What have we learned from the recent spate of incidents of police violence on black victims?

What have we learned from recent spate of incidents of police violence on black victims?  Tom Tomorrow has the answers, at least from one perspective. All of this seems to be symptoms of a much more serious, troubling, and deep-seated problem in our culture, in our country. Did all of our city police departments use training films taken in Selma during the 1960s? And even in a "nice" Midwestern college town minorities are subject to unjustified profiling and harassment at a rate well above that of others. A sharp-dressing, minority colleague who happened to drive a somewhat flashy car told me how often he got stopped by traffic police, 4-5 times a year, and a non-sharp dressing botanist who happens to drive a non-flashy car in the same has never been stopped ever. So it must be the car. Right.