Just one death caused by driver in lower drink-driving limit since law introduced
There has been only one confirmed road death in which the driver at fault had drunk enough alcohol to put them between the new and old drink-driving limits.
Labour transport spokeswoman Sue Moroney said the single death showed that lower-end drink-driving was not a high-risk area, and that a rise in the national road toll showed the Government's road safety measures were not working.
A total of 320 people died on the roads last year, compared with 294 in 2014. There have been 52 road deaths so far this year, against 49 by the same time last year.
Before the new limit of 50 milligrams of alcohol per 100 millilitres of blood, or 250 micrograms of alcohol per litre of breath, was introduced in December 2014, the Ministry of Transport estimated it would save three lives a year, as well as 64 minor and serious injuries.
But Moroney said figures provided to her by Associate Transport Minister Craig Foss showed the Government was diverting police resources to target good drivers for fine revenue.
"I'm worried that the police are spending a lot of time fining people, pulling people over for low-level speeding and low-level alcohol ... I think they would be justified if the road toll was going down, but it hasn't. The road toll is going up."
Foss said there was not enough data yet to gauge accurately whether the law was working.
"We will never know exactly how many [deaths] were prevented because they didn't happen ...
"Is Ms Moroney now advocating for the drink-drive limit to be raised? That would be surprising, given her party supported the introduction of the lower limit."
The old limit, of 80mg or 400mcg, remains the threshold for a criminal prosecution. Drivers caught between the two limits receive a $200 fine, 50 demerit points, and are banned from driving for the next 12 hours.
The single death caused by a driver between the two limits was in February 2015. Police could not say whether the driver's alcohol consumption was the lead cause of the crash.
Between December 2014 and August 2015, police issued 4917 infringement notices to motorists caught between the new and old limits.
A police headquarters spokeswoman there were "promising signs" the law change might be influencing drivers' behaviour because, since October 2015, almost 2500 fewer drivers had been caught over the old limit.
The Ministry of Transport will undertake a review of the lower drink-driving limit once it has three years of data.