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A new UC San Diego study found that while one-third of Californians use cannabis regularly, there are significant gaps in their knowledge about cannabis use and driving laws, even six years after legalization. The Impact 64 study surveyed over 4,000 cannabis users and revealed mixed awareness of regulations, such as containers needing to be unopened in a moving vehicle and the laws against smoking/ingesting cannabis while driving. The findings emphasize the need for targeted education initiatives to promote safe driving practices and public safety.

Survey: Californians Don’t Know Cannabis Driving Laws

Oct 24, 2025

Mg Magazine Newswire

MG Magazine



*SAN DIEGO, Calif.* — A new study from University of California San Diego
has found that, while a third of Californians use cannabis regularly, there
are significant gaps in knowledge around cannabis use and driving. The
researchers found that even six years after the legalization of
recreational cannabis use, adults in California demonstrate mixed awareness
and knowledge of driving-related laws and regulations.

The study results, published in *BMC Public Health*, come from a
large-scale survey of cannabis use in California, titled Impact 64, which
was funded by the California Department of Cannabis Control and surveyed
over 4,000 Californians who currently use cannabis.

“Many people who currently use cannabis are unaware of regulations and laws
around driving and cannabis use, putting themselves and others at risk,”
said the study’s first author Sara Baird, MD, associate physician diplomate
at the UC San Diego Herbert Wertheim School of Public Health and Human
Longevity Science. “There is a clear need for targeted education
initiatives to address these knowledge gaps and promote safe driving
practices.”

As cannabis use becomes more mainstream, concerns about its risks to public
health, such as impaired driving, have increased. In order to mitigate
these risks, the Impact 64 study gathered both qualitative and quantitative
data about cannabis use in California through an online questionnaire. This
included questions about the driving-related provisions of Proposition 64,
such as the requirement that all cannabis containers in a vehicle be
unopened and that drivers and passengers cannot smoke or ingest cannabis in
a moving vehicle.

“One of the unique strengths of the Impact 64 study is its comprehensive
and representative design,” said Thomas Marcotte, PhD, the study’s senior
author, co-principal investigator of Impact 64, professor of psychiatry and
co-director of the Center for Medicinal Cannabis Research at UC San Diego
School of Medicine. “This data paints a detailed picture of how many people
in California are using cannabis and what they understand about the laws
governing its use.”

The researchers found:

- 64% of current cannabis users reported feeling safe to drive 3 hours
or less after inhalation of flower products (e.g. smoking, dry herb
vaping), and 55% felt safe to drive 5 hours or less after consumption of
edible cannabis products.
- Only 59% were aware that any container of cannabis inside a moving
vehicle must be unopened and sealed, including if stored in the trunk.
- 62% of current cannabis users were aware that drivers and passengers
cannot smoke or ingest cannabis in a moving vehicle, and 73% knew it was
true that driving under the influence of cannabis can result in a DUI
citation and/or arrest.
- Those with lower knowledge of Prop 64 driving related regulations were
more likely to ever have been pulled over or involved in a crash while
under the influence of cannabis.

“We need to educate the public about the risks of driving under the
influence of cannabis and the laws that are in place to protect public
safety,” said Linda Hill, MD, MPH, principal investigator of Impact 64,
distinguished professor at the UC San Diego Herbert Wertheim School of
Public Health and Human Longevity Science, and affiliate faculty at the
Qualcomm Institute. “Our study highlights the need for targeted education
initiatives for cannabis users and medical providers.”

Read the full study.

Additional co-authors of the study include Daniel Ageze, Sarah Hacker and
Renee Dell’Acqua at UC San Diego Herbert Wertheim School of Public Health
and Human Longevity Science and Alice Gold, Ilene Lanin-Kettering and Tom
Shaughnessy and at Quester.

This study was funded by the California Department of Cannabis Control
(Grant #: 65334).

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