What is the interlock program?

The interlock program is a penalty which can be applied for a range of drink driving offences. It involves the installation of an electronic breath testing device to the ignition of a convicted driver’s vehicle.

Every time the driver attempts to start the car, they must provide a breath sample by blowing into the device. If any trace of alcohol is detected, the vehicle’s ignition system will be disabled and the vehicle won’t start.


Who does it apply to?

Since February 2015, the interlock program has been mandatory for drivers convicted of all high range PCA offences, and all second drink driving offences within five years.

It doesn’t matter if the second offence is in the lower category of seriousness, the court is still required to impose a mandatory interlock order.


How does the program work?

As part of imposing the mandatory interlock order, the convicted driver will face a disqualification period and then an interlock period.

This is designed to punish offenders, and ensure that they reflect on the actions which caused them to be disqualified from driving in the first place. It is up to the court to determine the duration of the initial disqualification period, in accordance with the minimum and maximum periods set by legislation.

The initial disqualification period under the interlock program is generally substantially shorter than the automatic period of disqualification imposed when someone does not undertake the program, meaning that drivers are able to return to driving earlier.

After the disqualification period is complete, the convicted driver will need to apply for an interlock licence at the Roads and Maritime Services (RMS). The driver will need to install the device (at a cost) and obtain a medical certificate which confirms that the driver understands the risks involved in consuming alcohol.

Once a driver holds the interlock licence, they will be subject to its terms for the interlock period determined by the court, generally ranging between 12 months to four years.

Obviously the greater the offence, the longer the interlock period. For example, a person convicted of high range PCA can expect to be disqualified for an initial period of six to nine months, with a subsequent interlock period of two years.


What is the cost?

Although compulsory, the program is a user pays system – in other words, a convicted driver must install the device at their own expense. The devices usually cost over $2,000, and an additional $2,000 per year to maintain. This alone should be incentive enough to avoid drink driving!


Interlock periods

Although the court has some discretion, generally the following disqualification and subsequent Interlock periods apply to offences:


First offence

Offence Minimum disqualification  Maximum disqualification Interlock period
High-Range PCA 6 months 9 months 2 years


Second offence

Offence Minimum disqualification  Maximum disqualification Interlock period
Novice/Special/Low Range PCA 1 month 3 months 12 months
Mid Range PCA 6 months 9 months 2 years
High Range PCA 9 months 12 months 4 years


Frequently asked questions


When do I apply for the interlock licence?

You apply at the conclusion of your initial disqualification period. However, as the Interlock order is mandatory (if your offence fits into the categories of either high range PCA or a second offence), the court will impose it whether or not you ask for it.


Can I be exempt from the order?

Nothing in law is impossible, but as it is a mandatory order it is certainly difficult to be exempt.

The only grounds on which you can generally apply to the court for an Interlock exemption order are because:

  • You have no access to a vehicle in which to install the interlock device. However the court takes the interpretation of “access” literally – if your partner has a car registered in their name only but it is still located at your home and you have access to it, this will not be a sufficient reason to be granted an exemption.
  • You suffer from a medical condition (which has been diagnosed by a registered medical practitioner) which prevents you from providing breath samples to unlock the device.

Your financial circumstances and any difficulties in paying the installation and regular upkeep of the device will not be considered in granting an exemption. It’s worth noting that if an exemption is granted, longer periods of disqualification apply.


Does the program apply to habitual offenders?

No, the interlock program is not relevant to habitual offender declarations.

Nyman Gibson Miralis provides expert advice and representation in all areas of drink driving and traffic law. 

Contact us if you require assistance.