Sixteen warnings have been issued in Wairarapa for serious violent and sexual offending since the "three strikes" legislation came into force in 2010.
But none have been issued with a second strike or final warning under the act.
Details released under the Official Information Act show 16 first strikes had been issued as at December 17 last year.
Warnings for sexual offending were the most frequent, with seven strikes issued, followed by robbery and extortion with five.
Two strikes were issued for injury causing grievous bodily harm, one for aggravated burglary and one for abduction and harassment.
Recent strikes issued in Wairarapa include to a 52-year-old Wairarapa farm manager who pleaded guilty last September to indecently assaulting two boys in 2011. The incidents involved two occasions when an 11 and 15-year-old boy stayed at the farm where the man worked.
During one incident, the older boy woke during the night to find the offender lying next to him, touching him indecently through his pants. The victim jumped out a window and hid in a nearby paddock, waiting for the farm manager to go back to sleep, before taking the man's car and driving home to tell his mother.
A man convicted of indecent assault in September 2011 as part of a string of offences at a Masterton party also earned a strike. The Masterton District Court heard how Tony Leveridge, then 48, become confrontational with other guests at the party, assaulted a 19-year-old female in a garage, slapped the home owner in the face and kicked a female police constable while being handcuffed, causing her to fall to the ground.
Nationwide as of last month, 2566 offenders had been awarded a first strike and 15 a second strike - or final warning - under the Sentencing and Parole Reform Act.
Dubbed the "three strikes" bill, the act came into force on June 1, 2010. Under the legislation, a convicted offender receives a standard sentence after one strike, a sentence with no parole for the second strike, and the maximum sentence for the offence and no parole for the third, unless the court considers that would be unjust. No one has yet received a third strike.
"At this stage, no offenders have been subject to the most severe consequences of the regime, although a number have received a final warning.
"I am confident the legislation is an effective deterrent to criminal offending and that the system is working as intended."
Local police declined to comment on the three strikes regime, saying its impact on reoffending rates was not quantifiable.
However, Sensible Sentencing Trust spokesman Garth McVicar agreed with Ms Collins, saying the trust loved the legislation.
"Everyone seems to be in favour of it. There only seems to be a minority of people who are opposed to it and I think it's ideologically opposed rather than [having] any factual base to it."
The drop-off in the number of offenders who received a second strike after receiving a first showed the system was a deterrent to offenders, he said.
There are 40 qualifying offences comprising all violent and sexual offences with a maximum penalty of seven years' imprisonment or more, including murder, attempted murder, manslaughter, wounding with intent to cause grievous bodily harm, sexual violation, abduction, kidnapping, and aggravated robbery.