An independent analysis commissioned by the New Zealand Transport Agency has put the number of “irregular” alcohol breath tests recorded by police at 42,678, around 12,000 more than the figure first reported when the issue surfaced last year.
The full report, produced by infrastructure consultancy WSP and released by NZTA to RNZ on Friday, examined breath testing data between 1 July 2024 and 30 September 2025. WSP initially identified up to 111,000 “unique anomalous tests” using two separate methodologies, before police pushed back on one of those methods and WSP removed it from the final count.
The remaining methodology produced the 42,678 figure that NZTA has now formally accepted.
The issue first came to public attention through RNZ reporting in 2025, which revealed that about 130 police officers around the country were under investigation after some 30,000 breath tests were “falsely or erroneously recorded”. Following that reporting, NZTA halted around 12 million dollars of road policing funding until it was satisfied that police had met agreed breath testing targets.
NZTA later commissioned WSP to work through the data and try to identify the full scale of the problem.
One of the techniques WSP used flagged tests carried out on a single device at a faster rate than a legitimate checkpoint could realistically process drivers. The reasoning was straightforward. If a handheld device records a string of tests only a few seconds apart, there is a reasonable question about whether those tests were performed on actual motorists or simply ghosted through the system.
Police told the reviewers that they did not support all of the findings, arguing that the analysis was based on “incorrect assumptions” and that many of the flagged tests could be explained by legitimate operational activity. Police also told WSP that an efficient checkpoint could in fact process drivers in under 20 seconds, which would account for some of the tight clustering picked up by the algorithm.
WSP accepted that point and removed the short interval clustering methodology from its final report. After a further review of the remaining data, it landed on the 42,678 figure.
An NZTA spokesperson told RNZ that police had now met their targets once the irregular tests were stripped out of the reporting. Between July 2025 and the end of March 2026, police carried out 3,178,981 breath screening tests, around 28 percent above the year to date target of 2,475,000. On the back of that, the agency has authorised 18 million dollars of funding for police road safety work.
“NZTA is continuing to work with NZ Police to ensure ongoing confidence in reporting of road policing activity through the Road Policing Investment Programme,” the spokesperson said.
Transport Minister Chris Bishop told RNZ it was “disappointing that this issue occurred at all” and said he was “also frustrated by how long it has taken to release the report”.
The numbers matter for a couple of reasons that go beyond bookkeeping. Breath testing volume is one of the headline measures NZTA uses to assess whether police are delivering on road safety contracts, because the deterrent effect of being stopped depends on drivers genuinely believing they could be tested on any given trip. If the underlying numbers are inflated by tests that never happened, the picture of how much enforcement activity is on the road becomes harder to trust.
The volume of tests being signed off as legitimate is still very large. Even on the higher figure, the 42,678 irregular tests represent a little over one percent of the total breath testing activity recorded during the period, with the overwhelming majority of stops appearing to be straightforward roadside breath checks. The independent review is essentially a stocktake to work out how much of that total can be relied on.
The fact that NZTA was willing to pull funding while questions hung over the data has set a useful precedent. Performance based contracts only work if the agency paying the money will check the numbers, and in this case the regulator did. The 12 million dollars of withheld funding has now flowed, but only after a formal independent count and a written report from WSP.
The 130 or so officers who were already under investigation when the issue first broke remain a separate workstream for police themselves. The WSP review focused on the data, not on individual conduct, and decisions about disciplinary outcomes for officers found to have entered tests that were not carried out will sit with police professional conduct processes.
For drivers, the practical effect is unchanged. Checkpoints are still being run around the country, and police are still meeting and exceeding their annual breath test volumes once the disputed entries are removed. If you do get pulled in at a checkpoint and end up over the limit, our guide on what happens if you are charged with drink driving in New Zealand walks through the next steps. The bigger question is cultural, namely whether reporting standards inside the road policing operation have tightened enough that something on this scale would not happen again. The release of the full WSP report is at least a starting point for answering that.
What do you think of how this has been handled? Should NZTA be running the numbers like this more often across other policing contracts, or is once enough? Let us know in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job π
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