The Ignition Interlock for Drunk Drivers The ignition interlock is a high tech system that eveuates the persons BAC (Blood Alcohol Content) to see if the individual has been drinking. The device works like a normal Breathalyzer. The device is mounted on the dashboard and in order for the car to start the individual must blow into the machine. The machine then evaluates the persons BAC and if that person shows no sign of alcohol use the car will start. If the results come back saying he has consumed alcohol the vehicle will not start. When the vehicle starts and has been for around an hour the person must again blow in