Canada's cannabis legalization and police-reported cannabis-related criminal incidents among youth, 2015-2021.

Background: We previously reported that the 2018 Canadian Cannabis Act, allowing youth to possess up to 5 g dried cannabis or equivalent for personal use/sharing, was associated with short-term (76 days) post-legalization reduction in police-reported cannabis-related crimes among youth. To establish whether the change might be sustained, we now estimate this association during a much longer time period by including an additional three years of post-legalization data.

Methods: Using national daily police-reported criminal incident data from January 1, 2015-December 31, 2021 from the Canadian Uniform Crime Reporting Survey (UCR-2), the study employed Seasonal Autoregressive Integrated Moving Average (SARIMA) time series models to assess the associations between legalization and youth (12-17 years) cannabis-related offenses (male, n = 34,508; female, n = 9529).

Results: Legalization was associated with significant reductions in both male and female police-reported cannabis-related offenses: females, 4.04 daily incidents [95% confidence interval (CI), 3.08; 5.01], a 62.1% decrease [standard error (se), 34.3%]; males, 12.42 daily offenses (95% CI, 8.99; 15.86), a reduction of 53.0% (se, 22.7%). There was no evidence of associations between cannabis legalization and patterns of property or violent crimes.

Conclusions: Results suggest that the impact of the Cannabis Act on reducing cannabis-related youth crimes is sustained, supporting the Act's objectives to reduce cannabis-related criminalization among youth and associated effects on the Canadian criminal justice system.