Media Center

News Publications Articles Videos
Drug Testing in the Age of Medical Marijuana: Proceed with Caution
August 29, 2019
Parsons Behle & Latimer Legal Briefings

In most states, the days are gone when all but a few private employers may safely maintain a zero-tolerance drug policy and automatically discipline or terminate employees who test positive for cannabis. As of the date of this article (August 2019), at least 33 states and the District of Columbia have legalized the use of medical cannabis and all but four of the remaining states have legalized the use of low THC CBD oil. Idaho is one of these four states.

Statutory requirements and protections for employers vary on a wide spectrum among the states that have legalized medical cannabis or CBD oil. On the conservative end of this spectrum, Georgia and Ohio’s medical cannabis statutes expressly provide that nothing in those statutes either requires employers to accommodate medical cannabis use or prohibits employers from terminating employees who test positive for cannabis. On the liberal end of the spectrum, New York’s statute affirmatively requires employers to accommodate medical cannabis use by expressly providing that a certified medical cannabis patient “shall be deemed to be having a ‘disability’ under [New York’s rights law.]” Other states fall somewhere between the two ends of this spectrum. Some states have statutes that expressly prohibit employment discrimination based on medical cannabis use but provide varying exceptions (such as Arizona, New Mexico, and Nevada). Some states have statutes that provide that the statutes should not be read to impose specified obligations on employers (such as Michigan and New Jersey), and some states have statutes that are entirely silent on private employer rights and obligations (such as California, Colorado and Utah).

To further complicate this issue, courts interpreting medical cannabis statutes in the employment context have reached widely varying results depending on the specific language of the statute at issue and the basis of the legal challenge. Early decisions largely favored employers, with many concluding that state medical cannabis statutes did not impose accommodation obligations, or discrimination restrictions, on employers based on the federal Controlled Substances Act (CSA), which makes the use or possession of cannabis illegal under federal law. As more courts weigh in on the subject, however, an increasing number are rejecting the CSA as a limitation on employer rights and obligations under state medical cannabis laws.

Federal law provides some limited protection. Employers of persons in certain occupations, such as truck drivers and airline pilots, may continue to test for and discipline employees who test positive for cannabis. And decisions under the Americans with Disabilities Act have consistently determined that there is no federal law obligation to accommodate users of medical cannabis. However, employers in states with a medical cannabis statute may not safely assume they do not have to accommodate medical marijuana use or that they may take adverse action based on such use solely because cannabis is illegal under federal law.

Employers face additional problems when testing for marijuana as generally, there are no accepted benchmarks for determining impairment when using cannabis. This is due to the diverse impacts of cannabis consumption on the human body and the complexity of the plant’s chemical makeup. Further, most current drug tests measure the presence of the metabolite THC-COOH rather than the psychoactive component of cannabis THC (delta-9-tetrahydrocannabinol). However, THC-COOH may not reach the level needed to cause a positive response at the screening cutoff mandated for federal workplace urine drug testing until hours after impairment (however defined) has ceased and, once reached, may trigger a positive result for hours or weeks. Thus, a positive urine test for THC-COOH cannot be used to infer either intoxication or marijuana use within any forensically useful timeframe. Although a drug test may reveal the presence of cannabis, an employer has no ability to determine whether an employee was impaired at the time of the test or whether he or she consumed cannabis over the weekend or while off-duty.

Marijuana testing is a complex area. Employers operating in states with medical cannabis statutes should examine their substance use and drug testing policies with attention to the specific statutes of those states and any court decisions applying those statutes.

Mark A. Wagner is an attorney in the employment and labor practice group at Parsons Behle & Latimer. To reach Mark about this or other employment-related matters, call (801) 532-1234 or send and email to


Practice Areas