As many as 200,000 youths charged with crimes today are tried in adult courts, where judges tend to be tougher and punishments harsher — including sentencing to adult prisons. But with juvenile crime now on the decline, youth advocates are seizing the moment to push for major changes in iron-fisted juvenile justice systems nationwide. Above all, they want to roll back harsh state punishments — triggered by the crack cocaine-fueled crime wave of the late 1980s and early '90s — that sent thousands of adolescents to adult courts and prisons. Many prosecutors say the get-tough approach offers society the best protection. But critics say young people often leave prison more bitter and dangerous than when they went in. Moreover, recent brain studies show weak impulse control in young people under age 18, prompting some states to reconsider their tough punishments. Prosecutors respond that even immature adolescents know right from wrong.