Commonly referred to as the Belmarsh case, A and Others v the United Kingdom is a landmark case decided by the European Court of Human Rights in 2009. The case involved a group of individuals who were arrested and detained in HM Prison Belmarsh by the UK government without trial or charge as part of its counter-terrorism efforts.
The individuals were suspected of being involved in international terrorism and were detained under the Anti-terrorism, Crime and Security Act 2001, which allowed the government to detain non-UK nationals without charge or trial if they were suspected of being involved in terrorism.
Although the House of Lords held in favour of the detainees in A and others v Secretary of State for the Home Department  and subsequent declaration of incompatibility did not render invalid the acts of detention and application of section 23 of the Anti-terrorism, Crime and Security Act 2001. The detainees remained in detention and appealed their case to the European Court of Human Rights, culminating in the A and Others v the United Kingdom.
The individuals argued that their detention was a violation of their right to liberty and security under Article 5 of the European Convention on Human Rights. They also argued that the use of the 2001 Act to detain them was discriminatory, as it only applied to non-UK nationals.
The European Court of Human Rights held that the use of the 2001 Act to detain the individuals was a violation of their right to liberty and security. The court found that the detention was arbitrary and disproportionate, as there was no evidence that the individuals posed a specific threat to national security or that there was any other compelling reason to justify their detention.
The case was significant in establishing that the use of detention without charge or trial in the context of counter-terrorism efforts must be based on individualised suspicion and must be proportionate to the threat posed by the individual. The case also underscored the importance of non-discrimination in the application of counter-terrorism measures, and the need to ensure that such measures do not disproportionately affect individuals on the basis of their nationality or other personal characteristics.