49 CFR Part 40 (commonly referred to as "Part 40") states:
- how drug and alcohol testing is conducted,
- who is authorized to participate in the drug and alcohol testing program, and
- what employees must do before they may return-to-duty following a drug and/or alcohol violation.
The DOT Agency and the USCG specific regulations state:
- the agency's prohibitions on drug and alcohol use,
- who is subject to the regulations,
- what testing is authorized,
- when testing is authorized, and
- the consequences of non-compliance.
The DOT Agencies and the USCG incorporate Part 40 into their regulations and enforce compliance of all their respective regulations.