Georgia Rose Dickey, Christopher James Brown, and Katrina Roma Epiha have all been re-sentenced to finite sentences with a minimum period of imprisonment.
Katrina Roma Epiha murdered Alicia Nathan when she stabbed her to death at Avonhead in Christchurch on August 5, 2017 over an argument about loud music.
Epiha, who plead guilty to the charge, was 18 at the time she murdered the mother of one.
Brown, who was found guilty of murder after a jury trial, and Dickey, who pleaded guilty to murder, both received life sentences with a non-parole period of 10 years for their part in the killing of Jack McAllister near Stadium Southland in Invercargill on June 7, 2017.
Dickey was aged 16 at the time; Brown was 19.
While neither stabbed Mr McAllister, they were convicted as a party to the murder taking place.
The argument was that the life sentences received by the three offenders were manifestly unjust, based on their specific circumstances, including their age, social deprivation and psychological conditions.
Sentences could be deemed manifestly unjust not only because of an offender’s youth and lack of brain development but also taking into account further mitigating circumstances in relation to the offending, personal factors, determinacy of their sentence and the impact of lifetime parole, the ruling said.
In the case of Epiha, her age, profound social and cultural deprivation, psychological issues and her accepting responsibility for her acts meant her sentence was manifestly unjust, the judges ruled.
Dickey’s role in the murder – essentially luring the victim to scene where he was attacked - and her personal circumstances led the Court of Appeal to deem her sentence manifestly unjust.
For Brown his peripheral part in the attack on Mr McAllister, mental-health issues, cognitive impairment, social deprivation, youth, remorse and the impact of prison on him, meant his appeal was also successful.
"In particular, the impact of an indeterminate sentence of life imprisonment is disproportionately severe in Mr Brown’s case because of his cognitive limitations," the judgement said.
Dickey received an amended sentence of 15 years’ imprisonment with minimum period of imprisonment of seven and-a-half years, Brown received a sentence of 12 years imprisonment with minimum period of imprisonment of six years and Epiha 13 years’ imprisonment with minimum period of imprisonment of seven years.
The court acknowledged there was no undoing the harm caused, and surviving victims of these murders were likely to think a sentence short of life imprisonment was disproportionate to their loss.
The judges said the decision should not be taken as a guideline judgement, saying they did not attempt to prescribe when it may be appropriate to find life imprisonment unfair for young people.
Creating sweeping change to how youth murderers were dealt with could only done by Parliament, the court stressed.
