The court noted “the designation that after age 18 an individual is a mature adult appears to be somewhat arbitrary.” The court cited scientific studies that show “the brain doesn’t finish developing until the mid-20s, far later than was previously thought” and that “[y]oung adults are more similar to adolescents than fully mature adults in important ways.”, Indeed, a recent Newsweek article discussing the Illinois decision noted that “18 as a threshold for adulthood is already a thing of the past” in other western countries. The Supreme Court held the sentences were unconstitutional because they failed to take into account the juvenile offenders’ “lessened culpability” and “capacity for change.” Justice Kagan cited scientific evidence that an adolescent’s “transient rashness, proclivity for risk, and inability to assess consequences,” mitigate against “imposing the harshest sentences on juvenile offenders, even when they commit terrible crimes.”. var gfRecaptchaPoller = setInterval( function() { A Houston Criminal Defense and Family Law Firm, A League City Criminal Defense and Family Law Firm, A Galveston Criminal Defense and Family Law Firm. Inspired by the German example, the governor of Connecticut has proposed that state raise its juvenile court cutoff age to 20 and institute “alternative ways to deal with people up to age 25.”.