July saw the conclusion of a highly contested and complex piece of litigation in the Courts of the British Indian Ocean Territory. The Judicial Committee of the Privy Council has refused the Commissioner permission to appeal a determination that he had unlawfully detained 12 claimants (including one child) on Diego Garcia – the largest island in the British Indian Ocean Territory (BIOT), which houses a UK-US military base – for years. They described the application for permission to appeal as ‘wholly devoid of merit’. This was the first case the Privy Council has determined on appeal from the BIOT Courts.

Background

The arrival, situation, and departure of Tamil asylum seekers on the BIOT have been covered by Free Movement previously. The unlawful detention claim was previously covered when the claimants were granted limited bail (arising from an application for interim relief in these proceedings).

On 26 July 2024, the court extended the bail grant to cover further areas on Diego Garcia, including a nature trail and a 1.5km track through a woodland area leading to a beach. This was contested and appealed to the BIOT Court of Appeal, which dismissed the Commissioner’s appeal.

The BIOT Supreme Court heard the substantive claim for judicial review on 16-19 September 2024. These proceedings involved an in-person site visit to the detention site on Diego Garcia and oral evidence was given, both of which are highly unusual in judicial review proceedings. The judge allowed the claim on all grounds, finding that the conditions the claimants were kept in amounted to unlawful detention. No defence was available to the Commissioner, and the orders which purported to legally justify detention (namely the Restriction of Movement Order 2023 and 2024) were found to be unlawfully made.

The BIOT Court of Appeal proceedings

The Commissioner appealed the judgment on four grounds, and the BIOT Court of Appeal determined his appeal on 16 December 2025. He argued that the judge had erred in law on four counts: first, in finding that the claimants were detained as a matter of law; second, in rejecting his case on the defence of necessity at common law; third, in applying the Hardial Singh principles when determining the lawfulness of the Restriction of Movement Orders in 2023 and 2024; and fourth, in her approach to determining the lawfulness of the Restriction of Movement Orders, by failing to have any, or any proper, regard to the relevant evidence.

The court rejected the first ground, upholding the judge’s conclusion that the confinement was direct and intentional, based on the factual findings of the court below. The findings included the physical features of the camp, the fact that the claimants were escorted when leaving the camp, and the fact that collective punishment was used when someone absconded.

The Commissioner argued that necessity justified the detention of the claimants due to the risks they posed to themselves and to the security of the military base. The court considered the arguments on necessity made by the Commissioner but found them to be without merit. This was based on the fact that the Commissioner, as the administrator of BIOT, has powers to act as both a legislator and an executive.

Section 10 of the BIOT (Constitution) Order 2004 enabled him to enact necessary and proportionate restrictions to the claimants’ liberty through legislation, but he did not pursue this option. This precluded the Commissioner from relying on the necessity defence. The court considered a defence may have been available immediately after the claimants’ arrival, but that such a defence could not be used to justify detention for a number of years, as the Commissioner had sought to argue.

The Commissioner also argued that the Restriction of Movement Orders, which provided the only potential legal authority for the claimant’s confinement, were not constrained by the Hardial Singh principles (the legal principles which apply to detention for immigration purposes in the UK). The court dismissed this ground of appeal, stating that:

the requirement of reasonableness stated in HS2 is a freestanding principle of the common law that applies to statutory provisions authorising the detention of an individual which do not expressly exclude a reasonableness requirement.

The Commissioner argued in his fourth ground of appeal that the judge failed to consider the evidence regarding the unique security concerns on Diego Garcia, which included witness statements from senior figures at the Foreign, Commonwealth and Development Office. He cited several ‘failures’ in the judge’s analysis of Diego Garcia’s function as a UK-US military base and the impact of the claimants’ presence on those functions.

The court found that the Commissioner’s argument focused on a small part of the evidence while ignoring the rest, especially the evidence given in cross-examination. This was described as a ‘highly selective exercise’. The court, reviewing the judgment on appeal, concluded that the judge was aware of the unique security concerns on Diego Garcia and gave them appropriate weight.

The appeal was dismissed on all grounds.

Further appeal to the Privy Council

The Commissioner then attempted to seek leave to appeal to the Judicial Committee of the Privy Council. His first application was refused by the BIOT Court of Appeal on 8 February 2026. He argued he had an appeal as of right due to secondary legislation on BIOT. An ‘appeal as of right’ means an appeal that does not require formal permission from the court to be brought, though as seen below, it does not necessarily mean the court does not have to determine the merit of an appeal.

The Court agreed that the Commissioner had an appeal ‘as of right’, but they still had to decide if the claim raised a ‘genuinely disputable issue’. The court concluded that it did not:

each of the Commissioner’s grounds of appeal lacked merit because they were just expressions of disagreement with the outcome and did not identify any properly arguable errors of law in the Court of Appeal’s judgment.

The Commissioner then renewed his appeal directly to the Privy Council. On 8 July 2026, Lord Reed, Lord Leggatt, Lady Rose refused permission to appeal, finding it was ‘wholly devoid of merit’.

Conclusion

The BIOT Supreme Court’s decision, upheld on appeal twice, is a welcome restatement of some basic principles of false imprisonment. The case is bleak and unsettling on its facts, and one of its most striking features was the defendant’s consistent stance that the conditions he kept the claimants in did not amount to detention, despite the overwhelming evidence to the contrary. The repeated rejection of this argument shows the court’s ability to protect and enforce fundamental rights, even on territories with little legislative protection against abuse (including protections granted by the European Convention on Human Rights, which was not extended to BIOT).

Now that liability has been determined, there remain claims for damages yet to be brought for not only the 12 claimants, but at least 64 people who were detained on Diego Garcia before being removed to the UK on 2 December 2024. This could potentially extend to others detained on the BIOT and voluntarily returned or travelled elsewhere. Given the length and conditions of detention, these claims could be very costly for the UK government.