An ignition interlock device is a device that is installed in a vehicle to prevent a driver from operating the vehicle if they have consumed alcohol. The device works by requiring the driver to blow into a breathalyzer before starting the car. If the device detects a blood alcohol concentration (BAC) above the preset limit, the vehicle will not start.
Suppose you pass the breathalyzer test, and the vehicle starts. In that case, you must continue to provide breath samples periodically while driving to ensure you have not consumed alcohol during the trip. These “rolling retests” are designed to prevent a driver from consuming alcohol after starting the vehicle and continuing to drive.
If the device detects alcohol during a rolling retest, an alarm will sound, and the vehicle’s lights will flash, and the device will record the event. However, the basic principle is to prevent you from operating your car if you have consumed alcohol.