 Studies have documented patterns of racial discrimination, as well as patterns of police brutality and disregard for the constitutional rights of African-Americans, by police departments in various American cities, including Los Angeles, New York, Chicago and Philadelphia.The term "black on black" violence has been criticized for being misleading and racially charged.One columnist writing in the wake of the killing of George Floyd has accused opponents of the Black Lives Matter movement of using "blacks killing blacks" rhetoric to avoid discussions about police brutality.