Atmiya Patel and his friend Brandon Stassen say the Rialmo, who was off duty, punched them with a closed fist, knocking the men to the ground. The incident is captured on silent bar surveillance video.
Patel testified the confrontation began when he was looking for his jacket at closing time. He thought Rialmo had it, while Rialmo thought Patel was trying to take his jacket.
"Patel may have thought it was his coat, the problem is, it was Rialmo's. Patel was trying to take it, one has the right to stop someday, force somebody who is trying to take property," said Rialmo's attorney Joel Brodsky.
Patel said Rialmo first shoved him, sending him "flying into the tables and chairs."
As he was trying to stand up and regain his balance, Rialmo hit him again, Patel told the judge.
Right after, Stassen said Rialmo hit him, knocking him unconscious. While both men say the attack was unprovoked and they never threatened Rialmo, Brodsky's claims Patel and Stassen were very intoxicated and they were the aggressors.
"The video you really see it happens fast, but when you slow it down, it's clear Rialmo was justified," Brodsky said.
Just last month, Rialmo faced a lengthy civil trial stemming from lawsuits filed in the officer's fatal shooting of Quintonio LeGrier. Bystander Bettie Jones was also killed.
The Chicago Police Board has not determined if Rialmo should lose his job.
If the officer is found guilty on the battery charges, Brodsky said Rialmo will most likely be fired.