For nearly two centuries, American society has struggled with how to administer justice to people who are deemed to be significantly mentally ill when they commit a criminal act.
And some experts say the guilty verdict rendered in Texas last month against Andrea Yates, who drowned all five of her children in a bathtub, demonstrates the extreme difficulty of proving a defendant not guilty by reason of insanity even when few doubt that the defendant is severely mentally ill.
"There are good studies showing that a successful insanity defense occurs in less than 1 percent of all criminal prosecutions," said Jeffrey Metzner, M.D., immediate past president of the American Academy of Psychiatry and Law (AAPL) and chair of APA’s Council on Psychiatry and the Law. "If Andrea Yates wasn’t found legally insane, you know it’s pretty difficult to find anyone not guilty by reason of insanity."
One indication of the problems with the insanity defense is the variations and permutations in the way states apply the insanity defense.
Yates was found guilty in a state that applies the M’Naghten Rule—an insanity definition formulated in 1843 and derived from English case law. That rule states that a person is "innocent by reason of insanity" if "at the time of committing the act, he was laboring under such a defect of reason from disease of the mind as not to know the nature and quality of the act he was doing, or if he did know it, that he did not know that what he was doing was wrong."
Because the jury was convinced that Yates knew that what she did was wrong, statutory law demanded a guilty verdict.
In June AAPL will issue "Practice Guidelines for Forensic Psychiatric Evaluation of Defendants Raising the Insanity Defense." The 60-page document will include a survey of states and their standards regarding the insanity defense (see map).
According to Howard Zonana, M.D., medical director of AAPL, Texas is joined by 24 other states in using the M’Naghten Rule, or some variation of it. Some of those states—but not Texas—add a reference to "irresistible impulse," allowing defendants to be considered not guilty by reason of insanity if they could not resist the criminal act, even if they knew it to be wrong.
Nineteen states and the District of Columbia apply a definition formulated by the American Law Institute (ALI) in the 1950s, or some variation of that definition. The ALI definition, allowing a somewhat broader understanding of insanity, holds that a person would "not be responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law."
One state—New Hampshire—applies a "product test," which requires juries to determine whether a criminal act was the "product" of mental illness. And five states have abolished the insanity defense altogether, according to Zonana.
Surely, in another state not ruled by the strict M’Naghten standard, Andrea Yates might have had a chance at a not-guilty verdict. "When you have a strict M’Naghten standard, you don’t get into the balancing of how delusions are affecting your thinking," Zonana said. "As long as you can say she knew it would be illegal, the state law demands a guilty verdict."
But experts note that the varying statutes are legal formulations—not medical ones—designed by legislatures to guide judges and juries in making what are invariably moral judgments. While psychiatrists who have examined a defendant may render opinions about mental health or illness, they do not have the expertise to render legal judgments, let alone moral ones.
As Metzner noted, even among psychiatrists there are bound to be differences about any particular standard. "Asking people about the insanity defense is like asking them about capital punishment," he said. "When you look at the insanity defense among psychiatrists, you are going to get a wide variety of opinions, and some would be opposed to it altogether."
Legal standards reflect a shifting moral consensus among the public. "For many years books have been written and debates held about what is the best standard for an insanity defense," said APA President-elect Paul Appelbaum, M.D. "There was a fairly broad consensus in the middle of the 20th century that the M’Naghten standard was too narrow."
It was that consensus that led to the ALI standard, which broadened the definition under which a defendant could be found not guilty. But the consensus shifted again with the case of John Hinckley, who shot former President Ronald Reagan and was found not guilty by reason of insanity. "After the Hinckley verdict, there was a swing back away from a broadened standard to a narrower standard," Appelbaum said.
Appelbaum suggested that ultimately the legal language used in statutes is subservient to the moral judgments that 12 men and women make in a jury room.
"It is clear that when juries are asked to consider the insanity defense, they are doing something much more than simply applying the legal standard that is handed to them," Appelbaum said. "They are making a moral judgment as to whether punishment is deserved. That’s a reasonable function, and I think it is precisely what we should ask our juries to do—to represent our morality at large.
"One would hope that they would exercise that function with good background knowledge and a full awareness of the facts about mental illness," he said. "Clearly, that’s not always the case because our juries share the popular misconceptions about the nature of mental illness."
He noted that in published studies of mock juries given case scenarios and asked to render judgments using a variety of standards, juries tend to come to the same conclusion regardless of the standard.
"In some abstract sense, it doesn’t seem to make much difference what the standard is," he said. "It’s pretty clear to me that in most cases what goes in a jury room is that the jurors do what they think is right."
While deterrence is a legitimate function of the law, so it seems is retribution. "It seems inherently just to our society to punish people for the violation of social norms," he said. "The worse the violation, the stronger the impulse to punish. Whatever we do with the standards is not going to change that dynamic."
Ultimately, then, fine-tuning legal statutes may be of little use in achieving justice for mentally ill defendants.
"If we want to change what goes on in the jury room and ensure that it reflects an accurate view of mental disorders," Appelbaum said, "the way to do that is through public education." ▪