Criminal justice in the United States used to be an exercise in local self-government. That is much less true today. Police officers used to live on the same streets they patrolled—which almost never happens today. Local district attorneys in metropolitan counties were elected by the votes of the urban working class, the same voters who were most often victimized by street crime, and whose sons were most often prosecuted for it. Today, suburban votes count for much more. Locally selected juries used to decide nearly half of all felony cases; today, the analogous figure is 5%.
On every front, the power of poor city neighborhoods has declined, and the power of middle- and upper-class suburbs has risen. If criminal justice in poor urban neighborhoods is dysfunctional, that may be because the residents of those neighborhoods are not permitted to decide for themselves how to deal with the crime in their midst.
http://www.law.upenn.edu/blogs/dskeel/archives/2008/03/race_and_crimestuntz.html#