DMV and CHP Partner with UC San Diego to Launch Groundbreaking Study to Improve Public Safety and Develop Best Practices to Detect Driving Impairment in Cannabis Users

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2415 First Avenue
Sacramento, CA 95818
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July 18, 2023

Sacramento – The California Department of Motor Vehicles, in partnership with the California Highway Patrol and the University of California, San Diego, is seeking 300 volunteers from the Sacramento area to participate in a study to test various methods to detect cannabis-impaired driving. The U.S. Food and Drug Administration-approved research project is set to begin in August.

Volunteers must be between the ages of 21 and 55, possess a valid California driver’s license, be a current cannabis user willing to abstain from cannabis use prior to participation, and live within approximately 15 miles of the CHP Academy in West Sacramento. Volunteers who are selected for the study will receive up to $150 for their participation.

Those interested in participating in the study can find out more today on the DMV website. Potential volunteers will be asked to complete a preliminary screening questionnaire.

Cannabis affects driving in ways that are distinct from other substances, such as alcohol. While having a blood-alcohol content (BAC) of greater than .08 percent is sufficient to conclude that a motorist is not able to safely operate a motor vehicle, no comparable number exists for cannabis.

“Throughout California, we are seeing an alarming increase in the number of crashes involving drivers impaired by drugs,” said CHP Commissioner Sean Duryee. “Working in collaboration with our traffic safety partners and key stakeholders on this groundbreaking study will provide potentially lifesaving information, resulting in safer roadways in California for all who use them.”

In the last three years, California has seen an increase of 62% in the number of fatal crashes involving drug-related impairment, from 173 in 2018 to 280 in 2021. This was in line with similarly alarming trends throughout the country, underscoring the importance of research to better understand how cannabis and other drugs impair driving and establishing best practices for detecting drug-impaired drivers.

The study will include random double-blind assignment of substance. Participating drivers will receive either a real cannabis product, a placebo, or no substance. This means that neither participants, researchers nor officers involved in the study will know whether a driver consumed cannabis at the time of that driver’s participation.

Participating drivers will operate a vehicle within a safe, closed-course environment at the California Highway Patrol Academy in West Sacramento, rather than a driving simulator. The vehicle will be equipped with instruments that record driver actions and vehicle movements. Every correction made by the driver to the steering wheel, changes in acceleration and braking, as well as the vehicle’s position to the accuracy of 2 centimeters will be measured multiple times per second.

“This is a great opportunity for folks to be part of a unique test with potential to impact Californians and traffic safety for decades,” said DMV Director Steve Gordon.

The current enforcement of cannabis (and other drug) impairment relies on behavioral methods of detecting impairment. These include the various cues that law enforcement officers are trained to look for, including erratic driving behaviors, field sobriety tests and an additional evaluation from a Drug Recognition Expert (DRE) to determine the substance(s) causing impairment.

The goal of this study, expected to last between nine and 18 months, is to determine how well these methods detect cannabis-impaired driving and to help identify new indicators of this kind of impairment.

This study is being conducted using funds allocated to the CHP for research on cannabis-impaired driving under Senate Bill 94 (2017). The Research and Development Branch of the DMV is conducting this study in collaboration with CHP and the Center for Medicinal Cannabis Research at the University of California, San Diego.


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