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December 5, 2006

When Questions of Science Come to a Courtroom, Truth Has Many Faces


Idealistic lawyers and idealistic scientists often describe themselves as engaging in a search for truth.

The scientists follow the scientific method. They state their hypotheses, describe the ways they test them, present their findings — and wait for another researcher to prove them wrong. Lawyers’ practice is built on the idea that the best way to shake the truth out of a complex dispute is for advocates on each side to argue it, as vigorously as they can, in front of an impartial judge or jury.

These approaches work more or less well on their own. But when a legal issue hinges on questions of science, they can clash. And the collision can resound all the way up to the Supreme Court.

Last Wednesday, the nine justices heard arguments in the first global warming case to come before the court. Massachusetts, 11 other states and several cities and environmental groups are saying that the federal Environmental Protection Agency has ignored the requirements of the Clean Air Act and otherwise shirked its responsibilities by failing to regulate emissions of heat-trapping gases, chiefly carbon dioxide.

As the case made its way to the court, it generated interesting questions like whether states have a right to bring such a suit and whether E.P.A. action would amount to unauthorized interference in foreign policy.

But much of the argument hinged on scientific questions. Is the earth’s climate changing? If so, are human activities contributing to the change?

Mainstream science has answers to these questions (yes and yes). But while it is impossible to argue that earth has not warmed up a bit in the last century, there are still some scientists with bright credentials and impressive academic affiliations who argue that people don’t have much do to with it. As Justice Anthony M. Kennedy suggested on Wednesday, maybe the court will decide to decide this issue for itself.

If it does, it will also confront issues outside the realm of mainstream science.

One is the standard of proof. Typically, scientists don’t accept a finding unless, statistically, the odds are less than 1 in 20 that it occurred by chance. This standard is higher than the typical standard of proof in civil trials (“preponderance of the evidence”) and lower than the standard for criminal trials (“beyond a reasonable doubt”).

The justices may also consider that when scientists confront a problem, they collect all the information they can about it and then draw conclusions.

Lawyers work in reverse. They know their desired outcome at the outset, so they gather arguments to support it. While it would be unethical for scientists reporting on their work to omit findings that don’t fit their hypotheses, lawyers are under no compunction to introduce evidence that hurts their cases; that’s the other side’s job.

Perhaps the knottiest problem, though, has been deciding what scientific evidence or testimony should be considered in the first place.

For years, the standard was “general acceptance” by scientists, which a federal appeals court enunciated in 1923 in Frye v. United States, a case involving lie detectors. The court ruled that lie detector technology had yet to win wide acceptance and barred its use.

Though the court noted that it was difficult to say “just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages,” the Frye standard prevailed until 1975, when Congress codified federal rules of evidence.

In these rules, the test became not wide acceptance, but whether the scientific, technical or other specialized information would assist the judge or jury in reaching a decision and whether witnesses seeking to testify about it had enough knowledge or expertise to make a valuable contribution.

Critics of this standard say it flooded courtrooms with junk science, as people with good (or seemingly good) credentials but bad ideas took the stand before judges and juries unable to differentiate between credible scientific claims and those with only an aroma of scientific respectability.

Eventually, in 1993, the Supreme Court spoke on the issue, in a case involving accusations that the drug Bendectin caused birth defects. In that case, Daubert v. Merrell Dow Pharmaceuticals, the court returned to the Frye “acceptance” standard but added new criteria, including whether the information had been tested or could be tested or whether other scientists had examined it in a process called peer review. (The court upheld the verdict that Bendectin was not guilty, but by then litigation had driven it from the market.)

The court elaborated on Daubert in 1998, in General Electric Company v. Joiner, ruling that judges could reject evidence if there was simply too great a gap between “the data and the opinion proffered.”

But how are judges to know? Few have advanced training in science.

Some of them have been taking things into their own hands.

For example, in a large case involving silicone breast implants, the judge chose a panel of advisers to recommend experts to review scientific aspects of the accusations. Their report cleared the implants of any role in systemic disease, but only after a multibillion-dollar trust had been established to compensate the supposed victims.

Other judges, worried about their ability to hear cases hinging on complex topics, have organized their own seminars on subjects like DNA evidence. According to Sheila Jasanoff, a lawyer and professor of science and technology studies at the Kennedy School at Harvard, scholars and officials have from time to time also proposed creating a judicial or quasijudicial “science court” to resolve factual disputes. Generally, lawyers don’t like these ideas, in part because they fear the influence such a supposedly objective entity might have with juries.

The idea “has largely been abandoned as unworkable,” Dr. Jasanoff wrote in her book “Science at the Bar” (Harvard University Press, 1997).

But even if lawyers and judges could routinely absorb a thorough grounding in the scientific issues they confront, there would still be trouble. For one thing, the state of scientific knowledge changes rapidly. Sometimes, there are multiple scientific views of a given issue, all potentially credible. And sometimes research on an issue does not even begin until it works its way into court. To an extent, that was the case with the silicone breast implants.

But without a method of providing courts with reliable scientific information, scientific research has an uncertain role in the courts, and especially the Supreme Court, as David L. Faigman put it in “Laboratory of Justice” (Times Books, 2004). Justice Antonin Scalia made this point on Wednesday, in a way, when he was corrected on where in the atmosphere carbon dioxide ends up.

“Troposphere, whatever,” Justice Scalia said. “I told you before I’m not a scientist.”

Mr. Faigman, a professor at the University of California Hastings College of the Law, criticizes what he calls the court’s “abdication” of any responsibility to determine scientific facts.

This practice cannot last, he wrote. “Science and technology today are so pervasive that the court cannot continue its slapdash ways,” he said. “The scientific revolution is everywhere; it cannot be ignored with impunity.”