24 UNITED NATIONS STANDARD MINIMUM RULES FOR THE TREATMENT OF PRISONERS Rule 78 1. So far as possible, prison staff shall include a sufficient number of specialists such as psychiatrists, psychologists, social workers, teachers and trade instructors. 2. The services of social workers, teachers and trade instructors shall be secured on a permanent basis, without thereby excluding part-time or voluntary workers. Rule 79 1. The prison director should be adequately qualified for his or her task by character, administrative ability, suitable training and experience. 2. The prison director shall devote his or her entire working time to official duties and shall not be appointed on a part-time basis. He or she shall reside on the premises of the prison or in its immediate vicinity. 3. When two or more prisons are under the authority of one director, he or she shall visit each of them at frequent intervals. A responsible resident official shall be in charge of each of these prisons. Rule 80 1. The prison director, his or her deputy, and the majority of other prison staff shall be able to speak the language of the greatest number of prisoners, or a language understood by the greatest number of them. 2. Whenever necessary, the services of a competent interpreter shall be used. Rule 81 1. In a prison for both men and women, the part of the prison set aside for women shall be under the authority of a responsible woman staff member who shall have the custody of the keys of all that part of the prison. 2. No male staff member shall enter the part of the prison set aside for women unless accompanied by a woman staff member. 3. Women prisoners shall be attended and supervised only by women staff members. This does not, however, preclude male staff members, particularly doctors and teachers, from carrying out their professional duties in prisons or parts of prisons set aside for women. Rule 82 1. Prison staff shall not, in their relations with the prisoners, use force except in self-defence or in cases of attempted escape, or active or passive physical resistance to an order based on law or regulations. Prison staff