BIOT Court of Appeal upholds judgment that Tamil asylum seekers were unlawfully detained on Diego Garcia

The British Indian Ocean Territory (“BIOT”) Court of Appeal has upheld the judgment of the BIOT Supreme Court that a group of Tamil asylum seekers were unlawfully detained on the island of Diego Garcia for more than three years.

The Commissioner argued that the Claimants were not detained, and that the restrictions on their liberty were lawful and necessary to protect the security of the military facility on Diego Garcia. 

In December 2024, the Supreme Court held that the Claimants had been detained and  that their detention was unnecessary and unlawful. The Commissioner appealed against that judgment to the Court of Appeal.

On 16 December 2025, the Court of Appeal dismissed the Commissioner’s appeal on all grounds. It confirmed that the conditions imposed on the Claimants amounted to detention as a matter of law, and that neither the defence of necessity at common law nor the Restriction of Movement Orders promulgated by the Commissioner provided a lawful basis the Claimants’ prolonged detention. The Court of Appeal also reaffirmed the fundamental nature of the Hardial Singh principles to the common law, with the consequence that it was unlawful for the Commissioner to detain individuals for an objectively unreasonable period.

The judgment is available here.

Press coverage includes BBC and The Guardian. 

Sarah Dobbie acted for two of the Claimants / Respondents, led by Helen Law of Matrix Chambers, and instructed by Wilson Solicitors and Duncan Lewis Solicitors.