Required for drivers who tested positive, refused, or otherwise violated the prohibitions of 49 CFR Part 382 Subpart B; and who have completed the return-to-duty process with a DOT-qualified substance abuse professional, and have tested negative for a return-to-duty test. This testing is prescribed by the substance abuse professional for a minimum of 6directly observed tests in 12 months, but can be extended an additional four years (§382.311 and §40.307).