Transfer Agreement - Chagos: A Decisive Turning Point at the House of Lords This Monday

On Monday, January 5, the House of Lords enters a crucial phase in reviewing the Diego Garcia Military Base and British Indian Ocean Territory Bill, as it studies amendments scheduled for formal discussion in the "report stage". This bill aims to transpose certain provisions of the treaty signed in May 2025 between the UK and Mauritius regarding the status and future of the Chagos Archipelago, including the US-British joint military base at Diego Garcia.

If passed, the bill will end British sovereignty over the archipelago while maintaining administration of the existing military base on Diego Garcia. It also includes related adjustments to British nationality law. This legislation is a prerequisite for the treaty's ratification by London, given that the UK operates under a dualist system where international agreements do not have domestic legal effect without implementing legislation.

The amendments submitted for this stage of the parliamentary process focus on four main areas. The first concerns consulting the Chagossian community, which has frequently been referenced in debates about the future of the archipelago. The second relates to environmental protection, given that Diego Garcia and its surrounding waters harbor strategic biodiversity. The third area addresses the operational sustainability of the military base, a central issue for both London and Washington. Finally, several proposals pertain to negotiations with Mauritius regarding a potential right of return for Chagossians.

The treaty signed on May 22, 2025, stipulates the transfer of sovereignty of the islands to Mauritius while granting the UK the right to exercise authority over Diego Garcia for an initial renewable period of 99 years. It also includes an economic partnership, in which the UK commits to providing Mauritius with average annual payments of £101 million (approximately Rs 6.3 billion at current exchange rates). However, payments will be higher in the initial years following the agreement.

The United States has publicly supported the agreement, stating that it "ensures the stable, long-term, and effective operation of the US-British joint military facility at Diego Garcia." For the British government, passing the bill is deemed "essential" to avoid any incompatibility between international commitments and domestic law. However, both a group of Chagossians living in Britain and the British opposition are staunchly opposed to the retrocession process.

Having already been approved by the House of Commons, the text has been under review by the House of Lords since November 4, 2025. The anticipated debates in early January are expected to clarify the political and legal conditions for implementing the agreement before its formal ratification.