Nearly 40 percent of all fatal traffic accidents in the U.S. involve drinking, resulting in annual death toll of 17,000, according to the National Highway Traffic Safety Administration. Yet, according to a recent survey by the Substance Abuse & Mental Health Services Administration, 17 percent of drivers age 21 and over admit to getting behind the wheel after consuming alcohol or using illegal drugs at least once a year. A surefire way to prevent at least some of such accidents? Immediately take away the license of anyone who fails a breath test, a move that already saves at least 800 lives a year, says a new study.

"Preconviction license suspension laws are clearly successful in reducing the rates of alcohol-related crashes," says the study's lead author, Alexander Wagenaar, an epidemiologist at the University of Florida (U.F.) College of Medicine in Gainesville. In contrast, "postconviction laws have virtually no effect." Bottom line: the roads will be safer if drunk drivers lose their driving privileges on the spot, rather than later.

Wagenaar and fellow U.F. epidemiologist Mildred Maldonado-Molina compared 26 years of federal crash data from 46 states with driver's license suspension laws. "We basically did 46 studies" estimating the impact of suspension laws on alcohol-related accidents for each state and then aggregated the results, Wagenaar says. Their findings, published in the August issue of the journal Alcoholism: Clinical and Experimental Research, confirm that laws mandating immediate license suspension reduce the number of drinking-and-driving fatalities by 5 percent, indicating that the measures appear to encourage people to hesitate before boozing and driving. Researchers say the laws seem to deter both social drinkers and carousers.

Legal scholars have long studied the influence of celerity (the time elapsed between crime and punishment) and found that swift (rather than delayed) discipline is more effective in preventing future crimes. "Theory would predict that celerity of punishment marginally adds to the deterrent effects of criminal punishment," says Jeffrey Fagan, a Columbia University law professor.

But Fagan also cautions that whisking away a driver's license instantly following a breathalyzer test has implications for people's rights. "Even if there is a public safety value to imposing punishment immediately [without due process of law], that may expose someone to an unjust punishment if their arrest violated their civil rights and procedural safeguards," he says. Some defendants may question the validity of the breath test or contend that the police did not have reasonable suspicion to pull them over, he notes.

Currently, all but nine states have laws on the books that require police officers to strip drunk drivers of their licenses before they have been convicted. The nine exceptions are Kentucky, Michigan, Montana, New Jersey, New York, Pennsylvania, Rhode Island, South Dakota and Tennessee.

Wagenaar says that all states should adopt preconviction suspensions, noting they are a cheap and efficient way to save hundreds and perhaps thousands of lives.