23rd June(US)
The Power of an Expert Witness
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During the murder trial of Andrea Yates in 2002, only one of a dozen mental health experts who testified concluded that the Houston mother was legally sane when she drowned her five children in the family bathtub.
That witness, called by prosecutors, was Park Dietz, a renowned forensic psychiatrist. As the prosecutors' only mental health expert, Dietz and his testimony helped convict Yates. The conviction later was overturned. When Yates is retried beginning Thursday, much of the attention again will be on Dietz, who is back on the prosecution's witness list. And now, 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.
Among them: whether Dietz, as Yates' attorneys plan to argue, improperly injected religion into his diagnosis when he concluded that Yates was sane when she killed her children on June 20, 2001.
Such questions have added intrigue to a case in which prosecutors' initial decision to seek the death penalty ignited a national debate over how mental illness and postpartum depression are viewed in criminal courts. The Yates case now has become a symbol of the influence that expert witnesses wield in trials across the USA each day - and a test of how psychiatrists' opinions are used in court.
The standards judges use in deciding whether to admit psychiatric opinions in court are less precise than those used to vet testimony about scientific evidence that is more obviously measurable, such as DNA or fingerprints.
In the Yates case, the issue is not whether Dietz qualifies as an expert on psychiatry. His 65-page résumé cites his multiple academic degrees and work as a university professor, practicing psychiatrist and consultant to the FBI, the Drug Enforcement Administration and the Secret Service. Dietz, 57, has testified - usually for the prosecution - at hundreds of trials, including those of John Hinckley, who shot President Reagan; "Unabomber" Theodore Kaczynski; and serial killer Jeffrey Dahmer. Dietz was paid $100,000 for his work on the Yates case, he said.
George Parnham, Yates' lead attorney, said the defence hopes to raise doubts about Dietz's analysis of Yates. The defence, Parnham said, will focus particularly on why Dietz found Yates to be sane - and therefore legally responsible for her actions - and why he came to the opposite conclusion in 2004 in a similar case involving Deanna Laney, a Texas mother who killed two of her sons.
Kaylynn Williford, a Harris County prosecutor, said Dietz's analysis in other cases is not relevant to the Yates case. She says she will ask the judge to limit Dietz's testimony to his analysis of Yates. If convicted, Yates could face life in prison, but not execution. That issue was settled at her first trial, when the jury rejected execution.
Texas law defines insanity as the inability to know right from wrong. At Yates' trial four years ago, Dietz testified that Yates knew that drowning her children was wrong. Jurors agreed with Dietz's opinion and rejected her insanity defense.
Two years after Yates was convicted and sentenced to life in prison, Dietz testified for the prosecution in the murder trial of Laney, a mother from Tyler, Texas, 100 miles east of Dallas. Laney had killed her sons Joshua, 8, and Luke, 6, with a rock and had maimed a third, Aaron, 2.
The similarities between the cases were striking. Laney and Yates, now both 41, were deeply religious, stay-at-home mothers when they killed their children. After interviewing them, Dietz found each woman to be mentally ill, psychotic and delusional, according to transcripts from both trials.
However, in Laney's case, Dietz testified she was insane because she had thought attacking her kids was the right thing to do. The jury agreed with Dietz's analysis and acquitted her by reason of insanity. She now is in a mental hospital.
A key difference in the Yates and Laney cases: Laney told Dietz she attacked her sons at God's direction. Dietz testified he took that as a sign she didn't know right from wrong. "I think it's understood that the ultimate test that God could ask of someone is to kill your own child," Dietz testified at the Laney trial. "The Bible has information on that very point."
On the other hand, Yates had told Dietz that she had drowned her children - Noah, 7; John, 5; Paul, 3; Luke, 2; and Mary, 6 months - at the direction of Satan, according to the trial transcript. She also told Dietz she thought it was wrong.
In an interview with USA TODAY, Dietz recalled why he came to different conclusions about the mental health of Laney and Yates.
"Mrs. Laney expected that her actions would result in her going to heaven," he said. "Mrs. Yates expected she would go to hell for her actions. She told me that. The big thing is that Mrs. Laney did not think what she was doing was wrong. Mrs. Yates did. Mrs. Laney did not see killing the children as a sin. Mrs. Yates did. Mrs. Laney thought God approved of the killing. Mrs. Yates thought God disapproved of the killing. Mrs. Laney did not expect punishment. Mrs. Yates did."
Transcripts from their trials indicate the two women told Dietz more about what they were thinking when they killed their kids. Yates told Dietz she was saving them from eternal damnation, Dietz testified. And at Laney's trial, he testified that Laney "would know it was illegal to kill" her kids.
In the interview, Dietz further explained his views: "Let's assume both of them understand that killing is against the law. Mrs. Laney believed herself to be doing the right thing at God's direction. Mrs. Yates believed herself to be doing the wrong thing, with Satan's prompting, and that it was sinful."
Yates' attorneys say Dietz improperly injected religion into his diagnosis. "There's no question," Parnham said. "He's used religious symbols inappropriately."
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."
Dietz disagrees. "Under Texas law, if a mentally ill person commits a murder in response to command hallucinations from God, they would surely be insane," he said. "If they did it at the direction of the chief of police, they are arguably insane. If they believed it at the direction of a gang leader, at the direction of Napoleon, at the direction of Satan, they are not insane. Gang leaders, Napoleon and Satan do not have moral authority in Texas.
"The issue is: Does the person believe they are doing the right thing or the wrong thing?"
© X-Pro 2006
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