Opinion – Will the Chagos Deal Survive? |
In May 2025, I authored an article entitled Chagos Deal Is Done: Sovereignty Is Returned to Mauritius. Arguably, that title was somewhat premature, as a great deal has happened since then. The past eight months have seen the legislation required to return the Chagos Archipelago to Mauritius progress through most of its parliamentary stages (though not without difficulty), opponents intensifying their objections, and signs of a possible change of heart by the Trump administration, which had previously been supportive. Yet although much has changed—at least rhetorically—the fundamentals of the case for returning Chagos to Mauritius remain sound.
The Diego Garcia Military Base and British Indian Ocean Territory Bill passed Second Reading on 9 September and completed Committee of the whole House and Remaining Stages on 20 October, with MPs voting 318–174 to retain the central clause formally ceding UK sovereignty over the British Indian Ocean Territory (BIOT)—the UK’s official designation for the Chagos Archipelago. The Bill then encountered closer scrutiny in the House of Lords. At Report Stage in early January 2026, peers added amendments aimed at increasing financial transparency, creating a mechanism to pause or halt payments if the base became unusable or if Mauritius failed to meet obligations following dispute‑resolution procedures, and requiring a referendum of Chagossians on the treaty’s terms. The changes were subsequently overturned in the Commons, with Ministers arguing that the treaty already included robust dispute‑settlement provisions and that a referendum cannot be used to reopen a concluded state‑to‑state agreement.
As debate intensified in late January, a final planned Lords sitting was paused—and remains so—partly because opposition peers linked the Bill’s timing to concerns about potential friction with the 1966 US–UK agreement governing defence use of BIOT. Opponents have cited Article 1, which states that “The Territory shall remain under United Kingdom sovereignty”, to argue that the UK cannot ratify a treaty recognising Mauritian sovereignty without first amending the 1966 framework. However, it does appear these concerns have been overstated. First, the 1966 document is an ‘exchange of notes’ and not a full treaty, meaning it is less formal. Second, it has........