Montana Department of Transportation

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Research

Driving After Cannabis Use

judges gavel over a photo of cannabis leaves

The purpose of this project was to develop a better understanding of the traffic safety culture (i.e., shared values, beliefs, and attitudes) of driving under the influence of cannabis (DUIC). A survey was developed based on an augmented integrated model of behavior and was implemented using mailed and internet-based methods. Adults age 18 and older from the U.S. responded. Two states with legalized recreational use of cannabis (Colorado and Washington) were oversampled. The survey measured DUIC behavior, intention, willingness, attitudes, behavioral beliefs, perceived norms, and perceived control. About half of the individuals who had used cannabis in the past 12 months reported driving within four hours of use. Partial correlation coefficients showed that many components of the model correlated with willingness to DUIC. Significant differences in attitudes and beliefs were found between non-users of cannabis, users of cannabis, and those who DUIC. No differences in beliefs or attitudes were found between states with and without legalized recreational use laws nor between states with legalized medical use laws. Recommendations for strategies to reduce DUIC are provided.