5 USC 6101 - Basic 40-hour workweek; work schedules; regulations

(a) 
(1) For the purpose of this subsection, employee includes an employee of the government of the District of Columbia and an employee whose pay is fixed and adjusted from time to time under section 5343 or 5349 of this title, or by a wage board or similar administrative authority serving the same purpose, but does not include an employee or individual excluded from the definition of employee in section 5541 (2) of this title, except as specifically provided under this paragraph.
(2) The head of each Executive agency, military department, and of the government of the District of Columbia shall
(A) establish a basic administrative workweek of 40 hours for each full-time employee in his organization; and
(B) require that the hours of work within that workweek be performed within a period of not more than 6 of any 7 consecutive days.
(3) Except when the head of an Executive agency, a military department, or of the government of the District of Columbia determines that his organization would be seriously handicapped in carrying out its functions or that costs would be substantially increased, he shall provide, with respect to each employee in his organization, that
(A) assignments to tours of duty are scheduled in advance over periods of not less than 1 week
(B) the basic 40-hour workweek is scheduled on 5 days, Monday through Friday when possible, and the 2 days outside the basic workweek are consecutive;
(C) the working hours in each day in the basic workweek are the same;
(D) the basic nonovertime workday may not exceed 8 hours;
(E) the occurrence of holidays may not affect the designation of the basic workweek; and
(F) breaks in working hours of more than 1 hour may not be scheduled in a basic workday.
(4) Notwithstanding paragraph (3) of this subsection, the head of an Executive agency, a military department, or of the government of the District of Columbia may establish special tours of duty, of not less than 40 hours, to enable employees to take courses in nearby colleges, universities, or other educational institutions that will equip them for more effective work in the agency. Premium pay may not be paid to an employee solely because his special tour of duty established under this paragraph results in his working on a day or at a time of day for which premium pay is otherwise authorized.
(5) The Architect of the Capitol may apply this subsection to employees under the Office of the Architect of the Capitol or the Botanic Garden. The Librarian of Congress may apply this subsection to employees under the Library of Congress.
(b) 
(1) For the purpose of this subsection, agency and employee have the meanings given them by section 5541 of this title.
(2) To the maximum extent practicable, the head of an agency shall schedule the time to be spent by an employee in a travel status away from his official duty station within the regularly scheduled workweek of the employee.
(c) The Office of Personnel Management may prescribe regulations, subject to the approval of the President, necessary for the administration of this section insofar as this section affects employees in or under an Executive agency.