What are mandatory interlock devices?

An interlock device is a handheld car breathalyzer that analyses the amount of alcohol in the user’s breath. It is attached to the ignition of a car to prevent the car from starting until the driver passes a breath test. The interlock device sets off an alarm, flashlight, or switches on the horn if a driver fails a retest. If a breathalyzer test is unsuccessful, the car will be immobilised.

A judge will impose an ignition interlock device on someone who is guilty of drunk driving. Interlocks are mandatory for many drink driving charges in NSW, and an interlock exemption order may be granted by a court under extremely specific conditions.

These devices are very costly, costing between $2200 - $2500 over the 12-month period plus a $310 fee for two monthly service and rental. If the device is damaged or lost, you will be responsible for the cost. Some providers offer monthly insurance, but if that isn’t the case, the devices can cost up to several thousand dollars to purchase outright. Tampering with an interlock device can leave you paying the full price as well as having additional penalties from your state monitoring authority.

The interlock device initiative aims to provide drunk drivers a chance to reinforce healthy behaviours. Additionally, it is to reduce the length of their suspension offering a substitute for lengthy licence suspensions. This allows for the duration of suspension to be shortened in exchange for the driver's consent to have an interlock device installed on their car.