Can Jurors Handle the Science Test? : Criminal justice: California courts have long held that laypeople can’t handle sophisticated scientific evidence.

The California courts have long stood firm on an especially restrictive approach to the admission of scientific testimony. In a 1976 decision, the California Supreme Court required that scientists base their testimony on generally accepted theories and techniques even though it was acknowledged that the traditional test had been criticized as being “too conservative.” Lay jurors, the court said, tend to give undue weight to scientific testimony. According to the court, in the minds of untrained laypersons, scientific evidence can “assume a posture of mystic infallibility.”

In late 1994, the court revisited the issue in People vs. Leahy. In the interim years, Daubert vs. Merrell Dow Pharmaceuticals, Inc., had liberalized the federal standards for introducing scientific testimony. In Leahy, one of the questions presented was whether the California court should follow the lead of Daubert and adopt a more receptive attitude toward scientific evidence. Ultimately, the California court

decided against doing so. Once again, the court conceded the “essentially conservative nature” of the traditional standard, automatically excluding testimony about novel scientific techniques. And, once again, the court observed that untutored lay jurors might be duped by the “misleading aura of certainty which often envelops a new scientific process.”

Given the court’s stated reason for the conservative approach toward scientific evidence, California judges should be following the Simpson case with fascination. The case seems to be testing--and undermining--the assumption to which this state’s high court has long subscribed. In Simpson, the prosecution has presented a mountain of scientific evidence against the defendant. If it is indeed true that lay jurors uncritically accept expert testimony, the defense should have changed its plea to guilty long ago.

Rather than presuming that the Simpson jurors will accept the prosecution’s scientific evidence at face value, many trial observers think that the jury is likely to attach too little weight to the evidence. Some fear that the jurors may discount the testimony because it strikes them as too complex and arcane.

There have been a few studies of how much significance lay jurors attach to scientific testimony, most of them at odds with the California court’s position.

The real task should be to compare scientific testimony against other types of evidence. To the extent that the courts single out scientific testimony and subject it to special restrictions, they force juries to rely on other types of evidence. Would we be more comfortable in the Simpson case if the jury were being asked to convict solely on the basis of a white witness’ identification of the black defendant as a person seen fleeing from the crime scene? For every proficiency study documenting a margin of error in DNA analysis, there are tens of studies concluding that cross-racial identifications can be untrustworthy. If there is a question about the validity of the outcome of a scientific experiment, in most cases the court can allow the other side to retest the evidence. In Simpson, Judge Lance A. Ito set aside a portion of some of the physical evidence to permit defense retesting. In contrast, when there is a doubt about the accuracy of an eyewitness identification, there is no time machine allowing us to re-create the event the witness observed.

Admittedly, reliance on scientific evidence is no quick fix for the ills of our judicial system. In the Simpson case, we have witnessed how hard the proponent of scientific testimony must work to present it clearly and simply. Likewise, we have seen how diligent and meticulous the opposition must be to expose flaws in the testimony. However, we should not allow the furor over “junk science” to blind us to the important contribution that science can make to the fact-finding process at trial. Rather than welcoming that contribution, the California courts have regarded scientific evidence with suspicion and in effect said that lay jurors cannot be trusted to evaluate expert testimony.

In his majority opinion in the Daubert case, Justice Harry A. Blackmun mentioned the argument that liberalizing the evidentiary standards for experts’ testimony will result in “befuddled juries . . . confounded by . . . pseudoscientific assertions.” However, he rejected that argument as resting on an “overly pessimistic” view of “the capabilities of the jury [and the] the adversary system.” If the observers of the Simpson jury are right, there is little risk that those jurors will simply rubberstamp the testimony by the prosecution’s experts. Perhaps the California courts have had it wrong all along.