New study: Majority of marijuana users drive while impaired

How dangerous is driving while high?

Recreational marijuana is legal for adults in Washington state, but a decision many are grappling with is whether it’s safe to drive after consuming marijuana.

A comprehensive study by insurance comparison site The Zebra that surveyed 811 anonymous legal marijuana users in March 2019 found that nearly 60% of marijuana users in legal states drove while high.

There are many laws and best practices across the country for drinking and driving, compounded by decades of science and research. However, data on the impact of using marijuana and driving is less established.


Here’s what we do know:

  • Marijuana does cause impairment: Studies have shown that marijuana impairs motor skills, cognitive functions, and other driving abilities. Experts agree that if you’re impaired, you shouldn’t be behind the wheel.
  • How long are you impaired by marijuana?: Research is still underway in regards to how long drivers should wait to drive after using recreational marijuana, but the current consensus is to wait from anywhere from 2-24 hours. Washington’s Liquor and Cannabis Board recommends waiting at least 5 hours for inhaled marijuana (or longer if the marijuana has been infused in an edible). Keep in mind that in Washington state, it’s illegal to drive under the influence of marijuana if you have more than 5 nanograms of active THC per milliliter of blood.
  • Marijuana and car accidents: It’s still unclear if marijuana has been driving a peak in crashes. According to the Insurance Institute for Highway Safety, there’s some evidence that crashes increased in recreational marijuana legal states, but the topic continues to be researched and debated.
  • Limited guidelines on marijuana and driving: There are clear guidelines when it comes to drivers who drink alcohol and how much they should consume before deciding to drive. With marijuana, those guidelines are less established. The state of Colorado suggests that users are likely impaired after using 10mg of THC, but results vary.

What the numbers show us

Data from The Zebra’s study revealed that most drivers decided if they were able to drive based on how impaired they felt. Meanwhile, nearly half of drivers noticed that their driving skills were impaired while they were using marijuana.

Overall, drivers have been making drastically different choices in regards to their marijuana consumption and driving. Forty percent of drivers in the study said they never drive while using marijuana, while the other 60% of drivers in the study admitted to using marijuana while driving.

The study also examined the marijuana habits of drivers. Sixty-eight percent of drivers said they usually waited between 2-4 hours before attempting to drive after getting high. However, 26% of people said they waited less than an hour. The remaining 6% said they didn’t think or know about their habits.

Drivers who participated in the study said that they typically consumed about one joint’s worth of marijuana.

Seattle crash victims can trust Aaron Engle Law

Drivers seem to be aware of the current limitations and lack of guidelines when it comes to using marijuana and driving. There’s also skepticism when it comes to new regulations being established.

Only one in three drivers believed that their state’s guidelines and laws about marijuana are effective. Two out of three people in the study thought police couldn’t accurately assess marijuana impairment.

Data for marijuana-related car crashes is still being researched. Crashes still happen every day related to a driver being under the influence.

If you or a loved one was injured in a car accident caused by an impaired driver, an insurance company may dispute your claim. Without the help of an experienced car accident lawyer, your claim could come down to your word vs. the word of the other driver.

At Aaron Engle Law in Seattle, our attorneys have the knowledge and experience to deal with every type of crash, including those caused by impaired drivers. Let us aggressively advocate for your best interests and fight for every dollar you deserve.

Contact us today for a free consultation.