Police unlawfully arrested, and used unjustified force on, a man in Lower Hutt on 23 December, says the Independent Police Conduct Authority.
A man came forward to the authority in October 2016 and complained about the arrest, which occurred while the officers were trying to serve a trespass notice on him.
The man had refused to discuss the trespass notice and tried to close a door on one of the officers. The officer then sprayed him with pepper spray and arrested him for common assault.
The authority found the man had clearly revoked the officers' authority to remain on the premises when he attempted to close the door on them.
He was therefore entitled under section 56 of the Crimes Act 1961 to use reasonable force to prevent the officers from trespassing.