A police officer described hearing a “pop” after he broke a young woman’s arm while arresting her during a callout to a fight involving up to 30 youths.

Now the police watchdog has ruled that while the use of force was reasonable, the officer’s restraint technique was “poor”.

The Independent Police Conduct Authority (IPCA) investigated the July 9, 2022, arrest and released its decision this week.

Hamilton police were called to 20 to 30 youths who had gathered outside a takeaway food shop. Some were fighting.

An officer told the authority he had arrested a man and was taking him to the police van when a young woman followed him.

She shouted and swore at the officers and questioned why her friend was being arrested. She was then told she was under arrest and grabbed by two officers.

The officer described holding the woman’s arm in an “escort hold”, a technique that provides minimal control but allows an officer to move to a more secure hold if necessary.

He said the woman started to struggle and kick so he changed his grip to move her arm behind her back in what he called a “rear wrist lock”.

As he did so, the officer stepped back to avoid being kicked and described hearing a pop as the woman’s elbow over-extended.

But the woman told the IPCA that officer had “out of nowhere” grabbed her arm.

“I don’t know how he snapped my arm and my elbow.”

The officer said he released the woman immediately, sat her down, and provided medical aid. She required several surgeries to repair the injury.

The officer relied on section 39 of the Crimes Act 1961, which allowed police to use “such force as may be necessary” when arresting someone.

However, the authority found that while the officer was reasonable in using force, the woman was short and “slight”.

It also said the officer had the assistance of his colleague who was holding the woman’s other arm.

It concluded that the cause of the broken arm was not due to excessive force, but “poor technique” as the officer moved from an “escort hold” to a “rear wrist lock”.

Emily Moorhouse is a Christchurch-based Open Justice journalist at NZME. She joined NZME in 2022. Before that, she was at the Christchurch Star.