Last updated : May 12, 2025
Although California passed Proposition 215 in 1996 (which legalized the use of medical cannabis), 2012 is the momentous year when the floodgates truly burst open when Washington and Colorado officially legalized the use of recreational marijuana for adults. Since then, another 26 states, Washington D.C., three overseas territories and three Native-American reservations have joined in the parade by either legalizing medical and recreational marijuana or both.
Amidst the fiery and passionate debates surrounding the issue, one aspect of marijuana decriminalization remains largely under the radar despite the huge social and economic impact—the negative effect of marijuana in the workplace.
Marijuana decriminalization and legalization advocates have regularly pointed out that there has never been even a single recorded case of death caused by marijuana overdose in the United States. This is probably technically true, since someone would need to consume over 15 grams of marijuana (a massive amount) to reach a level of toxicity that could directly lead to fatality. However, this is also a very narrow way of looking at the matter.
Numerous studies have long documented that high levels of tetrahydrocannabinol (THC) – the active psychoactive ingredient in cannabis plants—in the blood stream can significantly impair both motor skills and cognitive skills, which could lead (and has led) to accidents. Further, marijuana can affect users psychologically—there is even research which suggests that there is a relationship between marijuana and mental health disorders such as depression and schizophrenia.
For employers, the legalization of marijuana presents an expensive problem in the workplace through the loss of productivity, safety, and morale. With marijuana usage in the 160 million-strong workforce rising to 8.9%— a 75% increase in the last three years, business owners have legitimate concerns over the long-term economic impact that marijuana will have on revenue and profitability.
So how exactly does marijuana legalization hurt productivity in the workplace? We’ll take a look at the three chief factors.
Safety
Employees must meet certain mental and physical thresholds to perform their daily tasks safely. This is especially important in high-risk workplaces such as construction sites and manufacturing plants, and transportation. It is a well-documented fact that the consumption of marijuana degrades sensory perception, cognitive skills and short-term memory in addition to reaction time, hand-eye coordination and concentration. These impairments will affect the ability of employees to perform sophisticated tasks such as operating machinery or vehicles. As such, it is no exaggeration to conclude that the level of workplace safety is immediately compromised when employees consume marijuana. Any resulting accident will inevitably lead to loss of man-hours, healthcare costs, workers compensation claims, and medical leave—frequently involving other co-workers. Often, this also leads to costly and expensive lawsuits.
It is worth noting that the effects of marijuana are notoriously difficult to predict owing to the presence of various marijuana strains in the market, and reaction with other substances in the body. The acute effects of marijuana may dissipate after 48 hours—but a measurable reduction in reaction time, hand-eye coordination and concentration will persist for several days afterwards. Also, unlike blood-alcohol content, there is no standard, nationally-accepted metric for blood-content level of THC to indicate impairment. Mouth swab drug testing, however, can detect use from as little as a few minutes ago up to three days, which is always directly correlated with impairment.
Absenteeism, leave, and time off
The use of marijuana has long been linked to increased absenteeism rates. For instance, in a study by the Drug and Alcohol Testing Industry Association (DATIA), 9% of businesses polled reported high absenteeism rates, but following the implementation of a drug testing program, high absenteeism dropped to 4%—a staggering 56% decrease. This suggests that the deterrent effect of drug tests reduced drug use, which led to improvements in absenteeism rate.
In addition, a survey by the National Institute on Drug Abuse (Strategic Planning for Workplace Drug Abuse Programs) noted that employees which use drugs are 2.2 times more likely to request time off, 3 times more likely to be late, and 2.5 times more likely to be absent for eight days or more.
Compensation claims and healthcare expenses
Marijuana use in the workplace leads to accidents in the workplace, which often results in injuries to the user and co-workers, as well as damage to equipment and property. This will often lead to expensive workers compensation claims and related healthcare expenses, and sometimes, even costly and embarrassing law suits. Data from a survey by the National Institute on Drug Abuse reported that drug users are 3.6 times more likely to be involved in an accident in the workplace and 5 times more likely to file a compensation claim.
Substance abuse costs America over $193 billion annually through health care expenses, crime, and loss of productivity. With the legalization of marijuana, that cost is expected to soar in the coming years—and businesses will bear the brunt of the burden.
