Marijuana legalization and use are tied to a whole host of problems related to law enforcement, public safety, mental health, and other topics.

Here are a few examples of the harm that marijuana causes.


The National Highway Traffic Safety Administration and the CDC report that after alcohol, marijuana is the substance most often associated with impaired driving.

In Colorado traffic fatalities where the driver tested positive for marijuana have increased 138% since the state legalized marijuana in 2013.

The AAA Foundation for Traffic Safety estimates that the number of drivers involved in fatal crashes in Washington doubled after the state legalized marijuana.

A 2020 study published in JAMA Network Open found that more than 1 in 8 teen drivers reported recently driving after using marijuana, and teens were more than twice as likely to drive after using marijuana than they were to drink and drive.


Despite heavy regulation, authorities in Colorado seized more than five and a half tons of illicit marijuana intended for the black market in 2020.

This year, the Associated Press and NBC News have reported that organized crime and drug cartels are responsible for growing and distributing illicit market marijuana throughout Oregon and California despite legalization. Some of these criminal organizations are tied to labor trafficking, illegal immigration, theft, and violent crime.


In 2021 a study published in Addiction found infants were 35% more likely to be born preterm, have a low birth weight, and be small for their gestational age, and were more likely to die within a year of birth if their mother used marijuana heavily during pregnancy.

A 2022 study published in JAMA Pediatrics found children and adolescents face an increased risk of mental disorder if their mothers used marijuana during pregnancy.


Since its legalization in Colorado, ER visits and poison control calls have increased as a result of children accidentally eating food laced with marijuana.

According to the CDC, secondhand marijuana smoke contains THC and can be harmful to infants, children, and others exposed to it.


In a 2022 study published in The Lancet, researchers determined that THC concentrations in marijuana have more than doubled in the U.S. over the past decade, and that using marijuana with high levels of THC was linked to an increased risk of psychosis.

A 2019 study published in The Lancet found using marijuana with THC levels exceeding 10% increased the odds of a person suffering a psychotic episode.

A 2021 report published in the Journal of the American Medical Association found self-harm rates rose 46% among men ages 21 to 39 in states where commercial marijuana sales were legalized.


All of this underscores what we have said for years: Marijuana may be many things, but “harmless” simply is not one of them.

Articles appearing on this website are written with the aid of Family Council’s researchers and writers.