PUBLIC LAWS-CH. 512-AUG. 7 , 1947 Detail of officers of the line. Officers of Medical Service and Nurse Corps. Detail of officers of the line. Restriction. Appointment of boards, etc. Captain Officer in any grade except certain cap- tains and com- manders. (b) The officers composing these boards shall be officers on the active or retired list of the Navy. In case there be not a sufficient number of officers of the corps concerned legally or physically capac- itated to serve on a selection board of such corps, officers of the line on the active list of equivalent rank may be detailed to duty on such board to constitute the required minimum membership. (c) Boards for the recommendation of officers of the Medical Service Corps and of the Nurse Corps for promotion to grades above lieutenant (junior grade) shall be composed of not less than six nor more than nine officers above the grade of commander on the active or retired list of the Medical Corps: Provided,That in case there be not a sufficient number of officers of the Medical Corps legally or physically capacitated to serve on such a selection board, officers of the line of the active list of the grade of captain may be detailed to duty on such board to constitute the required minimum membership. (d) No officer may be a member of two successive selection boards for the consideration of officers for promotion to the same grade. (e) The boards prescribed in this section shall be appointed by the Secretary of the Navy and convened at least once each year at a time as soon as practicable after the report of a corresponding board for the selection of line officers has been approved by the President, and at such times as the Secretary of the Navy may direct: Provided, That a selection board to recommend officers of the Medical Service Corps for promotion to the grade of captain or officers of the Nurse Corps for promotion to the grade of commander or lieutenant com- mander shall be convened only if there exists a vacancy in the grade concerned or if the Secretary of the Navy estimates or determines that a vacancy will occur in the ensuing twelve-month period. OATH FOR MEMBERS OF SELECTION BOARDS SEC. 206. Each member of a board provided for in section 205 of this title shall swear, or affirm, that he will, without prejudice or partiality, and having in view both the special fitness of officers and the efficiency of the naval service, perform the duties imposed upon him as herein provided. ELIOIBiLTT OFP FFCERS FOR CONSIDERATION BY SELECTION BOARDS SEc. 207. (a) Captains within the following categories shall be eligible for consideration by a selection board for recommendation for continuation on the active list: (1) Those who have twice failed of selection for promotion to rear admiral, and (2) those who have failed of selection for promotion to rear admiral in the immediately preceding year and who are not recommended for promotion by the selection board concerned: Provided, That such captains who will complete thirty-five years' total commissioned service or who will attain the age of sixty-two years in the fiscal year in which such board is convened will not be eligible for consideration for continuation on the active list. (b) An officer in any grade, except captains in the Medical Service Corps and commanders in the Nurse Corps, shall become eligible for consideration by a selection board for promotion to the next higher grade when his running mate becomes eligible for such selection, except that officers of the Medical, Dental, Medical Service, and Chaplain Corps in the grades of lieutenant (junior grade) and lieu- tenant, and officers of the Nurse Corps in the grade of lieutenant (junior grade) shall not be eligible for such selection unless they are in the promoton zone in such grade or are senior to the officers in the promotion zone of the grade in which they are serving. An officer in 818 [61 STAT.