29 CFR Part 1630, Regulations to Implement the Equal Employment Provisions of the ADA (Title I Regulations with amendments issued through May 2016)

(2) Transportation employees. This part does not encourage, prohibit, or authorize the otherwise lawful exercise by entities subject to the jurisdiction of the Department of Transportation of authority to:

(i) Test employees of entities in, and applicants for, positions involving safety sensitive duties for the illegal use of drugs or for on-duty impairment by alcohol; and

(ii) Remove from safety-sensitive positions persons who test positive for illegal use of drugs or on-duty impairment by alcohol pursuant to paragraph (c)(2)(i) of this section.