49 U.S.C. § 31302Section
§ 31302. Commercial driver’s license requirement
No individual shall operate a commercial motor vehicle without a valid commercial driver’s license issued in accordance with section 31308. An individual operating a commercial motor vehicle may have only one driver’s license at any time and may have only one learner’s permit at any time.
(Pub. L. 103–272, §1(e), July 5, 1994, 108 Stat. 1015; Pub. L. 105–178, title IV, §4011(b)(1), June 9, 1998, 112 Stat. 407; Pub. L. 109–59, title IV, §4122(1), Aug. 10, 2005, 119 Stat. 1734.)