During the 2002 murder trial of Andrea Yates in Houston, only one of a dozen mental health experts testified that she was legally sane when she drowned her five children in the family bathtub. That witness, the prosecutors’ only mental health expert, was forensic psychiatrist Park Dietz. The conviction later was overturned. When Yates is retried beginning tomorrow, much of the attention again will be on Dietz, who is back on the prosecution’s witness list. There are questions about Dietz’s conclusions in the Yates case because of his testimony in another trial involving a Texas mother who killed two of her children.
One question is whether Dietz improperly injected religion into his diagnosis when he concluded that Yates was sane when she killed her children on June 20, 2001. USA Today says the case has become a symbol of the influence that expert witnesses wield in trials, and a test of how psychiatrists’ opinions are used in court. Michael Perlin, a professor at New York Law School who specializes in mental disability law, said societal values about good and evil should not be factors in determining whether a defendant is sane. “It shouldn’t make any difference where the voices come from, whether God or Satan or a pop star or Napoleon,” Perlin said. “If you’re responding to voices, that suggests a lack of a grasp on reality. They’re responding to an extra-worldly command in a delusional state.”