By virtue of the authority vested in me by title I of the Universal Military Training and Service Act (62 Stat. 604), as amended, I hereby prescribe the following amendment of the Selective Service Regulations prescribed by Executive Order No. 101292 of September 25, 1951, and constitution a portion of Chapter XVI of Title 32 of the Code of Federal Regulations:
Section 1622.23 of Part 1622, Classification Rules and Principles, is amended to read as follows:
§ 1622.23 Necessary employment defined. (a) Except as otherwise provided in paragraph (b) of this section, a registrant's employment in industry or other occupation, service in office, or activity in research, or medical, scientific, or other endeavors, shall be considered to be necessary to the maintenance of the national health, safety, or interest only when all of the following conditions exist:
(1) The registrant is, or but for a seasonal or temporary interruption would be, engaged in such activity.
(2) The registrant cannot be replaced because of a shortage of persons with his qualifications or skill in such activity.
(3) The removal of the registrant would cause a material loss of effectiveness in such activity.
(b) A registrant's activity as an apprentice in an apprentice training program may be considered to be necessary to the maintenance of the national health, safety, or interest when all of the following condition exist:
(1) The apprentice training program meets the standards and requirements prescribed by the Director of Selective Service based upon the recommendations of the Secretary of Labor.
(2) The program has been accepted by the Director of Selective Service for deferment purposes.
(3) The registrant has satisfactorily completed in the program a minimum amount of training prescribed by the Director Selective Service.
(4) The registrant is satisfactorily pursuing his training in the program and meeting the requirements, and standards of performance prescribed by the Director of the Selective Service.
(c) The President may, from time to time (1) designate special categories of occupation, employment, or activity, essential to the national health, safety, or interest; and (2) prescribe regulations governing the deferment of individual registrants engaged in such occupations, employments, or activities.
HARRY S. TRUMAN
THE WHITE HOUSE,
June 26, 1952
Harry S Truman, Executive Order 10366—Amending the Selctive Service Regulations Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/278703