What is an interlock device?

An interlock device, also known as an ignition interlock device (IID), is a small electronic device installed in a vehicle that measures a driver’s breath alcohol concentration (BAC) before allowing the vehicle to start. It is primarily used as a safety measure to prevent individuals from operating a motor vehicle while under the influence of alcohol.

The device is connected to the vehicle’s ignition system and requires the driver to blow into a mouthpiece to provide a breath sample. If the BAC of the breath sample is below a predetermined threshold (usually set at 0.02% or lower), the vehicle will start normally. However, if the BAC is above the threshold, the device will prevent the vehicle from starting.

In addition to the initial breath test, the interlock device also requires periodic rolling retests while the vehicle is in operation. These retests ensure that the driver remains alcohol-free during the course of the journey.

Interlock devices are often used as a requirement for individuals convicted of DUI (Driving Under the Influence) or DWI (Driving While Intoxicated) offenses. They help to monitor and control a driver’s alcohol consumption, promoting safer roads and preventing repeat offenses. The installation, maintenance, and monitoring of interlock devices are typically the responsibility of the offender, including associated costs.