Alcohol-activated locks which prevent drink-drivers from starting their car will soon be mandatory for repeat offenders.
Associate Transport Minister Craig Foss confirmed today that anyone convicted of two or more offences within five years will have one of the locks installed in their car.
Those who were caught driving with a reading of more than 3.2 times the legal alcohol limit would also get a sentence which required one of the devices.
At present, sentences which require alcohol interlocks are applied to around 100 recidivist drunk drivers a year.
Now that they are mandatory, they could be applied to between 4000 and 5000 people a year.
The driver will cover the costs of the breathalyser device. However, offenders may get support from a Government subsidy.
The Cabinet has approved around $4 million in funding for the interlock scheme.
The interlock is wired into the vehicle's ignition. Any breath-alcohol reading higher than zero will activate the lock.
Foss said interlocks had been shown to reduce reoffending rates by around 60 per cent.
"Most people who face a sentence like this do try their best to abide by that sentence and ... change their behaviour," he said.
The minister conceded that the locks were not foolproof - a drunk driver could get a sober person to start their car for them.
But there were stiff penalties for anyone who abused the system, Foss said.
Some of the devices also came with a camera which prevented people from tampering, he said.
The move was strongly backed by the Automobile Association (AA), which described it as a "much-needed advancement".
The devices had prevented 4137 attempts at drink-driving since they were introduced in 2013, AA spokesman Dylan Thomsen said.
"If a small number of interlocks can prevent 100 drink driving attempts each month then imagine how much impact thousands of interlocks will have."
Repeat drink driver Luke Bickerstaff, who had one of the locks installed after his second offence, said the device was frustrating at first.
"But ... it was a genuine lifesaver. It changes your whole behaviour and attitude towards drinking and driving.
"Every time you blow into that device it's a reminder of what you've done, your previous wrongdoing."
He said the devices required a driver to be breath-tested on more than one occasion, so could not be gamed easily.
DRINK DRIVING IN NZ
- cause of 77 deaths and 436 injuries a year
- 4000 to 5000 repeat drink-drive offences each year
- 100 drink-drive "attempts" prevented by alcohol interlocks a month
May 7 - Driver, 17, caught five times over the breath-alcohol limit with his 10-month old son in the car in Hamilton East.
Jan 26 - 55 year-old woman on zero alcohol license caught five times over the breath-alcohol limit in Kaitaia. Sentenced to four months' home detention.
Nov 27 - West Coast man, 56, sentenced to five months' jail after being convicted of his seventh drink-driving offence. In his most recent case, he was caught four times over the limit.