Legislation to put in place a "three strikes and you're out" policy for violent or sexual offenders has passed its first reading in Parliament, under urgency, on Wednesday.
The Sentencing and Parole Reform Bill passed by 64 votes to 58. National and ACT voted in support of the measure.
Under the legislation, criminals convicted a third time for violent or sexual offences would be sent to prison for life with a minimum non-parole period of 25 years.
The idea is ACT Party policy but is going through Parliament as a Government bill.
The National Party pledged to support the bill through to select committee as part of its agreement with ACT.
However, Justice Minister Simon Power is not ruling out the possibility of voting against the Government bill, if National decides to oppose it after hearing public submissions.
"We're not making any comment about that at this stage," he said. "Under the confidence and supply agreement we have agreed to support the legislation to select committee and to participate in that process in good faith."
The Maori Party, Green Party and Labour voted against the bill, saying the 'three strikes' approach is not an effective way of addressing violent crime.
Maori Party co-leader Tariana Turia said the legislation was not National Party policy and she would be surprised if the party followed through on it.
Ms Turia said it would be better to examine the underlying causes of violent crime.
Howard League for Penal Reform president Peter Williams QC said the legislation would bring misery and increased offending.
He told Morning Report that people jailed for 25 years with no prospect of parole will suffer mental illness and would be much more likely to commit suicide.
Sensible Sentencing Trust spokesperson Garth McVicar said there is nothing on the statute books at present to address recidivist violent or sexual offenders, and his organisation will produce statistical data showing heavy sentences do reduce crime.
Mr McVicar said the legislation would not mirror that in the United States which was flawed as it drew in those who had committed minor offences.
Legislation that would allow some of the country's worst young offenders to be sentenced to military-style "boot camps" also passed its first reading on Wednesday night.
