Employers Are Being Sued For Not Proving THC Impairment

Jul 23

Two men smoking a THC vape pen at an industrial site

THC Testing vs. Impairment: Legal Risks and Recent Employment Lawsuits

As cannabis legalization spreads, employers face growing conflicts between drug testing and fair treatment of employees. THC drug tests detect long-lived metabolites, not current impairment. Federally funded research confirms that “THC levels in biofluids…were not reliable indicators of marijuana intoxication” (nij.ojp.gov). Likewise, a recent American Bar Association report notes that the presence of THC in one’s system “has not been shown to be a predictable measure of cannabis impairment” (americanbar.org).

In practice, positive THC tests can just as easily reflect safe and responsible off-duty use as irresponsible and dangerous workplace cannabis use. At the same time, states with legal cannabis are increasingly explicitly protecting lawful off-duty cannabis use. For example, Arizona’s medical-marijuana law makes it illegal to fire an employee solely for a positive THC metabolite test unless the employee actually “used, possessed or was impaired” at work (cannabisnow.com).

Courts are increasingly finding that punishing medical or legal cannabis users on the basis of a positive test (without proof of on-the-job impairment) violates anti‐discrimination laws or lawful-off-duty-protection statutes. As an example, in one recent New York case, a city worker who was fired for testing positive on his prescribed cannabis won a $191K jury award plus $149K in fees and reinstatement (timesunion.com), underscoring the high stakes for employers who rely on chemical drug testing alone.

Why Employers Are Losing Marijuana Cases

Employers are losing these cases for two main reasons.

THC and THC metabolite tests are useless in determining active impairment. Simply put, THC and its metabolites linger in the body long after intoxication has passed, often for days for THC and weeks for its metabolites (nij.ojp.govtobii.com). Testing technologies such as oral fluid, blood, urine screens or hair analysis can only tell that a person used cannabis at some prior point; they cannot pinpoint when or whether the person was impaired at work. Law enforcement testing methods (e.g. DRE exams) are human-conducted and therefore subjective. By contrast, modern impairment detection technology tools are now emerging to identify real-time effects of drugs rather than past use.
State laws now often forbid punishing lawful off-duty use absent proof of on-duty impairment. At least nine states (including AZ, CA, CT, DE, NJ, NY, RI, etc.) have explicit non-discrimination or accommodation clauses for medical and/or recreational cannabis users (ncci.com). These laws generally limit the types of testing that can be used to take adverse action against an employee, or require evidence of actual intoxication or on-site use before discipline is allowed. For example, Arizona’s Medical Marijuana Act (AMMA) makes it illegal to fire someone just for a positive THC test unless the employee “used, possessed or was impaired by marijuana on the premises during or within eight hours after the employee’s working time” (cannabisnow.com). In practical terms, courts are rejecting “positive drug test equals impairment” logic - something that is utterly unsupported by science. As an example, one court observed that an employer “cannot just rely on a positive drug test to meet its burden” of showing on-the-job impairment (fennemorelaw.com).

In sum, firing or disciplining employees for positive chemical drug tests alone is increasingly treated as unlawful discrimination or unjust dismissal.

Key Legal Cases

Attorneys and juries are being challenged with the reality of legal cannabis and are quickly reacting. The science is incredibly clear - chemical tests of any kind cannot detect cannabis impairment. Employers must therefore respond in kind. It’s not just a financial imperative, it’s a cultural one. After all, telling employees in a state where cannabis is legal that they can’t use the substance is like telling them that they can’t have a beer or glass of wine with their dinner. That wouldn’t go over well, and neither does arbitrary limitations for cannabis use on personal time.

