Alcolock (or alcohol-interlock) programs were introduced in Sweden in 1999 to reduce drunk driving. The program has been used as a primary prevention strategy, to prevent impaired driving by individuals not pre-selected for prior offenses, and as a secondary prevention strategy, for driving while intoxicated (DWI) offenders. The Alcolock is a breathalyzer device attached to the ignition that measures blood alcohol concentration (BAC) and will block the vehicle from starting if the driver's BAC is higher than the lock point of 0.02%. The primary prevention program was first applied in commercial transport companies (buses, trucks, taxis); Alcolocks in commercial vehicles have been well accepted by professional drivers, their employers, and their passengers. The secondary prevention program is a voluntary 2-year program for DWI offenders focused on changing alcohol use habits. The program involves strict medical requirements including counseling and regular checkups by a medical doctor.

The goal of the Alcolock system is to reduce drunk driving.

During the program, alcohol consumption generally decreased significantly, as measured through five biological alcohol markers. The number of participants reporting dangerous or harmful alcohol habits dropped from 68% at baseline to 14% after one year in the program. The rate of DWI recidivism fell significantly from a yearly rate of approximately 5% to almost 0 (p < 0.001). These effects on recidivism are paralleled by significantly reduced rates of police-reported traffic accidents involving injuries and hospital admissions due to road accidents (p < 0.01). Those that successfully complete the program have lower rates of DWI recidivism 2.5 years after leaving the program.