S.C. Code Regs. 38-383.37. Employer responsibilities

No employer shall knowingly allow, require, permit, or authorize an employee to operate a commercial motor vehicle in the United States: (a) During any period in which the driver has a CMV driver's license suspended, revoked, or canceled by a State, has lost the right to operate a commercial motor vehicle in a State, or has been disqualified from operating a commercial motor vehicle; (b) During any period in which the employee has more than one commercial motor vehicle driver's license; (c) During any period in which the employee, or the motor vehicle he/she is driving, or the motor carrier operation, is subject to an out of service order; or (d) In violation of a Federal, State, or local law or regulation, pertaining to railroad-highway grade crossings.