The road to limiting the severity of the punishments for juveniles convicted of murder runs through Missouri.

In 2005, the U.S. Supreme Court ruled in a case from Missouri -- Simmons vs. Roper -- that juveniles could not be executed for murder because it amounted to cruel and unusual punishment.

Five years later, the Supreme Court took a second step, ruling out sentences of life without parole for juveniles who had not committed capital crimes.

Then, on Monday, a 5-4 court majority ruled that states could not require life without parole for juveniles convicted of murder.

The bold first step along this road was taken by the Missouri Supreme Court in Simmons vs. Roper. It is unusual for a state supreme court to get out in front of the U.S. Supreme Court by declaring a practice unconstitutional before the high court has ruled. This adventurism can result in a slap-down by the U.S. Supreme Court.

But, in Simmons, the Missouri Supreme Court's 4-3 decision to rule the juvenile death penalty unconstitutional became the framework for the U.S. Supreme Court opinion with the same result.

The facts in Simmons were horrible. Christopher Simmons, 17, had used duct tape to tie up Shirley Crook, who had recognized him at a burglary. Then he threw her off a train bridge into the Meramec River where she drowned.

Even in the face of such a cold-blooded murder, the supreme courts decided that juveniles didn't have the same kind of culpability for crimes as did adults because their brains and their personalities had not developed fully. The courts concluded that the juvenile death penalty offended the nation's evolving standard of decency and therefore the Eighth Amendment's bar on cruel and unusual punishment.

Mike Wolff was on the Missouri Supreme Court at the time, and he recalled that era fondly in an email on Monday. "In a more glorious era," he wrote. "Missouri started it all nearly 10 years ago in Simmons vs. Roper, where the MO Supremes 4-3 held the death penalty violates the 8th Amendment's prohibition of cruel and unusual punishment; that decision was affirmed 5-4 in Roper vs. Simmons in 2005."

But Wolff lost five years later when the issue of life without parole came before the court. As he recalled it, "Then in 2010, in a less glorious era, the MO Supremes 4-3 rejected the claim that life without parole for a juvenile offender violates the 8th Amendment. I wrote a 28-page dissent saying I could not tell the difference, and that life-without-parole sentences violate the 8th Amendment."

In the latter case, Antonio Andrews of St. Louis was challenging the life without parole sentence he received for killing St. Louis Police Officer Norvelle Brown, who had been chasing him. The murder got public attention because of the death of a young officer.

In his dissent, Wolff cited many of the same factors as he had in Simmons: Juveniles have less culpability and their brains are not fully developed. He concluded saying there really wasn't anything different about a death sentence and life without parole.

"Juveniles should not be sentenced to die in prison any more than they should be sent to prison to be executed," he wrote.

Missouri is one of 28 states, along with the District of Columbia, that require life without parole for some murders committed by juveniles. It is that kind of mandatory sentencing, which does not take into account the age or background of the defendant, that the court found unconstitutional on Monday. It did not rule out the possibility of a sentence of life without parole for a juvenile in an appropriate case but said that mandatory sentences of life without parole could not stand.

Both cases before the court involved children convicted of murder for acts when they were 14.

Kuntrell Jackson and two older youths tried to rob an Arkansas video store in 1999. One of the older robbers shot and killed a store clerk.

In the other case, Evan Miller and an older youth beat a 52-year-old neighbor in Alabama in 2003 after the three had spent the evening smoking marijuana and drinking. The youths set the house on fire and the neighbor died.

In one of her first important opinions on the court, Justice Elena Kagan wrote that under the mandatory sentencing laws “every juvenile will receive the same sentence as every other — the 17-year-old and the 14-year-old, the shooter and the accomplice, the child from a stable household and the child from a chaotic and abusive one.”

“Mandatory life without parole for a juvenile precludes consideration of his chronological age and its hallmark features — among them, immaturity, impetuosity, and failure to appreciate risks and consequences."

She added, “It prevents taking into account the family and home environment that surrounds him — and from which he cannot usually extricate himself — no matter how brutal or dysfunctional.”

The decision set off a torrent of dissents from the more conservative justices, with Justice Samuel Alito reading portions of his dissent from the bench.

"Even a 17 ½-year-old who sets off a bomb in a crowded mall or guns down a dozen students and teachers is a 'child' and must be given a chance to persuade a judge to permit his release into society," wrote Alito. "Nothing in the Constitution supports this arrogation of legislative authority."

Like Justices Clarence Thomas and Antonin Scalia, Alito does not accept the modern interpretation of cruel and unusual punishment as practices that violate society's evolving standards of decency -- a standard that has been in effect since the 1950s.

Alito questioned the basis of the standard and its importance in Eighth Amendment cases. He wrote: "Is it true that our society is inexorably evolving in the direction of greater and greater decency? Who says so, and how did this particular philosophy of history find its way into our fundamental law? And in any event, aren’t elected representatives more likely than unaccountable judges to reflect changing societal standards?"

More than 2,000 people are serving sentences of life without parole for murders that occurred before they were 18. That includes Antonio Andrews, who now can be tried again for a lighter sentence.

Wolff commented Monday, "After reading Kagan's opinion, I feel better now."