Many California Cannabis Users Unsure About Driving Laws Six Years After Legalization | Research

The takeaway

Six years after California legalized recreational cannabis, only 62% of users knew passengers cannot consume cannabis in a moving vehicle, and 13% said legalization made them more likely to drive under the influence.

Cannabis users who drive, public health educators, traffic safety researchers, policy makers

13% said legalization increased their likelihood of driving under the influence

What the researchers found

Among 4,020 current cannabis users in California, 62% knew about the in-vehicle consumption ban, 59% knew containers must be sealed, and 74% knew DUIC citations are possible. 64% felt safe driving within 3 hours of inhaling cannabis. Lower regulatory knowledge was associated with more adverse driving outcomes.

Why it matters

Mixed awareness of cannabis driving laws years after legalization suggests that regulatory knowledge gaps persist and may contribute to impaired driving. The association between lower knowledge and worse driving outcomes points to an actionable public health target.

The numbers in context

62% knew about in-vehicle consumption ban. 59% knew about sealed container requirement. 74% knew about DUIC citations. 64% felt safe driving within 3 hours of inhaling. 55% felt safe within 5 hours of edibles. 13% said legalization increased their likelihood of DUIC.

How the study worked

Large survey of 15,208 participants demographically matched to the 2020 California census. A subset of 4,020 current users, 523 former users, and 635 never-users completed detailed questionnaires about driving knowledge, attitudes, and behaviors. Chi-square analysis was used for descriptive analysis.

What this study cannot tell us

Self-reported data on driving behaviors and knowledge. California-specific results may not generalize. The survey cannot establish causation between knowledge gaps and driving outcomes.

How to read the evidence

Moderate: large census-matched survey with detailed questionnaire, but self-reported data and cross-sectional design

When this study was published

Published in 2025 surveying Californians after 2018 legalization

The bigger picture

Cannabis legalization without adequate public education about driving regulations may leave gaps that contribute to impaired driving. The finding that knowledge predicts driving outcomes suggests that education campaigns could reduce harm.

Questions still open

What types of public education campaigns most effectively improve cannabis driving knowledge? How does actual impairment duration compare to when users feel safe to drive?

Common questions

How long should you wait to drive after using cannabis?

This study found 64% of users felt safe driving within 3 hours of inhaling cannabis, but the study did not measure actual impairment. Research on cannabis impairment duration varies widely and depends on dose, tolerance, and individual factors.

Did legalization change driving behavior?

13% of current cannabis users reported that Proposition 64 increased their likelihood of driving under the influence. Those with less knowledge of driving-related regulations were more likely to report adverse driving outcomes.

Read the original research

Driving and cannabis use: a questionnaire about knowledge and behaviors after the legalization of recreational cannabis in California.

BMC public health, 25(1), 3219

View on PubMed ↗Publisher’s paper ↗

Citation

Baird, Sara; Ageze, Daniel; Hill, Linda L; Hacker, Sarah; Dell'Acqua, Renee; Gold, Alice; Lanin-Kettering, Ilene; Shaughnessy, Tom; Marcotte, Thomas D. (2025). Driving and cannabis use: a questionnaire about knowledge and behaviors after the legalization of recreational cannabis in California.. BMC public health, 25(1), 3219. https://doi.org/10.1186/s12889-025-24309-4