22 Article 20(d) OP guarantees that NPMs have the same right to conduct private interviews as the SPT does under Article 14(d) OP.44 Private interviews of persons who have been deprived of their liberty are a central source of information on the treatment and conditions of detention. The SPT noted that ‘[w]ith due respect for the security regulations in force in any given institution … it is possible to conduct interviews with detainees inside cells and without surveillance.’45 However, all detainees ‘must be treated with humanity and their private space within the cells should be respected’.46
23 Also with other persons who the NPM believes may supply relevant information, Article 20(d) provides for private interviews. Such valuable sources might be alleged victims who are no longer detained, family members of detainees, witnesses, lawyers, doctors, prison staff, NGO, and media representatives.47
24 Unless there are substantive reasons for doing otherwise, the NPM should conduct individual and private interviews with persons deprived of their liberty and employees of the institution in question, including medical personnel.48 If the size of the visiting team is limited, the SPT recommended that the members of the team give such interviews with detainees at least an equal priority with speaking to those in authority.49 As to the aim of the interview, the SPT formulated clearly that interviews should be used ‘to take a closer look at structural aspects of the system of deprivation of liberty in order to collect (p. 929) information and thus be in a position to undertake a comprehensive, substantiated analysis of institutional, legal and public policy risk factors’.50 The NPM should establish a policy setting out which types of information can be collected during group interviews and which types of information should be collected in private interviews only.51 As group interviews pose certain risks as reprisals and have the potential to rapidly get out of hand,52 the specific circumstances in the respective institution, the usefulness and relevance of such an interview should be evaluated.53
25 Holding an interview in private means out of ear and sight of the authorities to ensure confidentiality, privacy, and to avoid reprisals. Moreover, to preserve the anonymity of the source of possibly sensitive or critical information obtained during a private interview, a number of private interviews should be conducted.54 When reporting on systematic issues or crimes, attention must be taken to assess whether the sharing of information might inevitably lead to the disclosure of personal data or to the identification of a person who has not given express consent for his/her personal data to be revealed. In such cases ‘the obligation of confidentiality prevails’.55
26 At the beginning of the interview, the members of the NPM should introduce themselves by telling them their name, profession, and position in the NPM.56 To facilitate communication and trust-building, the interviewer should explain the NPM’s mandate, especially its preventive nature, and objectives.57 The interviewer ‘should also obtain the consent of the interviewee and make it clear that the interview is confidential, voluntary and can be interrupted at any time at the interviewee’s request’.58
27 The distribution of a leaflet by the NPM members to the detained persons is a useful tool recommended by the to inform about the NPM’s mandate and working methods, the concept of informed consent, and contact information. It should also encourage persons to report any reprisal to the NPM.59
28 It is of course important that the members of the NPM hold the interview in a professional manner keeping objective distance to staff and focusing on establishing a trustful relationship to the detainees by listening actively and showing interest.60 Moreover, they (p. 930) need to be sensitive to the vulnerable situation of the person deprived of liberty, paying due regard to the central ‘do no harm’ principle. The Istanbul Protocol and monitoring guides of the OHCHR and civil society organizations such as APT provide detailed guidance on how to adequately conduct interviews.61