Last updated : July 14, 2025
As of mid-2018, marijuana is legal for recreational use in nine states and the District of Columbia and is legal for medicinal use in 21 additional states. This trend towards the decriminalization of marijuana has numerous implications for American workplaces, most of them troublesome. Marijuana in the 21st century bears but a passing resemblance to the marijuana of the 1960s and 1970s. For example, the THC level (the level of the active ingredient) of 1960s marijuana was about one percent. Today’s marijuana contains around 18.7 percent THC, with some samples exceeding 20 percent.
Impact of marijuana use in the workplace
Although recreational marijuana use is now legal in many states, it can still have a negative impact on the workplace. For example, one study has found that marijuana users account for 85 percent more at work accidents than non-users. In addition, drivers who test positive for marijuana are more than twice as likely to be in a collision than those who haven’t used marijuana within the last 30 days. What’s more: these drivers are three to seven times more likely to have caused the crash. This is not only important for those companies who have employees on the road during the workday, as work crews or delivery persons, but also employees getting to and from work by car.
How prevalent is marijuana use?
In 2016, 9.5 percent of full-time workers and 12.5 percent of part-time workers reported using marijuana within the last 30 days. That means that virtually no workplace with ten or more employees is immune from being impacted by marijuana. As you would suspect, states where marijuana is legal have a higher rate of positive tests. Positive workplace marijuana tests have increased by 11 percent in Colorado and by 8 percent in Washington. How is a company supposed to maintain a safe and productive workplace in this “hazy” new environment?
What can be done?
For decades, HR departments around the country have maintained a zero tolerance policy towards marijuana use. Test positive and you are given a pink slip with no questions asked and no grounds for appeal. However, today’s legalized marijuana use, especially for medicinal purposes, has made this type of policy less defensible in some states. OSHA guidelines require businesses to provide an environment that is “free from recognizable hazards that are causing or likely to cause death of serious harm to employees.” Hiring marijuana users, whether they use for medicinal or recreational reasons, may not fulfill this OSHA mandate. In fact, workman’s compensation rules still lag behind marijuana laws. In 47 states, workman’s comp benefits are still restricted when drugs or alcohol are deemed to a contributing factor to an accident.
Do employers have to overlook marijuana use in their employees despite evidence that such use can impair their reasoning and motor skills? The answer is a guarded “no”. Legislation in most of the states where marijuana is legal allows for workplaces to set their own more restrictive rules about marijuana use. For example, in Massachusetts, the law states maintains “the authority of employers to enact and enforce workplace policies restricting the consumption of marijuana by employees”.
At minimum, employers in states where marijuana is legal need to have a written policy about drug and alcohol use, specifying in what situations, if any, marijuana use will be tolerated (such as with a doctor’s prescription). This policy needs to be distributed among employees and updated annually as new legislation regarding marijuana use in the workplace is enacted. The trick, difficult as it may be, is to find the balance between honoring employee rights and keeping employees safe at work.
Richard Matteucci of USA Mobile Drug Testing of Denver, explains: “It is critical for companies in states with legalization to express their policy in several forms. It is best to read the policy, sign the policy and reiterate the policy regularly.”
