CHAPTER 4 RIGHT TO PERSONAL LIBERTY available. Nevertheless, even in such truly exceptional cases, detention must be restricted to the shortest appropriate period of time.31 The different chapters of the Global Study provide a detailed legal analysis of the principles of ‘measure of last resort’ and ‘shortest appropriate period of time’ in their respective contexts. In its recently adopted General Comment No. 24 relating to the administration of child justice, the CRC-Committee has specified certain time limits.32 For instance, it recommends to States Parties that no child in conflict with the law below the age of 16 years should be deprived of liberty; police custody should never be longer than 24 hours and pretrial detention should not last longer than 30 days.33 However, the Committee has not yet specified a maximum duration of imprisonment of children after conviction by a criminal court. Article 37(a) only prohibits life imprisonment without possibility of release, although the CRC-Committee has observed that life imprisonment with the possibility of release can be regarded on strained terms with the objectives of child justice in Article 40(1) and the best interests of the child in Article 3(1) CRC.34 In view of the negative consequences of imprisonment for the health and development of children, the Global Study will therefore aim at specifying what ‘shortest appropriate period of time’ means for the imprisonment of children who have committed serious and violent crimes. 31 Cf. ‘Havana Rules’, op. cit., Rule 2: stating that deprivation of liberty of a child ‘should be a disposition of last resort and for the minimum necessary period and should be limited to exceptional cases’. On the meaning of the shortest appropriate period of time, which is not necessarily the same as the shortest possible period of time, see Liefaard (2008), op. cit., p. 12. 32 CRC-Committee, General Comment No. 24 (2019), replacing General Comment No. 10 (2007): Children’s rights in juvenile justice, CRC/C/ GC/24, 2019. 33 Cf. ‘Beijing Rules’, op. cit., Rule 13: providing that detention pending trial shall be used only for the ‘shortest possible period of time’ and that, whenever possible, ‘detention pending trial shall be replaced by alternative measures, such as close supervision, intensive care or placement with a family or in an educational setting or home’. Cf. ‘Havana Rules’, op. cit., Rule 17: ‘Detention before trial shall be avoided to the extent possible and limited to exceptional circumstances. Therefore, all efforts shall be made to apply alternative measures.’ 34 See CRC-Committee, General Comment No. 10 (2007): Children’s Rights in Juvenile Justice, CRC/C/GC/10, 25 April 2007, para. 77. 72