Drug testing raises numerous legal issues. Employees may claim drug tests violate their rights to privacy. Hair follicle testing is less intrusive than urinalysis but can actually produce more personal information: A short hair segment could record months of drug use. The National Labor Relations Board upheld a union member’s right to have representation after failing a drug test. This may “severely disrupt and limit” unionized employers’ ability to test and deal with employees who are under the influence.

Courts require that employers who administer drug tests to employees who have accidents focus on recent drug use. Several federal laws affect workplace drug testing, and multistate employers must ensure they also comply with state laws (some states permit medical marijuana use, for instance). Under the Americans with Disabilities Act, a court would probably consider a former drug user (who no longer uses illegal drugs and has successfully completed or is participating in a rehabilitation program) as a qualified applicant with a disability.

Under the Drug Free Workplace Act of 1988, federal contractors must maintain a workplace free from illegal drugs. While this doesn’t require contractors to conduct drug testing or rehabilitate affected employees, many do. Under the U.S. Department of Transportation workplace regulations, firms with over 50 eligible employees in transportation industries must conduct alcohol testing on workers with sensitive or safety-related jobs.