The US Department of Transportation requires employee drug testing for safety sensitive workers. 49 CFR Part 40, commonly referred to as Part 40. Part 40 is a DOT-wide regulation that describes drug and alcohol testing requirements and how to deal with violations.
Part 40 applies to all modes (FMCSA, FAA, FRA, FTA, PHMSA and USCG). Each DOT Agency has its own regulation which describes who is subject to testing and under what circumstances testing is required.
The DOT allows covered employers to employ various service agents to collect specimens, conduct laboratory analyses, medically review lab results and determine test outcomes, but employers cannot delegate responsibility to comply with all applicable requirements and procedures of 49 CFR Part 40.
This means that employers are responsible for all actions of their employees, representatives, and service agents in carrying out the requirements of the DOT agency regulations.
For information about drug and alcohol testing requirements for each agency: