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In 2018, Utah lowered the legal blood-alcohol limit (BAC) for drivers from 0.08% to 0.05%, making it the lowest limit in the country as of this writing. The news was initially faced with resistance from casual drinkers, alcohol industry lobbyists, and restaurant groups, who all warned about the possible effects of the mandate. While restaurateurs feared a loss of business, casual drinkers were concerned that the law would criminalize dinnertime "single-drink" outings on DUI-prone cars. With studies indicating that alcohol-induced impairment starts well before a BAC of 0.08%, Utah's decision, at least on paper, made sense. What was left was to see if this change would eventually have an effect on DUI cases and alcohol-related accidents.
Two years after Utah's revised BAC came into effect, the National Highway Traffic Safety Administration (NHTSA) published a study that appeared to show that Utah's revised BAC limit was indeed having an effect. A year after the change was implemented, Utah's fatal crash rate drop by 19.8% and the fatality rate decrease by 18.3%. If that wasn't all, there was no spike in the number of DUI arrests in the same period. Lastly, there was no major financial impact of the revised BAC limit when it came to tourism, restaurants, or alcohol sales in general — as some people had originally feared.
These findings indicate that the revised BAC law was a raging success without having too much of an effect on people's driving records. However, these conclusions were based on a single NHTSA study that mostly contained data from 2019. Given that many years have passed since the change happened, we decided to investigate what the true long-term impact of the BAC mandate has been.
Did the NHTSA study arrive at a hasty conclusion?
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Additional studies have indicated that the initial NHTSA report may have overestimated the real impact of Utah's lowered BAC law. One such study, published in 2024 in the journal Health Economics, found that while police-reported crashes dipped after Utah adopted the 0.05% limit, insurance-claim data did not show the same decline. The study concluded that this gap likely arose because drivers were more hesitant to report minor accidents (like a DUI on an electric scooter) to the police. This could be due to a concern that any accident might lead to a breath test under the new limit.
Meanwhile, another 2024 report from the Utah Commission on Criminal and Juvenile Justice revealed that DUI arrests and alcohol-related traffic deaths in Utah had already been declining several years before the 0.05% law came into force. That means that the drop in fatality rates may not have been caused by the BAC limit change, and could instead be part of a longer, ongoing decline in impaired-driving deaths. Additionally, the report noted that over 40% of people who were arrested under DUI charges in Utah typically had a BAC level of at least 0.15%, which is much higher than the 0.05 limit imposed by the state.
At the same time, 10% of arrests involved BAC levels between 0.05% and 0.07%, which would suggest that the law did have some impact on DUI rates. Ultimately, however, it is always challenging to determine the effects of a law through research because there can be so many other factors influencing population-level trends. While these newer studies do not entirely refute the early findings of the NHTSA study, they do remind us to be weary of oversimplifying complex trends before reaching a conclusion.
