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Do alcohol interlocks stop reoffending? NZTA's data

An alcohol interlock stops a car starting if the driver has been drinking. So once someone has been through an interlock, do they stay out of trouble?

We asked NZ Transport Agency Waka Kotahi (NZTA) under the Official Information Act. Most of the request was declined because NZTA said it would need substantial collation and research, but NZTA released a Driver Licence Register analysis it prepared for the Ministry of Transport in May 2025, which includes a count of interlock drivers who went on to reoffend [1]. Here is what it shows, and just as importantly, what it cannot tell you.

What NZTA counted as reoffending

This matters, so it is worth being precise. NZTA counted an interlock sentence as followed by reoffending if the driver had one of these offences dated on or after the day their interlock licence started [1]:

  • any alcohol or drug impaired driving offence
  • driving contrary to an alcohol interlock licence
  • driving contrary to a zero alcohol licence

That includes offences while on the interlock, offences after moving on to a zero alcohol licence (including after getting a standard licence back), and offences after an interlock licence was cancelled [1]. NZTA also notes the driver might not have held a current interlock licence at the time of the offence, for example if the licence had expired or they had been disqualified again [1]. Offences with no recorded date were left out, and the offence data runs to 12 June 2025 [1].

The headline number

Of 20,063 alcohol interlock sentences between 2012 and the end of 2024, 3,852 were followed by at least one of those offences [1]. That is about 19%, or nearly one in five.

Year by year

YearReoffendedDid not reoffendTotal sentenced to an interlockReoffended share
20134410114530%
20148713021740%
20158513922438%
201612018730739%
20177618225829%
201825966692528%
20197371,8022,53929%
20206371,8372,47426%
20216862,3273,01323%
20225462,5333,07918%
20233472,9493,29611%
20242283,3573,5856%

Figures are from NZTA's analysis [1]. The percentages are our own calculation from those figures, rounded.

Drivers sentenced to an interlock each year, and how many reoffended
Sentenced to an interlockReoffended
Drivers sentenced to an interlock each year, and how many reoffendedCOVID-19Lockdown 1Lockdown 2Interlocks mandatory08001,6002,4003,2004,0002013201520172019202120232013: 145 sentenced to an interlock2014: 217 sentenced to an interlock2015: 224 sentenced to an interlock2016: 307 sentenced to an interlock2017: 258 sentenced to an interlock2018: 925 sentenced to an interlock2019: 2,539 sentenced to an interlock2020: 2,474 sentenced to an interlock2021: 3,013 sentenced to an interlock2022: 3,079 sentenced to an interlock2023: 3,296 sentenced to an interlock2024: 3,585 sentenced to an interlock3,5852,539+174% on 20183,013+22% on 20202013: 44 followed by reoffending2014: 87 followed by reoffending2015: 85 followed by reoffending2016: 120 followed by reoffending2017: 76 followed by reoffending2018: 259 followed by reoffending2019: 737 followed by reoffending2020: 637 followed by reoffending2021: 686 followed by reoffending2022: 546 followed by reoffending2023: 347 followed by reoffending2024: 228 followed by reoffending737228
  • COVID-19 rules in place: 28 February 2020 (first case) to 12 September 2022 (traffic lights ended, most rules removed from 13 September 2022)
  • Lockdown 1: Alert Level 4 nationwide: 25 March 2020 to 27 April 2020
  • Lockdown 2: Alert Level 4: 17 August 2021 nationwide; outside Auckland ended 31 August 2021, Auckland ended 21 September 2021 (Auckland then stayed at Level 3 until 2 December 2021)
  • Interlocks mandatory: From 1 July 2018 alcohol interlocks became mandatory in sentencing for serious driving offences involving alcohol [1]
Each point is a full calendar year, plotted at mid-year, counted by the year of the interlock sentence. Hover or tap a point for its exact figure. Source: NZTA Driver Licence Register analysis released under the Official Information Act [1]; COVID-19 dates [3][4]. Reoffending is as recorded by 12 June 2025, so recent years have had less time for offences to show up.

The same figures as a share of each year's interlock sentences:

Share of drivers sentenced to an interlock who reoffended, by year
Share of drivers sentenced to an interlock who reoffended, by yearCOVID-19Lockdown 1Lockdown 2Interlocks mandatory0%10%20%30%40%50%2013201520172019202120232013: 30.3%2014: 40.1%2015: 37.9%2016: 39.1%2017: 29.5%2018: 28%2019: 29%2020: 25.7%2021: 22.8%2022: 17.7%2023: 10.5%2024: 6.4%40.1%6.4%30.3%
  • COVID-19 rules in place: 28 February 2020 (first case) to 12 September 2022 (traffic lights ended, most rules removed from 13 September 2022)
  • Lockdown 1: Alert Level 4 nationwide: 25 March 2020 to 27 April 2020
  • Lockdown 2: Alert Level 4: 17 August 2021 nationwide; outside Auckland ended 31 August 2021, Auckland ended 21 September 2021 (Auckland then stayed at Level 3 until 2 December 2021)
  • Interlocks mandatory: From 1 July 2018 alcohol interlocks became mandatory in sentencing for serious driving offences involving alcohol [1]
Each point is the share of drivers sentenced to an interlock that calendar year that were followed by a further offence, as recorded by 12 June 2025, plotted at mid-year. Our calculation from NZTA's figures [1]; COVID-19 dates [3][4]. The fall in recent years is mostly because those drivers have been followed for less time, see below.

