Police-Reported Impaired Driving After Recreational Cannabis Legalization in Canada.

INTRODUCTION

When Canada legalized recreational cannabis in 2018, it also enhanced enforcement against impaired driving. This observational study analyzed how police-reported impaired driving rates evolved after those 2 policy changes.

METHODS

The study analyzed province-level annual counts of driving impaired by alcohol, drugs (including but not limited to cannabis), or both during 2009-2023. The data were published in 2024 and analyzed in 2025. Interrupted time-series regressions tested for changes in annual impairment rates per million population aged ≥16 years after 2018. Further regressions tested whether the changes were associated with legal cannabis sales, cannabis use prevalence, police drug recognition expert employment, or COVID-19 pandemic restrictions.

RESULTS

During 2009-2018, alcohol-related impaired driving rates were decreasing, whereas those involving drugs were increasing. During 2019-2023, police reported 65 (95% CI=36, 93) extra drug-impaired incidents per million population annually or 42% more than the 2009-2018 trend had projected. Police also reported 280 (95% CI=134, 425) extra alcohol-impaired incidents per million population annually or 17% more than projected. New offenses covering mixed alcohol and drug impairment or unspecified-substance impairment added more incidents. Drug-impaired incidents were positively associated with drug expert employment, pandemic restrictions, and licensed cannabis sales (p<0.05). Alcohol-impaired incidents were positively associated with drug expert employment but negatively with pandemic restrictions (p<0.05).

CONCLUSIONS

Canada's police-reported impaired driving rates increased after 2018 for alcohol and more so for drugs. The changes seemed associated more with enhanced enforcement and pandemic disruptions rather than with legal cannabis sales or overall cannabis use.