On a chilly morning in November 2001, David Healy stood in a witness box in Kansas City, Kansas, and received a sobering lesson on the US legal system. A professor of psychological medicine at Cardiff University in Wales, Healy was an expert on serotonin, depression and the brain. He had served as secretary of the British Association for Psychopharmacology. Drug companies sought his advice. He was widely published in scientific journals.
Healy had crossed the Atlantic to testify in a lawsuit filed against the pharmaceutical firm Pfizer by the parents of a teenager who had hanged himself in his bedroom closet. Thirteen-year-old Matthew Miller had just started taking Zoloft, a drug that can ease depression by boosting serotonin levels in the brain. But the medication seemed to backfire. During his week on Zoloft, Matthew grew “more agitated than I had ever seen him,” his mother, Cheryl Miller, later recalled. She and her husband, Mark, believed their son’s suicide was a direct and gruesome side effect of the drug.
The Millers knew that psychiatrists had seen violent suicidal behavior in a handful of patients taking selective serotonin reuptake inhibitors (SSRIs) like Zoloft. They invited Healy to testify about this rare phenomenon. Though he routinely prescribed SSRIs in his own practice, Healy had become increasingly outspoken about the dangers of these antidepressants. He believed the evidence showed that the drug could be largely blamed for Matthew’s suicide.
Before the trial could begin, though, Pfizer used a tactic that has grown increasingly common in lawsuits involving scientific testimony: It filed a thirty-six-page challenge to block Healy from even appearing before a jury. “Dr. Healy’s reports consist of personal beliefs, speculation, innuendo, unscientific claims and theories, and mere musings,” Pfizer’s lawyers argued. “He has avoided, rather than followed, scientific methods in this case…. He knew what he was hired to say and, without bothering to explore the facts, said it.”
Pfizer’s challenge triggered a “Daubert hearing,” a procedure judges use to evaluate the credentials of scientific witnesses and the quality of their work. Now, in the half-empty courtroom, Healy found his research ripped apart.
Pfizer attorney Malcolm Wheeler read a statement by Healy that antidepressants can produce side effects tormenting enough to drive suicidal patients over the edge. Then, unexpectedly, Wheeler changed the subject to pizza. “[What] if a person who is depressed eats a piece of pizza and gets a stomachache because it’s greasy,” Wheeler asked, “and he just said, ‘That’s the last straw; I’m going to commit suicide’?” Could the pizza be held responsible?
Healy was taken aback by the question. “I think, Mr. Wheeler, you’re playing with the actual example slightly,” he said in his understated way.
“I am indeed,” Wheeler shot back.
It was a particularly stark unmeeting of the minds. But the encounter illustrates what often happens when science is called upon to settle questions of law.
People are exposed to risks all the time: They take medications, work around toxic chemicals, undergo risky surgeries, smoke cigarettes, use electronic devices that emit radiation. Sometimes they get sick or injured, either as a result of the exposure or simply by coincidence. It’s the role of science to determine what caused the harm, and the role of law to determine who must take the blame.