The US Supreme Court last month unanimously affirmed the right of trial judges to disallow scientific testimony they believe to be flawed. The decision may cut down on the use of so-called ‘junk science’ in the courtroom.
A decision handed down on 15 December reversed a ruling by a federal appeals court that a lower court judge had acted improperly in disallowing expert testimony linking polychlorinated biphenyls (PCBs) to cancer.
In the original case, an individual, Robert Joiner, sued General Electric and two other manufacturers of PCBs, claiming they had caused his lung cancer. But the judge threw out testimony from experts on Joiner's side, arguing that the epidemiological and animal studies on which the experts relied had failed to make a convincing connection between PCB exposure and Joiner's particular cancer.
In backing the original judge, the Supreme Court said that any judge's decision to admit or exclude expert scientific evidence should stand, unless it constituted an “abuse of discretion” or gross error of judgement. The court also said that the original judge was right to throw out the Joiner studies.
Legal experts say that the Supreme Court's position is important because it clears up an area of ambiguity from a 1993 decision on scientific evidence. Until now, judges were generally expected to admit any evidence based on legitimate scientific methodology — even if its conclusions seemed unbelievable or if the methodology was not well suited to the question.
Last month's decision appears to give judges freedom to consider both methodology and conclusions, just as a scientist might in judging the quality of research.
The court's willingness to take on this issue surprised some legal experts, and makes the case “more important for scientists than I thought it was going to be”, says Bert Black, an attorney with the Dallas firm Hughes and Luce. Black co-chairs the National Conference of Lawyers and Scientists, set up in 1974 by the American Association for the Advancement of Science (AAAS) and the American Bar Association.
Courts rely increasingly on expert scientific testimony, particularly in cases involving product liability and the health impact of toxic substances. Black says that not allowing judges to evaluate a scientific study's conclusions would lower the quality of their rulings.
Judges may now have to do more homework in areas of scientific complexity. In a separate concurrence to the Supreme Court's opinion, Justice Stephen Breyer wrote that judges should routinely seek the advice of scientists through pre-trial hearings, expert witnesses and specially-trained law clerks. Black says the AAAS is trying to set up a clearing-house of scientific experts willing to advise courts.
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American Journal of Public Health (2001)