Sean Unwin, pictured in 2006, when he was a member of a Canterbury boxing gym.

It's not often that the charge of assault using a chicken as a weapon comes up.

Even experienced Judge Stephen O'Driscoll said he had never seen a charge like that.

However, it got serious when defence counsel Kiran Paima described the Christchurch crime scene as a backyard "bloodbath".

Appearing in the Christchurch District Court was Sean Brian Unwin, who took great pride in the flock of chickens that lived in his yard.

A builder arrived to work on the property next door. His dog escaped from his car, jumped the fence, and took to the chickens.

Unwin then arrived and found the scene of carnage.

There was a heated exchange of words with the dog's owner, and then it got physical with Unwin brandishing a dead chicken, and hitting the dog's owner with it.

The police originally charged Unwin with assault using a chicken as a weapon, and using some very robust offensive language.

A few days after the incident, the dog owner wrote a letter saying he did not want Unwin prosecuted, and he was sorry about the loss of the chickens. He accepted that he did not have his dog under effective control.

Unwin appeared in court where he pleaded not guilty and was remanded for a case review hearing. Away from the courts, negotiations were under way.

By the time the case arrived at that case review hearing, police prosecutor Sergeant Jeff Kay agreed that there was some wriggle room available on the charges.

He told the judge the police would agree to make it an ordinary assault charge – taking poultry pummelling out of the charge, but leaving it as part of the facts – and dropping the offensive language charge.

Kay also said the police did not think any penalty was warranted. Unwin then pleaded guilty to the assault charge.

Judge O'Driscoll then considered the facts of the case and decided that Unwin would be convicted and ordered to come up for sentence in six months if called upon.

He noted that the two men regretted what had occurred, and had effectively sorted it out between them, so no restorative justice meeting would be held.

"Nothing I can say or do can change what has occurred," the judge said. "The victim has apologised for what happened. It was unintentional, but it did happen, and you over-reacted."

Unwin agreed he had.

"I hope you will both now be able to put this behind you," the judge said.