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

(b) Regulation of alcohol and drugs. A covered entity:

(1) May prohibit the illegal use of drugs and the use of alcohol at the workplace by all employees;

(2) May require that employees not be under the influence of alcohol or be engaging in the illegal use of drugs at the workplace;

(3) May require that all employees behave in conformance with the requirements established under the Drug-Free Workplace Act of 1988 (41 U.S.C. 701 et seq.);

(4) May hold an employee who engages in the illegal use of drugs or who is an alcoholic to the same qualification standards for employment or job performance and behavior to which the entity holds its other employees, even if any unsatisfactory performance or behavior is related to the employee's drug use or alcoholism;

(5) May require that its employees employed in an industry subject to such regulations comply with the standards established in the regulations (if any) of the Departments of Defense and Transportation, and of the Nuclear Regulatory Commission, regarding alcohol and the illegal use of drugs; and

(6) May require that employees employed in sensitive positions comply with the regulations (if any) of the Departments of Defense and Transportation and of the Nuclear Regulatory Commission that apply to employment in sensitive positions subject to such regulations.