It must be a long time since the UK had such a telling off from an international court. The “advisory” (link to PDF) from the International Court of Justice pulled no punches and some of the documents related to the colonial-style acquiring of the Chagos islands, discussed by the court, must have been highly embarrassing to the UK when they were first made public.

The final decision, namely that the UK had no right to the Chagos islands and should give them back to Mauritius as soon as possible, will not make the present UK government particularly happy. What, after all, does the outcome say about the UK’s desired image of itself as an upholder of international law and supporter of decolonialization around the world?

In a unanimous decision the judges held they were entitled to give a decision on the questions sent to them by the United Nations on the current status of the Chagos islands. These islands were formerly part of Mauritius. One of them, Diego Garcia, hosts what the US regards as a crucial defence presence, affecting its strategic position in South Asia, the Middle East and the entire Pacific region.

The Chagos Archipelago was split off from Mauritius by the UK shortly before Mauritius became independent from the UK in 1968. The UK then declared a new colony for itself, consisting of these and other islands, some of them acquired from Seychelles. Since then, following an agreement between the UK and the USA, the Chagos island of Diego Garcia has been used by the USA army for “defence purposes”. But the UN, whose members expressed concern based on questions of self-determination and colonialism at the time the split off was achieved, has now turned up the heat with an approach to the ICJ for an “advisory opinion” on the UK’s continued “occupation” of the archipelago.

And the temperature has risen even further with the ICJ’s ruling on 25 February 2019 that when the British took over administration of the archipelago in 1965 this was not the result of the “free expression” of Mauritius including the inhabitants of Chagos, forcibly removed from the island and not allowed to return.

The court also found that the process of decolonization of Mauritius was “not lawfully completed” at the time of independence and that the UK “is under an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible”, giving up the area completely including Diego Garcia, with its US strategic military base.

As the ICJ explained in its advisory, between 1814 and 1965 the Chagos Archipelago was administered by the UK as a dependency of what was then the colony of Mauritius. In 1965 the UK established a new colony consisting of several islands in the Indian Ocean, among them the Chagos Archipelago that had been “detached” from Mauritius by the UK as well as several islands “detached” from Seychelles by the UK. This caused “deep concern” from the UN over a perceived breach of the principle of self-determination.  

During June 2017 the UN General Assembly wrote to the ICJ to ask for an advisory opinion on the Chagos Archipelago.  The request was made in the context of the UN’s restated opposition to all vestiges of colonialism and forced removals designed to achieve a colonial purpose.

Was Mauritius fully decolonized at independence in 1968 following the UK’s “separation” of the Chagos Archipelago from Mauritius three years earlier, asked the UN. And what were the international law consequences of the fact that the UK continued to administer the Archipelago – particularly given that, thanks to the UK position, Mauritius could not implement a resettlement programme on the archipelago, chief among the intended settlers being people of Chagossian origin.

It is obviously a matter of great interest to many African countries, particularly given the continent's colonial history. Among the many parties that submitted written “statements” on these questions were the African Union – geographically, Mauritius is considered part of Africa – the UK, the USA, Seychelles, Madagascar, Lesotho, Botswana, Kenya, South Africa, Zambia and Namibia.

It can’t have been an easy process for the UK. In the oral proceedings, the UK had reiterated that it “fully accepts that the manner in which the Chagossians were removed from the Chagos Archipelago, and the way they were treated thereafter, was shameful and wrong, and it deeply regrets that fact”.

The court also reviewed confidential documents from the period of the “split off” from Mauritius, one of which disclosed concern in the UK by the government at the time that while decolonization had become politically desirable, the UK was acquiring yet another colony. The documents also show duplicity, bullying and other behaviour the UK would surely rather not be made public. 

Even before the UN asked the ICJ for its opinion, however, there had been several attempts to raise the Chagos issue in other courts. In 2012, for example, 1786 Chagossians put the issue back in the limelight, even though they were ultimately unsuccessful, when they asked the European Court of Human Rights to find the UK responsible for a breach of their international human rights.

In its final ruling forming part of the new advisory, the ICJ found that the decolonization of Mauritius was not conducted “in a manner consistent with the right of peoples to self-determination”. It added that it “follows that the UK’s continued administration … constitutes a wrongful act entailing the international responsibility of that State.”

“It is an unlawful act of a continuing character which arose as a result of the separation of the Chagos Archipelago from Mauritius”.

“Accordingly, the UK is under an obligation to bring an end to its administration of the (Chagos islands) as rapidly as possible, thereby enabling Mauritius to complete the recolonization of its territory in a manner consistent with the right of peoples to self-determination.”

The court said the general assembly should work out how to ensure the completion of the decolonization of Mauritius, but that “all member states must cooperate with the UN” to put those plans into effect.

The full text of the advisory, along with the individual submissions of the various countries, makes for fascinating reading. And here’s a tiny judicial detail not to miss: while the court was unanimous in its view that it had jurisdiction to write an advisory (some countries had argued against this), there were divisions on some of the rest of the decisions. Most interesting to note here, given US anxiety about possibly losing its base on Diego Garcia, is that US jurist, Judge Joan Donoghue, voted against all the decisions apart from the initial one that found the court could issue an advisory.