Laurence Steinberg, Distinguished University Professor of Psychology at Temple University, makes some excellent points in his op-ed piece in today's Washington Post, Judging a Juvenile Killer:

"The Supreme Court has held that the death penalty is unconstitutional for people who are under 16 at the time of their offenses. Currently, only 22 states permit the execution of juveniles -- and in practice, only seven have executed juveniles since the death penalty was reinstated in 1976. Half the states that permit capital punishment allow for the execution of juveniles, and 40 percent of states that permit capital punishment allow the execution of juveniles as young as 16. To those who say that 16 is old enough to know better, it is worth pointing out that in virtually every other area of the law, we treat 16-year-olds as if they are inherently less mature than adults."

"Malvo is not the best poster boy for repeal of the juvenile death penalty. But ongoing research on the links between brain maturation and psychological development in adolescence is beginning to explain why adolescents are not as capable of planning, or as thoughtful and self-controlled, as adults and, more important, why these deficiencies may be inherent to being an adolescent. It is true that the science is a long way from providing a definitive answer to the question of where we should set the age boundary for adult criminal responsibility. But executing juveniles puts the United States in rare company: The only other country that is still committed to the execution of juveniles is Iran. Until the data are in, we should join the rest of the world and prohibit the execution of people under the age of 18."