The government's police forces no longer provide security. They arrest and imprison (sometimes) criminals after they have already committed their crimes. Security is provided by agencies that compete for customers in the Free Market.
America's Founding Fathers recognized that religion and morality prevent crime, not jackbooted thugs on every corner.
Citizens should be more vigilant against police abuses, because the police are not subject to the restraining forces of the Free Market.
See also: The Expanding Federal Police Power
The Federal Government should not be involved in local police issues. The federalizing of local police is a dangerous trend which threatens our liberties.