NEW SOUTH WALES

Understanding How the NSW Interlock System Works and the Costs Involved

By Joshua Boorman · Published · NSW posts

In shortStudies show that drivers with prior convictions of drink driving offences have a higher risk of being involved in fatal road accidents than the average driver. Research also shows that interlock devices lead to less reoffenders while the system is installed in the vehicle.

  • Mandatory nature of interlock program
  • How the interlock works?
  • What the interlock device can do

New South Wales law · law checked 21 Oct 2026

Call 1300 941 900Make an enquiry about legal representation
Understanding How the NSW Interlock System Works and the Costs Involved
What's on this page

Studies show that drivers with prior convictions of drink driving offences have a higher risk of being involved in fatal road accidents than the average driver. Research also shows that interlock devices lead to less reoffenders while the system is installed in the vehicle.

Mandatory nature of interlock program

Like many jurisdictions in Australia, NSW is committed to improving road safety by helping drink drivers separate drinking and driving through the mandatory alcohol interlock program.

The alcohol interlock system became mandatory only in 2015 with the passage of the Road Transport Amendment Act of 2014. Under this statute, persons who are convicted of high range, repeat, and other serious drink driving offences are now required to install interlocks to the ignition systems of their vehicles.

How the interlock works?

Alcohol interlocks are electronic devices that are connected to the ignitions systems of vehicles such as cars, motorcycles and other heavy vehicles. The interlock has a breath testing device that collects breath samples from a vehicle’s driver, which the device analyses and tests for the presence of alcohol. A zero blood alcohol concentration is required for the vehicle to start. Without registering a zero blood alcohol concentration, the interlock will prevent the vehicle’s ignition from starting.

It is also understood that alcohol can take some time to enter a person’s blood stream. Thus, the interlock program requires random breath sampling periodically throughout the vehicle’s journey.

What the interlock device can do

In addition to analysing breath samples, the electronic interlock device also records:

  • All breath test results;
  • Photographs of the person providing the breath sample;
  • Any attempts to tamper the interlock device.

By closely monitoring the interlock participant’s driving, the system aims to help the convicted driver separate drinking and driving and reduce alcohol-related road incidents.

Costs of interlock device program

Drivers who are required to undergo the alcohol interlock program bear the costs of the device. Interlock costs are set by the approved providers and can change, so check current costs with an approved provider and Transport for NSW. The costs cover fees for:

  • Device installation;
  • Monthly lease;
  • Maintenance of the device; and
  • Removal

The participant will also bear additional expenses for repairing damaged units, unscheduled servicing, and for Roads and Maritime licencing fees for the issuance of an interlock licence.

Exemptions from the interlock device program

Unlike the interlock device program in other states, remote locations and financial hardship are not exempting factors from the coverage of the interlock program. In NSW, Roads and Maritime may provide assistance to offenders who meet the severe financial hardship criteria in order for them to participate in the interlock program.

But in limited situations, a party may be able to apply for an exemption in court if they can prove that:

  • Lack of access to a vehicle in which to install the device; or
  • Presence of a health condition that prevents the offender from providing a sufficient breath sample to an interlock device. A registered medical practitioner must issue a certificate on the medical condition of the offender.

The mandatory interlock program is for a minimum period is at least 12 months but depending on your offence and traffic history it can be a minimum period of 2 years, however the Court has a discretion to increase this period to a maximum of 4 years. This period will commence upon the expiration of the licence disqualification that is imposed as a penalty for drink driving.

Considering the burdens accompanying the interlock device program, it’s vital for anyone facing a charge of drink driving to engage the services of an experienced traffic and criminal lawyer who can raise effective defences in your situation.

In NSW, Boorman Lawyers are prepared to help you from the moment you come to us with your situation. We welcome your call today on 1300 941 900 to schedule your an initial discussion with one of our helpful solicitors.

Next steps after a high range drink driving charge

Put simply: This period will commence upon the expiration of the licence disqualification that is imposed as a penalty for drink driving. We appeared on this matter at courts across New South Wales. Preparation here involved medical material, the interlock requirements and evidence of hardship. If you have been charged with high range drink driving in New South Wales, call Joshua on 1300 941 900 to talk about your situation.

