Because the Roper decision was spurred on by dozens of individuals and organizations who provided resources, support and amicus briefs. Among them were the American Medical Association, the American Psychiatric Association and the National Association of Social Workers, all arguing that

adolescents behave differently than adults because their minds operate differently, their emotions are more volatile, and their brains are anatomically immature. To the extent that adolescents who commit capital offenses suffer from serious psychological disturbances that exacerbate the already existing vulnerabilities of youth, they can be expected to function at substandard levels.

Also, 27 religious organizations, arguing that

Because of their age and immaturity, minors lack the degree of culpability that would place them in the category this Court has described as those "most deserving" to be put to death.

Also uncounted (by me) child advocacy groups, including the Children's Defense Fund, the Child Welfare League of America, the National Association of Counsel for Children, the Children's Action Alliance and many more, arguing

a consensus has plainly emerged about youth's analogous disabilities in areas of reasoning, judgment and control of their impulses, as well as their lesser moral culpability for crimes they commit, such that Stanford [a 15 year old precedent holding that the death penalty for offenders who committed their crimes while 17 did not violate the Eighth Amendment] must also now be overruled. This consensus is reflected, inter alia, in the growing body of legislative and judicial restrictions on the rights and responsibilities of youth under 18 since Stanford was decided, the emergent research on adolescent development as it impacts culpability and the deterrence of youth, and the special risk of wrongful execution because of youth's special vulnerability to confessing to crimes they did not commit.

And legal organizations like the Attorneys General of eight states, the Coalition for Juvenile Justice, the Constitution Project and the ACLU, urging

Like the mentally retarded, juveniles have developmental limitations and deficiencies that make them less able to assist counsel, more likely to make false confessions, and overall more likely to be wrongfully convicted or wrongfully sentenced to death....

Due to the special circumstances of adolescence, defendants who are under the age of 18 are more vulnerable to disparities in the criminal justice system than adults.

Also: Human Rights Watch, 48 foreign nations, 15 Nobel Peace Prize recipients and nine former U.S. diplomats, arguing essentially that all the cool countries imprison juvenile offenders for a few years and are done with it. We don't care about that today.

These groups and luminaries didn't just materialize to urge the Court to find for Christopher Simmons, they continue their great good work today. (I'm not being facetious. Mostly. The organizations I recognize, especially the religious ones, are almost all coming from someplace good where they help people immensely.)

These dozens of influential and powerful entities from the arenas of medicine, science, social science, thought leadership, the law, the church, government, policy and activism, all believe that as a bright line proposition -- with no reasonable exception -- young men and women under 18 aren't as responsible for their actions, and needn't suffer the same consequences, as adults. As, in fact, young men and women who have celebrated their 18th birthday, even yesterday.

And many of them make it their business on a day to day basis to reach out to, counsel, guide and teach teenagers. Now, are they all hypnotizing these impressionable youths and making them think they can run around killing people with impunity? Of course not.

But be assured that if I ever reached out to, counseled or taught teenagers on a day to day basis, they would not come away with the impression that they are somehow developmentally incapable of knowing right from wrong, and that they could expect some kind of pass based on their age if they screwed up. Not because I'd make them write something like that 100 times on the blackboard, but because that's what I believe, and where I'm coming from. I'm sure it would rub off, and form the context for whatever it was I was trying to teach them.

The groups above are coming from another angle: Your minds operate differently. Your emotions are more volatile. You're immature. You have disabilities in areas of reasoning, judgment and control of your impulses. You have lesser moral culpability. You have developmental limitations and deficiencies, like the mentally retarded.

Having met some of my stepdaughter's friends, especially the male ones, I don't doubt that this is sometimes true in individual cases. Jurisprudentially, I see no reason why a jury couldn't thoughtfully consider whether someone who committed a heinous crime while 17 was morally culpable, mature and non-retarded enough to face the most severe adult penalty. But that argument was made (per Missouri law, the Simmons jury was instructed that age could be considered a mitigating factor), and lost, and is sort of tangential anyway.

But to proceed from the assumption that it's always true of everybody -- wouldn't that sort of seep into the heads of teens after a while? Particularly those disposed to make trouble? By which I mean young adults don't usually do bad things for the sake of doing bad things. Most people don't, in fact. They justify them. I'm poor. I don't have two parents. I was abused. They don't deserve what they have anyway.

I'm only 17. No one thinks I'm going to act responsibly anyway. The rules bend a little for me. Less is expected of me.

Juvenile crime is almost certainly not up because the Supreme Court voted 5-4 that the Eighth Amendment quite suddenly prohibited a form of punishment it clearly never had before. It is, I think, almost certainly up in part because of the efforts -- or, more charitably and accurately, the unintended consequences of the efforts -- of the people and groups that helped win those five votes.

(If you never have, do read this brief filed in Roper by the Attorney General of Alabama if you're unconvinced that some 17 year olds know exactly what they're doing and deserve the most severe punishment available.)