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Policy Impact: Impaired Driving

What's the Issue?

Each year, millions of people choose to drive while under the influence of alcohol, sometimes with devastating results. In 2009, almost 11,000 people were killed in crashes involving impaired drivers, nearly one-third of all traffic deaths.1

Alcohol-impaired driving crashes claim the lives of the most vulnerable: in a single year, these crashes killed more than 180 children younger than 14.2 Half of the children killed in alcohol-impaired driving crashes were riding in the car with the impaired driver.2

These deaths are preventable. Research has identified proven policies that can keep alcohol-impaired drivers off the road and save thousands of lives each year.

What Do We Know?

Drivers with previous driving while impaired (DWI) convictions pose a substantial risk of offending again. Data show that legally impaired drivers involved in fatal crashes were eight times more likely to have a prior DWI conviction than drivers who had not been drinking.2

Millions of adults drive while impaired, but only a fraction are arrested. In 2009, an estimated 1.4 million arrests were made for driving under the influence.3 This is less than one percent of the 147 million self-reported episodes of alcohol-impaired driving among U.S. adults each year.4

Young drivers who drink have the greatest risk of dying in an alcohol-impaired crash. At all levels of blood alcohol concentration (BAC), young drivers have a greater risk of dying in a crash than older drivers with the same BAC.5

In 2009, nearly one-third of drivers age 21 to 34 in a fatal crash were legally impaired.

Nearly one-third of crash deaths involve an alcohol impaired driver1

Pie chart showing that one-third of crash deaths involve an alcohol-impaired driver. Alcohol-impaired driving deaths = 10,839; other driving deaths = 22,969.

Impaired Drivers Involved in Fatal Crashes are Often Well Over the Illegal Threshold of 0.08% BAC2

Bar chart showing that in 2009, 84 percent (10,102) of the 12,012 drivers with a BAC of .01 or higher who were involved in fatal crashes had BAC levels at or above .08, and 56 percent (6,685) had BAC levels at or above .15. The most frequently recorded BAC level among drinking drivers in fatal crashes was .17.

What Can We Do?

While disturbing, the facts about alcohol-impaired driving also show the way forward. Policies must help keep drivers with a history of DWI from offending again, support high visibility enforcement of impaired driving laws, and better protect young drivers.

Alcohol-impaired driving is a serious, but preventable, problem. The following recommended policies are some of the proven-effective ways to prevent alcoholimpaired driving. They are key steps toward preventing the nearly 11,000 deaths caused by alcohol-impaired driving crashes every year.

CDC Recommendations

Ignition interlocks for all convicted DWI offenders
Ignition interlocks, or in-car breathalyzers, are devices that can be installed in vehicles to prevent persons who have consumed alcohol from driving. They are typically installed after a driver has been convicted of DWI.6

Research shows that ignition interlocks can reduce the rate of re-arrest among drivers convicted of DWI by a median of 67%,6 making them more effective than other prevention methods. Drivers with interlocks had fewer alcohol-impaired driving crashes than drivers who had their drivers’ licenses suspended because of a DWI conviction.6

States that mandate ignition interlocks for everyone convicted of DWI can reduce alcohol-impaired driving crashes and save lives.

Installation of ignition interlocks reduces re-arrest rates by a median of 67%.

Expanded use of sobriety checkpoints
At sobriety checkpoints, law enforcement officers stop drivers to assess their level of alcohol impairment. Checkpoints do more than simply increase arrests; they deter impaired driving by increasing drivers’ perceived risk of arrest if they choose to get behind the wheel after drinking.

Research has shown that checkpoints prevent impaired driving. A review of more than 20 studies shows that checkpoints resulted in a median 20% decrease in impaired driving crashes and deaths.7

States that have sobriety checkpoints should consider expanding their use. States without checkpoints should consider trying to gain authority to conduct this life-saving law enforcement practice.

Maintain and enforce minimum legal drinking age and zero tolerance laws
In all 50 states, the minimum legal drinking age (MLDA) prohibits the sale of alcohol to people under age 21. Maintaining 21 as the MLDA will prevent impaired driving among our least experienced drivers. Research shows that lowering the MLDA can increase alcohol-impaired crashes involving young drivers by a median of 10%.8

Equally important are laws that crack down on drivers under age 21 who drive after consuming alcohol. All states have “zero-tolerance laws” that prohibit young people from driving with any detectable BAC. Such measures lower the fatal crash rate between 9% and 24%.9

States should maintain their MLDA at 21and vigorously enforce MLDA and zero tolerance laws.

How State Ignition Interlock Laws Measure Up

As of February 2011, more than half of all states require some DWI offenders to install ignition interlocks, but only 13 states require interlocks for all convicted offenders, even on a first conviction.10

See alphabetical listing of states with rankings for ignition interlock systems.

Map of the United States


  1. Dept of Transportation (US), National Highway Traffic Safety Administration (NHTSA). Traffic Safety Facts 2009: Highlights of 2009 Motor Vehicle Crashes. Washington (DC): NHTSA; 2010. Available at URL:
  2. Dept of Transportation (US), National Highway Traffic Safety Administration (NHTSA). Traffic Safety Facts 2009: Alcohol-Impaired Driving. Washington (DC): NHTSA; 2009. Available at URL:
  3. Department of Justice (US), Federal Bureau of Investigation (FBI). Crime in the United States 2009: Uniform Crime Reports. Washington (DC): FBI; 2010 [cited 2010 Dec 20]. Available at URL:
  4. Shults RA, Beck L, Dellinger AM. Self-Reported Alcohol-Impaired Driving Among Adults in the United States, 2006 and 2008. Presented at: Safety 2010 World Conference: 2010 Sept. 21-24, London, ENG (Presentation #0264). Abstract available at URL:
  5. Zador PL, Krawchuk SA, Voas RB. Alcohol-related relative risk of driver fatalities and driver involvement in fatal crashes in relation to driver age and gender: an update using 1996 data. Journal of Studies on Alcohol 2000;61:387-95.
  6. Guide to Community Preventive Services. Reducing alcohol-impaired driving: ignition interlocks. [cited 2010 Oct 1]. Available at URL:
  7. Elder RW, Shults RA, Sleet DA, et al. Effectiveness of sobriety checkpoints for reducing alcohol-involved crashes. Traffic Injury Prevention 2002;3:266-74.
  8. Guide to Community Preventive Services. Reducing alcohol-impaired driving: maintaining current minimum legal drinking age (MLDA) laws. [cited 2010 Oct 1]. Available at URL:
  9. Guide to Community Preventive Services. Reducing alcohol-impaired driving: lower BAC for young or inexperienced drivers. [cited 2010 Oct 1]. Available at URL:
  10. CDC consulted the following sources to develop the “How state ignition interlock laws measure up” map:

    - Insurance Institute for Highway Safety. DUI/DWI Laws. [cited 2010 Dec 20] Available at URL:

    - MADD. Status of state ignition interlock laws. [cited 2010 Dec 20] Available at URL:

    - National Conference of State Legislatures. State ignition interlock laws. [cited 2010 Dec 20] Available at URL:

Policy Impact is a series of issue briefs from CDC’s Injury Center highlighting key public health issues and important, science-based policy actions that can be taken to address them.

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