Article 4 1. Each State Party shall allow visits, in accordance with the present Proto- col, by the mechanisms referred to in articles 2 and 3 to any place under its jurisdiction and control where persons are or may be deprived of their liberty, either by virtue of an order given by a public authority or at its instigation or with its consent or acquiescence (hereinafter referred to as places of detention). These visits shall be undertaken with a view to strengthening, if necessary, the protection of these persons against torture and other cruel, inhuman or degrading treatment or punishment. 2. For the purposes of the present Protocol, deprivation of liberty means any form of detention or imprisonment 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. Part II Subcommittee on Prevention Article 5 1. The Subcommittee on Prevention shall consist of ten members. After the fiftieth ratification of or accession to the present Protocol, the number of the members of the Subcommittee on Prevention shall increase to twenty-five. 2. The members of the Subcommittee on Prevention shall be chosen from among persons of high moral character, having proven professional experience in the field of the administration of justice, in particular criminal law, prison or police administration, or in the various fields relevant to the treatment of persons deprived of their liberty. 3. In the composition of the Subcommittee on Prevention due consideration shall be given to equitable geographic distribution and to the representation of different forms of civilization and legal systems of the States Parties. 4. In this composition consideration shall also be given to balanced gender representation on the basis of the principles of equality and non-discrimination. 99