Part II Preventing torture: NHRIs in action | Section III Acting as a control mechanism 4.1.2. National preventive mechanisms A State that has ratified the Optional Protocol is required to designate or establish one or several national preventive mechanisms (NPM). The Optional Protocol contains no specific requirement or guidance regarding the structure of NPMs. A State may therefore: • set up an entirely new Optional Protocol-based mechanism • designate an existing body (for example, the NHRI or ombudsman) • designate several mechanisms, which can include existing or new bodies. Chapter 10 provides a detailed analysis of some of the challenges faced by NHRIs that are designated as a NPM. NPMs have a mandate to conduct regular, unannounced visits to all places where persons are deprived of their liberty. They can also present observations on draft or existing legislation relevant to the prevention of torture. NPMs are also required to prepare an annual report of their activities, which should be made public and disseminated by the authorities. NPMs should be independent from the State and its authorities, both from a financial and a functional point of view. The mandate of NPMs should be reflected in their composition. They should be genderbalanced and include representatives of minority groups, as well as members from a variety of professional backgrounds. 4.1.3. Powers to visit places of detention For the first time in an international treaty, the Optional Protocol provides powers and guarantees for NPMs and the Subcommittee on Prevention of Torture to carry out visits to places of detention. Under the Optional Protocol, both the Subcommittee and NPMs have the authority to visit any place where persons are deprived of their liberty, such as: • prisons • police cells • pretrial detention centres • juvenile detention centres • administrative detention centres • military detention facilities • detention centres for migrants and asylum-seekers • temporary detention points in ports or airports • border checkpoints • medical institutions • psychiatric institutions. During these visits they are able to: • interview any detainee in private • interview any relevant officials • interview family members of a detainee • examine the records of all detainees • examine documents, such as disciplinary rules and prison records • inspect the entire premises of the place of detention. Chapter 7: Cooperating with international mechanisms | 79