Case May Turn on Jury’s Grasp of DNA

More than a dozen of the written questions handed to potential jurors in the O.J. Simpson murder trial inquire about their understanding of blood sampling, molecular biology, mathematics and other aspects of science.

This interest in science by Superior Court Judge Lance A. Ito and the prosecution and defense, who wrote the questionnaire, points up something we all know--the importance of DNA testing to the outcome of the trial. The curiosity about jurors’ knowledge of science, and their attitudes toward it, also is a reminder that both the prosecution and defense need to explain DNA to jurors who may know nothing of science--and may be hostile toward it.

For, in the end, the case may well be decided by the jurors’ understanding of the role of DNA (deoxyribonucleic acid), which is found in cells and determines how our bodies grow. As C.R. Calladine and Horace A. Drew wrote in “Understanding DNA,” our bodies “are made from billions of individual cells and DNA is the control center of each and every cell,” shaping us as if it were sending out “memos from the main office of a factory to its workshops.”

DNA varies from person to person and, according to a 1990 study by Congress’ Office of Technology Assessment, tests “can accurately disclose DNA patterns that reflect DNA differences among humans.”

DNA analysts say chances of two people having the same pattern are so remote that they express them with outrageous figures, such as 1 in 24 million or even 1 in 27 trillion. But some judges have insisted that the statistical probability is much greater, such as 1 in 250,000.

This numbers dispute is crucial to the Simpson case. The prosecution maintains that DNA found in blood and hair samples at Nicole Brown Simpson’s Brentwood townhouse and O.J. Simpson’s nearby mansion link him--and no one else--to her murder and that of her friend Ronald Lyle Goldman.

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The questionnaire probed prospective jurors’ attitudes on whether the prosecution contention is valid: What is your view concerning the reliability of DNA analysis to accurately identify a person as the possible source of blood or hair found at a crime scene?

General knowledge of DNA was important. The questionnaire seemed to be trying to determine whether jurors would come to the courtroom with preconceived notions on the subject. They were asked if they had read any book, articles or magazines concerning DNA analysis? Were they aware of other court cases involving DNA analysis?

This was followed by questions probing a knowledge of science in general. Among them: Have you ever taken courses in population genetics, statistics or molecular biology? Have you had any specialized training in medicine, science or biology? How comfortable do you feel dealing with mathematical concepts?

Other questions delved into personal experiences that might make a juror hostile or friendly toward science: Have you or anyone close to you undergone an amniocentesis? Were you confident of the results? Have you ever provided a urine or blood sample to be analyzed?

Another group of questions sought to determine attitudes toward “experts,” whether jurors were skeptical of them or tended to accept what they said.

In back of those questions was the knowledge by the judge and the attorneys that DNA testing is fairly new to crime-solving, and that most jurors know nothing of it. In fact, many of the jurors had left school before the basic concepts of DNA structure were understood.

The first time the procedure was used to solve a crime was in the mid-’80s when a distinguished British geneticist, Dr. Alec Jeffreys, showed that the DNA in a blood sample matched that in semen found in two rape-murder victims.

Since then, it has been used in a number of criminal cases. Despite its growing acceptance, though, both judges and lawyers have been concerned about whether jurors can understand it.

One of California’s leading prosecution DNA experts, Deputy Dist. Atty. George W. Clarke of San Diego County, made that point in a recent article in a legal journal.

He quoted a California appellate court opinion in which the justices seemed to be admitting that neither they nor jurors could understand the concept of DNA. “We cannot reasonably ask the average juror to decide such arcane questions . . . when we ourselves have struggled to grasp these concepts,” the justices said.

“The judicial system encourages resistance to new scientific techniques,” Clarke told me. “Judges fear jurors will blind themselves to the rest of the evidence. They believe we can’t let jurors hear (scientific evidence) because they can’t critically examine the techniques.”

In other words, the judges are afraid that the jurors will be conned by the experts while the prosecutors, wanting DNA evidence admitted, say jurors are smart enough to understand the science.

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Los Angeles County Deputy Dist. Atty. Lisa Kahn, the DNA expert on the Simpson prosecution team, knows about the difficulty of selling DNA evidence in a courtroom.

In 1990, she successfully prosecuted Henry Wilds, who eventually was sentenced to 49 years in prison for sexual assaults and robberies of two San Fernando Valley women.

“We were concerned that it would be too complex, but it was my experience that there is a way to present it to a jury as long you understand your audience and present it in a way that is understandable,” Kahn told me. “. . . It is my experience that jurors are very interested in scientific evidence.”

In the 1990 case, Kahn’s first witness was a well-known DNA lab official who, Kahn said, taught the jury fundamentals. He was followed by a distinguished Yale geneticist who continued the teaching process, explaining DNA even more. There were many more experts testifying on both sides.

Recognizing the importance of communicating DNA complexities to the jury, the defense is sending in two nationally known attorneys, Peter Neufeld and Barry Scheck, who are experts in challenging the admissibility of DNA evidence.

When the DNA lawyers take over, they will be arguing over the heart and soul of the Simpson case. And, unlike much of what has been presented to the public and in court so far, it will take more than a sound bite to explain.