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Traffic Law » Drink Driving » Mandatory Interlock Order

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Mandatory Interlock Order

The Interlock Program was first introduced in 2003 as a penalty option for Magistrates when sentencing persons charged with serious drink driving offences. However, new laws passed in February 2015 have made the Interlock Program mandatory under certain circumstances.

What is the interlock program?

The Alcohol Interlock Program allows drivers convicted of certain PCA offences to start driving earlier than they otherwise would be able to, on condition they only drive a vehicle with an Interlock device installed.

The device is wired to the ignition of a car to prevent the car from being started unless the driver passes a breath test.  To pass the breath test, the driver must return a reading of zero blood alcohol concentration.

To reduce the potential for bystanders to start the car, the interlock device is programmed to require retests to be taken at random intervals. Should a driver fail a retest the interlock device is programmed to sound an alarm of horn and lights until the ignition is turned off.  A breath test is then required to restart the car.

The obvious advantage of this program is that it allows a person to continue to drive their car legally. For many this will mean the ability to maintain their employment, studies and other commitments.

Another advantage is that it assists in rehabilitating repeat offenders by ensuring a person cannot drink and drive. However, the program does come at a cost, which includes both installation costs and monthly calibration fees.

What offences does the Mandatory Interlock Order apply to?

The effect of the new legislation is that the court will automatically impose a period of interlock in the following circumstances:

When a person commits two or more of the following offences within 5 years: Novice range
Special range
Low range
Mid range
High range
Drive under the influence of drugs (DUI)
Refuse breath analysis

Refuse blood sample if physically unable to submit to a breath analysis

When a person is a first time offender of mid or high range drink driving

When a person is a first time offender of refusal or failure to submit to a breath analysis, or the taking of a blood sample when the person is physically unable to submit to a breath analysis.

How long will I have the interlock device?

When being sentenced for one of the above matters, the court will order a licence disqualification period, and a minimum participation in the interlock program. The disqualification and interlock program periods for specific offences are outlined in the table below.



When the court has imposed an interlock period, it will commence once you have complete the disqualification period. You will be required to have an interlock device installed by an accredited interlock service provider. Regular check up’s on the device will also be required during the interlock period.  The costs of this procedure must be paid by the participant and can be quite expensive. However, concession rates are available.

Once the interlock is installed, you will not be able to drive your car before passing a breath test. Anyone else driving your car will also be required to submit to this test, and you may only drive another car if it has an interlock device installed. Penalties apply if these requirements are breached.

What is an Interlock Exemption Order?

The court may grant exemptions to the Interlock Program, but only in certain instances. For example, if a person does not have access to a vehicle to install an interlock device, there is a medical condition, or it would cause severe hardship.

If you choose to make an application for an interlock exemption, you will be subject to a longer period of disqualification.

How much does the interlock device cost?

The RMS has advised that the cost of installing and maintaining an interlock device are estimated to be about $2,200.00 a year.

What if I cannot afford the interlock program?

The RMS offers financial hardship assistance to those who may not be able to afford the installation and maintenance of the interlock device. If you are concerned about the financial costs involved of being subject to the interlock program, you will need to contact your nearest RMS to discuss your options.

What happens if I do not apply to the RMS for my interlock licence?

If the interlock period is not applied for or is not completed, then an offender will remain disqualified from driving for at least 5 years from the date of conviction.

What if I drive a vehicle that does not have the interlock device fitted to that vehicle?

It is an offence for someone who has an interlock licence to drive a vehicle that does not have an interlock device. Further penalties and licence disqualifications will apply should you drive a vehicle that does not have an alcohol interlock device fitted.