Jakob Christie says he was hit in the neck by a police baton when police forced entry into a house party in Khandallah four years ago.
He suffered a fracture to his neck and spent three months in a brace.
"It's kind of ruined my confidence in a lot of aspects. Before this happened I was an outgoing person and now I'm withdrawn," Mr Christie says.
Police had been called to a Homebush Rd property to remove gatecrashers.
"There were 60 to 100 young people in that house [in a] three ft wide hallway, alcohol, bottles, and violence had occurred," Assistant Police Commissioner Grant Nicholls says.
The Independent Police Conduct Authority (IPCA) received 10 formal complaints about police actions that night. It found police acted contrary to the law in entering a private residence and members of the tactical policing unit used unnecessary and excessive force.
The IPCA found on the balance of probabilities an officer struck one of the partygoers and broke their neck, but was unable to identify which officer was responsible. Neither were the police.
"There's some question around whether it was deliberate or otherwise and there are alternatives that could be proffered for how such an injury occurred," Mr Nicholls says.
Police are reviewing their policies around public order policing.
Complainants have waited three years for an outcome, something IPCA Judge Sir David Carruthers describes as inexcusable.
"Police failure to conduct a robust, thorough and timely investigation was unjustified, unreasonable and unfair," Sir David says.
Mr Christie agrees, calling for a formal apology from the police to all the partygoers. But that apology wasn't forthcoming today.
"We'll enter private discussions at an appropriate time," Mr Nicholls says.
Mr Christie's lawyer says he'll negotiate with police to reach a financial settlement, but he wouldn't disclose how much he's seeking.