The Solicitor-General is challenging a finite jail term imposed on one of the country's worst sex offenders.
Alosio Taimo was found guilty of nearly 100 sex charges relating to 17 victims after a trial at the High Court at Auckland last year.
Justice Moore jailed him for 22 years but stopped short of imposing an indefinite sentence of preventive detention.
Yesterday the Solicitor-General took the case to the Court of Appeal.
RNZ court reporter Anneke Smith was there.