Updated

When two 12-year-old Wisconsin girls were charged this week with stabbing a friend nearly to death, authorities had no choice but to send them to adult court.

In more than 20 states, kids as young as 10 are often charged as adults automatically, using laws intended to crack down on gangs and guns. But the practice has been widely questioned by juvenile-crime experts, who say that research shows many young offenders pose no long-term threats to society.

Emily Keller is an attorney with the Juvenile Law Center in Philadelphia. She says adolescent development has indicated that even expert psychologists can't differentiate between kids who are going to become repeat offenders and those who are likely to outgrow their behaviors.

The author of Wisconsin's law stands by it.