For the law on high range drink driving today, see our New South Wales traffic law guides. Each case turns on its own facts, so treat this courts across New South Wales result as general information, not legal advice. Call 1300 941 900 or make an enquiry about legal representation.

Law update since this post (checked 21 Oct 2026)

This post was first published on 23 December 2017. The narrative above is kept as published. These notes record later changes to the law.

  • Roads and Maritime Services (RMS) functions are now carried out by Transport for NSW.
  • The NSW mandatory alcohol interlock program has applied since 1 February 2015 and was extended to first-offence mid range offenders from 20 May 2019 (Road Transport Act 2013 Part 7.4A).

What clients say

Google reviews (opens in a new tab)Facebook reviews (opens in a new tab)

FAQs about this post

What happened at courts across New South Wales?

Studies show that drivers with prior convictions of drink driving offences have a higher risk of being involved in fatal road accidents than the average driver. Research also shows that interlock devices lead to less reoffenders while the system is installed in the vehicle.

What was the result of the high range drink driving charge?

In NSW, Roads and Maritime may provide assistance to offenders who meet the severe financial hardship criteria in order for them to participate in the interlock program.

Can I rely on this December 2017 post?

It dates from 23 December 2017. Any later changes to NSW law on high range drink driving are flagged in the dated note above; the NSW law pages are kept current.

Sources and date checked

Sources and references for this page, checked 21 Oct 2026.

This page is general information about New South Wales law only. It is not legal advice. Every matter turns on its own facts.

NSW Traffic Law

Choose your NSW traffic law topicNSW

Guides for New South Wales traffic law matters.

NSWDrink Driving OffencesRead guide →NSWDrink Driving PenaltiesRead guide →NSWDrink Driving DefencesRead guide →NSWDrug Driving Offences & PenaltiesRead guide →NSWHigh Range PCA Guideline JudgmentRead guide →NSWLicence Suspension AppealRead guide →NSWAlcohol Interlock LawsRead guide →NSWNo Conviction Drink DrivingRead guide →NSWTraffic Offenders ProgramRead guide →NSWDUI Court Process GuideRead guide →NSWDangerous DrivingRead guide →NSWDisqualified DrivingRead guide →
Enquire about legal representation

Enquire about legal representation

Call 1300 941 900 or make an enquiry about legal representation.

What to have ready

  • Court & next listing date: Which court is on your paperwork and when your matter is listed.
  • Charge or reading (if known): Tell us the charge or reading if you have it — you do not need your full police facts yet.
  • Work & driving needs: Let us know if you rely on your licence for work or family responsibilities.
No obligationConfidential
Boorman Lawyers TV

Real court days, NSW & QLD

Behind-the-scenes footage and case discussions from court days across New South Wales and Queensland.

Visit Boorman Lawyers TV →
Country to city — on the road to court (full 24s cut)
▶Sydney DUI Lawyer gets DUI & Disqualified Driving Offences Dismissed9:52 · NSW▶Cloncurry DUI Lawyers - Fishing Trip Ends in 2 x Drug Driving Case6:38 · QLD▶Parramatta DUI Lawyer: Case Study & Legal Advice6:39 · NSW▶Brisbane DUI Lawyer Explains: Minimum Penalty for Low Range Drink Driving6:04 · QLD▶Katoomba DUI Lawyer Shares How Cases Get Dismissed6:02 · NSW▶Cairns DUI Lawyer Shares Key Insights on Drink Driving Case4:19 · QLD▶How Lismore Drug Driving Lawyer Defended Repeat Offender at Court3:56 · NSW▶A week in the life of a Travelling Lawyer in 1 minute0:55 · NSW + QLD
Courts we attend

Find your court

Search for your courthouse to learn more about our legal services in your area.

Charged with a drink or drug driving offence?

Talk to us about legal representation for your court date.

Call 1300 941 900
Mon–Fri 8:30am – 6:00pmWe represent clients at courts throughout QLD, NSW & the ACT
Call 1300 941 900Make an enquiry