19 U.S.C. § 6e
Overtime compensation based on standard or daylight saving time
On and after June 30, 1949 , overtime compensation of customs officers and employees, as authorized by law, shall be based either on standard or daylight saving time, whichever is observed where overtime services are performed.
( June 30, 1949, ch. 286 , title I, 63 Stat. 360 .)