A woman at the Philadelphia Puerto Rican Day Parade was punched from behind by a police lieutenant, and amazingly, the victim was the one arrested.
This appears to be a pretty clear-cut case of excessive force. The cop, IDed as Lt. Jonathan Josey, is twice the size of this lady, and she was not threatening him in any manner.
In the shocking amateur footage, you see a group of officers surrounding a motor vehicle for some reason. The unidentified woman runs up to them, with a can of silly string in her hand, then turns and starts walking away. A moment later, Josey approaches the reveller from behind, and strikes her in the side of the face, knocking her to the pavement.
In fairness to the Philly police, this was a potentially explosive situation. There were hundreds of revelers gathered, many of them presumably intoxicated, and some were probably taunting the cops. What's more, this woman was jumping around, and acting bizarrely.
Nevertheless, there was no reason to overreact and punch this lady. The police supervisor could have just grabbed her and slapped on the cuffs. This incident needs to be thoroughly probed by Internal Affairs, and the lieutenant should be demoted.