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Alcohol Interlock Device (WA)

An alcohol interlock device measures and records the amount of alcohol on a person’s breath. It prevents a vehicle from starting if alcohol is detected. It also requests breath tests during a trip. If a test is failed or not taken, the vehicle’s horn and lights will activate.

In Western Australia, when a person is found guilty of a prescribed alcohol interlock offence, their driver’s licence is cancelled and they become known as an “alcohol offender”. When the person’s licence is reinstated, it will have an “I” (interlock) condition and the person becomes knowns as an “interlock-restricted driver”. This means that for a specified period, the person must have an alcohol interlock device installed on any vehicle they drive.

The use of alcohol interlock devices is governed by the Road Traffic Amendment (Alcohol Interlocks and Other Matters) Act 2015.

Alcohol interlock offences

Offences prescribed as alcohol interlock offences are:

  • driving under the influence of alcohol offences;
  • repeat drink driving offences within a five-year period;
  • failure to provide a breath, blood or urine sample to police;
  • dangerous driving causing death, bodily harm or grievous bodily harm, where the offender is affected by alcohol to such an extent that they are incapable of properly controlling the vehicle.

The Alcohol Interlock Scheme

All drivers who commit and are convicted of an alcohol interlock offence on or after 20 October 2016 must participate in the Alcohol Interlock Scheme.

An interlock condition is automatically applied to an alcohol offender’s licence when:

  • an extraordinary (restricted) licence is granted after a conviction for a prescribed alcohol interlock offence;
  • a driver’s licence is granted after a period of disqualification for a prescribed alcohol interlock offence;
  • a driver’s licence is granted to a person who has moved to WA and had an interlock condition imposed in another state.

A participant must comply with all requirements of the scheme, including a minimum participation period and demonstrating the separation of drinking and driving for 180 continuous days after leaving the scheme.

Participation in the scheme is terminated if the participant is convicted of another alcohol interlock offence, or if their licence is cancelled for another reason.


A person may be exempt from the scheme if they:

  • live more than 150 kilometres from where alcohol interlock services are provided;
  • have a medical condition which prevents them from operating an alcohol interlock device.

If a person chooses not to take part in the scheme, they are only permitted to drive a vehicle fitted with an alcohol interlock device, and must produce the vehicle for scheduled servicing of the device and for data to be downloaded from it. The person will retain their status as an alcohol offender or interlock-restricted driver until they complete the requirements of the scheme.

If an offender drives a vehicle that does not have an alcohol interlock device fitted, they risk a penalty of four months imprisonment or vehicle immobilisation.

Length of participation

The length of the alcohol interlock period depends on the offender’s driving history.

The minimum periods are:

  • driver’s licence holders: 180 continuous days;
  • extraordinary licence holders: the duration of the licence including 180 continuous days;
  • permanently disqualified alcohol offenders granted an extraordinary licence: a combined three years of restricted driving periods including 180 continuous days.

The device

Whenever the vehicle is used, the alcohol interlock device will record actions such as blowing into the device and turning the engine on and off. The data is downloaded by the device supplier at scheduled services and used by the Department of Transport to make decisions about the program participant’s licence. Only devices approved by the department can be used by an interlock-restricted driver in WA.

Breaches of the scheme

A “trigger” event will be recorded by the alcohol interlock device when a participant:

  • records a Blood Alcohol Content (BAC) of 0.02 or higher; or
  • refuses to take a breath test when the device requests.

If three or more triggers are recorded in a monthly scheduled inspection period, the person will have a breached a requirement of the scheme.

A person will also breach a requirement of the scheme if:

  • they tamper with the device, detected by the device or at an inspection;
  • they do not present the vehicle for inspection every month as required;
  • their driver’s licence expires or is suspended while they are taking part in the scheme.

For any breach, the participant will be required to attend Alcohol Assessment and Treatment conducted by the Mental Health Commission. The treatment is delivered by alcohol and drug counsellors

Installation and use of the device

Alcohol interlock devices can be fitted to most vehicles with an ignition, including motorcycles. An Accredited Service Provider (ASP) installs the device and shows the client how to use the device. Any person who drives the vehicle will need to be trained to use the device.

The vehicle then needs to be presented to the ASP for monthly scheduled servicing of the device and to have data downloaded from it.  If the device is not serviced, it will permanently lock the ignition seven days after the scheduled inspection date. An over-ride code must be bought from the ASP to unlock the ignition and an inspection date arranged to avoid another lock-out.


The ASP charges for installation, monthly leasing and servicing, and removal of the device. Concession-card holders may be entitled to a reduced fee.

Removal of the device

A participant can leave the scheme when:

  • the minimum participation period has been completed;
  • any period of disqualification has ended;
  • any alcohol assessment and treatment has been completed;
  • the separation of drinking and driving has been shown for 180 continuous days.

The participant receives written notification of successful completion of the scheme and that removal of the alcohol interlock device from a vehicle is authorised.

For advice or representation in any legal matter, please contact Armstrong Legal.

Sally Crosswell

This article was written by Sally Crosswell

Sally Crosswell has a Bachelor of Laws (Hons), a Bachelor of Communication and a Master of International and Community Development. She also completed a Graduate Diploma of Legal Practice at the College of Law. A former journalist, Sally has a keen interest in human rights law.

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