Some of my flickr friends were discussing their fear of photographing strangers. Here is a citizen photo-journalist who captured a trespassing ticket and the ensuring bloody events.
Turns out someone on the sidewalk yelled something to her, she turned to see the person, took her hands off of the car, and the cop got pissed. She gave attitude, I think he shoved her back on the car, so she struggled back up, and he shoved her around. He was at least 200 pounds. She was about 100. Her face was bloody.