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In a recent Q&A published on May 26, the Department of Transportation (DOT) issued a series of clarifications regarding the role of Medical Review Officers (MRO), the discussed impact of the federal marijuana rescheduling discussion, and what exceptions may exist for a positive marijuana drug test.
Here is what safety-sensitive employers need to know about the DOT’s comments.
The May 2026 DOT clarification answered a specific MRO medical marijuana question: whether a marijuana-positive laboratory result can be verified as negative when the employee claims the result came from a state-licensed marijuana product.
In short, their answer was no: there is currently no situation in which an MRO can verify a laboratory-confirmed marijuana positive as negative based on state-licensed marijuana use. An MRO must verify a confirmed positive test unless the employee presents a legitimate medical explanation for the positive result. State-licensed marijuana products do not meet that standard, even when the employee has state documentation.
That distinction matters because certain state laws may allow medical marijuana access but DOT regulations control the federal verification process for covered safety-sensitive employees.
The DOT defines a legitimate medical explanation as the use of a legally prescribed controlled substance that complies with federal prescription requirements. In these instances, the MRO must conduct a medical interview, review the applicant’s relevant medical history, and take reasonable steps to verify prescription records when the employee claims a prescription caused the positive result.
DOT’s Q&A specifically identifies state-issued medical marijuana cards, physician recommendations or certifications, and dispensary records or receipts as documents that do not satisfy Part 40’s legitimate medical explanation requirement.
In plain English, while a card may explain why the employee used marijuana, it does not allow the MRO to verify a DOT marijuana test positive result as negative.
This is why employers should avoid messaging that suggests “medical marijuana documentation” changes DOT drug-testing outcomes. It does not, under this DOT medical marijuana guidance.
The rescheduling conversation has created confusion because DOJ and DEA issued actions placing certain FDA-approved marijuana products and state-licensed medical marijuana products in Schedule III under the Controlled Substances Act.
In this Q&A, the DOT addressed that confusion directly: even after rescheduling, state-dispensed marijuana does not become an FDA-approved drug for Part 40 verification purposes.
The marijuana rescheduling DOT guidance is not a pass-through rule for MROs, and a state-licensed marijuana product is still not the same as a federally authorized prescription medication that can support a legitimate medical explanation.
Employers should review their safety-sensitive marijuana policy language to make sure it separates federal DOT-regulated testing from non-DOT workplace drug policies. The policy should clearly explain that state marijuana authorization cannot and will not change the MRO’s decision for DOT-covered roles.
This review is especially useful for employers with operations in multiple states, where medical marijuana DOT drug test questions may arise more often because state programs differ.
Employee communication should be direct and neutral: state marijuana documentation does not allow an MRO to change a confirmed positive marijuana result to negative under DOT Part 40.
Employees should also understand that DOT’s position applies to safety-sensitive functions, not every workplace role in every setting.
Employers should consider reinforcing these messages during onboarding, random testing reminders, reasonable suspicion training, and policy acknowledgments.
HR, safety, drug employer representatives, and vendor-facing teams should use the same language when an employee presents a medical marijuana card after a positive marijuana result. Mixed messages create avoidable confusion, especially when one team speaks in state-law terms and another team is applying DOT Part 40.
Employers should document any verified positive drug test result, employee communication, the applicable policy language, and any internal escalation to HR, safety, legal, or compliance leadership. If the employee raises a state marijuana issue, the employer should consider documenting that the issue was handled as a DOT Part 40 verification matter, not as a general federal vs. state marijuana drug testing debate.
DOT’s May 2026 clarification resolves a practical question that employers, DERs, MROs, and safety-sensitive employees continue to face: a medical marijuana claim under state law does not turn a confirmed positive marijuana result into a negative DOT result. Employers in safety-sensitive industries should review their policy language, align HR and safety communications, and make sure employee-facing materials explain that DOT Part 40 controls this specific testing decision.
No. DOT’s May 2026 Q&A says an MRO cannot verify a laboratory-confirmed marijuana positive as negative based on a state-issued medical marijuana card or similar state documentation.
A legitimate medical explanation generally requires a legally prescribed controlled substance that complies with federal prescription requirements. DOT states that state marijuana program documentation does not meet that Part 40 standard.
No change to this MRO verification rule is created by the rescheduling discussion. DOT’s May 2026 Q&A says state-dispensed marijuana still does not qualify as an FDA-approved prescribed medication for this Part 40 purpose.
No. DOT specifically lists physician recommendations and certifications among the documents that do not satisfy the legitimate medical explanation requirement for a marijuana-positive DOT result.
DOT’s answer is tied to federal prescription status. A state-licensed marijuana product is not treated as an FDA-approved prescribed drug for Part 40 verification, even when state law permits medical use.
DOT states that marijuana use under state marijuana programs is not compatible with safety-sensitive functions. Employees covered by DOT testing should not assume state authorization changes federal transportation drug-testing consequences.
At DISA Global Solutions, we understand the complexity of managing DOT compliance across the transportation industry. DISA supports safety-sensitive employers with DOT drug and alcohol testing program administration, MRO review coordination, random testing management, return-to-duty support, and other Part 40 requirements.
Our broader transportation compliance solutions also help employers manage modal-specific obligations across all six DOT agencies: FMCSA, FRA, FAA, FTA, PHMSA, and USCG. Together, these services support compliant program administration for trucking, rail, aviation, transit, pipeline, and maritime operations.
DISA can also support policy reviews, program audits, employee communication, and reporting workflows. With DISA’s comprehensive support, employers can navigate DOT drug-testing requirements, reduce confusion around marijuana guidance, and maintain clearer compliance processes across safety-sensitive operations.
DISA Global Solutions aims to provide accurate and informative content for educational purposes only and does not constitute legal advice. The reader retains full responsibility for the use of the information contained herein. Always consult with a professional or legal expert.
May 19, 2026
7
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