In safety-sensitive roles, how employers respond to suspected marijuana impairment matters both legally and operationally.
How should we respond when an employee appears impaired at work but still passes a drug test? In high-risk operations, a negative result doesn’t automatically eliminate safety concerns.
Why a Negative Test Does Not End the Inquiry
A drug test answers a narrow question: whether a substance or metabolite was detected above a threshold.
It does not determine:
- Current impairment or fitness for duty
- Immediate safety risk
- Cognitive or motor performance
- Compliance with all state employment protections
With marijuana, this gap is critical. THC detection does not reliably measure real-time impairment, and a negative test does not guarantee safe job performance.
Why Someone May Appear Impaired but Pass a Marijuana Test
This scenario is not uncommon. Possible explanations include:
- Timing gaps between use, impairment, and detection
- Limitations of urine and oral fluid testing
- Residual cognitive or motor effects
- Medical conditions, fatigue, or prescription medications
- Behavior that violates fitness-for-duty standards without triggering a positive test
This is why test results should inform decisions around fitness for duty rather than control them.
Best Practice? Focus on Fitness for Duty
Defensible programs in 2026 prioritize observable behavior and safety impact over assumptions about substance use.
Best practices include:
- Objective documentation of specific observations (speech, coordination, behavior)
- Supervisor training to support consistent reasonable suspicion decisions
- Immediate safety action, including temporary removal from duty when risk is present
- Policy-driven next steps aligned with job role and state law, not test results alone
This approach aligns with how regulators and courts increasingly evaluate impairment-related cases.
What Should Employers Avoid?
Even in safety-sensitive roles, employers should avoid:
- Assuming a negative test means the employee was fit for duty
- Disciplining solely based on suspected marijuana use
- Making medical or impairment diagnoses
- Applying inconsistent standards across roles or locations
- Treating marijuana exactly like alcohol without policy support
Consistency and documentation matter more than certainty.
Key Takeaway for 2026
The most important question is no longer, “Did they test positive?”
It is, “Were they fit to safely perform their job at that time?”
Employers that anchor policies in impairment risk, role-based standards, and documented observations are better positioned to protect safety and reduce exposure as marijuana laws continue to evolve.
Join Tomorrow’s Webinar
Want to learn more about how marijuana policy changes may impact workplace drug testing programs in 2026? Join Nurse Holly on February 5 at 1 PM for the webinar Marijuana & Drug Testing in 2026: What Will Protect You — and What Will Sink You, featuring Labor & Employment Attorney Tae Phillips (Ogletree Deakins), Dr. Scott Cherry, Chief Medical Officer, and Dara Wheeler, CMO & EVP of Product.