Marijuana Car Accident Statistics In California

California’s legalization of marijuana (cannabis) has demonstrably impacted the rates of accidents and fatal crashes involving drivers under the influence of the drug. As we move deeper into the post-legalization era, the data continues to evolve, painting a clearer picture of these consequences. Victims of car accidents involving a driver who is high or under the influence of cannabis while driving need competent professional representation as they navigate the complexities involved in a DUI case.

Car Accident Statistics Continue to Rise After The Legalization Of Marijuana In California

California’s Office of Traffic Safety (OTS) maintains an updated page - including statistics - entitled Drug Impaired Driving: DUI Doesn’t Just Mean Booze. This is an excellent page to review, especially if you have teen or young adult drivers under your care.

Just because marijuana has been legalized does not mean it is safe to use marijuana and drive. Nor does it mean that those under the influence are immune from DUI laws. Those who are under the influence of any amount of marijuana should not operate a motor vehicle and should use a designated driver.

If a driver who has used marijuana is involved in an accident, even if they are not considered “at fault,” proof that they are under the influence of alcohol or drugs can still result in the imposition of harsh penalties. Here are some of the most recent statistics about marijuana-related car accidents and other data on drug-impaired driving and DUIs.

Updated 2024-2025 Statistics:

• 50.3% of all drivers killed in motor vehicle crashes in California (who were tested) tested positive for legal and/or illegal drugs as of 2021 data - a significant increase from the previously reported 42%.
• Drug-involved crash fatalities now account for approximately 25% of all crash deaths in California, representing 751 fatalities related to drug-involved driving in 2021.
• People who drive immediately after using marijuana may increase their risk of getting into a crash by 20 to 35 percent. These rates increase if marijuana is ingested in edible form rather than smoked.
• Survey data from 2024 reveals that about 14% of California drivers test positive for drugs - nearly double the number of alcohol-impaired drivers on weekends. This represents a concerning trend in drug-impaired driving.
• Recent comprehensive studies show that after the legalization of recreational marijuana for adults 21 years and older, there was a 6% increase in injury crash rates and a 4% increase in fatal crash rates following legalization - slightly higher than earlier estimates.
• Legalization of the recreational use of marijuana and the subsequent onset of retail sales across multiple U.S. states continues to show consistent patterns, with California’s experience aligning with national trends of increased crash rates post-legalization.
• There is no difference between driving under the influence of medically-prescribed marijuana and recreational marijuana. As with other prescription drugs containing warnings about not operating motor vehicles, nobody should drive while under the influence of cannabis.

Why Does Being High Increase Car Accident Risk?

Many marijuana users feel that while they would never drive drunk, there is no risk of driving while under the influence of marijuana because it does not affect the brain in the same ways as alcohol. This is in fact false. Current data continues to establish a direct correlation between the legalization of recreational cannabis and over-the-counter sales with both higher crash rates and higher incidences of crash-related fatalities.

Marijuana slows reaction times

While alcohol tends to lead to an increase in reckless driving behavior, both alcohol and marijuana slow down reaction times. Studies also show that being under the influence of marijuana - which compromises the area of the brain that controls coordination, movement and balance - also negatively impacts a person’s perception of time, speed and attentiveness to the road.

Being under the influence of marijuana may increase reckless behavior

While research shows that being high typically results in driving too slow, or in a driver being ultra-cautious - sometimes to a fault - there are exceptional situations when this is not the case, such as when cannabis is mixed with other substances like alcohol or other recreational drugs. In these situations, the combination of marijuana and alcohol or other drugs can cause a person to behave - and drive - recklessly.

Having larger amounts of cannabis in the bloodstream is linked to reckless driving behaviors such as:

• Weaving in and out of lanes
• Slow reaction times to changing traffic lights or unexpected obstacles
• Lack of awareness of driving speed

The effects of THC are the greatest in the first 30 to 45 minutes after inhalation

The effects of marijuana on the brain are the most dramatic in the first 30 to 45 minutes after inhaling. If you ingest marijuana, these times are extended due to the body’s digestive processes. This discrepancy in reaction time is one of the reasons why it is more difficult to prove that marijuana is the cause of an accident.

What To Do If You Suspect A Driver Is Under The Influence Of Marijuana

Contact the police and share your suspicions immediately after you are involved an accident and suspect - or know - the driver was under the influence of marijuana. Proving a person is under the influence of marijuana can be tricky because the drug remains in the system longer than other substances. As a result, someone that used marijuana at some point in the recent past may not be experiencing the effects of the drug at the time they were driving.

Further complicating matters is that there is still no legal limit of blood alcohol concentration (“BAC”) equivalent for marijuana in California as of 2025. For example, alcohol is processed by the body very quickly, so California has a legal blood alcohol concentration (BAC) limit of .08 for drivers 21 years old or more. Drivers under 21 are considered under the influence with a BAC of .01 or higher. Marijuana is different because it can last in the bloodstream for up to 90 days after use. Also, because chemical tests for THC are not sufficiently reliable, and because experts cannot agree on how much it takes to impair driving to a dangerous degree, California has not yet adopted a BAC level for driving with THC in your system.

Recent developments in 2024-2025 include pilot programs for roadside THC impairment testing using oral fluid swabs and saliva screening devices, though courts still require blood testing for legally admissible evidence. This makes it harder to prove that the person responsible for your accident was driving under the influence of marijuana when the accident occurred.

Requesting that drivers provide blood and urine samples may be essential to proving marijuana was a cause of your accident. With that said, you should always consult with a personal injury attorney to ensure your case is facilitated in a way that honors your best interests.

Notable Changes Since 2023

Since the original publication of this article, several important developments have emerged:

• Enhanced law enforcement training: California has expanded Advanced Roadside Impaired Driving Enforcement (ARIDE) and Drug Recognition Evaluator (DRE) programs to better identify drug-impaired drivers.
• Increased prosecution focus: Dedicated prosecution teams for drug-impaired driving cases have been established, with specialized training for handling DUI drug cases through every step of the criminal process.
• Public education campaigns: New initiatives specifically target the dangers of driving under the influence of substances other than alcohol, working to shift social norms around drug-impaired driving.

Burneikis Law Can Help If You’ve Been Involved In An Accident With a DUI Driver

Were you involved in an accident involving a driver under the influence of marijuana or another substance? Contact Burneikis Law and schedule a consultation. We will discuss your case and determine what steps you should take to move forward with the insurance companies or others to make sure your rights are protected and that the at-fault driver’s intoxication is not swept under the rug. Contact us to get started.

This article was originally published in March 2023 and updated in September 2025 to reflect the most current available data and legal developments regarding marijuana-impaired driving in California.