considerations to be made when a child is being detained together with his or her parent, as well as detention of a child as part of the juvenile justice process. Because detention of children for reasons related to the migration status of them or their parents is prohibited under international law.374 7.1 International Law and Standards 7.1.1 Key Principles and Standards Concerning Deprivation of Liberty of Children Right to personal liberty 185. Under international law, every person has the right to liberty.375 In relation to children who are in contact with law, the Convention on the Rights of the Child requires that children be detained only as a last resort and for the shortest amount of time.376 As noted earlier, the Security Council has also urged Member States to consider non-judicial measures as alternatives to prosecution and detention for children formerly associated with armed groups.377 detainees are not violated. The Convention on the Rights of the Child prohibits the arbitrary or unlawful deprivation of liberty of a child.378 The Security Council has echoed the principle that no child should be deprived of his or her liberty unlawfully or arbitrarily and has called on all parties to conflict to cease unlawful or arbitrary detention.379 187. “Arbitrariness” should be interpreted broadly “to include elements of inappropriateness, injustice, lack of predictability and due process of law, as well as elements of reasonableness, necessity and proportionality”.380 Any decision to deprive a child of his or her liberty must take into account his or her best interests as a primary consideration, including with regard to the duration and conditions of detention.381 Detention must be based on grounds previously established by law. These grounds for detention cannot be assumed, particularly on blanket assumptions relating to the age of the child and must be determined on a case-by-case basis. Prohibition of arbitrary detention of children 186. International human rights law and standards set out minimum requirements to ensure that individuals are not deprived arbitrarily or unlawfully of their liberty and that rights of 374 Joint general comment No. 4 (2017) of the Committee on the Protection of the Rights of All Migrant Workers and Members of Their Families No. 23 (2017) of the Committee on the Rights of the Child, paras. 5-13. 375 International Covenant on Civil and Political Rights (1966), art. 9; Convention on the Rights of Persons with Disabilities (2006), art. 14, International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families (1990), art. 16. 378 Convention on the Rights of the Child (1989), art 37(b). 379 Security Council resolution 2225 (2015), para. 17; Security Council resolution 2427 (2018), para. 13. 376 Convention on the Rights of the Child (1989), art. 37. 380 Human Rights Committee, general comment No. 35 (2014) on article 9 (liberty and security of person), para. 13. 377 Security Council resolution 2427 (2018), para. 21. 381 Ibid., para. 18. 84.