Back in July, Edward Howard, a 25-year veteran of the force, was convicted of aggravated battery and official misconduct for the incident outside a South Side restaurant.
Howard struck a 19-year-old suspect three times across his face.
At a bench trial, Howard admitted striking the man, but said he was using profanity and was going to spit on him.
The suspect and two others were being arrested for trespassing. They were released a few hours later without being charged.