Labour, the Greens and the Maori Party all say they would repeal or alter the three-strikes legislation after the issuing of a second strike to Hastings man Elijah Whaanga.

Whaanga, 21, was sentenced to two years' jail and issued with his second strike by Judge Tony Adeane in the Napier District Court on April 18 after pleading guilty to two charges of aggravated robbery.

The offences involved Whaanga and an accomplice attacking victims on two occasions last August.

In one, Whaanga took a skateboard, hat and cigarette lighter from the victim after trying unsuccessfully to remove the victim's jacket.

The second involved Whaanga kicking the victim in his leg and taking his hat and cellphone.

Aggravated robbery, which carries a maximum sentence of 14 years' prison, can involve a robbery that causes the victim grievous bodily harm, robbery while armed with an offensive weapon, or robbery with an accomplice.

Whaanga, who now has 20 convictions as an adult, was given his first strike in 2010 for a violent aggravated robbery for which he was jointly charged.

He must now serve his sentence of two years without parole. If he is issued with a third strike, a judge must impose the maximum penalty without parole unless the court believes that would be manifestly unjust.

Critics say the controversial three-strikes legislation was meant for the very worst criminals. It was not appropriate for Whaanga, but the law meant Judge Adeane had no option but to issue the sentence he did, they say.

However, Justice Minister Judith Collins said Whaanga's case showed the law was working as intended.

Greens justice spokesman David Clendon said: "Judges know the detail and context of each case, but they are hamstrung by this legislation that says no matter what the circumstances they must impose the highest possible sentence ...

"Fourteen years is a sentence for manslaughter, a sustained beating, an assault on a child or even attempted murder."

The Greens would "definitely" seek to repeal the law if they came to power, Mr Clendon said.

Labour justice spokesman Andrew Little said the party had not committed to repeal the law but believed there were parts that might need to be altered.

"An offender like Elijah Whaanga needs to pay his dues to the community for his offending, but the community's best interests would be best served by him getting help to rewire his brain and change his attitudes."

Maori Party co-leader Pita Sharples said his party opposed the legislation "because we knew that it could be used in situations like this".

"We would repeal it if we could."

JUDGE'S WARNING

What Judge Tony Adeane told Elijah Whaanga:

His personal circumstances were "sadly typical" with "a propensity for violence and an inability to properly weigh the consequences of offending".

The two "street muggings" that netted Whaanga "trophies of minimal value" meant his outlook was now "bleak in the extreme".

Whaanga was "someone who takes recreation out in bullying and offending" and his offending had been escalating.

"You're a standover man with a propensity for robbery.

"At the tender age of 21 years, you face a prospect which needs to be spelled out very clearly for you this morning.

"When you next steal a hat or a cellphone or a jacket or a skateboard, you will be sent to the High Court and there you will be sentenced to 14 years' imprisonment without parole."