The problem is the presumption that any exercise of authority is automatically corrupt.
The Eric Garner threads exposed people on this site who really believe that you should be allowed to resist arrest if you want to, and that police officers have no authority to make you comply.
That's petulance and childishness, not skepticism and analysis.
However, would you agree that except for the most extreme circumstances, the police should be able to "make you comply" without ending your life?
...and if a law enforcement officer can't find a way to "make you comply" without killing you, they should probably find another line of work?
I understand that when officers are going up against superior force they need to do what they need to do. I get that. It doesn't mean they should walk into someone's yard and shoot their dog when it barks at them or "accidentally" kill criminals who are resisting.
In this particular case, the officer knew that Brown had already tried to get his gun once and was charging him again to presumably try once more. If the facts as they are reported are accurate, the officer had no other choice than to shoot him. The Garner case is not so clear. There were enough LEOs onsite that they should have been able to subdue him without killing him.