Drivers who exceed a new lower drink-drive limit will be hit with instant fines and demerit points, the Government says, but insists Kiwis will still be able to have "one or two" drinks before driving.

Transport Minister Gerry Brownlee today revealed that Cabinet had lower the legal blood alcohol limit from 80 to 50 milligrams of alcohol per 100 millilitres of blood for drivers aged over 20.

However, drivers caught between the new limit and the old one will not be subject to court action. Instead, police will be able to issue penalties on the spot.

The fines were likely to be $200 and 50 demerit points. This means two infringements within two years would see drivers lose their licences, Brownlee said.

Currently a first or second drink-driving offence that does not cause injury results in a six-month driving disqualification and a fine, typically around $630.

Brownlee said Cabinet was conscious of the need to reach a balance between ''the desire to indicate that we want people to be more cautious about the level of alcohol in their blood when they get behind the wheel and in fact determining that they are at a criminal level''.

A two-year review of the impact of lowering the legal blood alcohol limit by 30 milligrams suggested that each year 3.4 lives would be saved and 64 injury-causing crashes would be avoided. It would save $200 million in social costs over 10 years, Brownlee said.

"Data collected by Police over the past 22 months shows 53 drivers were involved in fatal and serious injury crashes with blood alcohol readings of between 51 and 80 milligrams per 100 millilitres of blood," he said.

Prime Minister John Key said the new rules reflected the international trends to new lower limits, ''the weight of public opinion'' and research which showed overall benefits.

''What this decision means is that you will still be able to have a couple of drinks with dinner, when you go out. It's not going to prevent your ability to engage in normal social activity,'' Key said.

''But it does send a message that we are serious about alcohol-related harm on our roads.''

Labour immediately claimed credit for the changes. Last month Palmerston North MP Iain Lees- Galloway's member's bill, proposing the blood alcohol limit be cut by the amount which the government announced today, was drawn from the ballot, meaning it would go before Parliament.

He has since claimed that he could have passed the bill even without the support of the National Party.

Today Lees-Galloway said it was his proposal which had led to today's decision.

''The government originally kicked for touch on this issue. It's been something which has been around which they could have moved on at any stage over the last three years,'' he said.

''Clearly my Bill being drawn from the ballot was the incentive they needed to get on with the job and I'm very pleased they've made this decision. It is the sensible one.''

He expected that Labour would support the government Bill so long as it was a priority, meaning the proposals would become law around the middle of next year.

''If that's going to be what happens with the government bill then yes, I think we should get in behind their Bill.''

CHANGE 'ABOUT TIME'



Police welcomed the decision, saying they would work to support the progress of legislation.

"Police will however be making no further comment until the legislation has gone through the appropriate process," Assistant Commissioner Road Policing Dave Cliff said in a statement.

AA motoring affairs general manager Mike Noon said the association supported the change.

"I think it's a fantastic decision from the Government that will save lives on our roads," he said.

More than two-thirds of AA members had indicated their support for a lower limit in surveys carried out by AA, Noon said.

"It has gotten to the stage where the public is strongly in favour of a lower limit, and that is why we have campaigned for this."

The AA would continue to lobby for alcohol interlocks on vehicles, as well as rehabilitative treatment for offenders. It would like the money from the fines to go towards treatment, he said.

"But the most substantive thing today is the limit has been lowered, and we welcome that."

Alcohol Healthwatch director Rebecca Williams said the announcement was a cause for celebration.

"I'm absolutely elated, although part of me is going, 'about time'," she said.

"It's a great outcome - they've been dragging their heels on this one for quite some time, but it's great to finally hear the announcement."

There had been a "huge discrepancy" after the youth alcohol limit was lowered to zero in 2011. These changes would ensure the adult limit was more in line, Williams said.

"We will see a change. We will see a drop in deaths and injuries, and I'm hoping we will see our roads become safer places," she said.

The New Zealand Drug Foundation also supported the Government’s move.

"We welcome and congratulate the Government’s move to lower the adult drink driving limit," executive director Ross Bell said.

"It shows they are taking road safety seriously. We’ve already seen the benefits of lowering the blood alcohol limit for those under 20. This new lower limit for adults will bring further road safety benefits," Bell said.