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Number 180                                                                                             May 1998
U.S. Department of Transportation
National Highway Traffic Safety Administration
400 Seventh Street, S.W., Washington, DC 20590


CALIFORNIA IMPOUNDS THE VEHICLES OF MOTORISTS CAUGHT DRIVING WITHOUT A VALID LICENSE
One strategy that has been pursued to reduce the number of motor vehicle crashes in the United States has been to identify and control high risk drivers through law enforcement and court imposed sanctions against the individual. These sanctions include fines; driver license actions such as suspensions or revocations; jail, community service, and alcohol treatment.

While suspending or revoking a driver's license is effective, these sanctions have limitations because they do not actually incapacitate the driver. Some studies have found that as many as 75 percent of these drivers continue to drive during periods of suspension or revocation. While other studies have shown that these individuals drive less often and more carefully during suspension and revocation periods, they still pose a threat. In California, drivers with suspended or revoked licenses have 3.7 times the fatal crash rate as the average driver.

The National Highway Traffic Safety Administration (NHTSA) sponsored a study by the California Department of Motor Vehicles to evaluate how vehicle impoundment affects the driving behavior of drivers who are unlicensed or whose licenses are suspended or revoked.

California's Impoundment Program
California began an impoundment program in January, 1995. Under the program, law enforcement officers can impound vehicles on the spot of drivers who do not have a valid license. The impoundment period lasts for 30 days. According to law enforcement agencies throughout the state, more than 100,000 vehicles are being impounded each year. For this study, two counties (Stockton and Riverside) and two cities (San Diego and Santa Barbara) linked driver record data with vehicle impoundment data. More than 6,300 unlicensed, suspended, or revoked drivers whose vehicles were impounded were compared to about the same number of drivers in 1994 whose vehicles would have been eligible for impoundment in the new program in 1995. For one year, the driving records were gathered and compared for convictions of driving while suspended (DWS) or driving while unlicensed (DWU), total traffic convictions, and crashes for both first time and repeat offenders.


Subsequent DWS or Convictions for First and Repeat Offenders
    Fewer Subsequent Offenses
The graph above shows that first offenders whose vehicles were impounded had an average rate of subsequent DWS or DWU conviction that was 24 percent lower than those whose vehicles had not been impounded. Repeat offenders had 34 percent fewer DWS or DWU convictions than their control group.


Subsequent Traffic Convictions for First and Repeat Offenders
Fewer Subsequent Traffic Convictions
Drivers whose vehicles were impounded also had fewer subsequent traffic convictions. For first offenders, recidivism was 18 percent lower than drivers who still had access to their vehicles. The differences were even more striking for repeat offenders. Repeat offenders whose vehicles were impounded had 22 percent fewer traffic convictions than those whose vehicles had not been impounded.
Fewer Subsequent Crashes
Both first time and repeat offenders whose vehicles were impounded also had fewer crashes. The next graph shows that there was a 25 percent reduction for first time offenders and a 38 percent reduction for repeat offenders in subsequent crashes.

Vehicle Impoundment Works
Vehicle impoundment is having a positive effect on traffic safety in California, reducing the number of crashes and subsequent citations. Importantly, it appears even more effective for repeat offenders -- those high risk drivers who traditionally have been resistant to change. Removing access to the vehicle by impounding it is one way to limit driving during periods of suspension or revocation.

How To Order
For a copy of the report, An Evaluation of the Specific Deterrent Effect of Vehicle Impoundment on Suspended, Revoked and Unlicensed Drivers in California, (52 pages), write to the Office of Research and Traffic Records, NTS-31, NHTSA, 400 Seventh Street, S.W., Washington, DC 20590, or send a fax to (202) 366-7096. Marv Levy was the contract manager for this project, email: mlevy@nhtsa.dot.gov


U.S. Department of Transportation National Highway Traffic Safety Administration 400 Seventh Street, S.W. NTS-31 Washington, DC 20590

Traffic Tech is a publication to disseminate information about traffic safety programs, including evaluations, innovative programs, and new publications. Feel free to copy it as you wish. If you would like to receive a copy contact: Linda Cosgrove, Ph.D., Editor, Evaluation Staff Traffic Safety Programs (202) 366-2759, fax (202) 366-7096 E-MAIL: lcosgrove@nhtsa.dot.gov