Use of DNA Puts Science on Trial
Popular faith in science is on trial during the painstaking presentation of DNA evidence in the O.J. Simpson courtroom.
The issue is not as clear-cut as it was in the 1920s, when John Thomas Scopes was tried in Tennessee for teaching Darwin’s theory of evolution in a classroom. Then, science really was on trial.
But DNA is now part of high school curriculum, firmly planted there after James Watson and Francis Crick discovered the structure of the DNA molecule, deoxyribonucleic acid. The molecule shapes our physical and mental attributes, proof to all but the most dedicated skeptics that Darwin was right.
In the Simpson trial, we are talking about the application of a well-accepted science, about convincing jurors that DNA technology is strong enough to prove beyond a reasonable doubt that the former football star brutally murdered his ex-wife Nicole Brown Simpson and Ronald Lyle Goldman.
It is a science that is evolving as rapidly as computer knowledge, state DNA expert Gary Sims told the jury Thursday. But there’s an important question: Is this science evolving too fast for the jury, and for a public that polls show is skeptical about the scientific community?
“The question is whether scientific evidence overpowers all other arguments,” says Caltech humanities professor Daniel J. Kevles, co-editor of “Code of Codes,” a collection of essays on ethical implications of DNA research.
Sometimes it doesn’t, Kevles said. For example, in 1945’s “trial of the century,” a jury found that actor Charlie Chaplin was the father of a young woman’s child even though a blood test showed he was not.
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In the Chaplin case, the jury’s perception of the actor overcame scientific evidence. Married four times, his love life was a scandal in that prudish era. “The jury was reading his character,” Kevles said.
In the Simpson case, he said, the prosecution faces the possibility that the jury, distrusting the Los Angeles Police Department, will discount the DNA evidence, even though it “points to guilt.” Some legal experts have said African American jurors, a majority of the jury, will be receptive to defense charges that the LAPD framed Simpson.
So, as in the Chaplin case, no matter what the scientists say or the lab reports reveal, the jury, or at least some members of it, may cling steadfastly to preconceived notions.
Skepticism toward science may also be triggered by the billions in numbers being flung around by the prosecution. Being a non-mathematician, I am puzzled about them myself. For example, I heard a DNA expert testify last week that only one in 6.8 billion people would probably have the same DNA pattern that was found in both Nicole Simpson’s blood and the bloody sock discovered in O.J. Simpson’s bedroom.
This made no sense to me since there are only 5.5 billion people on Earth. It sounded like the prosecution was magnifying figures for the sake of a headline, a thought that may also occur to some of the jurors.
On Thursday morning, I discussed this with a mathematician who seemed particularly well-equipped to help someone like me, John Allen Paulos of Temple University, author of “A Mathematician Reads the Newspaper.” An academic who writes about math for general readers, he’s well-known for his bestseller of a few years ago, “Innumeracy.”
“You’re not talking about people, you’re talking about odds,” he said. “The odds make perfectly good sense. Look at the game of bridge. There are 600 billion possible bridge hands. If you deal a bridge hand and ask someone the probability of having been dealt that hand, the answer would be one in 600 billion.”
In the Simpson case, he said, we are talking about analyzing the pattern of a small amount of DNA removed from blood. The genetic experts calculated the possibility of this pattern occurring in another person on Earth--or in a person yet unborn. The odds of this occurring, they concluded, are overwhelmingly unlikely.
This is an abstraction, a theoretical way of describing the chances of something occurring more than once. It’s hard for a non-mathematician, or a non-gambler, to understand. Yet Simpson’s fate may come down to this abstract concept, explained by prosecution scientists and attacked by those employed by the defense.
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The debate is taking place in an atmosphere of public uncertainty about science, but not distrust.
Last November, the National Public Opinion Center took a poll on public confidence in the scientific community. Only 38% of those surveyed had a “great deal” of confidence. This was higher than for any institution except for medicine. But 49% of the people had some confidence. Only a few were completely negative.
To Southwestern University law professor Myrna Raeder, such attitudes make sense. “I am troubled when people say, ‘If it is science, it must be right,’ ” she said.
It’s also important to remember that juries are continually asked to settle disputes over science, as is seen in lawsuits over cigarettes, asbestos, breast implants and pesticides. “People are more scientific than they used to be,” said Santa Monica attorney Paul Mones, whose book, “Stalking Justice,” tells the story of a breakthrough DNA murder conviction. “While everyone might not have a cell phone, they know what it is.”
He reminded me that fingerprinting was greeted with great popular skepticism when it was introduced 100 years ago. Now, fingerprints are considered routine evidence, stripped of the mystery that still surrounds DNA.
