Evaluating Utah's.05 BAC law: Alcohol-involved crash fatalities among 21-24y/o drivers compared to contiguous states.

Abstract

This study examined the change in alcohol crash fatalities among 21-24y/o drivers in Utah in comparison to its contiguous states before (2016) and after (2019) Utah enacted its.05g/dL blood alcohol concentration (BAC) per se law in 2018. Data from the Fatality Analysis Reporting System (FARS) were used. A difference-in-differences (DID) analysis was conducted to compare pre-law (2016) with post-law (2019) crash fatalities across four BAC levels (≥.01, ≥.05, ≥.08, and ≥.15g/dL) between Utah and contiguous states for 21-24y/o drivers involved in alcohol-impaired driving fatal crashes. We also present 11-year trends (2013-23) in alcohol-related crash fatalities per 100 million vehicle miles traveled (VMT) for 21-24y/o drivers. Of the 820 21-24y/o drivers involved in fatal crashes in Utah and six contiguous states, 371 (45.2%) were alcohol involved. Across 2013-2023, Utah consistently showed lower alcohol-related crash fatality per 100 million VMT across BAC thresholds compared to contiguous states. Following implementation of the.05 BAC law, Utah experienced notable post-policy declines over the 2016-2019 period, particularly among highly impaired drivers. DID models showed statistically significant reductions in crash fatalities for drivers with BAC ≥ .15 in Utah compared to contiguous states (p < .001), while effects at lower BAC levels were directionally protective but not statistically significant. Utah's.05 BAC law was associated with a significant reduction in the most severe alcohol-impaired crashes among young adult drivers, supporting lower BAC limits as an effective population-level injury prevention strategy for this known vulnerable population.