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

Area of Science:

• Public Health
• Criminology
• Transportation Safety

Background:

• Canada legalized recreational cannabis in 2018, coinciding with intensified impaired driving enforcement.
• This study examines the impact of these policy changes on police-reported impaired driving rates.

Purpose of the Study:

• To analyze trends in alcohol- and drug-impaired driving in Canada post-cannabis legalization and enhanced enforcement.
• To investigate associations between impaired driving rates and factors like cannabis sales, use, expert enforcement, and pandemic restrictions.

Main Methods:

• Analysis of province-level annual impaired driving counts (alcohol, drugs, or both) from 2009-2023.
• Interrupted time-series regressions to assess changes in impairment rates per capita after 2018.
• Regressions explored links to legal cannabis sales, use prevalence, drug recognition expert employment, and COVID-19 restrictions.

Main Results:

• Alcohol-impaired driving rates decreased pre-2018, while drug-impaired rates increased.
• Post-2018, drug-impaired incidents rose by 42% and alcohol-impaired incidents by 17% compared to projections.
• Increases in drug-impaired driving correlated with drug expert employment, pandemic restrictions, and cannabis sales.

Conclusions:

• Police-reported impaired driving for both alcohol and drugs increased in Canada after 2018.
• These increases appear more strongly associated with enhanced enforcement measures and pandemic-related disruptions than with legal cannabis sales or overall cannabis use.