Even decades after the civil-rights era, a cop shooting an unarmed black man is barely a crime -- a 2007 ColorLines investigation of police shootings in New York City found that in 12 instances when the victim was unarmed, only one officer was found criminally liable. There hasn't been a murder conviction on a police shooting in Oakland since 1983. As Kai Wright wrote in the aftermath of the Sean Bell verdict, "American law has been sanctioning the killing of black people to mollify white fear for centuries. ... We scare the shit out of America. And that fear excuses just about any reaction it spawns." Mehserle is profoundly unlucky to be punished at all.
http://www.prospect.org/csnc/blogs/adam_serwer_archive?month=07&year=2010&base_name=oscar_grant_a_victim_of_americ