Justice Fitzgerald also concluded the sentencing process "lacked transparency", which undermined public confidence in the justice system.
Deputy solicitor-general Madeleine Laracy last week sought leave to appeal Meyer’s sentence of home detention in favour of prison time.
The Tauranga teenager was last month sentenced to nine months’ home detention for the rape of four 15-year-old girls and the sexual violation of another.
He was 16 at the time of the offending.
The sentence drew the ire of the public, sparking numerous public protests.
Originally, both Crown prosecutor Anna Pollett and Meyer’s counsel Rachael Adams submitted a sentence of home detention would be most appropriate — despite Ms Pollett accepting imprisonment would be the ordinary sentence for this sort of offending, "and indeed [a sentence] of many years".
Justice Fitzgerald said yesterday it was "an error of law for the sentencing to proceed as it did".
"Whether the end sentence is around three years’ imprisonment as suggested by the Crown or somewhat higher ... the judge’s sentence of home detention was manifestly inadequate. The fact the judge did not engage in an orthodox sentencing analysis obscures the reality of this conclusion."
The sentencing process lacked transparency, she said.
Tauranga District Court judge Christopher Harding had said a sentence of imprisonment being typical of this level of offending is "undoubtedly correct".
But Judge Harding’s written sentencing decision did not detail how he instead reached a sentence of home detention, besides saying he accepted the probation report and the submissions of counsel.
During last week’s hearing in court, Ms Laracy told Justice Fitzgerald the conclusions of both the district court judge and Crown prosecutor were flawed.
"It remains incomprehensible, how from an eight-year [imprisonment] starting point, the judge can then move to accept home detention is the appropriate sentence.
"This is a significant error of law."
Ms Laracy argued a sentence of imprisonment was most appropriate.
Acting for Meyer, counsel Rachael Adams said it was hard to see the decision to appeal as anything more than the Crown reacting to public outrage.
Ms Adams argued the fact the Crown supported the home detention sentence meant if the sentence was quashed it would be "inhumane".
Justice Fitzgerald said as Meyer was now attending a sexual violence rehabilitation programme, the logistics of managing this within prison would be difficult.
"Given the delay, Mr Meyer has served over a third of his sentence.
"I accordingly accept that to sentence Mr Meyer now to a sentence of imprisonment carries with it a real risk of undermining progress to date in rehabilitation, through his engagement in an appropriate youth sexual offending programme. This is a particularly important factor in my view."
By Ethan Griffiths
