"Nate": "it seems clear that a lot of police treat black people differently than their whiter neighbors." 
I am afraid this is true...BUT, it is not "Racism" in the classical sense.
 
Much research has been done in the reactions of people of different races to photos
of "criminals"- Black & White; along with 'shooting scenarios'. Such research has shown
a marked difference in the response time to 'shoot', depending on whether the "criminal'
depicted is white or black.

Even Black Police Officers shot more quickly, with less hesitation, when the 'criminal' 
displayed is Black.
 
Recall Jesse Jackson once stating that he was strolling at night, and heard a noise behind him.
He later recounted "I was relieved to see a white man." 

And from where does such an ingrained response stem from? 
A history of a much higher crime rate among African-Americans.
Everyone knows this, even other African-Americans.