The Crown has conceded at the Supreme Court that an error may have been made at the trial of a Christchurch man who was found guilty of punching his four-year-old son in the face and pulling his ear.
Following his conviction for assaulting his son in 2007, James Mason was sentenced to nine months' supervision and ordered to attend anger management classes.
In May, the Court of Appeal upheld his conviction.
On Tuesday, the case went before the Supreme Court, where Mason's lawyer Greg King said his client had suffered a miscarriage of justice because the punching and ear-pulling incidents had been included in a single charge.
The Crown accepted an error was made in that respect and indicated it would not oppose the granting of the appeal.
Solicitor-General David Collins QC told the Supreme Court the jury was not properly instructed on the requirement that they be unanimous about which part of the charge they found James Mason guilty of, if any.
The Supreme Court reserved its decision.