Hetaraka Hikurangi Reihana, 21, pleaded guilty to the manslaughter of Merepeka Morehu-Clark, 14, and her 13-year-old sister Brooklyn, who died in an horrific Christmas Day road crash in 2011. The Crown said Reihana had been racing two relatives to a family urupa (cemetery) in the lead-up to the accident after a day of heavy drinking. He is due to be sentenced May 31.
Nationwide, 2566 offenders have been awarded a first strike and 15 a second strike - or final warning - under the Sentencing and Parole Reform Act.
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 manifestly unjust.
No one has yet received a third strike.
Justice Minister Judith Collins said yesterday the legislation's effects would be felt over time.
"I am confident the legislation is an effective deterrent to criminal offending and that the system is working as intended."
Sensible Sentencing Trust spokesman Garth McVicar agreed with Ms Collins, saying the trust liked the legislation.
Mr McVicar said he had received letters from current inmates who said they understood and supported the legislation.
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.
But Katikati Park Rd Dairy owner and stabbing victim Ramandeep Singh said the law was not tough enough.
He and his uncle were subjected to two serious violent attacks in 14 weeks last year.
"I think the three-strikes warning legislation is rubbish, you don't get a warning or second chance for a parking ticket or speeding fine."
He said he can accept giving a warning if the offender was a child but when they were over 18 there should be no second chances and the offender should serve their entire sentence.
"The politicians need to get more real. This is our life we're talking about here. After what happened to us, we feel fearful and on edge every day.
"I think if there is a little bit of harsh medicine first time up for violent offenders then maybe they won't do it again and it will also deter others."
Under three strikes, there are 40 qualifying offences including all major violent and sexual offences with a maximum penalty of seven years' jail or more, including murder, attempted murder, manslaughter, wounding with intent to cause grievous bodily harm, sexual violation, abduction, kidnapping and aggravated robbery.