The Government says while there is plenty of research on the link between road deaths and blood alcohol, there's not enough information specific to New Zealand.
The Government on Monday announced a package of changes aimed at reducing the impact of drink-drivers on the roads.
A zero blood alcohol limit is to be introduced for repeat drink-drivers and drivers under the age of 20.
There will also be tougher penalties for drink-driving causing death. Legislation is expected to be in place by early next year.
However, there will be no change in the standard legal blood alcohol limit from 80 milligrams of alcohol for every 100 millilitres of blood.
Political opponents claim there are dozens of research papers detailing the number of lives that could be saved if the limit was reduced to 50 milligrams.
But Transport Minister Steven Joyce says the Government has taken heed of the international research.
He says there are some significant gaps in domestic research, particularly in relation to the number of people who have accidents between when their blood alcohol level is between .05 and .08.
Research to establish the likely impact on the road toll of reducing the limit from from 80 milligrams (.08) of alcohol to 50 milligrams (.05) will be carried out over the next two years.
Labour calls for debate on lowering drink-drive limit
Labour Party leader Phil Goff believes there is already a case for lowering the blood alcohol limit for all drivers and it should be put to the public for debate.
"You've got to look across the board at a range of different initiatives. One of the initiatives in the mix needs to be to test whether the current limit for drunk driving is too high - it should go to the select committee."
But Mr Key says the public has to be firmly behind any move to lower the limit for all drivers.
"Over time, I think there is a possibility that the blood-alcohol level will be lowered. But we can't police every roadside kerb on every corner.
"We need to take people with us and we need New Zealanders on a large, mass scale saying they want to support those moves and I don't think we've made that case to them yet."
Mixed response to measures
The Automobile Association believes the Government's move to tackle drink-driving will have a big impact. Motoring affairs general manager Mike Noon says the targeted measures are long overdue and believes that lives will be saved.
The organisation Students Against Driving Drunk also believes the measures will save lives.
However, road safety advocates say the Government should be lowering the adult drink-driving limit.
The head of Preventive and Social Medicine at Otago University, Professor Jennie Connor, says overseas research shows lowering the blood alcohol limit does save lives.
The Motor Trade Association, Alcohol Healthwatch and the Safe and Sustainable Transport Association, agree that an opportunity has been missed.
Lawyer calls for infringement offence
A lawyer specialising in drink-driving says an infringement offence should be created for those caught with lower blood alcohol levels.
Chris Reid says he is pleased the Government is not lowering the blood alcohol limit, because of what he describes as the huge implications of gaining a criminal conviction.
Mr Reid says one way to reduce drink-driving death and injury would be to create a new infringement offence for drivers caught at lower blood alcohol levels.
Drivers caught between .05 and .08 should receive a fine and be suspended for two months, he says.