I do not know what happened in Ferguson, Missouri.
But I believe that people sometimes adopt stereotypes that have been assigned to them and that, in doing so, they become capable of actions that violate their deeply held personal beliefs.
-- If you give a group of young men badges, uniforms and guns and then form them into a group, they act one way.
-- If you tell another group of young men that they are tough and scary, and if the leaders of their peer group are belligerent and violent, they act another way.
We all want to believe that, as individuals, we are ethical people. Many of us, likely all of us, are flawed. It would behoove us to be humble about our righteousness.
Attached below is a documentary about a famous psychology study -- The Stanford Prison Experiment -- conducted in the early 1970s. College psychology students have been shown videos about this study for decades.
It followed the famous and disappointing Millgram experiments of the 1960s, which sought to establish that Americans were more individualistic and less likely to participate in official persecution of other people, as had occurred among Germans during the rise of Hitler and the Nazis in Germany. The experiments absolutely refuted the notion that Americans were singularly high-minded and ethical.
The Stanford Prison Experiment demonstrated the point at greater length. Within a couple days, the student volunteers, and even the professor himself, were acting out stereotypes that would have been unthinkable to them in any other context.
Watch and see for yourself.