Alcohol-related crashes in Utah fell nearly 9% over the four years after the state cut its drunk-driving limit to 0.05%, according to a new study from the Insurance Institute for Highway Safety. Utah remains the only state in the country with a limit that low. Every other state, along with Washington, D.C., sets the legal threshold at 0.08%.
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The result arrives as the holiday drinking season starts, and as Utah’s experiment moves past the point where a skeptic could blame a one-year blip.
What Utah changed on December 30, 2018
Utah was the first state to lower its blood alcohol concentration limit from 0.08% to 0.05%, and the law took effect on December 30, 2018, more than a year after it passed. The IIHS release describes the study as an extended evaluation of the law’s effect on crashes, written by IIHS senior research scientist Angela Eichelberger and independent researcher Scott Tippetts.
For a typical adult the difference between the two limits is not large in drinks, which is part of why the law drew attention. The IIHS overview of alcohol and driving notes that fatal crash risk climbs above 0.05% and rises faster after 0.08%. IIHS President David Harkey said crash risk increases with the amount of alcohol in the body but spikes noticeably at 0.05%, and that a lower limit is grounded in science.
Counting Utah crashes against three neighbouring states
The new paper widens the definition of an alcohol-involved crash. An earlier evaluation counted only crashes where police reported alcohol. This one also counts crashes where alcohol-positive test results were added to the record later, and crashes where the driver refused a test. Investigators then tracked the first four years of crashes after the law took effect.
Against Utah’s own past, the share of crashes involving alcohol dipped when the law was passed and dropped a further 9% once it took effect. Alcohol-related crashes overall fell nearly 9% across the four-year window, and injury crashes involving alcohol fell 12%.
The comparison with neighbors is where the finding sharpens. IIHS measured Utah against Arizona, Colorado and Idaho, and found that Utah’s share of alcohol-involved crashes dropped 12% to 21% relative to those states, where the comparable rates rose.
Where the evidence is thinner
Not every measure agreed. A proxy that treats single-vehicle nighttime crashes as a stand-in for drunk driving produced inconclusive results, according to the study as summarized by IIHS. The pandemic also complicates the picture: alcohol-involved crashes spiked 46% in March through May of 2020, though the average monthly share across the 34-month pandemic period rose only 6%. Excluding the pandemic months produced a larger reduction, but one that was not statistically significant because less data remained.
The researchers also flagged a cultural factor they could not model. Utah has one of the country’s lowest rates of alcohol-involved crashes, partly because many residents abstain for religious reasons, so results may differ elsewhere. A low baseline could cut either way, since a state with more drinking drivers might have more room to improve.
Publicity before the law took effect may also have changed behavior early, which is why the researchers analyzed the period between passage and implementation separately.
A second line of evidence, and the national toll
The IIHS paper is not the only recent look at Utah. In June, a team led by Kaigang Li and Federico Vaca, reporting in the American Journal of Preventive Medicine, compared county-level fatality data for 2013 through 2023 in Utah and six neighboring states, and found that alcohol-related crash fatalities fell significantly more in Utah, with no comparable change in non-alcohol deaths. The IIHS topic page separately reports a 20% drop in Utah’s fatal crash rate from 2016 to 2019, against 6% nationally.
The national stakes frame why other legislatures are watching. Harkey said more than 10,000 people die each year in alcohol-related crashes in the United States, and that Utah’s results should make other states take note. The federal government’s drunk-driving page at NHTSA and the CDC’s impaired-driving resources track the same toll from a national view.
The national numbers explain the interest. Per IIHS, 29% of fatally injured drivers in 2024 had a blood alcohol concentration of 0.08% or higher, a share that has changed little since 1994, and the institute describes progress on alcohol-impaired driving as stalled. Drivers below the legal limit can also be charged with impaired driving if they show signs of impairment, such as weaving, so a lower number changes where the automatic line sits rather than creating the offense.
No other statehouse has yet followed Utah’s lead, and the study does not say whether one will. The open question is whether a result built partly on a state with unusually low drinking rates can be carried into places where it is far more common.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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