May 29, 2007

California weighs in on Atkins

States are using various approaches to comply with the U.S. Supreme Court's ban on executing mentally retarded offenders. (The 2002 case of Atkins v. Georgia held that such punishment was cruel and unusual, in violation of the Eighth Amendment.) Now, the California Supreme Court has weighed in, with an intriguing opinion in the case of Jorge Junior Vidal.

The Court unanimously held that a defendant may be spared the death penalty because he is mentally deficient in one area, even if his overall IQ score falls in the normal range. The decision overturned an appeals court finding that “full-scale IQ” was the best measure of intelligence.

Vidal was one of seven Tulare County men who faced the death penalty for the grizzly 2001 torture-killing of a 17-year-old youth. As a child, Vidal underwent intelligence testing due to his severe academic problems. Although his full-scale IQ on the widely used Wechsler test consistently fell above the typical cutoff score of 70 for mental retardation, this was due to a large split between his low verbal IQ score and his high performance IQ (which measures non-verbal skills such as ability to solve puzzles).

At issue in his case was how to determine whether he was mentally retarded for purposes of the death penalty. Under California’s Penal Code Section 1376, mental retardation is defined as “significantly subaverage general intellectual functioning existing concurrently with deficits in adaptive behavior and manifested before the age of 18.” In Atkins, the U.S. Supreme Court did not specify how “general intellectual functioning” was to be determined.

At the trial level, two psychologists testified that Vidal’s full-scale IQ score was misleading. They opined that Vidal’s verbal abilities were more important in this context, because they involve the ability to process information and to think logically. Individuals with low verbal IQs, they argued, have problems interpreting social cues and are more likely to go along with a group. The prosecution countered with a psychologist who testified that the most accurate measure of mental retardation was the full-scale IQ score.

The state Supreme Court ruled that a specific test score or legal rule cannot determine “general intellectual functioning.” Rather, the court must consider the defendant’s overall capacity based on the specific evidence in that case.

In a great discussion of the distinction between science and law, the Court chastised the appellate court for taking sides in a psychological debate: “An appellate court cannot convert a disputed factual assertion into a rule of law simply by labeling it a ‘legal standard.’ … [The question here is] whether, when both sides of a scientific dispute have been presented by expert testimony, an appellate court may declare the debate’s winner as a matter of law.”

The decision is likely to affect dozens of cases statewide by giving judges broader discretion to spare defendants from the death penalty based on low intellectual functioning.

The court's decision is available at: