Background on: Alcohol-impaired driving


Alcohol is a major factor in traffic crashes. Based on data from the U.S. Department of Transportation, National Highway Traffic Safety Administration (NHTSA), 10,142 people died in alcohol-impaired crashes in 2019. These crashes involve at least one driver or motorcycle operator with a blood alcohol concentration (BAC) of 0.08 grams per deciliter or above, the legal definition of impaired driving in most states. According to NHTSA, alcohol-impaired crash fatalities accounted for 28 percent of all crash fatalities in 2019, the lowest proportion on record.

Combating the alcohol-impaired driving problem

Despite significant reductions in alcohol-related fatalities in the past 30 years, progress stalled in the mid-2000s as fatalities plateaued at 10,000 lives a year lost. Organizations such as the U.S. Department of Transportation, the Insurance Institute for Highway Safety, the Governors Highway Safety Administration and Mothers Against Drunk Driving (MADD) have developed blueprints designed to prevent alcohol-impaired deaths. While about two dozen specific laws and administrative solutions have been identified, most organizations have focused on a handful of laws that have been proven to be effective in reducing fatalities involving alcohol-impaired driving.

The definition of alcohol-impaired driving was consistent throughout the United States until December 2018. All states and the District of Columbia except Utah define impairment as driving with a BAC (blood alcohol concentration) at or above 0.08 grams per deciliter. In Utah, the BAC limit was lowered to 0.05 in December 2018. In addition, they all have zero tolerance laws prohibiting drivers under the age of 21 from drinking and driving. Generally, the BAC limit in these cases is 0.02 percent. Campaigns combating alcohol-impaired driving especially target drivers under the age of 21, repeat offenders and 21-to 34-year-olds, the age group that is responsible for more alcohol-related fatal crashes than any other. Young drivers are least responsive to arguments against impaired driving, according to NHTSA.

A major tool in preventing fatalities is discouraging impaired driving which requires strong laws and enforcement. Laws that enforce the BAC level are administrative license revocation, where a driver’s license is immediately taken away if a BAC tests proves the driver’s BAC is over 0.08 grams per deciliter or the driver refuses to take a BAC test. Well-publicized programs that bring attention to the problem are important deterrents, and include sobriety checkpoints, where law enforcers screen drivers for evidence of impaired driving.

Another key tool is preventing repeat offenses. Research has underscored the danger of repeat offenders. The National Highway Traffic Safety Administration (NHTSA) has said that out of the 1.5 million arrests of impaired drivers each year, one-third are repeat offenders. Based on data for 2007, the agency said that drivers with a BAC of 0.08 grams per deciliter or higher involved in fatal crashes were eight times more likely to have a prior conviction for driving while impaired than drivers who had no alcohol in their blood. A report published in May 2010 by the American Journal of Public Health studying over 100 million driving records spanning the years 1973 to 2008 found that the recidivism rate among first offenders more closely resembles that of second offenders than of nonoffenders. This finding indicates that leniency for first offenders is not appropriate, according to the Director of Law Enforcement at the American Association of Motor Vehicle Administrators. Research collated by the National Traffic Law Center and MADD found that first offenders are very likely to have driven impaired before their first arrest. Studies found that on average, one arrest is made for every 88 instances of driving over the legal limit defining alcohol-impaired driving.

Ignition interlocks, which require drivers to blow into a breathalyzer-like device to ensure the individual is sober before allowing the vehicle to start, were first mandated by New Mexico in 2005. Only five states (Indiana, Montana, North Dakota, South Dakota and Wisconsin) have no laws that mandate interlock use for any driver, whether they are first offenders or repeat offenders.

Ignition interlocks­­ have been shown to reduce fatalities. The Johns Hopkins Bloomberg School of Public Health found in a report released in January 2017 that traffic fatalities declined by 7 percent in states that mandate ignition interlocks for first-time alcohol-impaired offenders. The researchers studied traffic fatalities for about five years before states began passing interlock laws in the late 1980s through 2013, when all states required them under some circumstances. The Centers for Disease Control (CDC) has studied ignition interlocks and based on the strong evidence of their effectiveness in reducing re-arrest rates recommends their use. In March 2018 the Insurance Institute for Highway Safety (IIHS) reported that that laws requiring all impaired driving offenders to install ignition interlocks reduce the number of impaired drivers in fatal crashes by 16 percent. The IIHS says that if all states adopted the most stringent laws—those that require interlocks for all offenders, including first offenders, over 500 additional lives could be saved each year. In comparison to the 16 percent of impaired drivers—including first offenders—who would be kept off U.S roads if the strictest laws were enacted, only 3 percent of impaired drivers would be kept off the road if interlocks were mandated for repeat offenders only, and only 8 percent if repeat offenders and very high blood-alcohol content impaired drivers were mandated to use the devices.

As a condition of their use, interlocks are programmed for random retests after the driver has shown sobriety at the onset of driving. These rolling retests can occur at any point in a driver’s route, including heavy traffic or high-speed highways. A 2019 New York Times report found that there have been some crashes caused by drivers who became distracted by using interlocks for random on-route tests. In North Carolina, a state that makes most crash records public, there were 58 crashes attributed to ignition interlock use over 10 years.  Data was not available for other states.

Historic perspective

Awareness of the problems associated with alcohol-impaired driving increased dramatically in the 1990s in response to the rise of citizen activist groups, notably Mothers Against Drunk Drivers (MADD), and advertising campaigns and publicity efforts by organizations such as the Insurance Information Institute. Existing laws were strengthened, new laws were passed and task forces were created in several states. In addition, there was a noticeable change in attitudes toward drinking and driving.

Federal Legislation: In 1984 Congress enacted legislation that required highway construction funds to be withheld from states that did not adopt 21 as the legal drinking age for alcoholic beverages. This was the first time that federal legislation used financial incentives to persuade states to enact alcohol-impaired driving laws. The Omnibus Drug Initiative Act of 1988 (also called the Drunk Driving Prevention Act), helped to increase the adoption of the administrative license revocation law (ALR), which allows a driver's license to be seized when his or her BAC (blood alcohol concentration) is over the level that defines driving while intoxicated or when the driver refuses to take a BAC test. It has been shown to be one of the most effective deterrents to impaired driving. Other laws enacted include those that prohibit open alcoholic beverage containers in the passenger compartments of motor vehicles, make BAC tests mandatory for drivers involved in serious or fatal accidents, prevent drivers under 21 from obtaining alcohol and provide for vehicle registration cancellation when drivers have had their licenses suspended or revoked due to alcohol-related offenses.

The 1991 Surface Transportation Efficiency Act mandated that states had to pass four out of five laws that were recognized as having the greatest effect on impaired driving: ALR laws; lowering the legal BAC limit to 0.08 grams per deciliter; using sobriety checkpoints, which remove impaired drivers from the road immediately and remind other drivers that random checks could occur at any time; establishing effective systems for preventing drivers under 21 from obtaining alcohol; and providing education programs for convicted alcohol-impaired drivers, funded by the fines assessed against those drivers. Enacting other laws brought additional funds. In 1995 the National Highway Bill further encouraged states to enact the 0.02 BAC level for drivers under 21 by holding back a portion of federal highway funds.

By the late 1990s the campaign against impaired driving focused on lowering the national limit for alcohol-impaired driving from 0.10 to 0.08 grams per deciliter BAC. The 2000 Transportation Appropriations Act mandated that states that did not enact the 0.08 grams per deciliter BAC standard would forfeit highway construction funds. By 2004 all states and the District of Columbia had enacted the 0.08 grams per deciliter BAC standard.

The Safe, Accountable, Flexible and Efficient Transportation Equity Act of 2005 included funding incentives for states that pass laws that target three types of impaired drivers: repeat offenders, drivers with BACs over 0.15 percent (“higher-risk drunk drivers”) and drivers whose licenses were previously revoked for impaired driving. It also withholds a certain percentage of funding from states that do not have an open container law (one that prohibits at least the driver of a car from having an open container of alcohol in the passenger compartment of a motor vehicle). Among the more serious penalties included for convicted higher-risk impaired drivers are license revocation; vehicle impoundment; and use of ignition interlocks.

MAP-21, enacted in 2012, contained a formula where states could be classified into three groups using average impaired driving fatality rates. States having the worst rates must assess their impaired driving programs and convene a task force to develop prevention plans before grant funds are disbursed, among other requirements. MAP-21 also allows states to receive separate grants for adopting and enforcing mandatory interlock laws for all drivers convicted of impaired driving. It also required that states that did not have open container or minimum penalties for repeat offenders have some state highway funds withheld.

Legal climate: Alcohol-impaired driving laws have been tested frequently in court. In 1990, for example, the New Jersey Supreme Court ruled that drivers accused of impaired driving do not have the right to a jury trial. Utah is the only other state to deny jury trials in these cases. The constitutionality of roadblocks to check driver sobriety was contested in state courts in the 1980s, and in 1990 the issue came before the U.S. Supreme Court, which ruled in Michigan vs. Sitz (No.88-1897) that sobriety checkpoints are a valid tool for detecting and apprehending intoxicated drivers and do not violate the Fourth Amendment that prohibits illegal search and seizure. (It was later remanded to the state court, which ruled it unconstitutional in Michigan). Despite the decision, roadblocks are still opposed in some state courts. and about 10 states prohibit the use of sobriety checkpoints, according to the Insurance Institute for Highway Safety.

