Study: Enactment of California’s Medical Marijuana Law Associated with Sustained Decline in Traffic Fatalities

Irvine, CA: The enactment of California’s 1996 medical cannabis access law is associated with a significant and a sustained decline in motor vehicle fatalities, according to data published in the Journal of Experimental Criminology.

A team of investigators from the University of California at Irvine assessed the relationship between the enactment of California’s medical cannabis law and statewide traffic fatalities. They estimated that California experienced a greater decline in fatal accidents compared to synthetic controls.

"California’s 1996 MML (medical marijuana law) appears to have produced a large, sustained decrease in statewide motor vehicle fatalities," they concluded. "To summarize, our results suggest that Proposition 215 led to a reduction in statewide motor vehicle fatalities amounting to an annual average reduction between 588 and 902 fewer motor vehicle fatalities annually between 1996 and 2015."

Separate reviews assessing the impact of statewide marijuana liberalization laws on traffic safety have also generally failed to identify any significant uptick in traffic accidents or fatalities attributable to the change in law.

Full text of the study, "Marijuana medicalization and motor vehicle fatalities: A synthetic control group approach," appears in the Journal of Experimental Criminology. Additional information is available from the NORML fact-sheet, "Marijuana and Psychomotor Performance."