The consequence is immediate and it is not discretionary. Under § 382.501(a), a driver who has engaged in conduct prohibited by subpart B — any of the prohibitions § 9.2 set out, including a refusal — or by another DOT agency’s alcohol or controlled substances rule shall not perform safety-sensitive functions, including driving a commercial motor vehicle, except as subpart F provides. § 382.501(b) puts the mirror duty on the employer: it shall not permit a driver to perform them once it has determined a violation. Note what § 382.501 does NOT say. It says nothing about firing anyone and nothing about a license. It removes the driver from the function, which is why § 9.1’s definition of a safety-sensitive function is the load-bearing one here too — what is removed is far more than driving.

The route back is set out by reference rather than described. § 382.503(a) states that no driver who has engaged in prohibited conduct shall perform safety-sensitive functions, and no employer shall permit it, unless the driver has met the requirements of 49 CFR part 40, subpart O — and § 382.309 and § 382.311 say the same of return-to-duty testing and follow-up testing, that they must be performed in accordance with that subpart. Part 382 therefore fixes the obligation and Part 40 supplies the procedure. What that procedure holds is better learned before you need it: under 49 CFR 40.305, a return-to-duty test cannot occur until a substance abuse professional has determined that the employee has successfully complied with prescribed education or treatment, and the employee must produce a negative drug test result, or an alcohol test below 0.02, before resuming safety-sensitive duties.

Two things in that procedure regularly surprise drivers, and both are in the same section. First, meeting every condition does not oblige anyone to give you your job back: 49 CFR 40.305(b) says an employer must not return an employee to safety-sensitive duties until the conditions are met, and then says plainly that it is not required to return them because they have been — that is a personnel decision left to the employer, subject to collective bargaining agreements or other legal requirements. The substance abuse professional does not decide it either; 49 CFR 40.305(c) forbids a fitness-for-duty determination as part of the re-evaluation unless another DOT agency regulation requires one. Second, a separate gate can be standing whatever the testing says. § 382.503(b) provides that a driver whose commercial driving privilege has been removed from their license under § 382.501(a) shall not drive a commercial motor vehicle until the State Driver Licensing Agency reinstates the commercial learner’s permit or commercial driver’s license privilege. Completing the process with a substance abuse professional does not reinstate anything on the license itself.