112 Human Rights in Counter-Terrorism Investigations 3.6.1 Prolonged Detention Detainees whose cases are still under investigation may be kept in detention pending trial, which should take place within a reasonable time. Such extended detention should, however, be the exception, and the release of the detainee pending trial can be decided by a judicial authority and subject to particular conditions. Any prolonged detention, whether before or after charges are brought against a suspect, should be as short as possible, and detainees should be treated in accordance with the presumption of innocence. Particular human rights concerns arise when detention is unduly prolonged or not subjected to periodic judicial review. Prolonged and indefinite detention, as well as the uncertainty as to its duration, render any detention arbitrary and illegal. They also raise concerns related to the prohibition of torture or inhumane or degrading treatment, due to their potential effects on the mental health of the terrorism suspect. Investigations of terrorism-related offences cannot justify keeping detainees without charging them or for a prolonged or indefinite duration without trial. Detainees suspected of terrorism-related offences sometimes may be kept in solitary confinement. This is designed to ensure that they have no opportunity to contact other suspects involved in the crimes with which they are charged and, thus, to interfere with the course of justice. It may also be justified by the potential danger posed by the suspect and should end as soon as the suspect no longer poses a security risk. However, solitary confinement should be strictly justified on these grounds and not used as a punishment. Any detainee subjected to solitary confinement should have access to an independent judicial authority to review the lawfulness of his or her isolation, including its potential continuation. Solitary confinement of suspects poses serious human rights concerns. The impact of the solitary confinement on the suspect’s mental and physical health should also be closely monitored, and any failure to end isolation in the case of negative effects would amount to cruel, inhuman and degrading treatment. Extended periods of confinement may amount to inhuman or degrading treatment, taking into consideration the purpose of the application of solitary confinement, the conditions, such as the level of sensory deprivation and social isolation, the length and effects of the treatment on the detainee’s mental and physical health, and the particular