Short answer
Pre-employment cannabis screening is legal in most US states. Federal law does not ban it. Employers may test for THC and refuse to hire based on a positive result. State laws create exceptions. About 10 states limit pre-employment testing for cannabis. Safety-sensitive roles and federal contractors are exempt from those state limits.
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Federal law
Cannabis is a Schedule I controlled substance under the Controlled Substances Act, 21 U.S.C. § 812. The Drug-Free Workplace Act of 1988, 41 U.S.C. § 8101, requires federal contractors and grantees to maintain a drug-free workplace. The Department of Transportation requires cannabis testing for safety-sensitive transportation workers under 49 CFR Part 40. That covers truck drivers, pilots, rail workers, and transit operators. Federal law does not protect medical cannabis users from job loss. Courts have upheld terminations for positive tests even in states with legal cannabis.
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State laws that limit screening
Some states restrict pre-employment cannabis testing. Examples:
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- California: AB 2188, effective Jan 1, 2024, Cal. Gov. Code § 12954. Employers cannot use a positive test for non-psychoactive THC metabolites. Exemptions: federal contractors, construction, DOT jobs.
- Washington: SB 5123, effective Jan 1, 2024. Bans pre-employment cannabis testing for most jobs. Exemptions: safety-sensitive, federal contractors.
- Nevada: NRS 613.132, effective 2020. Bans pre-employment cannabis testing. Exemptions: safety-sensitive, firefighters, EMTs, drivers.
- New York: N.Y. Labor Law § 201-d. Employers cannot test for cannabis in most cases. Exemptions: federal law, safety-sensitive.
- Connecticut, New Jersey, Rhode Island, Montana, and others have medical cannabis protections. Rules vary. Check state law.
What tests detect
Urine tests detect THC-COOH, a non-psychoactive metabolite. It stays in urine for 1 to 30 days. Heavy users can test positive for weeks. Hair tests detect use for up to 90 days. Saliva tests detect THC for 1 to 2 days. Blood tests detect active THC for hours. No test shows impairment. A positive result means prior use, not current intoxication.
Employer limits and exceptions
Employers can still screen in most states. They can refuse to hire for a positive cannabis test. Exceptions: some state laws require accommodation for medical cannabis users. But federal contractors and safety-sensitive roles are exempt. Safety-sensitive jobs include equipment operators, drivers, and jobs with firearms. Also, federal law preempts state protections for DOT workers.
Bottom line
Pre-employment cannabis screening is legal in most of the US. Federal law permits it. State laws that limit it cover about 10 states. Many state laws have broad exemptions. Check your state statute and job type. The law changes often. This guide is not legal advice.