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Missouri Marijuana Legalization and Employers


A 2022 amendment to the Missouri constitution changes how employers can treat users of medical marijuana. While the new law does forbid some employment actions, it’s not a free pass for workers to use cannabis whenever they want.

Here’s a rundown of what businesses and managers need to know about medical marijuana use in Missouri.

Disclaimer: PEG Staffing is not a legal firm. The information in this article is for information only and should not be considered a substitute for legal advice.


The Missouri legislature legalized marijuana for medical purposes in 2018. While that law made it legal for qualifying patients to use marijuana, it said nothing about employment. Businesses were free to continue practicing whatever cannabis-related policies they had in place before the change, including making a cannabis-positive drug test a firable offense.

In late 2022, the legislature passed another amendment. Under the new law, if a person has a medical marijuana card, employers cannot discriminate or take adverse action against them based on their marijuana use – as long as they follow the rules of the law.


There are a few provisions of the new law that are especially important for employers to understand.

  • You can’t discipline an employee or refuse to hire a job candidate based on their use of marijuana outside of work as long as they hold a valid medical marijuana card.
  • You can’t discriminate against an employee or job candidate based on a cannabis-positive drug test if they take medical marijuana.
  • People with misdemeanor (and some felony) marijuana-related convictions can now have them expunged from their criminal record. After expungement, the person is not required to acknowledge the conviction. This is an important consideration for employers who uncover drug convictions in background checks.

You may have heard the 2022 law also legalized the recreational use of marijuana in Missouri. That’s true, but the law offers no job protections to recreational users. The only protected users employers need to worry about are people who hold a valid medical marijuana card.


There are a couple of exceptions to the job protections medical marijuana users receive. Medical marijuana is still prohibited under federal law. Businesses that are federally funded or regulated may discriminate against marijuana users if an employee’s marijuana use could cause them to lose federal benefits.

“For example, a trucking company has to operate under federal Department of Transportation regulations,” explained Drew Lammert, a partner at St. Louis-based law firm McCarthy, Leonard & Kaemmerer. “So the protections don’t apply to them because they could lose a monetary or license-related benefit under federal law.”

The anti-discrimination provision also doesn’t apply to safety-sensitive positions. And you can still refuse employment to medical marijuana users if marijuana use legitimately impacts the user’s ability to do the job, if it affects the safety of others, or if it conflicts with bona fide job qualifications.


Even though marijuana use is now legal in Missouri, it is not a protected activity. As an employer, you still have the right to forbid employees from using marijuana at work, from bringing marijuana onto your business property, and from coming to work while under the influence of marijuana.

“The new law restricts employers from taking adverse action based on off-duty marijuana use by qualifying medical patients,” Lammert said. “Whether the use is recreational or medical, there are no protections for someone consuming, using, possessing, or under the influence while at work.”

You can view recreational marijuana much like alcohol, Lammert said. Employees can legally possess and consume it on their own time, but it’s a given that they shouldn’t be bringing it to work.

And while the law says employers can’t discriminate against users of medical marijuana, it specifies that patients are only protected for use that takes place off-site during non-working hours. Even if your employee has a medical marijuana card, you can prohibit them from bringing cannabis to work or coming to work high.

“Missouri is an at-will state,” Lammert said. “If you even suspect someone is under the influence, you can terminate them.”


In addition to his legal career, Lammert is the CEO of Kind Goods, a company that cultivates, processes, and distributes cannabis products. He also sits on the board of the Missouri Cannabis Trade Association. As a lawyer and a business owner, he has some suggestions for Missouri employers to stay on the right side of the new law.


Now is a great time to review your hiring and onboarding process – especially if they include background checks or drug screenings.

Since people can now ask to have certain marijuana-related convictions expunged from their records, you may want to give those convictions less weight when they come up in a background check.

After all, there may be past convictions that don’t show up because they’ve already been expunged. A conviction that shows up today might be in the process of expungement and disappear from the record next week.

“As a business owner, I would just abandon background checks for marijuana-related offenses,” Lammert advised.

You may also want to take THC – the psychoactive component in cannabis – off the list of substances searched for in drug screenings. THC can be detectable in a person’s system up to 30 days after marijuana was last consumed, so a drug test is not a reliable way to tell if someone used the drug during working or personal hours.

Complicating matters even further, regular cannabis users – such as people who use marijuana to treat medical conditions – may develop a baseline level of THC. The substance metabolizes so slowly, these individuals may test positive for cannabis months after their last use.


Companies that administer post-accident drug testing should contact their workers’ compensation insurance carrier to find out how injury claims will be handled in light of the new law.

“All these protections can be out there, but whether your workers’ comp insurer covers the claim is a different ball of wax,” Lammert cautioned. “That insurance policy is a private contract between the employer and the insurer. So if they’re going to exclude a claim if marijuana usage was related to the injury, you’re going to want to know that now.”

A 2020 study from the University of Toronto found no correlation between marijuana use and workplace accident rates. But insurance companies are notoriously cautious.

With cannabis still illegal at the federal level, whether the courts will side with workers or insurers in such cases remains to be seen, Lammert said. As a business, you don’t want to be blindsided by an out-of-state insurer denying a workers’ comp claim because the employee tested positive for marijuana.


Many small businesses don’t have official marijuana policies on the books. When marijuana use was against the law, they could rely on blanket policies prohibiting illegal activities.

If you don’t have policies regulating the possession and use of marijuana, now is the time to document some. Here are a few things to keep in mind:

      • You can’t prohibit employees from using marijuana on their own time unless they fall under one of the exceptions we covered earlier.
      • You can, however, prohibit employees from using marijuana products on the job. You can also prohibit the possession of marijuana on company property and forbid workers from performing their jobs while under the influence.
      • A series of studies between 2014 and 2021 found it’s unclear whether drivers who use marijuana are more likely to crash. However, overall crash rates jumped in several states after legislatures legalized cannabis. With that in mind, you may want to consider implementing a policy that prohibits driving company vehicles or driving for work purposes while under the influence.
      • Whatever policies you revise or implement, be sure you revise employee handbooks to reflect the change. Notify employees of the new policies and make the new rules easy to find and reference.


Be sure supervisors and human resources staff are prepared to enforce your new policies. Train them on the new rules and on how to handle marijuana-related incidents.

Because THC metabolizes so slowly, remaining in a person’s system days or weeks after the effects of the drug have worn off, you can’t rely on drug testing to tell if an employee is impaired. Supervisors should be trained in recognizing the symptoms of marijuana impairment and in what to do next.

“I think the first thing to do is ask the employee if they’re under the influence,” Lammert said. “If they answer yes, there’s no need to ask further. If they answer no, you need to determine what evidence you have that they are. It comes down to the evidence, because there’s no scientific way to prove it.”


Over the next few years, businesses and employees will test the definitions and boundaries of the new law in the courts. Each claim will define what employers can and can’t do a little more clearly.

All a responsible business can do is make its  best effort to comply with the law, respect its  employees’ rights, and protect itself  from liability. As the rules evolve, be prepared to evolve your policies along with them.

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