Why the recent years look so much better (and probably are not)

It is tempting to read that table as reoffending falling from 40% to 6%. That would be a mistake.

Someone sentenced to an interlock in 2014 had more than ten years for a further offence to show up before the data was pulled in June 2025. Someone sentenced to an interlock in 2024 had, at most, around 18 months, and much of that time they were driving a car that would not start if they had been drinking [1]. Fewer offences have had time to happen, so the recent percentages will almost certainly rise as those drivers are followed for longer.

A fairer comparison is between groups with a long follow-up:

  • 2013 to 2017 (before interlocks became mandatory for serious offending): 412 of 1,151, or about 36%, went on to reoffend [1].
  • 2019 to 2021 (the first full years after interlocks became mandatory on 1 July 2018): 2,060 of 8,026, or about 26% [1].

Even here, the earlier group has had several more years for offences to appear, and the two groups are different kinds of offender. Before July 2018 interlocks were a sentencing option, and after it they were mandatory for serious offending, so the people getting them changed [1]. The data does not tell us why the rates differ, and we will not pretend it does.

What you can fairly take from it

  • For a lot of people, the interlock is not the end of it. In the 2019 to 2021 groups, about one in four drivers had a further alcohol or drug impaired driving offence, or drove in breach of their interlock or zero alcohol licence, by June 2025 [1].
  • The zero alcohol licence is where many people get caught out. The count includes offences committed after moving from the interlock to a zero alcohol licence [1]. That licence lasts 3 years and the limit is zero [2]. A couple of drinks that would be legal for most drivers is an offence for you.
  • A second offence costs far more than the first. A previous qualifying conviction within 5 years means a mandatory interlock sentence for the next offence regardless of the reading, and repeat offending can lead to indefinite disqualification [2].

If you are on an interlock or zero alcohol licence now

The practical lesson is simple: treat the whole period, interlock and zero alcohol licence together, as a period where you do not drink and drive at all. Not a little, not the next morning after a big night, not once. The data shows plenty of people who got through the interlock and then came unstuck afterwards [1].

Where a limited licence fits

If you are subject to an alcohol interlock sentence, or have a repeat drink or drug driving offence within 5 years, you cannot apply for a limited licence [2]. Some first-time drink drivers with lower readings may be eligible. NZ Limited Licence prepares limited licence application documents. We are not lawyers, we do not appear in court, and the decision is always the judge's. Phone 0800 437 005.

For how interlock numbers have grown since 2018, and how long people take to get off one, see Alcohol interlocks in NZ: what NZTA's own numbers show.

Sources

  1. NZ Transport Agency Waka Kotahi, response to Official Information Act requests OIA-23159 and OIA-23285 (2 September 2026), Attachment 1: Driver Licence Register analysis of alcohol interlock licences and reoffending prepared for the Ministry of Transport (report date 30 May 2025; offence data as at 12 June 2025). Released to NZ Limited Licence; not published online.
  2. Land Transport Act 1998 (version as at 4 September 2026), sections 65, 65AB, 65AE, 65AG and 103, New Zealand Legislation, https://www.legislation.govt.nz/act/public/1998/0110/latest/whole.html (accessed 27 September 2026)
  3. History of the COVID-19 Alert System, Unite against COVID-19 (New Zealand Government), https://covid19.govt.nz/about-our-covid-19-response/history-of-the-covid-19-alert-system/ (page last updated 29 June 2022; site since retired, archived copy at web.archive.org accessed 27 September 2026)
  4. The next phase of our COVID-19 response, Unite against COVID-19 (New Zealand Government), covid19.govt.nz (page last updated 23 September 2022; site since retired, archived copy at web.archive.org accessed 27 September 2026)

Frequently asked questions

How many alcohol interlock drivers reoffend in New Zealand?

Of 20,063 interlock sentences from 2012 to 2024, 3,852 (about 19%) were followed by another alcohol or drug impaired driving offence or a breach of an interlock or zero alcohol licence, as recorded by June 2025.

Does reoffending include the zero alcohol licence period?

Yes. NZTA's count includes offences committed after the driver moved from an interlock licence to a zero alcohol licence.

Why do recent years show lower reoffending?

Mostly because those drivers have been followed for a much shorter time. A driver sentenced to an interlock in 2024 had at most around 18 months for an offence to be recorded before the data was extracted.

Can I get a limited licence while on an interlock sentence?

No. A person subject to an alcohol interlock sentence cannot apply for a limited licence.

Start your application →Call 0800 437 005
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