Any employee to the extent that such employee is exempted by regulations, order, or certificate of the Secretary issued under section 14.

Sec. 14. (a) The Secretary of Labor, to the extent necessary in order to prevent curtailment of opportunities for employment, shall by regulations or by orders provide for the employment of learners, of apprentices, and of messengers employed primarily in delivering letters and messages, under special certificates issued pursuant to regulations of the Secretary, at such wages lower than the minimum wage applicable under section 6 and subject to such limitations as to time, number, proportion, and length of service as the Secretary shall prescribe.

(b) The Secretary, to the extent necessary in order to prevent curtailment of opportunities for employment, shall by regulation or order provide for the employment of full-time students, regardless of age but in compliance with applicable child labor laws, on a part-time basis in retail or service establishments (not to exceed twenty hours in any workweek) or on a part-time or a full-time basis in such establishments during school vacations, under special certificates issued pursuant to regulations of the Secretary, at a wage rate not less than 85 per centum of the minimum wage applicable under section 6, except that the proportion of student hours of employment to total hours of employment of all employees in any establishment may not exceed (1) such proportion for the corresponding month of the 12-month period preceding May 1, 1961, (2) in the case of a retail or service establishment whose employees (other than employees engaged in commerce or in the production of goods for commerce) are covered by this Act for the first time on or after the effective date of the Fair Labor Standards Amendments of 1966, such proportion for the corresponding month of the 12-month period immediately prior to such date, or (3) in the case of a retail or service establishment coming into existence after May 1, 1961, or a retail or service establishment for which records of student hours worked are not available, a proportion of student hours of employment to total hours of employment of all employees based on the practice during the 12-month period preceding May 1, 1961, in (A) similar establishments of the same employer in the same general metropolitan area in which the new establishment is located, (B) similar establishments of the same employer in the same or nearby counties if the new establishment is not in a metropolitan area, or (C) other establishments of the same general character operating in the community or the nearest comparable community. Before the Secretary may issue a certificate under this subsection he must find that such employment will not create a substantial probability of reducing the full-time employment opportunities of persons other than those employed under this subsection.

(d)(1) Except as otherwise provided in paragraphs (2) and (3) of this subsection, the Secretary of Labor, to the extent necessary in order to prevent curtailment of opportunities for employment, shall by regulation or order provide for the employment under special certificates of individuals * * * whose earning or productive capacity is impaired by age or physical or mental deficiency or injury, at wages which are lower than the minimum wage applicable under section 6 of this Act but not less than 50 per centum of such wage and which are commensurate with those paid nonhandicapped workers in industry in the vicinity for essentially the same type, quality, and quantity of work.

(2) The Secretary, pursuant to such regulations as he shall prescribe and upon certification of the State agency administering or supervising the administration of vocational rehabilitation services, may issue special certificates for the employment of—

(A) handicapped workers engaged in work which is incidental to training or evaluation programs, and

(B) multihandicapped individuals and other individuals whose earning capacity is so severly impaired that they are unable to engage in competitive employment,

(3)(A) The Secretary may by regulation or order provide for the employment of handicapped clients in work activities centers under special certificates at wages which are less than the minimums applicable under section 6 of this Act or prescribed by paragraph (1) of this subsection and which constitute equitable compensation for such clients in work activities centers.

(B) For purposes of this section, the term “work activities centers” shall mean centers planned and designed exclusively to provide therapeutic activities for handicapped clients whose physical or mental impairment is so severe as to make their productive capacity inconsequential.