Among violent crimes committed in the United States, the most common is drunk driving. Alcohol-related crashes cause a death every 31 minutes and a non-fatal injury every two minutes. In 2004, 16,694 Americans died in alcohol-related motor vehicle crashes--39 percent of all traffic deaths.

Efforts to prevent drunk driving are making a difference, however, especially among the youngest drivers. Over the past 20 years, deaths from alcohol-related crashes have decreased by 60 percent for drivers ages 16 to 17, and by 55 percent for drivers ages 18 to 20.

These gains are due in part to vigorous law enforcement. "The most effective intervention to reduce drunk driving, particularly among non-chemically dependent people, is to increase the arrest rate for DWI [driving while intoxicated]," says Stephen Simon, director of the Minnesota Criminal Justice System DWI Task Force. "When the arrest rate increases, DWI and crashes decrease."

Other prevention strategies are recommended in a 2001 study published by the U.S. Centers for Disease Control (CDC) and the Task Force on Community Preventive Services. This research review, supported by more recent studies, cites strong evidence for blood alcohol concentration laws, sobriety checkpoints, and zero-tolerance laws.

Blood alcohol concentration (BAC) laws make it a crime in all 50 states, the District of Columbia, and Puerto Rico to drive with a BAC level of .08 percent and higher. To reach this level of intoxication, a 170-pound man needs to have at least four drinks in one hour on an empty stomach; a 137-pound woman needs about three drinks.

Research pinpoints the .08 percent BAC level as a point where the risk of fatal crashes increases significantly. Almost any driver with this much alcohol is impaired behind the wheel.

State laws that lowered the BAC for drivers from 0.10 percent to 0.08 percent have reduced alcohol-related deaths by an average of 7 percent, according to the CDC.

Sobriety checkpoints are specific locations where police or highway patrol officers stop all drivers--or a predetermined percentage of them--to test BAC levels. This law enforcement strategy is highly visible and meant to deter potential drunk drivers as much as catch existing ones.

A review of 23 studies from around the world indicates that sobriety checkpoints consistently reduce alcohol-related crashes by about 20 percent. The results are similar for short-term "blitzes" and for checkpoints continuing over several years. In other words, the effectiveness of checkpoints does not seem to diminish over time.

Zero-tolerance laws in all 50 states set the legal BAC limit for drivers younger than age 21 at 0.00 or 0.02 percent. Consequences for those who break the law typically include fines and driving restrictions--in some states, total loss of a driver's license until age 21. Such legislation has decreased fatal crashes in this age group by nearly 20 percent as well.

Other strategies that have proved effective include stiffer laws against repeat DWI offenders. Examples include vehicle sanctions--impounding the drunk driver's car or license plate. "This law is very cost-effective at reducing DWI among repeat offenders," says Simon. "It takes almost no time for the officer and is implemented at the time of arrest." In some states, officers can confiscate or suspend a drunk driver's license at the same time. Many states also mandate alcohol abuse treatment for multiple DWI offenders.

Technology also holds promise, especially interlock devices, which automatically detect levels of alcohol in a driver's breath and lock the vehicle's ignition if the amount is too high.

The strategies that could affect you most directly are those that involve personal behavior. If you drink, don't drive. In addition:

• Choose a non-drinking friend as a designated driver.
• If you've had too much to drink at a party, ask if you can stay over at your host's house.
• Take a taxi or check your local Yellow Pages for a free Safe Rides or Sober Ride program.
• Always wear your seat belt--your best defense against drunk drivers.

--Published April 3, 2006