8 MONITORING OF CUSTODIAL SETTINGS IN UKRAINE inhuman or degrading treatment or punishment. As stipulated in part two of OPCAT Article 4, “deprivation of liberty means any form of detention or imprison- ment or the placement of a person in a public or private custodial setting which that person is not permitted to leave at will by order of any judicial, administrative or other authority.” For efficient performance of their functions NPMs, under Article 19 of OPCAT, are granted the following powers: (a) To regularly examine the treatment of the persons deprived of their liberty in places of detention as defined in article 4, with a view to strengthening, if necessary, their protection against torture, cruel, inhuman or degrading treatment or punishment; (b) To make recommendations to the relevant authorities with the aim of improving the treatment and the conditions of the persons deprived of their liberty and to prevent torture and cruel, inhuman or degrading treatment or punishment, taking into consideration the relevant norms of the United Nations; (c) To submit proposals and observations concerning existing or draft legislation. Under Article 20, the State Parties grant NPMs : (a) Access to all information concerning the number of persons deprived of their liberty in places of detention as defined in article 4, as well as the number of places and their location; (b) Access to all information referring to the treatment of those persons as well as their conditions of detention; (c) Access to all places of detention and their installations and facilities; (d) The opportunity to have private interviews with the persons deprived of their liberty without witnesses, either personally or with a translator if deemed necessary, as well as with any other person who the national preventive mechanism believes may supply relevant information; (e) The liberty to choose the places they want to visit and the persons they want to interview; (f ) The right to have contacts with the Subcommittee on Prevention, to send it information and to meet with it.