The Supreme Court contemplates executing juveniles.

The Supreme Court press gallery is positioned directly across from the massive Adolph Weinman frieze on the south wall of the ceremonial courtroom—the one with Moses, packed in amidst "great lawgivers of history," Ten Commandments in hand. Following yesterday's decision by the court to hear a pair of Ten Commandments cases, reporters around me are speculating about what will happen to the poor Decalogue. Someone suggests the Supremes should just ditch the first four commandments as a matter of federal constitutional law. (Weinman's already done this by coyly draping Moses' beard and robe anywhere on the tablets "God" might appear.) Someone opines that Mohammed and the Quran probably need to come down as well. I'm hoping one of the justices will knit a teeny little commandment-cozy, to slip over the statue.

Today's oral argument in Roper v. Simmons asks whether the execution of people who were 16 or 17 years old when they committed their crimes constitutes "cruel and unusual punishment" under the Eighth Amendment. Obviously the Founders didn't think executions of adolescents were cruel and unusual, so we know where Scalia's vote will go. But Scalia is cruelly pinned beneath the ruling in Trop v. Dulles—a 1958 case holding that the Eighth Amendment "must draw its meaning from the evolving standards of decency that mark the progress of a maturing society." Unlike much of the court's jurisprudence, this analysis does not require poring over texts or channeling Thomas Jefferson. Instead, the court is asked to blink directly into the bright light of science and current events to determine whether "evolving standards of decency" mandate a change in the notion of what is cruel and unusual. Among the justices who believe the human race is evolving in what is decidedly the wrong direction, this is pure hell. Even contemplating the New Age notion that a "teenage brain" exists must be cruel and unusual punishment for Clarence Thomas. But this is the test. So, away they go.

Christopher Simmons was 17 when, in 1993, he robbed and abducted Shirley Crook. He tied and gagged her with electrical wire and duct tape and threw her off a railroad bridge from which she plummeted and drowned. Simmons evidently bragged to friends that he'd get away with this since he was a minor. The jury disagreed, convicting him of first-degree murder and sentencing him to death.

The last time the Supreme Court heard a case about the constitutionality of executing 16- and 17-year-olds was in 1989—when it decided Stanford v. Kentucky. A plurality of the court determined then that there was no social or historical consensus that the death penalty was cruel and unusual for teens of those ages, even though in 1988 the court had determined that such a consensus existed for offenders under 15. In 2002 the court voted 6-3 to ban the execution of the mentally retarded in Atkins v. Virginia, using the "evolving standards" test to find that most states no longer believed it acceptable to execute them and that the mentally retarded had diminished culpability for their crimes.

The Atkins decision somehow emboldened the Missouri Supreme Court—that was deciding Simmons' case—to just overrule the Supremes' original Stanford decision completely. Leaning on the reasoning in Atkins, the Missouri court decided that a new consensus walks among us and that the Supreme Court had missed the boat. Nine out of 10 dentists agree: It's bad to kill teenagers.

James Layton, the state solicitor of Missouri, is here this morning to remind the high court that it's been dissed. He argues that the proper age to be executed should be left in the hands of legislatures and that the issue of an individual's culpability and maturity are best left to a jury. "Some 17-year-olds are culpable," he says, "and some are not."

Justice Ruth Bader Ginsburg suggests that society treats those under 18 as not-adult in dozens of ways—they are unable to vote, serve on juries or in the military, or buy tobacco. "Why would you be death-eligible at 18 but not eligible to be a member of the community?"

Justice Antonin Scalia heads the other way: "Why stop at the death penalty?" he asks. "Why not say anyone under 18 is immune from all punishment?" (He doesn't really mean this. This is just his way.)

Everyone's eyes are on Sandra Day O'Connor again today. Hers was the swing vote in Thompson v. Oklahoma—the case banning executions for 15-year-olds. Her concurrence was also the key to Stanford v. Kentucky—the case allowing executions for 16-year-olds. We know four justices already oppose killing minors because in 2002, John Paul Stevens, David Souter, Ruth Bader Ginsburg, and Stephen Breyer all dissented when the Supremes refused to hear a case on this issue. They did not mince words: "The practice of executing such offenders is a relic of the past and is inconsistent with evolving standards of decency in a civilized society. We should put an end to this shameful practice."

So, they need one more vote. But O'Connor says virtually nothing today. She asks a single question of Layton: "Isn't there about the same consensus that existed in Atkins [the case about the mentally retarded]? Aren't we obliged to look at that?" That's all she says, folks. Read your tea leaves here.