A group of NSW police officers were exposed as liars by CCTV footage which showed they assaulted a 23-year-old Aboriginal man, not the other way round, a magistrate has found.

Ballina Local Court Magistrate David Heilpern today referred the incident to the Police Integrity Commission, after finding that three officers had lied under oath and had "debased" the "administration of justice".

In a costs judgment handed down today, Magistrate Heilpern found that on January 14 last year Corey Barker was arrested after an altercation on a street in Ballina, after it was alleged he threw a plastic bottle towards police and then resisted arrest.

When taken to the police station, officers say he yelled and was disruptive in the dock which led them to move him to the rear cells.

The officers claimed that, when they attempted to move the young man, he allegedly assaulted a senior constable, punching him in the face and throwing his arms around in a bid to break free.