The randomized control trial (RCT) found that the interlock program was effective in reducing the recidivism of DDs while the IID was installed in the vehicle; relative risk was 0.36 (95 percent confidence interval 0.21 to 0.63). Controlled trials supported this conclusion; however, neither the RCT nor the controlled trials provided evidence of any program effect continuing once the device has been removed. The authors advise that in order to eliminate potential selection bias, more RCTs should be conducted in examining the effectiveness of IID programs. Future studies should address ways to improve DD recidivism rates in the long term by addressing the major challenges of participation rates, compliance, and durability. The IID is part of a multi-dimensional program intended to reduce recidivism in convicted DDs. In order to operate a vehicle equipped with an IID, the driver must first provide a breath specimen that meets maximum limits for the presence of alcohol. Only then will the vehicle's engine start. As a measure to reduce defeat of the IID by having someone else blow into the mouth piece, random retests are required while the vehicle is running. Other components of the program include information seminars for the driver and downloading data from the device's data logger, which logs all test attempts and records all passes, warnings, and failures. The study methodology involved an electronic search and a search of other resources in order to identify RCT's and controlled trials in which offenders have been charged with DD and have either been sentenced to participate in an IID program or the usual punishment.