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. 5. No two members of the Subcommittee on Prevention may be nationals of the same State. 6. The members of the Subcommittee on Prevention shall serve in their individual capacity, shall be independent and impartial and shall be available to serve the Subcommittee on Prevention efficiently. Article 6 1. Each State Party may nominate, in accordance with paragraph 2 of the present article, up to two candidates possessing the qualifications and meeting the requirements set out in article 5, and in doing so shall provide detailed information on the qualifications of the nominees. 2. (a) The nominees shall have the nationality of a State Party to the present Protocol; (b) At least one of the two candidates shall have the nationality of the nominating State Party; (c) No more than two nationals of a State Party shall be nominated; (d) Before a State Party nominates a national of another State Party, it shall seek and obtain the consent of that State Party. 3. At least five months before the date of the meeting of the States Parties during which the elections will be held, the Secretary-General of the United Nations shall address a letter to the States Parties inviting them to submit their nominations within three months. The Secretary-General shall submit a list, in alphabetical order, of all persons thus nominated, indicating the States Parties that have nominated them. Article 7 1. The members of the Subcommittee on Prevention shall be elected in the following manner: (a) Primary consideration shall be given to the fulfilment of the requirements and criteria of article 5 of the present Protocol; (b) The initial election shall be held no later than six months after the entry into force of the present Protocol; IMPLEMENTATION OF THE DUTIES AND POWERS OF THE NPM IN 2017 NATIONAL PREVENTIVE MECHANISM UNDER THE OPTIONAL PROTOCOL TO THE UN CONVENTION AGAINST TORTURE AND OTHER CRUEL, INHUMAN OR DEGRADING TREATMENT OR PUNISHMENT 107