IPCA authority chair, judge Colin Doherty believed the officer had retaliated in anger to the woman's attitude and the force used was disproportionate and excessive.
"The officer's frustration resulted in him using force which good policing would have avoided."
On the day of the incident, the officer - along with three other officers, approached the woman and her friends who were drinking in a liquor-ban area.
They told the women to pour out their remaining alcohol, then the officer had a verbal exchange with the woman, where he used unprofessional and inappropriate language.
The woman then kicked some empty cans and the officer immediately grabbed her arm and arrested her for disorderly behaviour.
The officer alleged the woman tried to hit him, however CCTV footage did not support his account.
The officer placed the woman in a headlock then pulled her backwards onto the ground.
It appeared the woman kicked the officer as she struggled to get him to release her.
The investigation began after one of the officers at the scene expressed concern about the level of force used by his colleague during the arrest and his inappropriate language towards the woman.
Police acknowledged and accepted the IPCA findings in relation to the incident.
Southland Area Commander Inspector Mike Bowman said the use of the force was not justified on this occasion.
"Using a headlock as a restraint method is not an approved or a current tactic, and the actions of the officer have not met the high standard we have of our staff."
Following the recommendation of a national advisory panel, police decided to not to file any charges against the officer.
However, the officer involved was subject to an ongoing employment investigation.