DOT Clarifies State Marijuana Laws Don't Override Federal Safety Rules

Federal Rules Trump State Legalization for Safety-Sensitive Jobs

DOT's May 27 guidance states that federal drug-testing protocols remain in effect for all safety-sensitive transportation workers, even in states where recreational or medical marijuana is legal. The clarification comes as 38 states have legalized medical cannabis and 24 have legalized adult-use programs, creating widespread confusion among workers in federally regulated industries.

The guidance applies to employees covered by DOT drug-testing regulations under 49 CFR Part 40, including:

• Federal Aviation Administration (FAA) pilots and flight attendants
• Federal Motor Carrier Safety Administration (FMCSA) commercial drivers
• Federal Railroad Administration (FRA) train operators
• Federal Transit Administration (FTA) transit workers
• Pipeline and Hazardous Materials Safety Administration (PHMSA) pipeline operators

A positive test for delta-9-THC or its metabolites remains grounds for disqualification, termination, or mandatory substance-abuse treatment. State law doesn't change that.

No Medical Marijuana Exception Under Current DOT Policy

DOT doesn't recognize state-issued medical marijuana cards as a valid explanation for a positive drug test. Workers with qualifying conditions under state medical cannabis programs face the same consequences as recreational users if they test positive.

This policy has been consistent since DOT first addressed the issue in a 2009 notice, but the agency's latest statement comes amid renewed pressure from labor groups seeking carve-outs for off-duty use. The Association of Flight Attendants-CWA distributed the guidance through its Employee Assistance Program, signaling that the union is preparing members for enforcement rather than advocating for policy change.

DOT's position mirrors the Federal Motor Carrier Safety Administration's 2023 clarification on CBD use, which warned drivers that even hemp-derived products could trigger positive tests if they contain trace delta-9-THC above the 50 ng/mL cutoff.

Testing Thresholds and Detection Windows Create Gray Areas

DOT drug tests measure delta-9-THC metabolites at a 50 ng/mL screening threshold and a 15 ng/mL confirmation threshold. Workers can test positive days or weeks after last use. For infrequent users, detection windows typically range from 3 to 7 days, while daily users can test positive for 30 days or longer due to THC's lipid solubility and slow release from fat tissue.

The guidance doesn't address whether DOT will adopt impairment-based testing methods, such as saliva tests or performance assessments, which some states have explored for workplace enforcement. Colorado and Montana have enacted laws protecting off-duty marijuana use for non-safety-sensitive workers, but those statutes explicitly exempt DOT-regulated employees.

Workers in states with employment-protection laws should note: federal transportation safety regulations preempt state labor protections for DOT-covered jobs.

Flight Attendants and Pilots Face Strictest Scrutiny

FAA regulations prohibit pilots and flight attendants from performing safety-sensitive duties within 8 hours of cannabis use, regardless of impairment, and ban use entirely for those holding medical certificates. The FAA's zero-tolerance policy extends beyond THC to include CBD products, which the agency warned in 2020 could contain unlabeled THC and jeopardize medical certification.

Flight attendants represented by AFA-CWA are subject to random drug testing under 14 CFR Part 121, with annual testing rates set at 25% of the covered workforce. A positive test triggers removal from duty. It also requires mandatory evaluation by a Substance Abuse Professional and a return-to-duty test before reinstatement.

The union's decision to distribute DOT's guidance through its EAP suggests it's focusing on harm reduction and member education rather than challenging the federal framework.

Commercial Drivers Still Barred Despite State Reforms

FMCSA maintains a zero-tolerance policy for commercial motor vehicle operators, with no distinction between on-duty and off-duty use. The agency's Drug and Alcohol Clearinghouse, launched in 2020, tracks all CDL holders who test positive, refuse testing, or complete return-to-duty protocols. As of March 2026, the clearinghouse listed over 175,000 drivers with unresolved violations, the majority involving marijuana.

State-level efforts to protect off-duty cannabis use haven't changed FMCSA policy. New York's 2021 legalization law, for example, prohibits employment discrimination based on off-duty marijuana use but explicitly exempts DOT-regulated workers. Similar carve-outs appear in legalization statutes in New Jersey, Connecticut, and Illinois.

What to Watch: Rescheduling and Workplace Policy Lag

DOT's guidance arrives as the DEA considers rescheduling marijuana from Schedule I to Schedule III, a move that wouldn't automatically change workplace drug-testing rules. Even under Schedule III, cannabis would remain a controlled substance, and DOT has broad authority under the Omnibus Transportation Employee Testing Act of 1991 to prohibit its use by safety-sensitive workers.

Labor advocates have called for impairment-based standards rather than metabolite testing. DOT hasn't signaled any shift in policy. The agency's May 27 clarification suggests it's doubling down on the current framework rather than exploring alternatives.

For full background on this story, see the CannIntel topic hub on DOT marijuana employment rules.

The Takeaway for Transportation Workers

State legalization doesn't change federal rules. Safety-sensitive workers under DOT jurisdiction face the same testing protocols and consequences whether they're in California or Kansas. Until Congress amends the Omnibus Transportation Employee Testing Act or DOT adopts impairment-based standards, off-duty cannabis use remains a disqualifying event. Enforcement won't vary.