In 1990, California implemented a driver suspension law requiring the Department of Motor Vehicles (DMV) to suspend the driving privileges of persons with a blood alcohol content (BAC) above a specified level. In addition, separate legislation expanded the DMV's power to administratively impact licenses by extending the period of suspension or revocation for those who refuse a BAC test. California's APS law authorizes the arresting officer to confiscate the offending driver's license at the time of arrest and serve a notice of suspension to become effective 45 days later. All such law enforcement actions are automatically reviewed by the DMV to assure compliance with the law. The offender has the right to challenge a suspension through a DMV administrative hearing. To evaluate the deterrent effect of the APS law, data were obtained from a random sample of 800 DUI cases in Sacramento County, 393 before the APS law and 407 after. The court file of each case was coded by such variables as age, gender, type of attorney representation, number of prior DUI convictions, failure to appear, conviction offense, and BAC. Analysis results showed that the APS law failed to significantly modify the behavior of DUI offenders. Further, no significant differences were observed between first and recidivist DUI offenders. Increases in the penalties for refusing a BAC test did not significantly reduce the refusal rate, and the reconviction rate of those who refused a BAC test actually increased somewhat. 23 references, 1 note, 4 tables, and 3 figures