Battery can be one of the most trumped up charges out there. I was on jury duty last year and saw a case where some drunk college kid was charged with battery because he put his hand non-threateningly on a cop's shoulder while he was trying to (albeit drunkenly) explain something to the cop.
Then the cops proceeded to beat the s*** out of him in jail for nothing more than taunting them. He sued the city and appeared to have quite a good case. Not sure what came from it.