The basis for using asset-forfeiture law in this regard is that the vehicles of drunk drivers constitute the instrumentality of their offenses. In an assessment of the effectiveness of this sanction, data were obtained from the Portland Police Data System, from the Asset Forfeiture Unit's vehicle seizure records, and from the monthly reports of the Traffic Division. The data consisted of all citations issued from January 1, 1989, to December 31, 1994, for driving under the influence of intoxicants (DUII), driving while licenses were suspended or revoked (DWS), and arrests as habitual traffic offenders (HO). The vehicle- seizure data consisted of records for all seizures of vehicles for felony DWS or HO subsequent to the institution of the forfeiture ordinance in mid-December 1989 (n=746). Traffic Division data consisted of a record of hours patrolled by Traffic Division officers by shift and the number of DUII citations they issued for each month from January 1986 to December 1993. Event- history analysis techniques were applied to arrest data that covered 5 years of forfeiture enforcement. Findings show that perpetrators whose vehicles were seized could be expected to be rearrested on average half as often as those whose vehicles were not seized. The most plausible explanation for this result is that the forfeiture program has reduced the threat to public safety from these problem motorists. 1 table and 4 notes