Utah’s stricter 0.05 BAC limit significantly reduces drunk driving fatalities, analysis finds

A new analysis has found that after Utah lowered the legal blood alcohol concentration (BAC) limit for driving from 0.08 to 0.05 g/dL, alcohol-related crash fatalities declined significantly more in Utah than in its six contiguous states. The findings from the study published in the American Journal of Preventive Medicine, provide timely evidence that lowering the BAC limit may save lives and point to broad public safety benefits.

Driving under the influence of alcohol remains a major risk factor for motor vehicle crashes, with recent data showing stagnating reductions or a rise in fatalities over the past decade. In 2023, 12,429 crash fatalities in the U.S. involved at least one alcohol-impaired driver. Over the period 2014–2023, alcohol-impaired driving crashes consistently accounted for 28%–32% of all annual traffic fatalities in the U.S.

International research has consistently demonstrated that lowering the legal BAC limit to 0.05 effectively reduces alcohol-related crash injuries and fatalities by 11% or more. Utah was the first U.S. state to lower the legal BAC limit for driving from 0.08 to 0.05—the law was passed in 2017 and took effect in 2018—and remains the only state that enforces the lower limit. To date, all other states maintain a 0.08 threshold.

How the study compared states

Investigators in the current study analyzed national fatal crash data from the Fatality Analysis Reporting System (FARS) and compared county-level crash fatalities in Utah with those in Arizona, Colorado, Idaho, Nevada, New Mexico and Wyoming before and after the Utah 0.05 BAC law took effect (2013–2023). For the difference-in-differences analysis, a subsample including only crashes that occurred in 2016 and 2019 was used.

The most important finding was that Utah experienced larger declines in alcohol-related fatalities, while non-alcohol-related fatalities did not show the same policy-related change.

Lead author and co-investigator Kaigang Li, Ph.D., MEd, Department of Health and Exercise Science, Colorado State University, and Colorado School of Public Health, Fort Collins, says, “This is one of the most rigorous U.S.-based evaluations of a 0.05 BAC law using county-level comparative data. At a time when alcohol-impaired driving deaths remain a persistent national public health problem, these findings provide timely evidence that lowering the BAC limit may save lives.”

The researchers were highly encouraged to see that reductions were not limited only to drivers near the 0.05 threshold but extended across higher BAC levels as well. This suggests the law may have had a broader deterrent effect on drinking and driving behavior.

Barriers to wider adoption

Despite documented lifesaving policy benefits in Utah and other nations, and strong endorsement from the National Transportation Safety Board (NTSB), political resistance, public misunderstanding and cultural norms remain barriers to adopting a national 0.05 BAC limit, the investigators point out.

Lead investigator Federico E. Vaca, MD, MPH, University of California Irvine School of Medicine, Irvine, notes, “In the last decade for which we have federally published U.S. crash data (2014–2023) available, the number of alcohol-impaired driving crash fatalities increased by 25% and the corresponding fatality rate increased by 15%.

“There is just so much opportunity here for collective prevention efforts to reduce serious injury and save more lives on our roadways. Each year of delay in enacting this policy represents a lost opportunity to prevent thousands of fatalities among drivers, passengers and all road users.”

Li concludes, “Our findings suggest that stronger impaired-driving laws can influence drivers’ behavior and reduce preventable traffic deaths. Utah’s experience shows important and additional evidence for policymakers nationwide.”

Who’s behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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