detention, that is, detention for the purposes of public security or for questioning and intelligence-gathering, is likely to be more difficult to justify, even in the context of an investigation involving terrorism. In exceptional circumstances it may be justifiable for a strictly limited period if absolutely necessary because of the particular circumstances of the individual concerned and taking into account the level of the threat.26 If a person being questioned or held is not themselves suspected of involvement in any terrorist offence, detention is, in our view, unlikely ever to be justifiable.27 Detention of non-suspects may also impinge upon other rights such as the right of freedom of association. For completeness, we note that some of the Conventions on Terrorism establish a process by which a person who commits an offence in the terms of the particular Convention or is alleged to have done so, must be taken into custody or otherwise secured by the State Party in whose territory that person is found.28 Article 6(1) of the Montreal Convention stipulates, for example, that: Upon being satisfied that the circumstances so warrant, any Contracting State in the territory of which the offender or the alleged offender is present, shall take him into custody or take other measures to ensure his presence. Article 10(2) of the Draft Terrorism Convention is drafted similarly although it sets out the reasons for which a person should be detained or otherwise made available for trial: Upon being satisfied that the circumstances so warrant, the State Party in whose territory the offender or alleged offender is present shall take the appropriate measures under its domestic law so as to ensure that person’s presence for the purpose of prosecution or extradition.29 26 See Human Rights Committee General Comment 8, Article 9 (1982) at para 4 “if so-called preventive detention is used, for reasons of public security … it must not be arbitrary, and must be based on grounds and procedures established by law”. Reasons for the detention must be given and court control of the detention must be available. 27 The Advisory Council refers to the case of Brogan v United Kingdom (1988) 11 EHRR 117, paras 58-62, in which the European Court of Human Rights recognised that, while the investigation of terrorist offences presented the authorities with special problems which had the effect of prolonging the period during which persons suspected of serious terrorist offences might be kept in custody before being brought before a judicial officer, it could not justify dispensing altogether with judicial control. In addition, the Court considered that the scope for flexibility in interpreting and applying the notion of ‘promptness’ (in terms of bringing a detained person before a judicial officer) was very limited with a wide interpretation impairing the essence of the right. 28 Article 6(1), Montreal Convention; Article 6(1), Hague Convention; Article 7, Maritime Navigation Convention; Article 13, Tokyo Convention. The Conventions on Terrorism that allow detention, however, only do so for the purposes of prosecution or extradition. 29 See also Article 6, Hostages Convention; Article 6, Internationally Protected Persons Convention and Article 9, Nuclear Materials Convention. 38