The new law includes alterations in arrest procedures, the creation of a .10 offense expanding the definition of drunk driving and reducing the burden of proof, a restriction on prosecutor discretion requiring that any amendment of a drunk driving charge go before a judge, and a foreshortening of judicial sentencing discretion. Using various data sources -- arrest frequency and distribution, local correctional data on type of jail confinement, citation data giving details on all citations and case dispositions, and data on assessment programs mandated for those convicted of drunken driving -- the research focused on four major issues: law enforcement, prosecution, adjudication, and corrections -and across many variables related to the issuance, handling, and disposition of drunk driving complaints. Overall results indicate that the changes did not induce a significant number in the number of arrests for drunken driving. Throughout several counties, a substantial reduction in volume of charges upheld in A-citations issued under the new law was noticed, and reductions were noticed in volume and frequency of amendments to drunk-driving charges. Outcomes of adjudication conferring guilt on drunk-driving charges differed only marginally across the evaluation period, and the jail population has not changed dramatically as a result of the legislation. Overall, the study concludes that criminal justice system performance under the new law differed widely across local jurisdictions. The new law apparently has altered practices and routines (compliance is widespread), but has not drastically affected case-related outcomes. Tabular and graphic data from the study are provided, and the survey instrument, a county index, and a 26-item bibliography are provided.