8 Oversight mechanisms Persons deprived of liberty are confined to locations outside public scrutiny, so they are at higher risk of human rights violations than other people. Effective oversight systems are, therefore, necessary to prevent abuse and essential to ensure accountability for human rights violations. This chapter describes the preventive role of monitoring bodies and explains the role of child protection authorities and Schengen evaluations. Monitoring or oversight bodies often act only after someone complains. This chapter ends by illustrating the importance of complaint mechanisms for children deprived of liberty. 8.1. Independent monitoring bodies The protection of fundamental rights would be incomplete without a mechanism to prevent violations from occurring. Therefore, mechanisms to ensure preventive action are essential, in particular when it comes to the detention of vulnerable persons, such as children. One of the most common and widespread methods of preventing violations is preventive monitoring. This happens at both the international and European levels. Secondary EU law also recognises the important role of monitoring bodies. UNHCR and entities working on its behalf must have the opportunity to communicate with and visit detained applicants, according to Article 10 (3) of the Reception Conditions Directive. Relevant and competent national, international and non-governmental organisations and bodies must have the opportunity to visit detention facilities under Article 16 (4) of the Return Directive. The UN has several mechanisms for monitoring detention facilities. The Working Group on Arbitrary Detention conducts country-level field missions. Since January 2015 it has visited only one immigration detention facility in the EU, in Malta.383 383 UN, OHCHR (2017), Country visits-Working Group on Arbitrary Detention. Tools and guidance: Practical guide to monitoring child detention places Defence for Children International has published a practical guide to monitoring places where children are deprived of liberty. The guide applies to all types of deprivation of liberty. It takes into account the practical experience of a number of national and international bodies, and draws on the experience of experts working in the field. It aims to assist and strengthen the capability of monitoring bodies to effectively carry out a visit to facilities where children are detained. The guide was released on 15 February 2016 and is available through the Defence for Children’s website. It complements the 2014 guidance by the Association for the Prevention of Torture, the International Detention Coalition and UNHRC “Monitoring Immigration Detention, Practical Guide”, which is specific to immigration detention. 87