Stupid? No. They simply abuse their power because they know they can get away with it without too bad of consequences. A man beat a fifteen yr old girl for kicking her shoe in his direction and being a little "uncooperative" even after they had her in the cell. He simply had to shut the door, instead he went back in and tackled her into a wall.
http://www.youtube.com/watch?v=bDzQ8Vay3Pg&playnext=1&list=PLDD0182EDC95D3425&feature=results_mainWhen someone has power, they always abuse it. As is the case with every government on this planet right now. That includes the wonderful U.S. of A.