American society operates upon a White male property rights construct; even though within a Constitutional construct framework.
Thus, policing is an expression of property rights policy; protecting White men and their property.
Blacks are viewed as the property of White men; even White women are defined as property (case in point miscegenation laws).
Law enforcement constabularies (departments) are only instruments of enforcing the property rights legalized system of White Male Privileges.
Hence, in America, we have policing without equal justice; therefore, police departments function as arresting officers, prosecutors, Judges, and juries: just us (Blacks), not JUSTICE.