He said he thought the legislation sent a strong message to first strike offenders.
However, Wairarapa-based former Act Party candidate Shane Atkinson said he believed the legislation was bad law in its underlying principle as well as its process and performance.
Mr Atkinson - who stressed his views were his own and not those of the Act Party - said he didn't believe the heavy sentences the legislation brought about acted as deterrents.
Three strikes took away sentencing options for judges, he said.
Steve Treloar, of Wanganui's Prisoners' Aid and Rehabilitation Society, said "three strikes" legislation was set up as a deterrent but any number of factors could have contributed to a drop in offending in the Wanganui area.
Some good work was being done around drug and alcohol clinics and cognitive thinking programmes for offenders, he said.
Sensible Sentencing Trust Tauranga spokesman Ken Evans said the very low number of second warnings issued in his area suggested the system was working.
Crime had dropped dramatically locally as well as nationally since the "three strikes" legislation came in, said Mr Evans.
Sensible Sentencing Trust Northland co-ordinator Steve Detlaff said the legislation was a step in the right direction.
"Even if we keep one criminal behind bars who would have come out and committed further crimes, then we've done our job, we've made a difference to somebody who would have been a victim but now won't be," he said.
Rotorua Sensible Sentencing Trust spokesman Peter Bentley agreed if the legislation could just make one person think twice about committing a crime, then it had been a success.
Rotorua's Families Matter law practice director Martin Hine said proper research was needed to determine whether the legislation was having an effect.
It would be interesting to see which forms of offending had increased or decreased over the period the legislation had been in place, he said.
The Sentencing and Parole Reform Act 2010 came into force in June 2010, creating a three stage regime of increasing consequences for repeat serious violent offenders, according to the Ministry of Justice.
There were 40 qualifying offences, comprising all major violent and sexual offences with a maximum penalty of seven years imprisonment or more.
A first warning was issued when an offender aged 18 or over who did not have any previous warnings, was convicted of a qualifying offence. Once an offender had received a first strike warning, it stayed on their record forever, according to the ministry.
If an offender was convicted of a second qualifying offence they received a final warning and - if sentenced to imprisonment - would serve the sentence in full without the possibility of parole.
On conviction of a third qualifying offence the court must impose the maximum penalty for the offence. The court must also order the sentence be served without parole, unless the court considered it would be manifestly unjust, according to the ministry.
