Inquirer Editorial: Cop's sucker punch gives force another black eye
http://www.philly.com/philly/opinion/inquirer/20121003_Inquirer_Editorial__Cop_s_sucker_punch_gives_force_another_black_eye.html
An arrest may occur (2) by any act that indicates an intention to take the arrestee into custody and that subjects the arrestee to the actual control and will of the person making the arrest.” [http://legal-dictionary.thefreedictionary.com/arrest]
Was her walking away from him an attempt to resist arrest??? Was she resisting being handcuffed when she was on the ground???