A systematic review of 17 studies found cannabis decriminalization and legalization consistently reduced arrests by 13-87%, but racial and ethnic disparities in enforcement persisted or even increased in some cases.
Policymakers, criminal justice advocates, and anyone interested in the equity effects of cannabis legalization.
13-87% reduction in cannabis offences, but racial disparities persist
What the researchers found
100% of studies (7/7) showed significant reductions after decriminalization (13.5-78% reduction). 75% of studies (6/8) showed reductions after legalization (33-87%). Legalization consistently reduced adult offences but not always youth offences. Despite absolute reductions across racial groups, relative disparities were variable, increasing in some jurisdictions while decreasing in others.
Why it matters
Reducing criminal justice harms is a primary justification for cannabis legalization. This review confirms that both decriminalization and legalization achieve this goal but reveals that they do not automatically eliminate racial disparities in enforcement, which was another stated goal.
The numbers in context
17 studies from 2,806 screened. Decriminalization: 13.5-78% reduction in offences (7/7 studies). Legalization: 33-87% reduction (6/8 studies). In previously decriminalized states, legalization added 35-84% further reduction (2/3 studies). Youth reductions less consistent than adult.
How the study worked
Systematic review of 7 databases yielding 17 studies from North America (15 USA, 2 Canada). Examined changes in cannabis arrests, charges, convictions, and referrals after four policy types: medical legalization, decriminalization, non-medical legalization, and commercialization. Synthesis without meta-analysis.
What this study cannot tell us
All 17 studies were from North America. Limited evidence on commercialization effects (only 2 studies). Youth-specific data was sparse. The review could not account for differences in implementation and enforcement across jurisdictions.
How to read the evidence
Systematic review of 17 studies with consistent findings on offence reduction. Strong evidence for overall effects; mixed evidence on disparity impacts.
When this study was published
Published in 2025.
The bigger picture
The persistence of racial disparities despite absolute reductions in cannabis offences suggests that enforcement patterns reflect deeper systemic issues beyond cannabis policy. Additional interventions beyond legalization are needed to achieve equity in criminal justice outcomes.
Questions still open
- What additional policies beyond legalization are needed to eliminate racial enforcement disparities? Why does legalization reduce adult but not always youth cannabis offences?
Common questions
Does legalization eliminate cannabis arrests?
Why do racial disparities persist after legalization?
Read the original research
Evaluating the association between cannabis decriminalization and legalization and cannabis arrests and related disparities: A Systematic review.
The International journal on drug policy, 137, 104705
Citation
McCarthy, Stephen D S; Gaudreault, Adrienne; Xiao, Jennifer; Fischer, Benedikt; Hall, Wayne; Lee, Kathryn; Kang, Rachel; Aslanyan, Garry; Sood, Manish M; Myran, Daniel T. (2025). Evaluating the association between cannabis decriminalization and legalization and cannabis arrests and related disparities: A Systematic review.. The International journal on drug policy, 137, 104705. https://doi.org/10.1016/j.drugpo.2025.104705