He hoped the decrease would filter down to the lower threshold as people started to understand what their bodies could handle.
From December 1, the breath-alcohol limit for adult drivers was lowered from 400mcg to 250mcg.
Drivers with breath alcohol between 251-400mcg face an infringement fee of $200 and receive 50 demerit points. They are not charged by police, or put before the courts - a mechanism aimed at changing behaviour without putting undue pressure on the already overloaded district court system.
Drivers who blow over 400mcg still face a criminal charge.
Police statistics showed that by the end of June, 4971 drivers had been pinged, paying a total of $972,700 in fines.
In December 806 drivers were caught nationally, and by June that figure had dropped to 638.
The month with the most fines issued was May - 709 drivers were caught over the limit.
The district with the highest number of drivers fined was Canterbury with 657 tickets issued, 588 in the wider Christchurch area. Waikato came a close second with 586 drivers, 334 in Hamilton city.
A further 236 were caught in the Auckland CBD and fringe suburbs, and 163 drivers blew over the limit on the city's motorways.
Mr Greally said the rate at which police had been breath testing motorists had decreased since the law change.
"We're actually targeting with a bit more intel behind us. We are deploying staff to risk [areas] rather than testing high volumes of drivers."
Each district had different risk factors and areas for drivers and each road policing tailored its breath testing to individual environments and driver behaviours.
Mr Greally said it was hard to pick any trends with only seven months worth of information.
Licensed premises were reporting the same number of patrons, but they were drinking less, he said.
Police do not profit from drink-driving infringements. The money goes back into central government.
"It's never been about revenue and never will be for us," said Mr Greally. "It's about road safety."
Associate Transport Minister Craig Foss described the combination of an infringement fee and demerit points as "a significant deterrent while not criminalising people at the lower end of the offending range".
"Officials estimated a lower adult limit would result in an additional 19,100 drivers caught in the [251-400 mcg] range in the first year."
If the lower adult limit followed the pattern seen when the zero-alcohol limit for under-20 drivers was set in August 2011, the number of people caught at all levels should reduce over time.
The New Zealand Transport Agency said the lower adult drink-drive limit is estimated to have a net benefit of $200 million over 10 years.
Their statistics show that alcohol is a factor in around 30 per cent of New Zealand's fatal road crashes. Over the last 10 years fatal crashes caused by drink-driving have claimed the lives of around 1100 people and caused serious injuries to another 5300.
THE FIGURES (All district figures are totals that INCLUDE the city pulled out below)
• NORTHLAND 320
• WHANGAREI 183
• AUCKLAND DISTRICT 556
• AUCKLAND CENTRAL 236
• COUNTIES MANUKAU 544
• WAITEMATA 519
• AUCKLAND MOTORWAYS 163
• WAIKATO 586
• HAMILTON 334
• BAY OF PLENTY 513
• ROTORUA
• CENTRAL 443
• WHANGANUI 119
• EASTERN 345
• WELLINGTON DISTRICT 545
• WELLINGTON CITY 200
• CANTERBURY 657
• CANTERBURY METRO/CHRISTCHURCH 588
• SOUTHERN 306
• TASMAN 226
FINES BY MONTH - NATIONAL
• DECEMBER 806
• JANUARY 774
• FEBRUARY 644
• MARCH 695
• APRIL651
• MAY 709
• JUN 638