According to today's NYT editorial, "Criminalizing Children":
The National Rifle Association and President Obama responded to the Newtown, Conn., shootings by recommending that more police officers be placed in the nation’s schools. But a growing body of research suggests that, contrary to popular wisdom, a larger police presence in schools generally does little to improve safety. It can also create a repressive environment in which children are arrested or issued summonses for minor misdeeds — like cutting class or talking back — that once would have been dealt with by the principal.
Children as young as 12 have been treated as criminals for shoving matches and even adolescent misconduct like cursing in school. This is worrisome because young people who spend time in adult jails are more likely to have problems with law enforcement later on. Moreover, federal data suggest a pattern of discrimination in the arrests, with black and Hispanic children more likely to be affected than their white peers.