Zero Tolerance Laws

Young drivers are less likely than adults to drive while impaired, but their crash risk is substantially higher when they do. Drivers are considered to be alcohol-impaired when their blood alcohol concentration (BAC) level is greater than 0.01 g/dL.

In 2021, 27% of young drivers (ages15-20) involved in fatal crashes had blood alcohol concentrations (BACs) of .01 g/dL or higher; 22% of those young drivers had BACs of .08 g/dL or higher. A goal of public policy should be to enact zero tolerance laws with no acceptable BAC level. The aim of these zero tolerance laws is help prevent impaired driving.

While other countries have seen progress in alcohol-related crash deaths, the US as a whole has not. The US legal drinking limit is higher than in other countries, affecting the safety of all drivers, and among young drivers there is no safe limit for alcohol. It has long been known that any amount of alcohol is dangerous for young drivers and that the risk increases with greater amounts of alcohol in their system.

Alcohol affects reaction times and ability to drive safely as do other substances, like marijuana and prescription pills, that affect alertness. Youth who drive under the influence of alcohol or drugs put themselves and others at risk.  Adolescent drinkers are also more likely to ride as passengers of impaired drivers.

The dangers associated with alcohol and driving are exacerbated with the sadly common situation of binge drinking, a pattern of drinking that brings the person’s BAC to 0.8 grams percent or above in a short time – typically five drinks for men and four drinks for women in about two hours, according to the Centers for Disease Control and Prevention (CDC). This is a common dangerous practice, unfortunately, among adolescents who “pre-game” before going out.

Since 1988, all 50 states and the District of Columbia have implemented zero tolerance laws that set a limit of 0.02% BAC or lower for drivers under age 21. The 0.02 limit is equivalent to about one drink for the average person.

Although zero tolerance laws have been challenged based on their effectiveness, they have helped to significantly reduce the number of fatal crashes involving intoxicated young drivers. The first four states to reduce the legal BAC limit for young drivers (Maine, North Carolina, Wisconsin, and New Mexico) experienced a 34% decline in nighttime fatal crashes among young drivers. This decline was about one-third greater than a similar decline in four nearby states. An additional study of 12 states that passed zero tolerance laws reported a 20% reduction in single-vehicle nighttime fatal crashes among 15- to 25-year-old drivers.

Sixteen states have zero tolerance laws in effect for one or more drugs.

To learn more about zero tolerance laws in your state, visit the Mothers Against Drunk Driving website.

National Minimum Drinking Age Act

Until the 1980s, each state had its own laws determining the minimum drinking age. This led to the creation of “blood borders,” where teens would drive to states with lower drinking ages and be involved in fatal crashes on the return trip. In 1984, following an overall increase in alcohol-related traffic fatalities and injuries, Congress passed the National Minimum Drinking Age Act (NMDA), or the Federal Uniform Drinking Age Act, requiring states to legislate and enforce 21 as a minimum age for purchasing and publicly possessing alcoholic beverages. Since July 1988, all 50 states and the District of Columbia have enforced a legal drinking age of 21. The National Highway Traffic Safety Administration (NHTSA) estimates that Minimum Drinking Age laws have saved 31,959 lives since 1975.

Alcohol Policy Scale (APS)

To identify associations between alcohol policy environments and crash deaths among young people in the US, researchers used the Alcohol Policy Scale (APS) to rate alcohol policies and implementation in all 50 states and Washington DC. For each state and year, a panel of policy experts independently assessed each policy with regard to its efficacy for reducing excessive drinking or alcohol-related harm and the degree of legislative implementation for each policy.

States were ranked on how restrictive their alcohol policies were, including higher alcohol taxes and zero-tolerance policies for drivers younger than age 21. Then they cross-referenced the APS scores with crash data from the Fatality Analysis Reporting System (FARS). A 10 percentage-point increase in a state’s APS score was associated with a 9% decrease in the odds of alcohol-related crash fatalities. This research shows the effect of comprehensive alcohol policies on alcohol-related MVC fatalities among young people. 

Learn about marijuana driving laws.


In 2021, 27% of young drivers (ages15-20) involved in fatal crashes had blood alcohol concentrations (BACs) of .01 g/dL or higher; 22%  of those young drivers had BACs of .08 g/dL or higher.