I was arrested for "resisting arrest" after questioning two young punk cops that dragged my younger sister backwards from her bedroom during a house party at her house in college. I continually asked on what grounds they were arresting me and was never given an answer other than that I was arrested for resisting arrest. It was total bullshit but the whole point is that the cops can do whatever they want to you, like it or not.

PS once they put me in the cop car and I knew they were seriously going to take me to jail, the cop in the car said "I bet you hate it when men grope your sister..." as his partner was frisking her outside the car... Real quality humans.