Introduction Detention of migrants is a reality in a growing number of countries within and outside the OSCE region, despite being admissible as a last resort only under international standards1, which specify that immigration detention should only be used for the shortest possible period and for the purpose of documenting the entry, recording claims of the person concerned and determining her/his identity. In practice, an increasing number of states are using collective and systematic detention as a way to cope with large incoming flows of migrants, including children, to their territories. In that context, risks of torture and ill-treatment are high. Vulnerabilities during immigration detention may be exacerbated by detainees’ lack of access to appropriate information, including legal support, language barriers and the inability to challenge the irregularity of their detention. Moreover, certain groups or individuals have additional needs and are in a situation of increased vulnerability in detention, including: children (whether accompanied or not); people suffering from trauma, including victims of torture; people with disabilities; members of ethnic minorities; the elderly; LGBTI people; or those with urgent medical needs.2 National Preventive Mechanisms (NPMs) established under the Optional Protocol to the UN Convention against Torture (OPCAT), which numbered 39 in the OSCE region as of December 2018, can play a crucial role in preventing risks of torture and ill-treatment thanks to their preventive monitoring mandate. In the OSCE region as elsewhere, besides NPMs, civil society organizations (CSOs) play a crucial role in improving the treatment and conditions of individuals deprived of their liberty and preventing further abuses they may be subjected to. CSOs have diverse and complementary mandates to do so, including: service-providing to people deprived of their liberty; detention monitoring; investigating allegations of torture and bringing perpetrators to justice; obtaining redress, including guarantees of non-repetition; and providing rehabilitation for torture victims. CSOs’ interactions with NPMs are varied and range from playing a watchdog role towards NPMs and the implementation of the OPCAT system, to full-fledged collaboration on joint initiatives and projects, including by being an integral element of the NPM system. The regional meeting brought together NPMs and CSOs from 29 OSCE participating States. In addition, participants included representatives from the Civic Solidarity Platform (CSP), a network of over 90 NGOs from across the OSCE region, the UN Special Rapporteur on torture, and representatives of the United Nations Subcommittee on the Prevention of Torture (SPT) and the Council of Europe, including the European Committee for the Prevention of Torture (CPT). Participants discussed key challenges and identified promising practices regarding the monitoring of immigration detention and the collaboration between NPMs and CSOs. See. E.g. CPT, Factsheet on Immigration Detention, March 2017, page 2. Detention that goes beyond the timeframe of those purposes, should be the outcome of a legal process, based on a case-by-case analysis and is only admissible for reasons such as the likelihood of absconding, the risk of committing crimes or of acting against national security (see .e.g. Report of the Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment, 26 February 2018, A/HRC/37/50, https://www.ohchr.org/Documents/Issues/Torture/A_HRC_37_50_EN.pdf. 2 Monitoring Immigration Detention – Practical Manual, APT, UNHCR and IDC, 2014, https://www.apt.ch/content/files_res/monitoring-immigration-detention_practical-manual.pdf. 1 5