The judge's decision drew a vitriolic response from the offender's ex-partner, a health professional who has since moved to Auckland with their son.
She stood up in the public gallery and told Judge Recordon how the ordeal had changed her life.
"I'm pretty devastated because I've lived with the truth," she said.
"There's been a major impact on my career. I've had to give up all may work for my head-injured child.
"We live in a state house, hand to mouth. Our lives have been hugely affected and I've seen no justice for me or my son. I've lost faith in the justice system ? it's not just."
Judge Recordon explained his ruling.
He said it was the offender's work with charity that persuaded him to grant the discharge, rather than the general impact on his life and career.
Police prosecutors submitted the man had not played an active role in the charity -- which cannot be named -- but the judge said that was contradicted by affidavits and references defence counsel had put before the court.
"The fact he had earlier been discharged without conviction and there was a breach of a court order made it a rather difficult exercise but the discretion was exercised in his favour," Judge Recordon said.
The impromptu back and forth with the public gallery carried on for some time but was eventually concluded by the judge who reminded them there were legal avenues to appeal his decision.
After the hearing the mother of the victim expressed her disappointment and was particularly irate that no police prosecutor had turned up to court.
"That just about says it all," she said.
