What’s The Legal Blood Alcohol Limit For Driving?

In late 2018, Utah reduced its legal drunk-driving limit from a blood-alcohol content (B.A.C.) of .08 to .05.

A year after this law was enacted, the National Highway Traffic Safety Administration reported that fatal car crashes in the state had decreased by nearly 20 percent.

“I never expected to see such a significant impact in Utah,” said James Fell, a principal research scientist specializing in traffic safety at the independent research organization NORC, based at the University of Chicago. He noted that Utah already had one of the lowest impaired driving rates in the United States.

Currently, Utah is the only state with a .05 drunk-driving limit; all other states maintain a .08 limit. However, on an international scale, Utah is not alone. Countries such as Australia, France, Thailand, and about 50 others have a B.A.C. limit of .05, with more than 30 nations setting even stricter limits.

As U.S. drunk-driving fatalities have risen in recent years—by about 33 percent between 2019 and 2022, according to the most recent data—several other states, including New York, Washington, Hawaii, and Connecticut, are now contemplating similar legislation to lower the legal driving limit.

“We’re losing over 13,000 people annually on the highways,” said Thomas Chapman, a member of the National Transportation Safety Board. “It’s just an astonishing number.” In 2022, drunk-driving accidents accounted for 32 percent of all traffic fatalities.

The current national drunk-driving limit wasn’t established until 2000, when Congress passed a bill requiring all states to set their B.A.C. limit at .08 to continue receiving federal highway funds. Before then, some states used .08, while others set the limit at .10.

At that time, some researchers and advocates argued that the limit should be as low as .05, said Linda Degutis, a lecturer at the Yale School of Public Health and former director focused on injury prevention at the Centers for Disease Control and Prevention. “The .08 was essentially a compromise,” she explained.

Experts argue that scientific evidence strongly supports a lower B.A.C. limit. Multiple studies have demonstrated that cognitive functions, such as sustained attention and multitasking, are already impaired at .05. People also tend to become drowsy at even lower levels of intoxication. And in driving simulators used in lab settings, individuals consistently perform worse with any amount of alcohol in their system.

When examining how these impairments impact driving in real-world conditions, one study found that individuals with a B.A.C. of .05 had a 38 percent higher risk of being involved in a car crash compared to those with no alcohol in their system; at .08, the risk increased to 169 percent. Additionally, an analysis conducted by Mr. Fell in 2017 estimated that lowering the legal limit nationally to .05 could reduce alcohol-related fatal crashes by 11 percent, potentially saving nearly 1,800 lives per year.

Generally speaking, a B.A.C. of .05 results from consuming two drinks in two hours for a 150-pound woman, and three drinks in two hours for a 200-pound man. Factors such as body weight, the time elapsed since the first drink, and whether food has been consumed all influence B.A.C. levels. It’s also important to note that “a drink” typically refers to one 12-ounce beer with 5 percent alcohol, one 5-ounce glass of wine, or one 1.5-ounce shot of spirits. Stronger beers, generous wine pours, and mixed drinks with multiple shots will raise B.A.C. levels even higher.

A lower B.A.C. limit is supported by a wide range of organizations, including the National Transportation Safety Board, the National Safety Council, the National Academies of Sciences, Engineering and Medicine, and advocacy groups such as Mothers Against Drunk Driving. Even AB InBev, the beer company behind brands like Budweiser, Corona, and Stella Artois, does not oppose lowering the limit.

According to experts interviewed for this article, one of the primary opponents is the hospitality industry, which contends that a B.A.C. limit of .05 would negatively impact restaurants and bars. (National and state alcohol and restaurant groups did not respond to multiple requests for comment.) During the push for a national limit in 2000, Dr. Degutis mentioned that industry representatives argued that if the limit were set too low, people wouldn’t be able to enjoy a glass of wine or a cocktail with dinner.

“We know that it takes a little more than one glass of wine or one cocktail to reach a B.A.C. of .05,” Dr. Degutis said. “But, you know, this was their argument: that this would really harm their economy and their ability to attract customers.”

In Utah, however, there was little evidence to support these concerns. The National Highway Traffic Safety Administration found that alcohol sales in the state continued to rise steadily from 2012 to 2020 and were not negatively impacted by the law’s passage or implementation. This study provided “important” evidence that a lower B.A.C. limit did not have a “negative impact on alcohol sales, tax revenues, or tourism,” Mr. Chapman noted.

Rather than drinking less, the report suggested that people were more likely to seek alternative transportation home.

In approximately half of all fatal alcohol-related crashes, drivers have a B.A.C. of .15 or higher, so a lower limit may not deter the worst offenders any more effectively than current laws. However, it could influence those who are mindful of the limit but may not recognize when they are impaired.

“The reason it works is that it serves as a general deterrent to drinking and driving,” Mr. Fell explained. “People don’t know exactly what .05 means; all they know is that the legal limit for drinking has been lowered, so they need to be more cautious.”