`BASED on your calculations as a renowned astronomer, Dr. Luna, you testified that the moon was full on the night in question."
"That is correct."
"In your expert opinion, professor, could the full moon have caused the defendant to behave in an irrational manner?"
That hypothetical trial scenario is farfetched; but it's one that Supreme Court Justice Harry Blackmun whimsically used to illustrate the kind of "junk science" that should be barred from the courtroom. Justice Blackmun's opinion in Daubert v. Merrell Dow Pharmaceuticals, decided by the high court in June, takes a big step toward settling a heated debate in legal and scholarly circles over the use of scientific evidence in trials.
The debate is hardly new, but it has intensified in recent years as rapid advances in medical, biological, and environmental research have armed plaintiffs - and plaintiffs' lawyers - with a new arsenal of theories regarding the causes of ills. In the view of many scientists and defense lawyers, however, the "science" purporting to support some theories is flawed or, in a few cases, downright fraudulent.
The junk-science dispute went public in recent years largely through the writings of Peter Huber, a Washington-based senior fellow at the conservative Manhattan Institute who is a leading advocate of tort reform (the cause subsequently picked up by former Vice President Quayle). In a 1988 book cataloging the "problems of our modern liability system," Mr. Huber identified "junk science [as] the most insidious and the least noted." He focused more directly on the problem in a 1991 book, "Galileo's Revenge:
Junk Science in the Courtroom."
In Huber's view, American courtrooms are being swept by a tidal wave of testimony from scientists and physicians who are proffering half-baked, untested, and even specious notions about the causes of illness to help people recover multimillion-dollar awards from chemical and drug companies and other deep-pocket corporations. Huber has exhorted judges to probe more deeply before allowing "expert witnesses" to testify.
But Huber has critics among scientists, legal scholars, and lawyers, who say he has overstated his argument and has engaged in the same selective use of data that he charges "junk scientists" with. Last month Kenneth Chesebro, a lawyer who appealed the decision of lower courts in the Daubert case to exclude certain evidence linking birth defects to the prescription drug Bendectin, published a stinging retort to "Galileo's Revenge" in the American University Law Review.
At issue in the scuffle among Huber, attorney Chesebro, and others is not the truth of specific scientific theories, but rather the criteria and procedures to be used by judges in allowing or excluding evidence on such theories. At the poles in the dispute are those who would allow juries to hear and decide among virtually all plausible scientific theories (even they would, it's assumed, exclude testimony regarding the effects of the moon on human behavior) and those who would admit only evidence that ha s gained "general acceptance" in the scientific community.
In its Daubert decision, the Supreme Court came down near the middle. The justices ruled that the lower courts - which had applied a "general acceptance" standard to bar certain evidence regarding the effects of Bendectin - were too restrictive toward potentially groundbreaking scientific research. At the same time, the high court rejected the let-in-anything school: It emphasized that judges have a "gatekeeping" responsibility to scrutinize scientific evidence, and Blackmun suggested criteria for judges
to use in evaluating proposed expert testimony. Judges' focus, he said, "must be solely on principles and methodology, not on the conclusions that they generate."
In a partial dissent, Chief Justice William Rehnquist grumbled that the ruling will require federal judges (and the state judges who will follow their lead) "to become amateur scientists." But other people on both sides of the issue - including Huber and Chesebro - seem to be satisfied with the high court's decision.
The scholarly adversaries and others in the field also agree, however, that the fight over junk science is far from over. It will take time for judges to assimilate the Supreme Court's instruction and devise standards for performing their gatekeeping role. Still, no one is accusing the justices of junk law.