Trumpeting "black-on-black" crime doesn't address how unarmed black people have been disproportionately brutalized by police. And the general homicide rate doesn't justify police violence against black people. Railing against "black-on-black" crime diverts attention from the issue of police brutality, while reinforcing the idea that black people are hopelessly criminal by nature.
Former New York City Mayor Rudy Giuliani on NBC's Meet the Press used this language last November. "White police officers won't be there if you weren't killing each other 70% of the time," Giuliani said.
In reality, when homicides are broken down by race, according to the U.S. Department of Justice, white people kill other white people just as much as black people kill other black people. Meanwhile, as the Huffington Post noted, analysis from ProPublica shows that young black males are 21 times more likely to be shot dead by police than their white counterparts.
https://mic.com/articles/115322/9-excuses-people-are-no-longer-allowed-to-make-about-police-violence#.ZBlqQzvuR