Many will enjoy The Last Colony and it will undoubtedly sell well. It might also be nominated for prizes, as was Philippe Sands’s East West Street. That earlier book blended the author’s personal exploration of family history with a study of two of the most impactful contributors to the history of international law, Hersch Lauterpacht and Raphael Lemkin, and the concepts that they gave us: crimes against humanity and genocide. The crucial link in the triple helix was the Ukrainian city of Lviv. This is where Sands’s own Jewish grandparents started life and where those two great Jewish lawyers studied.

The Last Colony shares the elements that shaped East West Street: a personal angle and a discussion of international law, here revolving around a particular case. The personal dominates the book in two ways. First, the author uses the voice of Liseby Elysé, born on the Chagossian island of Peros Banhos in 1953 and compulsorily resettled two decades later, to provide an emotional, perhaps sentimental, dimension to the narrative. Second, the author’s own perspective runs through the book – there is quite a lot of ‘I did this’ and ‘I did that’, which I can understand (occasionally having written this way myself), but some might find it a little irritating.

The case at the heart of this book is the Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, an advisory opinion case heard at the International Court of Justice (ICJ) in The Hague in 2019. In a sense, the book is a report of that case, in which Sands, a barrister specialising in international law, successfully represented Mauritius against the UK. It is also a bit of propaganda, an attempt to extend debate beyond the ICJ advisory opinion, which, as Sands notes, is not a judgment.

To put the case in context, it is necessary to revisit the history of the Chagos archipelago. In 1507, Portugal discovered Mauritius and the uninhabited islands around it, including the Chagos archipelago (over two thousand kilometres from the main island, with the separate colony of the Maldives four times as near), though there are undocumented claims of earlier Arab discovery. Subsequently, sovereignty over Mauritius (and the Chagos islands) was held by, and transferred between, the Netherlands, France and Britain. British rule continued until 1968, when London gave independence to Mauritius but decided to retain sovereignty over the Chagos islands. The UK engineered an agreement with the new Mauritian government to that end, paying Mauritius £3 million and declaring that the islands had no permanent population, only contract workers. Thus was created the British Indian Ocean Territory, an overseas dependency. The British decision was heavily influenced by the United States, as the retention of sovereignty of the Chagos islands was considered necessary for strategic purposes. Over the coming decades, the atoll of Diego Garcia became a major US military base, enabling operations across the globe, including the campaigns in Iraq and Afghanistan (it was also the site of at least two incidents involving rendition flights). Security considerations – defence of the UK, defence of the West – resulted in the US lease of the base being extended for twenty years in 2016. London will continue to apply the doctrine of sovereignty until that need has gone, if it ever does.

In its advisory opinion, the ICJ stated that the Chagos archipelago had been wrongfully detached from Mauritius at the time of its independence and suggested that the UK should transfer sovereignty over the islands to Mauritius as soon as possible. The case hinged on the issue of self-determination, a principle established at the UN, including through UN General Assembly Resolution 1514, adopted in 1960, which called for an end to colonial rule. As decolonisation progressed globally, this resolution – non-binding but gaining customary international law status in the absence of persistent objection – was taken to imply that territory should not be detached from colonies at the point of independence without the agreement of the populations concerned. This was to allow fulfilment of the principle of self-determination.

Sands sets out the case presented by him and others on behalf of Mauritius. In doing so, he writes about the ideas and legal principles relating to self-determination and decolonisation. He does not, however, balance this with a proper discussion of sovereignty, the fundamental doctrine in both international law and international politics. That core concept is about the exercise of absolute rights over a polity. Under the doctrine, a state rightfully exercising sovereignty cannot be told – or advised – what to do (though, in practice, politics inevitably shapes this).

The Last Colony is, among other things, part of the campaign to shift the British position through political pressure. As with all good propaganda, Sands’s case is based in truth, if not the whole of it. When lawyers present a case, he says, they need ‘to tell a story, and to do so in such a way that it can connect’ to judges; ‘how the facts are presented can influence the reaction of an individual judge,’ he writes. Sands has applied the same principles when writing this book, which is structured more like a work of fiction than one of law, reinforcing the sense that there is an intent to manipulate. Passages about Elysé introduce and then interrupt material on history, law and the specific case at the ICJ; in the conclusion, Sands describes taking her back to the island of Peros Banhos on board a scientific survey vessel on a dubious pretext.

The truth that underpins the propaganda is that Elysé and between one and two thousand other Chagossians were, in effect, forcibly removed from Chagos to Mauritius, the Seychelles or the UK by the British authorities between 1965 and 1973, even though Washington had been content to use unpopulated Diego Garcia and leave inhabitants on the other islands. The essence of the case at the ICJ is that the right of those individuals to self-determination has not been fulfilled and that London acted in a consciously dishonest manner both in removing the population and in engineering the agreement on Chagos’s detachment from Mauritius. The last element, though, is just a part of politics and diplomacy. Many an agreement has been agreed historically through the use of pressure and inducement – that is part of international life. However, what is beyond contest is that the removals were, as the UK’s solicitor general stated at the ICJ hearings, ‘shameful and wrong’. While many British people have been obliged by compulsory purchase orders to move from their homes for the greater benefit of society, it was a shock to the British conscience to read of the abrupt and inhumane manner in which Peros Banhos and other islands were cleared of their populations. That gives power to Sands’s argument, whatever limits it might have in other respects.

This book will be popular, riding as it does the tide of ‘decolonisation’, including in international courts. The UK government lost the Chagos case at the ICJ and a vote on the issue in the UN General Assembly because international law and its interpretation are political, as Sands discusses in the book, and there are clear majorities in both institutions from the decolonised world antipathetic to the UK and the USA. So this book, by a prominent international lawyer, is a political work, aimed at creating pressure for the advisory opinion to be given practical effect.

Consequently, readers should approach it with caution – and also because it contains a number of errors and misstatements. Constraints of space prevent all of these from being discussed here, but examples where both author and editor should have done better include the unfortunate suggestion that the estimable Dame Karen Pierce, formerly UK ambassador to the UN, ‘dissembled’ when setting out the British position at the UN, and the statement that there were fifteen members of the UN Security Council at its inception (in fact, there were eleven – it was expanded to fifteen as a response to decolonisation in 1965). Nonetheless, whatever its flaws, the book provides an important and readable account of the Chagos case and of how lawyers do and should approach courts, as well as presenting the unpalatable truth about how Liseby Elysé and her fellow Chagossians were treated.