The police watchdog says an officer was NOT justified in punching a man in custody in the head three times

Authorities were called to the man's Waimauku property late in 2022 - after he'd been heard in an argument with his partner.

Two officers arrested him, believing he'd tried to punch them.

In the patrol car, the man headbutted the window and spat at an officer, who punched him in the jaw three times.

The Independent Police Conduct Authority says the force used was disproportionate and excessive.