After a long trial period, an alcohol interlock program was permanently introduced in Sweden in 2012. Participation in the program is voluntary and the duration of the program is one or two years, depending on the severity of the drink driving offence. An evaluation of the program during the trial period showed a participation rate of about 11%. Aim: The main aim of the study was to estimate the participation rate in the interlock program and evaluate if the changes made from the trial period had led to increased participation. Reasons for denied participation and the time between the drink driving offence and decision about participation in the program were also studied.

A sample of about 3600 drivers who had their license withdrawn due to drink driving was investigated. The data includes age and gender, information about the drink driving offence and the application process.

The participation rate in the permanent program is about 30%. The age group with the highest participation is drivers between 35 and 64 years old with about 35% participation. Moreover, the participation rate of drivers with BAC > 1 g/L is almost twice as high as the rate for drivers with BAC < 1 g/L.

The study shows that the participation rate has increased from about 11% in the trial period to about 30% in the permanent program. Thus, the attempt of increasing the rate has been successful.