Stronger alcohol and cannabis policies each independently reduced substance-involved motor vehicle deaths
Using a decade of US crash fatality data, more restrictive alcohol policies reduced alcohol-involved deaths, and more restrictive cannabis policies reduced cannabis-involved deaths, with no interference between policy domains.
Quick Facts
What This Study Found
A 10-point increase in alcohol policy scores was associated with 6.3% lower odds of alcohol-involved crash fatalities. A 10-point increase in cannabis policy scores was associated with reduced cannabis involvement (AOR = 0.956) and co-involvement (AOR = 0.962). Cannabis policies did not affect alcohol policy effectiveness.
Key Numbers
Alcohol policy: AOR = 0.937 for BAC > 0.00%. Cannabis policy: AOR = 0.956 for cannabis involvement; AOR = 0.962 for co-involvement. No significant policy interaction.
How They Did This
Analysis of FARS data across 50 states and DC (2010-2019). State-year alcohol and cannabis policy scores measured policy exposure. Multivariable mixed logistic regression estimated associations with BAC thresholds and THC involvement in crash fatalities.
Why This Research Matters
A key concern has been whether cannabis legalization might undermine alcohol control. This study shows the two policy domains operate independently, providing reassurance for policymakers.
The Bigger Picture
As more states legalize cannabis, both policy domains matter independently. Strong policies in both areas can work together to reduce substance-involved traffic deaths.
What This Study Doesn't Tell Us
Ecological design. Composite policy scores. 2010-2019 data may not capture newer legalization effects. THC detection indicates recent use, not impairment.
Questions This Raises
- ?Which specific cannabis policy components drive the protective association?
- ?Has the relationship changed post-2019?
Trust & Context
- Key Stat:
- Cannabis policy restrictiveness independently reduced cannabis-involved crash deaths without affecting alcohol policy benefits
- Evidence Grade:
- Large national dataset with robust modeling and validated policy scores, but ecological design limits specificity.
- Study Age:
- 2026 publication using 2010-2019 data
- Original Title:
- Relationships of Changing State Cannabis Policies With Alcohol Policy Effectiveness and Alcohol or Cannabis Involvement in Motor Vehicle Fatalities.
- Published In:
- American journal of preventive medicine, 70(1), 108137 (2026)
- Authors:
- Naimi, Timothy S(4), Zhao, Jinhui(2), Lira, Marlene C(4), Pacula, Rosalie Liccardo
- Database ID:
- RTHC-08515
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does cannabis legalization increase drunk driving deaths?
No evidence of that. Cannabis policy changes did not affect the relationship between alcohol policies and alcohol-involved crash deaths.
Do stricter cannabis laws reduce crash deaths?
Yes. More restrictive cannabis policies were associated with fewer cannabis-involved and co-involved fatalities, though effect sizes were modest.
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Cite This Study
https://rethinkthc.com/research/RTHC-08515APA
Naimi, Timothy S; Zhao, Jinhui; Lira, Marlene C; Pacula, Rosalie Liccardo. (2026). Relationships of Changing State Cannabis Policies With Alcohol Policy Effectiveness and Alcohol or Cannabis Involvement in Motor Vehicle Fatalities.. American journal of preventive medicine, 70(1), 108137. https://doi.org/10.1016/j.amepre.2025.108137
MLA
Naimi, Timothy S, et al. "Relationships of Changing State Cannabis Policies With Alcohol Policy Effectiveness and Alcohol or Cannabis Involvement in Motor Vehicle Fatalities.." American journal of preventive medicine, 2026. https://doi.org/10.1016/j.amepre.2025.108137
RethinkTHC
RethinkTHC Research Database. "Relationships of Changing State Cannabis Policies With Alcoh..." RTHC-08515. Retrieved from https://rethinkthc.com/research/naimi-2026-relationships-of-changing-state
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.