He was taken to the ground a second time while being taken to a custody van, and also claimed that one of the officers made a racist comment.
He was released from Wellington Central Station an hour later with a formal written warning for obstruction.
Later that day he went to the hospital with a head injury he thought had happened when he hit the concrete at some point during the arrest. It took several weeks to recover from the injury.
The man then made a formal complaint that he was arrested unlawfully, that excessive force was used, and that a racist comment was made towards him.
A Police investigation determined that the arrest was lawful, the force used by the officers was appropriate, and that no racist comments were made.
The IPCA found otherwise, in that the man was not obstructing either officer, and should not have been arrested or issued a formal written warning. Based on its own investigation it found the use of force was unjustified because the arrest was not lawful. The authority was unable to determine if a racist comment had been made.
It also found the man had not resisted the police, who had less forceful options available to them. They should have also reported the visible head injury and should have completed a tactical options report.
The authority was satisfied that two other officers involved in taking the man to the police custody unit were not aware of the injury, and it was therefore reasonable for them to have taken him there.
His rights were upheld while he was in custody but a further two more officers should have by then been able to see the man's visible head injury and sought medical care accordingly.
The police said in response to today's IPCA report that they supported the way the matter was handled by the officers involved.
"We are satisfied that our staff made the right decision to arrest this person for obstruction," acting Wellington District Commander Tracey Thompson said.
"The officers had good cause to suspect that an offence had occurred and made the appropriate decision to arrest the person.
"Our staff are faced with challenging situations which require them to act decisively."