Another important case decided by the U.S. Supreme Court in 1990 was Pennsylvania vs. Muniz (No.89-213), in which the court ruled that videotaped evidence of impaired physical performance by an impaired driver is admissible.

In 2013 the U.S. Supreme Court ruled in Missouri vs. McNeely that police officers must attempt to get a warrant before forcing impaired driving suspects to submit to a blood test. Despite the fact that blood alcohol levels will become lower over time, the court said that the dissipation of alcohol does not amount to an automatic exception to the ruling. If police officers can reasonably obtain a warrant within the amount of time that would not affect a blood test, they must do so.


Commercial servers: Most states and the District of Columbia have laws on the books or case law (law that comes about through a court ruling rather than an act of the legislature) that hold commercial servers of alcohol liable for the harm caused by their intoxicated patrons.

Social hosts: Many states have enacted laws or have case law that permit social hosts who serve liquor to people who subsequently are involved in crashes to be held liable for any injury or death. These laws may have limited application, for example, many laws specify that the drinker must be obviously intoxicated. In some cases, the laws only pertain to serving alcohol to minors. Homeowners insurance usually provides some liquor liability coverage, but limits are typically only $100,000 to $300,000.

Charts and graphs

Total Traffic And Alcohol-Impaired Crash Fatalities, 1985-2021 (1)


    Alcohol-impaired crash fatalities (1)
Year Total traffic
Number As a percent of
all crash deaths
1985 43,825 18,125 41%
1990 44,599 17,705 40
1995 41,817 13,478 32
2000 41,945 13,324 32
2005 43,510 13,582 31
2010 32,999 10,136 31
2011 32,479 9,865 30
2012 33,782 10,336 31
2013 32,894 10,110 31
2014 32,744 9,943 30
2015 35,485 10,320 30
2016 37,806 10,967 29
2017 37,473 10,880 29
2018 36,835 10,710 29
2019 36,355 10,196 28
2020 39,007 11,718 30
2021 42,939 13,384 31

(1) Alcohol-impaired driving crashes are crashes that involve at least one driver or a motorcycle operator with a blood alcohol concentration (BAC) of 0.08 grams per deciliter or above, the legal definition of alcohol-impaired driving in most states.

Source: U.S. Department of Transportation, National Highway Traffic Safety Administration.

View Archived Tables

Percent Of Drivers Involved In Fatal Crashes Impaired By Alcohol By Age, 2012 And 2021 (1)


Age 2012 2021 Point change
15 to 20 17% 17% 0 pts.
21 to 24 32 27 -5
25 to 34 29 27 -2
35 to 44 24 23 -1
45 to 54 21 20 -1
55 to 64 13 16 3
65 to 74 8 12 4
Over 74 5 8 3

(1) Alcohol-impaired driving crashes are crashes that involve at least one driver or a motorcycle operator with a blood alcohol concentration (BAC) of 0.08 grams per deciliter or above, the legal definition of alcohol-impaired driving in most states.

Source: U.S. Department of Transportation, National Highway Traffic Safety Administration.

View Archived Tables

Persons Killed In Total And Alcohol-Impaired Crashes By Person Type, 2021


    Alcohol-impaired crash fatalities (1)
Person type Total killed Number Percent of
total killed
Vehicle occupants      
     Driver 21,786 7,668 35%
     Passenger 6,527 2,078 32
     Unknown occupant 45 8 18
     Total 28,358 9,754 34%
Motorcyclists 5,932 2,023 34%
     Pedestrian 7,388 1,383 19
     Pedalcyclist 966 157 16
     Other/unknown 295 67 23
     Total 8,649 1,607 19%
Total 42,939 13,384 31%

(1) Alcohol-impaired driving crashes are crashes that involve at least one driver or a motorcycle operator with a blood alcohol concentration (BAC) of 0.08 grams per deciliter or greater, the legal definition of alcohol-impaired driving.

Source: U.S. Department of Transportation, National Highway Traffic Safety Administration.

View Archived Tables


Additional resources

"Traffic Safety Facts, Alcohol," U.S. Department of Transportation, The National Center for Statistics and Analysis, NHTSA, annual issues.

Mothers Against Drunk Driving (MADD)

The Insurance Institute for Highway Safety (IIHS)

The Governors Highway Safety Administration

Governors Highway Safety Association Alcohol-Impaired Driving Chart

IIHS, Alcohol Laws


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Facts + Statistics: Alcohol-impaired driving
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