Paul Tranter, a Staff Sergeant with the Waterloo Police Service, was charged with assault causing bodily harm to Jamie McFadyen during a booking process.
The defense argued the force used was justified under section 25 of the Criminal Code to prevent injury to another officer.
The court found that the Crown failed to prove beyond a reasonable doubt that the force used was objectively unnecessary, unreasonable, or disproportionate, considering the volatile circumstances and the perceived threat to the officer.
Tranter was found not guilty.