The International Court of Justice issued an advisory opinion Feb. 26 outlining the legal consequences of separation of the Chagos Archipelago from Mauritius in 1965. The UK and Mauritius, by virtue of the Lancaster House agreement, detached the Chagos Archipelago form Mauritius and established the British Indian Ocean Territory (BIOT). The British subsequently allowed the United States to establish a military base on the island Diego Garcia, with many inhabitants forcibly removed, and those who left voluntarily prevented from returning. The ICJ opinion, which is nonbinding, says the UK did not lawfully decolonize the islands through the Lancaster House agreement. The court urged the UK to end its continued administration over Chagos Archipelago: "[T]he United Kingdom has an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible." The opinion states that "all Member States must cooperate with the United Nations to complete the decolonization of Mauritius."

The government of the island nation of Mauritius presented its claim Sept. 3 to the International Court of Justice (ICJ) that the British government forced the transfer of the Chagos Islands as a condition of independence in 1965. The UK leased the island of Diego Garcia within the Chagos archipelago to the US in 1966, which was used to build a military base that required the forced removal of around 1,500 people. The population has yet to be allowed to return home. The former prime minister of Mauritius and current parliamentarian Anerood Jugnauth told the ICJ, “The choice we were faced with was no choice at all: it was independence with detachment [of the Chagos archipelago] or no independence with detachment anyway.” The location of the Chagos Islands in the central Indian Ocean is seen as geopolitically strategic for policing the Persian Gulf. In 2016 the US lease for the base was extended until 2036.