Civilization has developed an imperfect but constructive system for transitioning error-prone children to responsible adulthood: We designate by law at what ages young people are designated partly and then fully responsible for their actions.
Sixteen-year-olds can drive, but not vote or sign contracts. At 18 they are generally recognized as full adults, though they still are deemed insufficiently mature to drink alcohol. That must wait til age 21.
Some individuals, of course, act responsibly at much younger ages, while others act foolishly and even criminally their entire lives. But all in all the age of majority — 18 for most purposes — serves the dual purposes of preparing young people for responsible adulthood without making them harshly culpable for bad acts that may stem at least in part from youthful lapses of judgment.
That is the reasoning of U.S. Supreme Court Justice Anthony Kennedy, who wrote for the majority that on Tuesday ruled as unconstitutional the death penalty for those under age 18.
In essence, he argued, the state may levy the ultimate punishment only on individuals who are deemed fully responsible for their actions under the law. It was similar reasoning that led the high court three years ago to prohibit the execution of mentally retarded individuals.
It’s an imperfect system. Just as there are responsible teens, there are also some cold, calculating teen killers. But the justice system itself is imperfect — occasionally resulting in a wrongful execution.
Tuesday’s ruling removes one of the imperfections.