While license suspension/revocation have been shown to be effective, it is also known that most suspended/revoked (S/R) drivers violate their S/R order and continue to drive, accruing traffic convictions and becoming involved in crashes. In an attempt to strengthen license actions and to better control S/R and unlicensed drivers, California enacted two laws effective January 1995 which provide for the impoundment/forfeiture of vehicles driven by S/R and unlicensed drivers. The current study evaluates the general deterrent impact of vehicle impoundment on the crash rates for the general population of S/R drivers in California, regardless of whether they have been apprehended and punished for driving-while-suspended. Crash rates for S/R drivers, as well as a control group of non-S/R drivers, were examined over a 5-year period consisting of 3 years prior to the implementation of vehicle impoundment/forfeiture and 2 years subsequent. Interrupted time series statistical models used to analyse the data showed that while there was a statistically significant drop in crashes for S/R drivers at the point at which the laws became effective, there was also a significant drop for control drivers, who shouldn't be affected by the laws since they are not S/R. Additional analyses which jointly estimated crashes for both S/R and control groups revealed that the drop in crashes for S/R drivers was no longer statistically significant once the crash rate for control drivers was statistically accounted for. Thus, this study failed to find compelling evidence of a general deterrent impact of vehicle impoundment/forfeiture in California. (A)
Abstract