The Independent Police Conduct Authority says it doesn't condone the actions taken by a police officer against a man in Ashburton last year.
Photo: RNZ / Richard Tindiller
In a report released by the authority today, it found the officer's actions constituted assault.
Police said they attended an incident involving a man who was arrested after crashing his car into a bollard in Ashburton in July last year.
The authority found the arrest to be lawful, but found the force used against the man at the police station was not justified and constituted an assault.
It also found that there was a delay in seeking medical attention for the man, which was unacceptable.
"Officer A provided appropriate medical assistance to [the man] when in the police car. [The man] received appropriate medical assistance once he was in hospital.
"However, necessary treatment was delayed by police attempting to conduct an [evidential breath test] rather than addressing his injuries."
When the police first arrived on the scene, they could see the driver was slumped behind the wheel and wasn't wearing trousers when they approached his car.
The situation escalated in the view of one of the officers after the man threw his trousers out of the driver's window, which was perceived as an action of active resistance.
It was reported the trousers hit one of the officers, but there are conflicting reports from both officers leading up to the man's arrest.
Police used force to extract the man from the vehicle after he failed a roadside breath test and refused to accompany them for further testing.
An officer grabbed the driver's door handle, pulled it open, grabbed the man and put him face down on the road.
Once the man had been pulled to his feet, one of the officers noticed a fresh cut to the man's lower lip, which was understood to be as a result of the incident.
At the police station, one of the officers believed the man may spit blood, so he executed a leg sweep and spun him round to the left, but the man received an additional injury after his head made contact with a wall heater.
The man was taken to Ashburton Hospital, where the police were advised by staff that they would keep the man overnight for further assessment.
The man had sustained lacerations to his upper lip and chin which required stitches, as well as bruising to his left check.
Canterbury district commander John Price said the police need to keep their cool when they 're put under pressure.
"Our staff are constantly put in difficult situations, and although these dynamic situations can develop in a matter of seconds we expect police staff to act professionally.
"It is expected at all times our behaviour and actions model police values."
Commander Price said the officer in question was returned to frontline duties following the investigation, but has since resigned for unrelated reasons.