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Traffic Law » Drink Driving » Mandatory Interlock Licence Order

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Mandatory Interlock Licence 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.

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     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.

    Offences to which the mandatory Interlock Program applies

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

    1. When a person commits two or more of the following offences within 5 years
    2. When a person is a first time offender of mid or high range drink driving
    3. 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

     Structure of an interlock order

    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.

    Mandatory Interlock Offence Min. Disqualification period Max. Disqualification period Min. Interlock Period
    Second or subsequent offence: Novice Range Special Range Low Range 1 month 3 months 12 months
    First offence: Mid Range 1 month 3 months 12 months
    Second or subsequent offence:Mid Range 6 months 9 months 24 months
    First offence:High Range 6 months 9 months 24 months
    Second or subsequent offence: High Range 9 months 12 months 48 months
    Second or subsequent offence: Driving under the influence of alcohol or a drug 6 months 9 months 24 months
    First offence: Refuse or fail to comply with directions for a breath analysis or blood test 6 months 9 months 24 months
    Second or subsequent offence: Refuse or fail to comply with directions for a breath analysis or blood test 9 months 12 months 48 months

    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.

     Consequences of not participating in the program

    A person who receives an Interlock Program order from the court but does not enter into the Interlock Program will instead be disqualified from driving for a period of five years.


    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.