"Three strikes" is Act Party policy and Mr Lennox has been involved with the party since its inception.
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 Whanganui'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 Whanganui 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.
Sensible Sentencing Trust Northland co-ordinator Steve Detlaff said the legislation was a step in the right direction.
Rotorua Sensible Sentencing Trust spokesman Peter Bentley said if the legislation could just make one person think twice about committing a crime, then it had been a success.
The director of the Families Matter law practice in Rotorua, Martin Hine, said proper research was needed to determine whether the legislation was having an effect. He said it would be interesting to see which forms of offending had increased or decreased over the period the legislation had been in place.
