Stronger alcohol and cannabis policies each independently reduced substance-involved motor vehicle deaths | Research

The takeaway

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.

Traffic safety policymakers, cannabis regulators, alcohol policy researchers

Cannabis policy restrictiveness independently reduced cannabis-involved crash deaths without affecting alcohol policy benefits

What the researchers 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.

Why it 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 numbers in context

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 the study worked

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.

What this study cannot tell us

Ecological design. Composite policy scores. 2010-2019 data may not capture newer legalization effects. THC detection indicates recent use, not impairment.

How to read the evidence

Large national dataset with robust modeling and validated policy scores, but ecological design limits specificity.

When this study was published

2026 publication using 2010-2019 data

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.

Questions still open

Which specific cannabis policy components drive the protective association? Has the relationship changed post-2019?

Common 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.

Read the original research

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

View on PubMed ↗Publisher’s paper ↗

Citation

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