The Impacts Of Marijuana Legalization Regarding Impaired Driving (2025 UPDATE)

“Don’t drive high.” This was the message that the Canadian government aimed to deliver to all drivers after marijuana was legalized on 17 October 2018. Yet, even as of 2025, the relationship between cannabis use and impaired driving remains complex and not fully understood.

Some research suggests that since legalization, there has been a noticeable rise in high-risk behaviours following cannabis consumption, most notably, driving under the influence of cannabis (DUIC).

Other studies acknowledge that cannabis can impair the cognitive and psychomotor skills required for safe driving. However, the degree of impairment may vary significantly depending on individual factors, the dosage and method of consumption, as well as the amount of time elapsed between use and operating a vehicle.

What Do We Currently Know about Cannabis Use and Driving in Canada?

According to survey data from Statistics Canada, 13% of people who use marijuana and have a driver’s license said they drove within two hours of using cannabis. Some also mentioned that they drank alcohol as well.

Traffic fatality statistics also show that after the legalization of marijuana, the number of fatal traffic accidents increased: in 2018, there were 1,922 deaths as a result of traffic accidents; in 2019, this figure reached 2,228.

It should be noted that detecting and proving impairment caused by drugs (including cannabis) differs from detecting and proving impairment caused by alcohol and is more complex. Today, there are several ways to assess DUIC-related cases and incidents:

• Population surveys, where a representative sample of Canadians self-report their driving behaviours following cannabis or other drug use;
• Roadside surveys, which involve collecting saliva samples from voluntary drivers, typically at night and during the summer months;
• Incident reports filed by police and the Canada Border Services Agency (CBSA);
• Toxicological analyses of injured drivers in hospitals and trauma centers.

None of these sources is definitive on its own, and each comes with methodological limitations. In many cases, where alcohol is detected in a driver’s blood, further testing for THC levels is not pursued, as the presence of alcohol alone may establish impairment. 

As a result, there remains no clear scientific consensus regarding the correlation between blood concentrations of tetrahydrocannabinol (THC), marijuana’s main psychoactive substance, and the degree of impairment.

How Marijuana Legalization Has Impacted Drug-Impaired Driving Across Age Groups

The Canadian Centre on Substance Use and Addiction (CCSA) commissioned a study to examine the impact of marijuana legalization on youth aged 12 to 17, including a group who were charged with drug-impaired driving between 2019 and 2021:

Data shows that the number of drug-impaired driving charges (note that this includes all drugs, not just cannabis, as well as combinations of alcohol and drugs) in Canada has increased significantly since the legalization of marijuana. In 2015, there were 2,594 such charges. By 2021, that number had nearly doubled, reaching 5,079.

Young people aged 12 to 17 represent a small proportion of those charged with driving under the influence (less than 3% over the entire study period). Although the number of charges for drug-impaired driving among this group rose to 77 after cannabis legalization, the figure declined substantially by 2021, dropping to 49 charges.

These trends suggest that the overall rise in drug-impaired driving charges post-legalization has occurred primarily among adults, particularly those aged 35 and older.

Legal and Enforcement Efforts to Address DUIC

As with other criminal offences, DUIC is addressed through a combination of prevention, detection, and deterrence strategies.

Prevention and Detection

Since the legalization of marijuana, federal and provincial governments, along with law enforcement agencies, have implemented a range of initiatives aimed at preventing cannabis-impaired driving. These include:

• Public awareness campaigns across various media platforms;
• Educational initiatives targeting secondary school students;
• Informational campaigns are conducted in licensed cannabis retail stores.

Detection of impaired driving continues to rely on standard police practices, such as roadside checkpoints and the use of screening tools, including the Approved Drug Screening Equipment (ADSE) and the Standardized Field Sobriety Test (SFST). When initial signs of impairment are observed, further investigation may involve a Drug Recognition Evaluation (DRE) and/or blood sampling.

Standardized Field Sobriety Test (SFST) Training

Originally developed to detect alcohol-impaired driving, the SFST is an observational test composed of three components:

• Walk and Turn
• One Leg Stand
• Horizontal Gaze Nystagmus

In 2008, the SFST was officially approved for use by Canadian law enforcement as a roadside screening method for detecting alcohol-impaired driving. Although research into its scientific validity in detecting drug-induced impairment (including cannabis) is ongoing, its use has been upheld in numerous Canadian court decisions.

SFST training is delivered through various channels. In some provinces and territories, instruction is limited to police colleges. However, in most jurisdictions, such as British Columbia and Ontario, training is conducted collaboratively between police colleges and local law enforcement agencies.

Driving Under the Influence of Cannabis: What You Need to Know

To help clarify the legal and safety implications of driving under the influence of cannabis (DUIC) in Canada, the following key points are essential for public awareness:

• Cannabis-impaired driving is illegal in Canada. Law enforcement officers are equipped with a range of tools and protocols to detect impairment on the road.
• Marijuana impairs driving ability, making it difficult to perform tasks such as staying in lane, maintaining a constant speed, and making the right decisions on the road;
• Combining alcohol and cannabis impairs driving ability to a greater extent than using either substance alone;
• Using marijuana in vehicles (even parked ones) is prohibited — this applies to both drivers and passengers;
• Cannabis affects each person differently, and its effects depend on the product used, the method of consumption, and the amount consumed. 

When you use marijuana, its effects make it difficult for you to realize that you are intoxicated, so plan your use in advance or use it well before you plan to drive (at least 6 hours in advance).

If you are charged with driving under the influence of cannabis, do not attempt to handle the matter on your own. Consult a qualified DUI lawyer who can help you navigate the legal process and work toward the best possible outcome.

Conclusion

Across most Canadian provinces, various data sources, including population surveys and police-reported incidents, demonstrate a consistent trend over the past 10 to 12 years: a rise in incidents related to cannabis-impaired driving.

Despite this, some cannabis users believe that its use does not affect their ability to drive. Only 25% of Canadians believe that they are likely to be caught if they drive under the influence of cannabis. 

It can be said that the legalization of marijuana has contributed to an increase in the number of cannabis-impaired driving charges, but this is more likely due to enhanced police detection and enforcement measures than to legalization itself. Increased public awareness and other measures to prevent cannabis-impaired driving play an important role in slowing the increase and promoting safer driving.

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