The following court cases are just a few recent examples of cases in which employees have challenged dismissals without proof of marijuana impairment:

Barbuto v. Advantage Sales & Marketing, LLC (Massachusetts, 2017) – In this landmark case a Massachusetts worker with a lawful medical marijuana prescription was terminated after a pre-employment THC test. The Massachusetts Supreme Judicial Court ruled she could sue her employer for disability discrimination. The Court held that a patient “terminated…because she tested positive for marijuana as a result of her lawful medical use” may seek a remedy under the state disability law (law.justia.com.) This case was later settled in 2018 (ncci.com), but it established that medical cannabis users are entitled to protection and reasonable accommodation under Massachusetts law, absent evidence of on-duty impairment.
Noffsinger v. SSC Niantic Operating Co. (Connecticut, 2018) – A Connecticut nursing home rescinded a job offer after a prospective hire disclosed she was a registered medical cannabis patient and then tested positive for THC. A federal court granted summary judgment to the candidate, holding that Connecticut’s Palliative Use of Marijuana Act prohibits refusing to hire someone solely due to medical marijuana use (jacksonlewis.com). The court flatly stated that “refusing to hire a medical marijuana user because she tested positive on a pre-employment drug test violates Connecticut law” (jacksonlewis.com). In other words, the employer’s reliance on federal drug policy did not override the state’s law protecting off-duty medical cannabis patients.
Fisher v. Airgas USA, LLC (6th Circuit Court, 2024) – Murray Fisher, a cancer patient, was fired after testing positive for THC metabolites, in this case, from a legal hemp-derived CBD tincture used for pain relief. The Sixth Circuit reversed summary judgment for the employer, allowing Fisher’s disability-discrimination claim to proceed. The court emphasized that Airgas never reasonably investigated Fisher’s explanation that hemp (not marijuana) caused the positive test. Without any meaningful inquiry into the source of THC, the employer could not have an “honest belief” of impairment. The appeals court therefore “reverse[d]” the grant of summary judgment and remanded the case (law.justia.com). This critical ruling signals that employers cannot rely upon a positive test result—especially when the substance used (e.g. hemp extract) was legally permissible and potentially caused the result.
Whitmire v. Wal-Mart Stores, Inc. (Arizona, 2019) – In Arizona, a Walmart employee with a state medical-marijuana card was fired after a workplace injury led to a drug test that returned positive. The federal judge ruled in her favor on summary judgment for her discrimination claim under the Arizona Medical Marijuana Act (AMMA). The court first recognized that Arizona’s law allows a private cause of action for medical cannabis users (fennemorelaw.com). It further held that Wal-Mart could not simply rely on the test result to prove impairment. Under Arizona law, firing was lawful only if she was “impaired” on the job. In Whitmire’s case, the positive chemical test alone did not establish she was using or impaired at work, so her termination violated the AMMA (cannabisnow.com). Wal-Mart’s “honest belief” defense failed because the employer offered no evidence of actual work impairment. This case is one of the first in the U.S. to enforce that distinction and is often cited as a blueprint: off-duty use plus no proven on-site impairment means no discipline.
Palmiter v. Commonwealth Health Systems, Inc. (Pennsylvania, 2021) – A Pennsylvania hospital dismissed a woman after she tested positive for THC; she had a state medical-marijuana card. The state Superior Court held that Pennsylvania’s Medical Marijuana Act contains an implied right to sue and therefore she could bring a discrimination claim. The court explicitly held that the MMA “allows an employee to sue his employer for taking adverse action based on his status as a certified medical marijuana user” (law.justia.com). In short, Palmiter was permitted to pursue her lawsuit under state law, even though she was never ultimately reinstated or awarded damages in the published opinion. The key takeaway is that Pennsylvania law prohibits firing or refusing to hire someone solely for off-duty medical cannabis use, absent proof of on-the-job drug use.
Wilson v. Transparent Glazing Systems (BC Human Rights Tribunal 2008) – Canadian example: A British Columbia glazier with a prescription for medical cannabis was fired after a supervisor suspected impairment and she tested positive. The BC Tribunal agreed she had been discriminated against on the basis of disability (chronic pain). It directed the employer to cease such practices and awarded Wilson a modest sum in damages (cannabisatwork.com). The tribunal expressly noted that an off-duty prescription user should not be treated like an intoxicated employee, echoing the alcohol analogy. Although the case upheld the firing on other grounds, its discrimination ruling and damages award underscore that even in Canada, blanket firing for THC can violate human rights protections (cannabisatwork.com).
Enever v. Barloworld Equipment SA (South Africa LAC 2024) – International context: In 2024 South Africa’s Labour Appeal Court unanimously held that an office worker’s dismissal for testing positive for THC (after off-duty private cannabis use) was “automatically unfair” discrimination. The employee was awarded two years’ pay. The court bluntly recognized that a THC blood test does not measure impairment: unlike alcohol, cannabis stays in the body long after any intoxication. It faulted the employer’s zero-tolerance policy, finding it forced employees to choose between work and lawful home use (lexology.com). This case parallels U.S. reasoning: a mere positive THC result, without evidence of on-the-job use or impairment, cannot justify termination (lexology.com).

