The party which brought Three Strikes into law is now supporting changes which stopped 100 of the country's most dangerous inmates from prison programmes intended to reduce offending.
Act Party leader David Seymour said the law was never intended to be a barrier to reducing reoffending.
The NZ Herald revealed this week that the Three Strikes law appears to have done exactly that for the 100 Second Strike offenders released since 2012.
Those offenders - locked up for serious violent of sexual crime - are forced by law to serve their full sentences without parole.
• 100 dangerous inmates released without going through reintegration programmes
• Official: 'Evidence' cited on Three Strikes doesn't actually show it's working
• Sensible Sentencing Trust lawyer David Garrett's claims 'tough on crime' works
The law clashes with the legal framework under which Corrections runs, which prohibits allowing inmates who don't qualify for parole off prison grounds.
The clash means those inmates are not able to take up reintegration programmes such as release-to-work schemes which allow inmates to develop work habits and save money for their eventual release.
Corrections considers reintegration programmes to be a critical tool in helping reduce reoffending.
Seymour said: "I didn't realise that was a feature of the Corrections Regulations. It was certainly never an intention of the law."
He said the intent of the law was to deter those who had offended from doing so again and the clash was an "unintended consequence".
Green Party justice spokeswoman Golriz Ghahraman called the oversight "dangerous".
"This piece of law encapsulates what is wrong with the 'tough on crime' approach. It over-simplifies everything.
"It's more about vengeance than keeping everyone safe."
Ghahraman said the answer to New Zealand's high rate of imprisonment was far more complex than could be addressed by laws such as Three Strikes. She said it involved social and economic change and better understanding of the backgrounds of those who entered prison.
She said she welcomed National leader Simon Bridges' concession he would consider whether changes were needed.
Bridges had previously told the Herald the law was fit for purpose.
After the Herald revealed serious offenders were blocked from positive programmes, he said: "While we don't believe the premise of Three Strikes should be watered down, we would be willing to look at the issue of reintegration for serious offenders."
The Ministry of Justice has found no evidence the Three Strikes law has actually stopped anyone from reoffending.
Corrections minister Kelvin Davis has said the issue had been raised with him by an inmate and he wanted changes.
Three Strikes was introduced in 2010 as part of a deal between the National Party and Act Party to form a government. The law was written by former Act MP David Garrett, lawyer for the Sensible Sentencing Trust. Garrett left Parliament after admitting to criminal indiscretions he had not previously declared.