The argument that age diminishes personal culpability applies to offenders under 18 years of age and is supported by recent scientific research. This research confirms that adolescence is a time of transition. The adolescent is subject to great limitations in judgment and maturity. For social and biological reasons, teens have increased difficulty making mature decisions and understanding the consequences of their actions. Research suggests that these limitations persist until the early 20's. Often, adolescents grow out of these less mature ways of dealing with problems, including destructive behavior. Several risk factors can trigger violence in adolescents including being witness to domestic violence or substance abuse within the family, being poorly or inappropriately supervised, and being the victim of physical or sexual assault. Juveniles that commit murder come from environments rife with these triggers. Studies show that more than half of all youths that pass through the juvenile justice system do not return. This understanding does not excuse adolescents from punishments for violent crime. But it clearly lessons their culpability. This is why society has imposed across-the-board restrictions on voting rights, alcohol and tobacco use, and serving in the armed forces. This is also why those under 18 are referred to as “minors” and “juveniles.” The death penalty for juveniles is a grave contradiction. It is contrary to the most fundamental notions of fairness, which accords punishment according to culpability. 1 footnote, 20 references