No driver shall report for duty or remain on duty requiring the performance of safety-sensitive functions while having an alcohol concentration of 0.04 or greater. No employer having knowledge that a driver has an alcohol concentration of 0.04 or greater shall permit the driver to perform or continue to perform safety-sensitive functions.

No driver shall use alcohol while performing safety-sensitive functions. No employer having actual knowledge that a driver is using alcohol while performing safety-sensitive functions shall permit the driver to perform or continue to perform safety-sensitive functions.

No driver shall perform safety-sensitive functions within four hours after using alcohol. No employer having actual knowledge that a driver has used alcohol within four hours shall permit a driver to perform or continue to perform safety-sensitive functions.

No driver required to take a post-accident alcohol test under § 382.303 shall use alcohol for eight hours following the accident, or until he/she undergoes a post-accident alcohol test, whichever occurs first.

No driver shall refuse to submit to a pre-employment controlled substance test required under § 382.301, a post-accident alcohol or controlled substance test required under § 382.303, a random alcohol or controlled substances test required under § 382.305, a reasonable suspicion alcohol or controlled substance test required under § 382.307, a return-to-duty alcohol or controlled substances test required under § 382.309, or a follow-up alcohol or controlled substance test required under § 382.311. No employer shall permit a driver who refuses to submit to such tests to perform or continue to perform safety-sensitive functions.

(a) No driver shall report for duty or remain on duty requiring the performance of safety sensitive functions when the driver uses any drug or substance identified in 21 CFR 1308.11 Schedule I.

(b) No driver shall report for duty or remain on duty requiring the performance of safety-sensitive functions when the driver uses any non-Schedule I drug or substance that is identified in the other Schedules in 21 CFR part 1308 except when the use is prescribed by a licensed medical practitioner, as defined in § 382.107, who is familiar with the driver's medical history and has advised the driver that the substance will not adversely affect the driver's ability to safely operate a commercial motor vehicle.

(c) No employer having actual knowledge that a driver has used a controlled substance, as defined in § 382.107, shall permit the driver to perform or continue to perform a safety-sensitive function, except when the use is prescribed by a licensed medical practitioner, as defined in § 382.107, who is familiar with the driver's medical history and has advised the driver that the substance will not adversely affect the driver's ability to safely operate a commercial motor vehicle.

(d) An employer may require a driver to inform the employer of any therapeutic drug use.

No driver shall report for duty, remain on duty or perform a safety-sensitive function, if the driver tests positive or has adulterated or substituted a test specimen for controlled substances. No employer having knowledge that a driver has tested positive or has adulterated or substituted a test specimen for controlled substances shall permit the driver to perform or continue to perform safety-sensitive functions.

No employer may allow, require, permit or authorize a driver to operate a commercial motor vehicle during any period in which an employer determines that a driver is not in compliance with the return-to-duty requirements in 49 CFR part 40, subpart O, after the occurrence of any of the following events:

(a) The driver receives a positive, adulterated, or substituted drug test result conducted under part 40 of this title.

(b) The driver receives an alcohol confirmation test result of 0.04 or higher alcohol concentration conducted under part 40 of this title.

(c) The driver refused to submit to a test for drugs or alcohol required under this part.

(d) The driver used alcohol prior to a post-accident alcohol test in violation of § 382.209.

(e) An employer has actual knowledge, as defined at § 382.107, that a driver has:

(1) Used alcohol while performing safety-sensitive functions in violation of § 382.205;

(2) Used alcohol within four hours of performing safety-sensitive functions in violation of § 382.207; or

(3) Used a controlled substance, except when the use is prescribed by a licensed medical practitioner who is familiar with the driver's medical history and has advised the driver that the substance will not adversely affect the driver's ability to safely operate a commercial motor vehicle.