The purpose of the alcohol ignition interlock
Breath alcohol testing or 'breathanalysing' is based on the assumption that breath alcohol content (BrAC) is fairly consistent with blood alcohol concentration (BAC).
An alcohol ignition interlock is a breath alcohol tester that has been integrated into the electrical and control systems of a vehicle. The purpose of the alcohol interlock is to prevent a driver with a BAC that exceeds the preset level from starting the vehicle or to prevent a drunk driver from operating the vehicle.