Police increased the number of roadside breath tests by almost 80 per cent last year, catching 10 per cent more drink-drivers than in 2007.
Figures issued by Transport Minister Steven Joyce yesterday, based on police data, show that 2.91 million breath tests were taken last year and that 34,272 drivers faced excess alcohol charges.
That was an increase of 78.8 per cent on the 1.63 million breath tests police took in 2007, from which 30,968 charges were laid.
But despite the modest increase in offences compared with the extra enforcement effort, the police say it was a measure of success that they charged only one in every 85 drivers tested last year, compared with one in 53 in 2007.
National road policing manager Superintendent Paula Rose was pleased more people seemed to be heeding road safety advertising, although she said enforcement efforts would be maintained this year, as there was still too much drink-driving.
Although drivers faced a greater than 50 per cent chance last year of being stopped at police checkpoints, Ms Rose said, some still thought they were immune to detection.
It was therefore important for the police to maintain round-the-clock enforcement, to get the message through that drivers could expect to be stopped "any time, anywhere".
The decline in the proportion of offenders caught last year, compared with the number of drivers tested, was not reflected in any substantial reduction in road deaths for which alcohol or drugs were blamed.
Although deaths from crashes caused by alcohol or drugs fell 7 per cent, from 128 in 2007 to 119 last year, the overall road toll declined by 15 per cent to 366 fatalities.
That left alcohol or drugs being blamed for 32.5 per cent of fatal crashes compared with 30.3 per cent in 2007.
Mr Joyce said last night that although the reduced alcohol offending rate was encouraging, this year's road toll was heading back towards the 2007 level of 422 deaths.
He said transport officials generally attributed last year's lower toll to high fuel prices and consequential lighter traffic volumes.
The rising toll since then was increasing the importance of a new road safety strategy on which the Government has invited the public to comment on a list of 61 possible initiatives.
These include reducing the alcohol limit to 50mg from 80mg per 100mls of blood for adult drivers, and to zero for those under 20.