Marijuana Use in the Workplace: 7 Things Employers Need to Know

For industries that have a zero-tolerance policy, marijuana impairment isn't the issue — use is. Marijuana use in the workplace isn't going to disappear anytime soon, either. Thirty states have legalized medical marijuana and nine of these have also legalized the recreational use of marijuana. Other states are considering legalization, while Canada is set to legalize marijuana in October 2018. A recent Pew Research study revealed that 61 percent of Americans now support the legalization of marijuana – double the percentage who supported legalization in 2000. This raises complex issues for employees around both testing and tolerance.

Here we answer some of key questions around marijuana in the workplace.

Are Medical Marijuana Users Protected by the ADA?

No, because marijuana – even medically prescribed marijuana – is still considered to be a Schedule 1 narcotic under federal law. Users are not protected by the American Disabilities Act (ADA), but they are protected against discrimination by some state laws.

Can I Ban Marijuana Use at My Work Site?

That depends. For Department of Transportation (DOT) governed employers the answer is simple: Yes. Marijuana use, either on the job or off, is prohibited for DOT-governed employees.  

Federal contractors also must abide by the Federal Drug-free Workplace Act or risk losing out on federal contracts. Employees in safety sensitive positions must not be impaired at work by any substance, whether it is illegal or legally prescribed.

For other employees the answer is less clear. In some states it is possible to ban marijuana use for workers whether they are on-duty or off. Even in most states that have legalized medical marijuana, it's often still possible for an employer to ban or restrict its use. But case law continues to evolve, and legal advice specific to your state and situation is your best protection.

What Does Current Case Law Say?

Although a recent California federal district court reaffirmed that an employer has the right to discipline employees — even when a physician has prescribed marijuana — other judgements have drifted in the opposite direction.

A 2017 case in Massachusetts ruled against an employer who fired an employee over the use of medical marijuana concluding that the employer should have tried to find ways to accommodate the employee. In 2017, a Rhode Island court ruled against an employer who had refused to hire a job applicant over the applicant's medical marijuana use, while a Connecticut court made a similar ruling against another employer.

What Are the Regulations Around Testing for Marijuana?

All DOT regulated employees are regularly tested for marijuana use. Detection of the drug alone is enough to warrant termination, suspension or other consequences.

Other employers can also choose to test for marijuana but should have implemented a clear policy that outlines both the testing procedures and consequences if an employee is found to be using the drug.

Outside DOT, the same rules surround medical marijuana testing that exist for other medically prescribed pharmaceuticals. This includes requirements for the Medical Review Officer to request information and assertions from the prescribing physician that the employee can still perform his or her job safely along with other reporting requirements.

What Do I Need to Know About Marijuana and Potential Safety Issues?

Marijuana use has been linked to a variety of risk factors in the workplace, including decreased cognitive abilities and daytime sleepiness. More worrisome for employers, numerous studies have also linked increases in workplace injury to marijuana use. One of these studies on a group of workers who had tested positive for marijuana use in a pre-employment drug test found that they had 55 percent more industrial accidents, 85 percent more injuries, and a 75 percent higher absentee rate than those who had tested negative.

The effects of marijuana can also last several days. Additional studies concluded that two days after smoking marijuana cigarettes, participants in another study remained impaired on arithmetic and recall tasks.

What is Marijuana Impairment?

Unfortunately, impairment is the issue for some industries, and there is no accurate way to tell if someone is currently impaired or if they simply used marijuana during personal time days ago.

Marijuana impairment is difficult to judge, particularly by assessing the amount consumed. Unlike alcohol, which has an easily identifiable alcohol content, the amounts of delta-9-tetrahydrocannabinol (THC) — the primary psychoactive substance in marijuana — can vary widely. In fact, the THC levels. for street marijuana have increased from 3 percent in the 1980s to 12 percent in 2012.

5 ng/mL of THC (detected via oral fluid testing) is the often-quoted level indicating impairment and is used by law enforcement in several states, but it is imprecise. In fact, while 5 ng/ML might confirm impairment, levels below that don't always translate to sobriety. A variety of factors, including the method of ingestion and patterns of use, can affect the impairment levels of users. Casual and chronic users vary widely in their tolerance for marijuana, and for levels ranging from 2 to 5 ng/ML, casual users are likely to be impaired while chronic users may be impaired.

Urinalysis can detect marijuana that has been in the system for several weeks, which doesn't necessarily equate to impairment. Blood testing is considered more accurate for tests related to impairment.

What Should Employers Do About Marijuana in the Workplace?

If your state has (or is) considered legalizing medical or recreational marijuana, here are some things you can do to mitigate potential concerns and risks in your workplace.

  • First, make a list of all safety sensitive and non-safety sensitive positions in your company. Having this list in place from the start makes it easier to apply and defend any restrictive policies.
  • Draft a company policy that clearly outlines testing, penalties, and any accommodations you are willing to offer for users of marijuana and medical marijuana.
  • Include policies regarding off-site use of marijuana and medical marijuana.
  • Create clear policies and procedures for supervisors advising them on identifying and acting on potential marijuana impairment in your employees.
  • Create an employee education program that includes the side effects of marijuana use and your company's policies regarding it. Offer the education program as part of your on-boarding and then review periodically with all staff.
  • Have your legal team review your policies and procedures for compliance with the federal and state regulations that apply to your specific business.

Your best protection is a clear company policy drafted after a careful review of state anti-discrimination laws and sound legal advice.

John Hawes is the co-founder of, an online resource for employment testing and employee wellness. He is also the CCO and co-founder of SureHire Occupational Health Testing and a former physical therapist.

Posted on Jul 23, 2018