Detecting Impairment (Not Just THC or THC Metabolites)

Recognizing these legal risks, employers are exploring new ways to detect actual impairment rather than old-fashioned chemical drug-panel tests. No standardized “THC breathalyzer” or simple biomarker exists for real-time cannabis impairment. But several innovative technologies are emerging:

Eye-movement and cognitive tests (e.g. Gaize): New systems use automated versions of law-enforcement sobriety exams. For instance, Gaize employs a VR headset and eye-tracking to run the same ocular tests used by certified drug-recognition experts (tobii.com). By analyzing involuntary eye movements and pupil response, Gaize claims to identify impairment patterns in a few minutes. Tobii’s report explains that Gaize’s platform is “based on the Drug Recognition Expert eye tests and decades of… research in detecting drug-impaired drivers” (tobii.com). These apps have the advantage of directly measuring functional impairment (e.g. slowed reaction, visual effects), rather than inferring it from metabolites. Cognitive screening apps are another example: one recent summary notes that “tech companies are developing cognitive screening tools that detect impairment in about 90 seconds, regardless of the cause…through workers’ smartphones” (aware360.com). Such tests, like baseline neurocognitive apps or digital field-sobriety games, evaluate focus, memory or coordination to flag impairment on the spot.
App-based tools: Some mobile apps, like Predictive Safety’s Alert Meter, are able to detect impaired employees as well. These tools work by having users play short games and measuring performance against a baseline. A poor score on the game may mean that someone is experiencing impairment.
Reasonable Suspicion and Field Sobriety Tests: Traditional human-conducted reasonable suspicion incidents and field sobriety tests remain useful. These are inherently subjective, so should always be paired with objective data. Objective impairment detection technologies (like Gaize) are logical additions to these processes.

Leading companies now integrate multiple tools and techniques to ensure accuracy and employee fairness. As an example, Gaize customers use a combination of Gaize’s ocular testing technology and chemical drug tests to create a complete picture of an incident.

Conclusion

Bottom line: employers that rely solely on traditional chemical drug tests face growing legal and financial peril. Courts are consistently rejecting the notion that a positive chemical drug test equals impairment. The cited cases above show multiple six-figure jury awards and judgments (and mandated reinstatements) when employers punished employees for lawful cannabis use absent on-site impairment (timesunion.com, lexology.com). These verdicts highlight not just the moral of fairness, but hard dollars at stake – tens or hundreds of thousands per case. In contrast, investing in real‐time impairment detection promises better safety and ROI. Safety agencies report that regular drug testing can significantly reduce workplace accidents (intelligentfingerprinting.com). By accurately identifying only those actually impaired on the job, companies can prevent accidents without wrongfully penalizing off-duty behavior. Modern tools – from cognitive phone-screening apps to eye-tracking headsets to cannabis breathalyzers – aim to align policy with function, enhancing workplace safety while minimizing legal risk. In the emerging legal landscape, such impairment-focused technologies can pay for themselves by avoiding costly litigation and insurance claims that outdated drug-panel testing invites (timesunion.com, intelligentfingerprinting.com).

Sources: Recent court decisions and analyses from Massachusetts, Connecticut, Ohio, Arizona, Pennsylvania, and other jurisdictions (law.justia.com jacksonlewis.com, law.justia.com, cannabisnow.com, law.justia.com, lexology.com) (also see citations). Regulatory and scientific reports on THC impairment (nij.ojp.gov, americanbar.org, tobii.com). Coverage of new impairment-testing technologies (tobii.com, ndwa.org, aware360.com). Industry ROI data and legal commentary on drug testing (intelligentfingerprinting.com, timesunion.com).