The deputy Solicitor General has described the home detention sentence passed down to a teenager who raped four girls as "manifestly inadequate", as an appeal is today launched in the High Court.

Open Justice revealed last month that Jayden Desmond Meyer, 18, was sentenced to nine months' home dentention 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 last month.

Both Crown prosecutor Anna Pollett and Meyer's lawyer Rachael Adams submitted at the time that a sentence of home detention would be most appropriate - despite the Crown accepting imprisonment would be the ordinary sentence for this sort of offending; "and indeed one of many years".

Tauranga District Court Judge Christopher Harding agreed, saying a sentence of imprisonment being typical of this level of offending is "undoubtedly correct".

His 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.

Last week, Crown Law decided to challenge that ruling, with deputy Solicitor General Madelaine Laracy filing an appeal against the sentence.

According to the notice of appeal, the Solicitor General was first made aware of the prosecution a day after Open Justice revealed the sentence.

In the document, Laracy says Judge Harding "did not follow orthodox sentencing methodology".

"He did not specify a starting point, quantify the overall discount, or state a nominal end sentence."

"The sentence is disproportionate, in all of the circumstances, to the seriousness of the offending."

• Jayden Meyer's home detention sentence is appealed by Crown
• Teen sentenced to nine months' home detention after raping four girls
• Crown appeals teen rapist's home detention sentence

The appeal was filed six weeks out of time, with Meyer having now completed two months of his sentence.

"The Solicitor-General recognises that an appeal out of time, in respect of a young person who has served two months of a sentence on home detention, is a troubling proposition.

The solicitor general further recognises that the Crown Solicitor did not seek a sentence of imprisonment, and considered home detention with judicial monitoring was an appropriate sentence."

Meyer's case is being heard in the Rotorua High Court this afternoon where the Crown will speak to it's appeal.