The incident was recorded by a surveillance camera and Eyewitness News was the first to show you the video.
"No justice, no peace," the protesters chanted. "Stop police brutality in the black community!"
The two minute video captured a plain clothes narcotics detective confronting 15 year old Travis Rattray back in March 2010.
Detective Angel Pared checked his pockets then all of a sudden unloads, punching him in the face and slamming him into a window.
Travis and his mother gave reporter Phil Lipof the exclusive video and interview.
Travis and his mother didn't say a word on the steps of city hall on Tuesday because they're worried it could hurt their civil lawsuit, but they came here to show they're still fighting the city, the police department and the officers involved.
A jury found Pared not guilty last Thursday of aggravated assault, the most serious charge he faced, but they were deadlocked on three lesser charges including falsifying reports.
Protestors believe he should be fired.
"You have to be Stevie Wonder not to see that this baby was clearly punched by this officer. I don't know what this jury was thinking," demonstrator Donna Jackson said.
"We're saying when he comes up for departmental review, we sound the drum and raise all the hell we need," demonstrator Zayid Muhammed said.
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