4. When establishing national preventive mechanisms, States Parties shall give due consideration to the Principles relating to the status of national institutions for the promotion and protection of human rights. Article 19 The national preventive mechanisms shall be granted at a minimum the power: (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 and other 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 other 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. Article 20 In order to enable the national preventive mechanisms to fulfil their mandate, the States Parties to the present Protocol undertake to grant them: (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. Article 21 1. No authority or official shall order, apply, permit or tolerate any sanction against any person or organization for having communicated to the national preventive mechanism any information, whether true or false, and no such person or organization shall be otherwise prejudiced in any way. 2. Confidential information collected by the national preventive mechanism shall be privileged. No personal data shall be published without the express consent of the person concerned. 94