The Ignition Interlock program places a license restriction on drivers with multiple alcohol offenses. Drivers who are repeat offenders, have violated a previously imposed alcohol-related driving restriction, or have accumulated enough points on their license may be required to participate. Participants in the program are required to have an Alcohol Breath-Analyzed Ignition Interlock Device installed in their vehicle's ignition system. The driver must blow into the device and if breath alcohol levels exceed the accepted level set on the device the vehicle will not start. Participants in the program are responsible for all costs, including the cost of obtaining a restricted driver's license, the installation, and monthly maintenance costs of the ignition device. The duration participation in the program is determined on an individual basis by a case manager, and may be extended due to violations during a monitoring period. In addition to restricted licensing, participants are required to participate in treatment or support programs.

The goal of the Ignition Interlock program is to reduce drunk driving among alcohol traffic offenders.

The Ignition Interlock program was evaluated using a randomized controlled trial that compared the intervention group with a conventional post-licensing treatment program group. Arrest rates for traffic offenses were compared for one year during the program and one year after unrestricted driving privileges were returned. The alcohol traffic violation rate during the first year was significantly less for participants in the program than those in the control group (2.4% vs. 6.7%, relative risk 0.36, 95% CI = 0.21, 0.63). This represents a 64% reduction in the risk of committing an alcohol traffic violation within the first year among intervention participants. There were no significant differences between the groups after license restrictions were lifted.