49 CFR §382.503

1. (a)No driver who has engaged in conduct prohibited by subpart B of this part shall perform safety-sensitive functions, including driving a commercial motor vehicle, unless the driver has met the requirements of part 40, subpart O, of this title. No employer shall permit a driver who has engaged in conduct prohibited by subpart B of this part to perform safety-sensitive functions, including driving a commercial motor vehicle, unless the driver has met the requirements of part 40, subpart O, of this title.
2. (b)No driver whose commercial driving privilege has been removed from the driver's license, pursuant to § 382.501(a), shall drive a commercial motor vehicle until the State Driver Licensing Agency reinstates the CLP or CDL privilege to the driver's license.