| Title: | Driving and cannabis use: a questionnaire about knowledge and behaviors after the legalization of recreational cannabis in California |
| Authors: | Sara Baird, Daniel Ageze, Linda L. Hill, Sarah Hacker, Renee Dell’Acqua, Alice Gold, Ilene Lanin-Kettering, Tom Shaughnessy & Thomas D. Marcotte |
| Year: | 2025 |
| Journal: | BMC Public Health |
A new study from CMCR Co-Director Tom Marcotte, PhD, Linda Hill, MD, MPH, Professor of the Herbert Wertheim School of Public Health, Sara Baird, and colleagues from UC San Diego surveyed over 15,000 adults after California legalized recreational cannabis in 2018 to examine what drivers know—and how they behave—when it comes to cannabis use and driving. The study, published in BMC Public Health, analyzed responses from more than 5,000 Californians, including 4,000 current cannabis users.
While most participants recognized that driving under the influence of cannabis (DUIC) is illegal, many remained unaware of specific restrictions—such as the prohibition on using cannabis or having an open container in a moving vehicle. Among current users, 64% felt safe driving within three hours of smoking cannabis, and 55% within five hours of eating an edible—both windows during which impairment may persist.
Thirteen percent of users said legalization increased their likelihood of DUIC, and those with lower knowledge of cannabis-driving laws were more likely to report having been pulled over or involved in a crash while under the influence. These findings underscore a persistent gap between perceived and actual safety when it comes to cannabis-impaired driving.
The authors conclude that six years after legalization, knowledge about cannabis-related driving laws remains mixed, with concerning trends in self-reported risk behaviors. They recommend public education campaigns to increase awareness about legal restrictions, realistic impairment duration, and the risks of driving soon after cannabis use—key steps to promoting road safety in the post-legalization era.
Read the full publication here.
Citation: Baird, S., Ageze, D., Hill, L.L. et al. Driving and cannabis use: a questionnaire about knowledge and behaviors after the legalization of recreational cannabis in California. BMC Public Health 25, 3219 (2025). https://doi.org/10.1186/s12889-025-24309-4