius
In 2017, the UN General Assembly (UNGA) asked for an advisory opinion from the ICJ following Articles 96(1) of the UN Charter and 65(1) of the Statute of the ICJ. The request was articulated around two questions: whether the process of decolonization in Mauritius was lawfully completed when it gained independence, and the legal consequences and obligations arising from the continued administration of the Chagos Islands by the UK.
In 2019, the ICJ rendered its advisory opinion, ruling on the customary law character of the right to territorial integrity of a non-self-governing territory as a corollary of the right to self-determination, and the erga omnes character of the obligation to respect the right to self-determination. Several participants advised the ICJ to decline to exercise its jurisdiction as a matter of discretion, but the ICJ found no compelling reasons to do so. The ICJ held that the process of decolonization of Mauritius was not lawfully completed and that the UK was under an obligation to bring to an end its administration of the Chagos Islands as quickly as possible.
In their separate opinions, several ICJ judges blamed this decision as too timid. Judge Sebutinde criticised the court for not having found a peremptory breach that would have rendered void all acts taken by the UK in its relations with the BIOT, including the 1966 agreement with the US over the establishment of the military base of Diego Garcia. Some authors argue that this advisory opinion could have broader consequences for territories where the administering power adjusted the colonial territory prior to independence, like in Mayotte, the Scattered Islands, Cyprus, Falkland Islands or the Malvinas.
Following the ICJ’s advisory opinion, the UNGA voted on a six-month deadline for the UK to comply to the opinion. Australia voted against the resolution, arguing that the UNGA was not supposed to ask a State to implement such a non-binding opinion. The UK refused the deadline, stating that the defence facilities on Diego Garcia still helped to protect people in Britain and around the world from terrorist threats, organised crime and piracy.
Legal actions for the return of digital assets to the Chagossians
In 2020, two Chagossians sent a communication to the African Commission on Human Rights and Peoples’ Rights pursuant to Article 55 of the African Charter on Human and Peoples’ Rights (ACHPR). As African people colonized by a non-African State, the applicants requested restitution of the Chagossians’ digital assets, requiring that the revenues obtained through the use of the domain name “.io” shouldn’t be collected by the UK, but rather by the Chagossians. Thus, this domain name was created and owned by the BIOT since 1997 and was managed by a company based on Diego Garcia. No response has yet been received and the dispute is still pending.
Today, Chagossians are still fighting to return back to the Chagos Islands. On the graves of many in Port Louis (Mauritius), headstones are engraved with messages grieving of their inability to return. However, not all Chagossians would like to see the military base of Diego Garcia close, as it might offer them job opportunities. The UK began to take small groups of Chagossians back to the Chagos Islands for brief “heritage” visits. Oliver Bancoult, head of the Chagos Refugees Group, told the BBC: « I boycott those trips. The British are trying to buy our silence. That’s why we say our dignity is not for sale ». With the passage of time, as more and more Chagossians are passing away, their claims are taken over by their descendants.
The Chagossians have exhausted so much litigation possibilities to try and find redress for their sufferings. Although they haven’t always ruled in their favour, judges have been sensitive to their situation and encouraged them to try new litigation possibilities. The 2019 ICJ opinion, although not binding, surely carries a great moral authority and increases the pressure on the UK to hand back sovereignty of the Chagos islands to Mauritius. Thus, the ICJ opinion seems to undermine the UK’s credibility in challenging the illegality of China’s assertive island building and maritime claims in the South China Sea.
Diplômée Master 1 Droit économique – Sciences Po Paris
 Article VIII, Treaty of Paris (1814).
 British Indian Ocean Territory Order (BIOT) Order in Council, SI 1965/120 (1965).
 This was also argued by Judges James Kateka and Rüdiger Wolfrum in their dissenting opinions in the case PCA (2015) In the Matter of the Chagos Marine Protected Area Arbitration (Mauritius v. United Kingdom), where the two dissenting judges at the time
 Immigration Ordinance No. 1 (1971); BIOT (Constitution) Order (2004); BIOT (Immigration) Order (2004).
 Most of them only spoke a Creole specific to the Chagos Islands, and only knew how to work in the copra production.
 La Croix (2019) Les Chagos, litige international et drame humain de cinq décennies, referring to the 1979 Iranian revolution, the 1990-1991 and 2003-2006 wars in Irak and the US military presence in Afghanistan in 2001.
 The petition “We the people, The U.S. Government Must Redress Wrongs against the Chagossians” reached 25.000 signature in 2012, https://petitions.obamawhitehouse.archives.gov/petition/us-government-must-redress-wrongs-against-chagossians/.
 Van Lierop M (2012) Protest strategy change in the case of the Chagossians.
 United Nations General Assembly (1965) Question of Mauritius. A/RES/2066 (XX) ; United Nations General Assembly (1966) A/RES/2232(XXI) ; United Nations General Assembly (1967) A/RES/2357(XXII).
 Organization of African Unity (1980) AHG/Res. 99 to 101 (XVII). Freetown, Sierra Leone ; Organization of African Unity (2000) AHG/Dec.159 (XXXVI). Lome, Togo ; African Union (2010) Decision on the sovereignty of the Republic of Mauritius over the Chagos Archipelago. Assembly/AU/Dec.331(XV). Kampala, Uganda ; African Union (2017) Resolution on Chagos Archipelago, Doc. EX.CL/994(XXX). Assembly/AU/Res.1(XXVIII). Addis Ababa, Ethiopia.
