Cannabis Use Rose in Canada, but Impaired Driving Did Not

When Canada legalized non-medical cannabis in 2018, many people feared the roads would become significantly more dangerous. Critics predicted that more cannabis use would inevitably lead to more people driving while impaired, increasing crashes, injuries, and fatalities. Now, nearly eight years later, researchers have a much clearer picture of what actually happened, and the findings are more nuanced than many expected.

A 2026 study¹ published in the Journal of Transport & Health examined Canada’s post-legalization experience and found something surprising. The findings suggest that legalization alone did not trigger a sustained surge in cannabis-impaired driving as suspected. Instead, changing public attitudes, education campaigns, and law enforcement efforts may have encouraged more responsible decision-making among cannabis consumers. Let’s take a closer look at the findings and how other countries may be able to model Canada’s policies for road safety alongside cannabis legalization.

Cannabis Use Increased After Legalization

Legalization made cannabis more accessible through regulated retail stores and established clear rules for adult use. Unsurprisingly, surveys showed that cannabis consumption became more common among Canadian adults after legalization. For some observers, this increase immediately raised concerns about road safety. Many believed that if more people were using cannabis, it seemed logical that more people would choose to drive after consuming it.

However, the research suggests that the relationship between cannabis use and impaired driving is far more complex.

Cannabis-Impaired Driving Declined

The researchers reviewed national survey data as well that was collected after legalization and found that cannabis-impaired driving did not experience a dramatic rise. For cannabis consumers specifically, DUIs involving cannabis decreased. Across the general population, which includes both cannabis users and non-users, the prevalence of cannabis DUIs remained relatively stable during the first several years after legalization. While there was a slight increase from 2022 to 2023, the increase was modest rather than the dramatic spike many initially feared.

The data suggests that legalization itself was not the sole factor determining impaired-driving behavior. Instead, other influences likely shaped how Canadians responded to the changing legal landscape.

Cannabis Related Traffic Collisions

The researchers also examined evidence surrounding motor vehicle collisions involving THC, the primary psychoactive compound in cannabis. Early studies conducted during the first few years after legalization produced mixed findings. Some suggested increases in injuries and fatalities involving drivers who tested positive for THC, while others found less consistent trends.

More recent evidence, however, suggests that these increases may have begun returning toward pre-legalization levels. However, interpreting these findings remains challenging because detecting THC does not necessarily prove that a driver was impaired at the time of a crash, as THC can remain detectable in the body long after its impairing effects have worn off, making it difficult to establish a direct relationship between positive test results and impairment.

Researchers continue working to better understand how cannabis affects driving performance and how impairment can be measured accurately so we can truly understand how often cannabis consumption is leading to car accidents.

Why Did Cannabis Impaired Driving Decline?

The study points to several factors that may help explain why cannabis-impaired driving became less common among cannabis consumers despite higher overall cannabis consumption. One likely contributor is increased public awareness. Legalization was accompanied by widespread public-health campaigns that emphasized the dangers of driving while impaired by cannabis. These campaigns sought to educate consumers about delayed reaction times, reduced attention, impaired coordination, and poor decision-making behind the wheel.

At the same time, Canada strengthened enforcement measures surrounding cannabis-impaired driving. Law enforcement agencies adopted additional training, roadside testing methods, and legal tools designed to discourage impaired driving.

Legalization itself may also have encouraged more open conversations about responsible cannabis use. As cannabis became legally regulated, public messaging shifted beyond simply discouraging use to promoting safer behaviors among adults who chose to consume cannabis.

Together, these efforts have helped reshape public perceptions about the risks of driving after using cannabis.

Why Public Perception Matters

One of the most interesting aspects of the research is the role that risk perception appears to play. People are generally less likely to engage in risky behaviors when they clearly understand the potential consequences.

In the matter of cannabis, public-health messaging helped create awareness that it can impair driving ability, even if users feel capable of operating a vehicle, and conveyed the dangers of doing so. This growing recognition of impairment may have encouraged more cannabis consumers to wait longer before driving, arrange alternative transportation, or avoid driving altogether after consuming cannabis.

The findings reinforce an important public-health principle: that education can influence behavior when it effectively communicates risk.

Cannabis Education Still Has Work to Do

Although Canada’s experience is encouraging in several respects, the researchers caution against assuming the issue has been solved. Public-health campaigns appear to have played an important role, but many of these programs have not been rigorously evaluated. More research is needed to determine which messages are most effective, which audiences respond best, and how campaigns can continue reducing impaired driving.

Improving the evaluation of these educational initiatives could help policymakers invest in programs that produce measurable improvements in road safety.

More Cannabis Users Could Still Mean More Cases

One of the study’s most important takeaways is that percentages do not always tell the whole story. Even if a smaller proportion of cannabis users chooses to drive while impaired, the total number of impaired driving incidents could still increase if the overall number of cannabis consumers continues to grow.

For example, if cannabis use expands substantially over time, even a lower rate of impaired driving among users could translate into more impaired drivers on the road simply because there are more cannabis users overall. This means policy makers cannot rely solely on the encouraging decline observed among cannabis users, as continued education, research, enforcement, and ongoing monitoring remain essential for protecting public safety.

What Canada’s Experience Teaches

Canada’s legalization experience offers valuable insights for other countries considering cannabis reform. The evidence suggests that legalization did not automatically produce a lasting increase in cannabis impaired driving. Instead, greater recognition of the risks, likely reinforced through public-health campaigns, stronger enforcement, and THC-testing measures, appears to have encouraged safer behavior.

At the same time, researchers emphasize that continued vigilance is necessary. As cannabis use continues to evolve, public-health education must evolve alongside it. Better evaluation of awareness campaigns, ongoing enforcement, and continued research into cannabis impairment will all play important roles in maintaining road safety.

Ultimately, the study highlights an important lesson: that policy changes alone do not determine public behavior. Education, responsible regulation, and informed decision-making can all help shape how people respond, and Canada’s experience suggests those efforts may make a meaningful difference.

References:

^{1. Christine M. Wickens, Patricia Di Ciano, Bernard Le Foll, Driving under the influence of cannabis (DUIC): A risky proposition?, Journal of Transport & Health, Volume 51, 2026, 102404, ISSN 2214-1405, https://doi.org/10.1016/j.jth.2026.102404}