It may not be that simple, legal experts say; the often-misunderstood issue of mental retardation can increase, rather than lessen, the complexity of a death penalty case.
Mr. Penry's lawyers are asking the court to consider whether the jury was given the opportunity to consider the issues of mental retardation and child abuse as mitigating factors in deciding to sentence Mr. Penry to death.
When his appellate lawyers, who found the school records and other evidence of retardation, tried to raise the issue in federal court, they were barred from doing so, because the issue had not been raised during the trial.
The court said jurors had flawed instructions on weighing his retardation, and the court did not directly address the issue of whether a mentally retarded person should be executed.
If the judge ruled against the defendant, defense lawyers could raise the issue in the sentencing phase, and a finding of retardation would require a unanimous jury.
Although the court did not directly address the broader issue of whether a mentally retarded person should be executed, the justices ruled 6 to 3 that jurors in Mr. Penry's case received flawed instructions about how they should consider his retardation.
For years, affected Amish children who seemed healthy at birth soon suffered brain damage and other forms of retardation.
But in the sentencing phase, the jury considered evidence of retardation, and gave the defendant life in prison.
The achievement, reported in the March issue of Genome Research, moves genome scientists a big step closer to sequencing the X chromosome and should speed their hunt for genes involved in everything from sexual maturation to mental retardation.
Paul Greengard and colleagues report in the 10 December 2009 issue of Neuron that improper functioning of the protein complex GLP/G9a is linked in mice to a mental retardation like effect known as 9q34 syndrome.
