Marijuana, a Schedule 1 drug under the federal Controlled Substances Act (CSA), is the most commonly detected illicit drug in employment drug testing. According to Quest Diagnostics, in 2018, approximately 3% of urine-based workplace drug screenings tested positive for marijuana. Notwithstanding marijuana’s illegality under federal law, 33 states and the District of Columbia have legalized marijuana for recreational or medicinal use. And it is big business. The Colorado Department of Revenue recently revealed that its tax, license and fee revenue from marijuana has reached $1.02 billion. Legal marijuana appears here to stay in the United States.
Many state and local jurisdictions have enacted anti-discrimination laws concerning marijuana use. Generally, such laws prohibit employers from taking adverse action against an employee who uses marijuana in conformance with the local jurisdiction’s marijuana laws, so long as the employee does not consume cannabis at work and is not impaired while on the job. But because of the way the human body metabolizes cannabis—traces of marijuana can persist in a person’s body for as long as 30 days after it was last used—it is difficult for employers to determine, much less prove, whether an employee is actually impaired by marijuana on company time, as opposed to outside of work on personal time. That difficulty creates liability for employers who act on a positive drug test. Even if an employee is impaired at work, proving so can be challenging, and employers therefore need to proceed carefully when executing their drug policies.
In the first wave of employment cases concerning marijuana use since marijuana legalization began, the courts tended to side with employers. In California, employers can terminate workers who test positive for cannabis so long as the employer complies with its “drug-free” policy. In Colorado, the Colorado Supreme Court in 2015 unanimously affirmed a lower court decision that a company was within its rights to terminate an employee for using marijuana. According to the Colorado Supreme Court, the state’s medical marijuana law did not preempt the company’s “zero tolerance” policy.