The amount New Zealanders could consume while staying under the drink-drive limit would drop by two to three beers if a Labour MP's bid to lower the threshold is backed by Parliament.
Labour MP Iain Lees-Galloway's bill was pulled from the ballot yesterday. If supported it would cut the legal blood alcohol limit from 80mg to 50mg per 100ml of blood.
New Zealand's limit is among the highest in the world, matched only by the US and the UK.
The lower threshold would mean the average male would be over the limit after four to six 330ml beers consumed over two hours, instead of six to nine beers under the current limit. The average female would be over the limit after three to five beers, instead of four to six beers.
An Environmental Science and Research study showed that a 165cm woman weighing 70kg would exceed the proposed breath alcohol content if she drank five beers (3.3 glasses of wine) over two hours, and could be over the limit after two and a half.
The bill would lower the breath alcohol limit from 400 micrograms of alcohol per litre of breath to 250 micrograms.
Mr Lees-Galloway proposed the lower limit as an amendment to the Alcohol Law Reform Bill last year but it was narrowly defeated. Labour, Greens, New Zealand First, the Maori Party and Mana backed it, though not all had confirmed they would repeat their support. If they did, the bill would still require a vote from either United Future or the Act Party to pass.
United Future leader Peter Dunne said yesterday that he had previously stated his support for a 50mg limit. Act Party leader John Banks said he supported a lower limit, but only if it was paired with stronger sanctions for recidivist drink-drivers.
The Government was already reviewing the drink-drive limit, and research which measured the number of injuries and deaths caused by drivers with a blood alcohol content (BAC) of 50mg to 80mg has just been completed.
Acting Transport Minister Michael Woodhouse's office said Government would wait for the results of the two-year study before it decided whether lower limits were needed. If Cabinet backed it, Government was likely to introduce its own legislation.
Mr Lees-Galloway said the evidence already existed and a change was needed as soon as possible.
Senior roading police told the Law and Order Committee last week that lowering the limit overseas had reduced road trauma without exception, and predicted that the change would save between 10 and 25 lives a year in New Zealand.
Some have pointed out that most alcohol-related crashes were caused by people who drank double or triple the legal limit, not people who were marginally over the limit, but Assistant Commissioner Dave Cliff said this was not the case.
"The research says that when you reduce BAC level, the whole distribution of offending moves to the left, so high-end drinkers drink less, the risk declines across the whole population - that's the impact you see."