Utah law linked to drop in alcohol-related crashes

Utah's stricter alcohol limit linked to lasting drop in alcohol-related crashes

October 27, 2026

Utah saw a long-term drop in alcohol-related crashes after it imposed a stricter limit on the amount of alcohol drivers are allowed to have in their system, a new study from the Insurance Institute for Highway Safety shows.

Utah became the first U.S. state to lower the blood alcohol concentration (BAC) threshold for impaired driving to 0.05% from 0.08% in December 2018 and remains the only one. The stricter limit was associated with a nearly 9% reduction in alcohol-related crashes over the next four years, researchers found.

"Crash risk increases with the amount of alcohol in your system, but it spikes noticeably at 0.05%," IIHS President David Harkey said. "A lower limit is grounded in science and also sends a message that buzzed driving is drunk driving, as the slogan goes."

U.S. states began widely adopting per se laws, which make it a crime to drive with a BAC above a certain limit even if the driver does not appear to be intoxicated, in the 1980s. Limits were initially set as high as 0.15%, and remained at 0.10% in many states for quite some time. A BAC limit of 0.08% only became universal in 2005, after the Department of Transportation made it a requirement to receive certain federal highway funds.

In 2013, the National Transportation Safety Board recommended that states lower their limits further, to 0.05%. A BAC of this level significantly impairs depth perception and slows reaction time, the agency argued, and other industrialized nations had seen immediate drops in fatal collisions when they adopted a 0.05% limit.

Utah's 0.05% per se law went into effect on Dec. 30, 2018. While an earlier study showed a substantial drop in fatal crashes over the first year, the impact on alcohol-involved crashes was unclear.

To bring the picture into focus, IIHS Senior Research Scientist Angela Eichelberger and independent researcher Scott Tippetts analyzed the first four years of crash data. While the earlier study relied on police reports of alcohol involvement, the new study also counted other crashes as alcohol-involved. These included cases in which alcohol-positive test results were added to the crash report later and cases in which the driver refused to take a BAC test.

In addition, the IIHS researchers looked at changes in the number of single-vehicle nighttime crashes - which can be used as a proxy for alcohol involvement. They also compared Utah's alcohol-involved crash rates before and after the implementation of the law with crash rates in Arizona, Idaho and Colorado.

Several complicating factors influenced the results. First, Utah has always had one of the lowest rates of alcohol-involved crashes in the United States because many residents abstain from alcohol for religious reasons. Secondly, the state passed its 0.05% BAC law with great fanfare more than a year before it was implemented, and the publicity may have affected people's behavior before the law took effect. Finally, the COVID-19 pandemic, which resulted in spikes in alcohol use and drinking and driving nationwide, occurred midway through the study period.

The IIHS researchers accounted for the pre-implementation fanfare by looking at the period between the law's passage and when it took effect separately. To account for the pandemic, they examined two different post-implementation periods (before the pandemic and the entire time including the pandemic).

They could not account for Utah's unique alcohol culture. That could mean that a 0.05% per se law might not have as large an impact in other states. However, it could also mean the effect in other states could be even larger. That's because the base level of alcohol-involved crashes in Utah was relatively low, making it harder to move the needle.

Nevertheless, the reduction in Utah was substantial, the study showed.

Relative to the previous several years, the percentage of crashes involving alcohol dipped when the 0.05% per se law was passed and dropped a further 9% when the law went into effect.

While alcohol-involved crashes in Utah spiked 46% in March-May 2020 with the COVID-19 lockdown, the dramatic increase was fleeting. Over the entire 34-month COVID-19 pandemic, the average share of crashes each month that involved alcohol increased by 6%. When those nearly three years are excluded, the reduction in alcohol-involved crashes associated with the law change is larger but not statistically significant due to the smaller amount of data.

The other analyses mostly bolstered those results. While the results for single-vehicle nighttime crashes were inconclusive, the percentage of injury crashes involving alcohol fell 12%. Moreover, though alcohol-involvement rates also spiked in Arizona, Colorado and Idaho at the onset of the pandemic, those states did not show reductions comparable to Utah's in the period following its implementation of the new law.

In fact, the long-term effect of Utah's 0.05% law looks more impressive against the comparison states, where the rate of alcohol-involved crashes increased. Relative to the three other states, the share of crashes that involved alcohol in Utah dropped 12%-21%.

The relative decrease was similar even when the pandemic was excluded.

"These encouraging results from Utah should make other states take note," Harkey said. "More than 10,000 people lose their lives in alcohol-related crashes every year in the U.S. We need to use every tool we have, including stricter BAC limits, to reduce that toll."