 Non-aligned movement (2016) NAM2016/CoB/Doc.11. Island of Margarita, Bolivarian Republic of Venezuela.
 As conferred by Section 11(1) of the BIOT Order (1965).
 High Court of Justice, Queen’s Bench Division (2000) R (Bancoult) v. Secretary of State for Foreign and Commonwealth Office EWHC 413.
 BIOT (Immigration) Ordinance No. 4 (2000).
 BIOT (Constitution) Order (2004); BIOT (Immigration) Order (2004).
 The Queen, on the application of Bancoult R v. The Secretary of State for Foreign & Commonwealth Affairs Rev 1 (No 2) (2006) EWHC 1038.
 Following the case R (Quark Fishing Ltd) v. Secretary of State for Foreign and Commonwealth Affairs (2005) UKHL 57 and High Court of Justice, Queen’s Bench Division (2000) R (Bancoult) v. Secretary of State for Foreign and Commonwealth Office EWHC 413.
 The court found that, contrary to what the defendant argued, the Colonial Laws Validity Act (1865) did not preclude any public law irrationality challenge.
 R (Bancoult) v. Secretary of State for Foreign and Commonwealth Affairs (No. 2) (2007) EWCA Civ 498.
 R (Bancoult) v. Secretary of State for Foreign and Commonwealth Affairs (2008) UKHL 61.
 Lord Bingham draws an analogy with the law of estoppel and cites the case Grundt v. Great Boulder Pty Gold Mines Ltd (1937) 59 CLR 641 : it is enough if the representee would suffer detriment if the representor were to resile from his representation.
 Agreement between the Government of the United Kingdom of Great Britain and Northern Island and the Government of Mauritius concerning the Ilois (1982), implemented in Mauritius by Ilois Trust Fund Act (1982).
 United States District Court for the District of Columbia, Olivier Bancoult et al. v. Robert S McNamara et al. (2004).
 Under the Westfall Act 28 U.S.C. § 2679, if the Attorney General certifies that an employee of the US federal government was “acting within the scope of his office or employment” at the time of an incident, any claims arising out of that incident are converted into claims against the US. The Attorney General so certified in the case United States District Court for the District of Columbia, Olivier Bancoult et al. v. Robert S McNamara et al. (2004).
 Following Baker v. Carr, 369 U.S. 186, 217, 82 S.Ct. 691, 7 L.Ed.2d 663 (1962).
 Following the case Three Rivers District Council v The Bank of England (No 3)  2 AC 1,  2 WLR 1220.
 High Court of Justice, Queen’s Bench Division, Chagos Islanders v. The Attorney general and Her Majesty’s British Indian Ocean Territory Commissioner (2003) EWHC 2222 QB
 Following the Limitation Act (1980).
 Court of Appeal, Supreme Court of Judicature, Chagos Islanders v. Attorney General and Her Majesty’s British Indian Ocean Territory Commissioner (2004), EWCA (Civ) 997.
 Supreme Court of Mauritius (1989) Vencatassen v. Ilois Trust Fund, 1989 MR 123.
 Following Article 3 (prohibition of torture), Article 6 (access to court and right to a fair trial), Article 8 (right for private life and home) and Article 13 (no effective remedy) of the European Convention on Human Rights (ECHR), and Article 1 of Protocol No. 1 (protection of property).
 Through the terms of Articles 24 and 27(2), Vienna Convention on Diplomatic Relations (1961), as incorporated into English law by the Diplomatic Privileges Act (1964). The UK also advanced that such a disclosure constituted an offence under section 6 of the Official Secrets Act 1989.
 R (Bancoult) v. Secretary of State for Foreign and Commonwealth Affairs (N. 3)  EWHC 1502.
 R (Bancoult) v. Secretary of State for Foreign and Commonwealth Affairs  WLR 2921.
 R (Bancoult) v. Secretatry of State for Foreign and Commonwealth Affairs (N. 3)  UKSC 3.
 R v. Bow Street Metropolitan Stipendiary Magistrate, Ex p Pinochet Ugarte (No 2) (2000) 1 AC 119 ; Taylor v. Lawrence (2002) EWCA Civ 90 ; Bain v. The Queen  UKPC 4 ; In re U  EWCA Civ 52 ; Feakins v. Department of Environment, Food and Rural Affairs  EWCA Civ 699.
 R (on the application of Bancoult (No 2)) v. Secretary of State for Foreign and Commonwealth Affairs (2016) UKSC 35.
 Following Chapter XI, UN Charter (1945).
 Following Article 14 (right to property), Article 19 (principle of equality), Article 20 (right to self-determination), Article 21 (right to free disposal of their wealth and natural resources) and Article 22 (right to development) of the ACHPR.
 Communication before the African Commission on Human & People’s Rights (Bernard NOURRICE Solomon Pierre PROSPER, Complainants in their Individual Capacities & as Representatives of the Chagossian People v. Republic of Mauritius) (2020).
 For instance, one of them reads: « I fear my wish will not come true before I die – to see my motherland again”.
 This is also an option envisaged by The Nobel Prize in Literature 2008, Jean-Marie Le Clezio, who sent a letter to The Nobel Peace Prize 2009 and President of the US, Barack Obama, as reproduced in Le Monde (2009) Lavez l’injustice faite aux Chagossiens: lettre au président Barack Obama.
 Such visits have been organized every one or two years between 2006 and 2019 and funded by the BIOT.
 Samaranayake N (2020) The Chagos Archipelago Dispute : Law, Diplomacy and Military Basing.