No Safe Harbor: DOT Rejects State-Licensed Marijuana as Basis to Overturn Positive Drug Test Results

Seyfarth Synopsis: In late May 2026, the Office of Drug and Alcohol Policy and Compliance and the Office of the General Counsel of the U.S. Department of Transportation (DOT) issued a new Question and Answer (Q&A) addressing how its drug testing regulations apply considering the recent rescheduling of certain marijuana products under federal law. The Q&A provides important clarification for employers with safety-sensitive employees subject to DOT regulations—and reinforces that, despite shifting federal policy, DOT drug testing requirements remain unchanged in key respects.

Key Takeaway: Positive Marijuana Test Results Cannot Be “Explained Away” by State-Legal Use

The central question addressed by the DOT is whether a Medical Review Officer (MRO) may verify a laboratory-confirmed positive marijuana test result as “negative” if the employee claims the result was caused by use of a state-legal marijuana product.

The DOT’s answer is unequivocal: No.

Specifically, the DOT explains:

• There is no circumstance in which an MRO may verify a marijuana-positive test result as negative based on an individual’s use of a state-licensed marijuana product.
• Even after rescheduling, marijuana obtained through state medical programs is not an FDA-approved drug.
• A valid medical explanation under DOT rules requires a legally prescribed controlled substance that complies with federal law.
• Documentation such as medical marijuana cards, physician recommendations, or dispensary receipts does not satisfy DOT requirements.

The DOT further reiterates that marijuana use—even if allowed under state law—is not compatible with safety-sensitive duties.

Reinforcing a Key Theme From Rescheduling

This guidance aligns closely with a point we emphasized in our prior alert: rescheduling does not equate to full federal legalization or alignment with traditional prescription drug frameworks. As discussed previously:

• The April 2026 order is limited to specific categories, including FDA-approved marijuana-derived products and marijuana dispensed under state medical programs.
• Most marijuana remains federally prohibited, and even Schedule III marijuana is not automatically treated like conventional prescription medication.

The DOT Q&A underscores that distinction in a particularly concrete way. Even where marijuana has been moved to Schedule III, it still cannot be treated as a “legitimate medical explanation” unless it meets federal prescription standards—which, at present, state-dispensed marijuana does not.

In other words, while rescheduling may affect other areas of employment law (including accommodation and off-duty conduct analysis), it does not alter DOT drug testing outcomes.

Practical Implications for DOT-Regulated Employers

The new Q&A provides helpful clarity for employers navigating uncertainty following the rescheduling announcement:

• No Change to MRO Verification Standards. MROs must continue to verify positive marijuana drug test results as positive unless there is a qualifying federally lawful prescription—which does not include state-authorized marijuana.
• State-Legal Medical Marijuana Remains Insufficient. Employees cannot rely on medical marijuana cards; physician certifications or recommendations, or state program participation to avoid a verified positive test result under DOT regulations.
• Zero Tolerance for Safety-Sensitive Roles Remains Intact. The DOT reiterates that marijuana use is incompatible with safety-sensitive functions, reinforcing employers’ obligation to enforce strict compliance with the regulations and their policies.
• Continued Divergence Between DOT Rules and Broader Employment Law Trends. As we noted in our earlier alert, employers may face increasing pressure under state medical marijuana laws, disability accommodation frameworks, and off-duty conduct protections. However, the DOT Q&A confirms that these evolving considerations do not apply in the same way to federally regulated safety-sensitive positions.

What Employers Should Do Now

Considering the DOT’s guidance and the broader rescheduling landscape, employers should:

• Maintain existing DOT drug testing programs without modification
• Train HR and compliance teams on the continued strict treatment of marijuana positive test result under DOT rules
• Avoid relying on state-law concepts (such as “lawful use”) when making determinations under DOT regulations
• Clearly communicate expectations to  employees in safety-sensitive roles under DOT-agency regulations, particularly given widespread confusion following rescheduling
• Coordinate multi-jurisdictional compliance strategies, recognizing the growing divergence between DOT requirements and non-DOT employment law

Looking Ahead

The DOT’s Q&A is an early—but significant—signal of how it will interpret and apply marijuana rescheduling in its regulatory frameworks. While the April 2026 rescheduling order introduced a more nuanced federal approach to marijuana, the DOT has made clear that, for drug testing purposes, the practical impact is minimal.

As a result, employers should continue to operate under a dual framework:

• Evolving obligations and risks under state law and non-DOT federal law
• Strict, unchanged requirements for DOT-regulated safety-sensitive roles

We will continue to monitor developments from the DOT, the DEA, and other agencies as the regulatory landscape evolves.