It is not solely a problem of individual police incompetance or lack of psychological fitness. The problem with US law enforcement is institutional shift of mandate away from maintaining order to engaging in the 50 year "drug war" that turns citizens into enemy combatants. In this context of a "war" against a huge segment of US population does the behaviors of police officers comprehensible. The US police have military grade equipments from submachine guns to armored personelle carriers; the police is clearly engaged in a literal war. The US government created this hostile atmosphere with Nixon's, then Reagan's "drug war," which was just a thinly veiled attempt at using the police to war against minorities (uppity blacks) and social progressives (hippies, socialists, anarchists). The US public is only just recognizing this war; this is not a new behavior by the police.