May 26, 2004; Page B1

In 1993, when 17-year-old Christopher Simmons abducted and murdered his neighbor, little did he know that some of the nation’s top brain researchers and psychiatrists would one day rush to his defense before the Supreme Court.

Emerging scientific research is shedding light on what people have long suspected: The brain changes dramatically during adolescence and these changes may account for the impulsive, often irrational behaviors seen in some teenagers.

Now psychiatrists, lawyers and lawmakers are using this emerging science to argue that such adolescent brain changes should be considered as mitigating factors when teenagers are being sentenced to the death penalty.

The Supreme Court has agreed to take up the Simmons case this fall to reconsider whether executing people for crimes committed when they were 16 or 17 is “cruel and unusual punishment.”

Although the Supreme Court in 1989 set the minimum age for the death penalty at 16, the American Academy of Child and Adolescent Psychiatry, the American Psychiatric Association and the American Society for Adolescent Psychiatry recently issued statements opposing capital punishment for juveniles. They plan to file a joint legal brief on Mr. Simmons’s behalf to the Supreme Court. The groups haven’t taken a stand on the death penalty for adults.

Nineteen states still permit executions of convicts as young as 16; most recently, Sean Sellers of Oklahoma was executed in 1999 at the age of 29 for a murder committed when he was 16. Nationwide, 73 people are on death row for crimes they committed when they were youths, and 22 have been put to death since the high court ruling reinstituted the death penalty in 1976. Last year, two people who committed crimes while they were under age 18 were sentenced to death.

In 1993, Mr. Simmons and Charles Benjamin, who was 15, broke into a neighbor’s home in Fenton, Mo. Once inside they encountered owner Shirley Ann Crook. Fearing she would recognize them, they bound Ms. Crook, 46, with duct tape and an electrical cord, drove her to a railroad bridge and shoved her into the Meramec River, where she drowned.

Mr. Benjamin, who was too young to face the death penalty, was sentenced to life in prison. Mr. Simmons was convicted of murder and sent to death row. He told friends he thought he could get away with the crime because he was a minor, according to the Missouri attorney general. Last summer, the Missouri Supreme Court ruled that Mr. Simmons’ death sentence violated the U.S. Constitution’s Eighth Amendment against cruel and unusual punishment and that Mr. Simmons was too young to be held fully responsible for his crime.

The legal argument is expected to center around the what previous Supreme Court rulings have called the “evolving standard of decency,” or the notion that as a society matures, so does its notion of what constitutes cruel and unusual punishment. (Congo, Iran, Nigeria and Saudi Arabia are the only other countries with a juvenile death penalty.)

Part of the argument against juvenile executions will focus on how developing brains in juveniles differ from adults. Such research helped persuade lawmakers in some states to vote to raise the age for the death penalty to 18.

“Kids may know the difference between right and wrong, but that does not stop them from doing dumb and dangerous things that they would never think of doing as adults,” said David Fassler, a child psychiatrist and professor of psychiatry at the University of Vermont.

Proponents of this argument contend that because the part of the brain that might inhibit criminal behavior isn’t fully developed, teens lack the ability to make sound decisions and are more prone to impulsive behavior. They agree the crimes are horrible, and those convicted should be punished, but not be put to death.

The psychiatrists point to brain research that shows that the frontal lobe, the part of the brain that controls reason, develops last. Researchers at David Geffin School of Medicine at the University of California at Los Angeles, Harvard Medical School and the National Institute of Mental Health and elsewhere have conducted a series of studies in recent years that “map” the development of the brain from childhood to adulthood.

Using magnetic resonance imaging, the researchers have been able to scan the brains of children in different age groups to compile three-dimensional images that track the brain’s development. They found that the amygdala, the more primitive part of the brain responsible for impulse and emotion, controls decision-making into early adulthood.

The researchers found that a small area in the frontal lobe of the brain — known as the prefrontal cortex — controls the most advanced functions of the brain and is the last part to develop. The prefrontal cortex is located just behind the forehead and is known as the “CEO” of the body, because it allows humans to plan, anticipate consequences, control impulses, prioritize thoughts and think in the abstract. This part of the brain continues to develop for individuals into their 20s.

So far, the researchers haven’t demonstrated a direct link between brain development and behavior, and death-penalty advocates are challenging what research already exists.

“There is science, and then there is junk science,” said Dianne Clements, president of Justice for All, a Houston nonprofit victim-advocacy group. “This is an effort by those in the scientific community who oppose the death penalty to use science to argue their position.”

Ms. Clements said case facts show teens who kill realize their actions were wrong because they often try to cover up and destroy evidence to avoid getting caught. What’s more, most relatives of murder victims don’t think a killer’s age at the time of the crime should result in a lesser sentence, she said.

But some lawmakers think a criminal’s age should be taken into account. “It’s just intuitive,” said Cale Case, a Wyoming Republican state senator who co-sponsored a bill that raised the minimum age for the state’s death penalty to 18. “I had two teen-age daughters, and one was very compulsive. But they have become very responsible adults.”

Stephen Harper, an assistant public defender in Miami who has represented juveniles facing capital punishment, also notes science is often ahead of the law. He pointed out how the courts were slow to embrace the use of DNA evidence linking individuals to crimes.

“If you just focus on how horrible the crime was, a lot of people do not care how old the offender was,” Mr. Harper said. “But the brain research begins to demonstrate that adolescents are less culpable than adults.”

Nevertheless, some scientists say the research isn’t complete. “I don’t think it is there yet, but we are working on it,” said Elizabeth Sowell, a professor of neurology at UCLA. “I think what we have found is relevant and the court may want to consider it. But there is no absolute proof. I think the scientists who say the evidence to date should be used to end the death penalty [for juveniles] may be going out on a limb.”