A state appeals court in Los Angeles issued a sweeping decision Thursday that will make it easier for DNA test results to be admissible in California courts.
A three-justice panel of the state's 2nd Appellate District said the thorny question of whether genetic profiling evidence satisfies legal requirements for the use of scientific evidence "has been unequivocally answered in the affirmative."
The panel issued the ruling while upholding the convictions of a Los Angeles man for raping and robbing two North Hollywood women in a case where DNA evidence played a critical role.
"Expert scientific testimony has the potential to create a misleading aura of certainty," Justice William Masterson said. "But even exercising the greatest possible restraint," Masterson said, it has become apparent that so-called RFLP DNA profiling has achieved acceptance within the scientific community.
Restriction fragment length polymorphism tests, or RFLP tests, seek to determine the probability that the DNA of a defendant matches DNA extracted from evidence recovered at a crime scene.
This type of DNA testing is being used in the O.J. Simpson murder case. The testing in the case decided Thursday was performed by Cellmark Diagnostics of Maryland, the same firm used in the Simpson case.
But Thursday's decision will have no immediate impact because Simpson's lawyers have waived their right at a pretrial hearing to contest the admissibility of RFLP tests.
In support of their ruling, the appellate justices emphasized that in a recent article in the journal Nature, one of the original opponents of RFLP analysis teamed up with a former adversary to proclaim that "the DNA fingerprinting wars are over."
Thursday's decision is binding on all Superior Court and Municipal Court judges in Los Angeles, San Luis Obispo and Santa Barbara counties, which are within the jurisdiction of the 2nd District, and is likely to be followed by courts in many other parts of the state, legal experts said.
A state appeals courts in Santa Ana previously approved the use of DNA profiling evidence, but state appeals courts in Fresno and San Francisco have rejected its use.
"This whole line of conflicting opinions . . . points up the need for the state Supreme Court to take up the issue of the admissibility of DNA and get a statewide ruling," said Thomas A. Schaaf of the State Public Defenders Office, who represented defendant Henry Wilds in the case decided Thursday. The California Supreme Court has yet to issue a decision on the question.
Lawyers from the California attorney general's office, who successfully argued the case on appeal, did not respond to calls seeking comment. But Southwestern University law professor Myrna Raeder, a DNA expert, expressed confidence that prosecutors would be pleased with the ruling.
She said the decision is significant because it unequivocally clears the way for RFLP profiling evidence to be brought before juries in Los Angeles and the other counties in the jurisdiction of the second appellate district.
"We no longer have to worry in Los Angeles about" holding a lengthy, complicated, pretrial hearing on the admissibility of RFLP tests, Raeder said.
Raeder emphasized that "the decision has nothing to do with the admissibility of PCR tests," another type of DNA testing used frequently.
To illustrate the impact of Thursday's ruling, Raeder referred to the Simpson case. Earlier this month, Simpson's defense lawyers waived their right to what is known as a Kelly Frye hearing, where the admissibility of scientific evidence is debated. In some instances, such hearings have lasted up to six months in California because of the complex mix of biology, statistics and warring expert witnesses.
"Had the defense in the Simpson case not withdrawn their Kelly Frye challenge on RFLP evidence, Judge Lance Ito would have been much relieved by this decision," Raeder said. "It would have permitted him to simply end the hearing, by saying, 'I am now bound by this decision as to the admissibility of RFLP.' "
With the issue of admissibility resolved, it will be left to juries to determine how much weight to give to DNA evidence, Raeder said.
However, she said the decision was less clear about what sort of statistics can be presented to a jury, meaning that there will still be considerable contested terrain in the presentation of DNA evidence.
In the Wilds case, DNA extracted from his blood was compared to DNA extracted from sperm cells recovered from two of the rape victims. "Expert testimony established that the DNA from these three sources was identical," according to the appellate decision.
There has been heated debate in the scientific community about how much statistical significance should be accorded to any possible DNA match.
In the Wilds case, Cellmark's original probability estimate of a random match included a calculation of 1 in 186 billion. The National Research Council has contended that such figures are unreasonable and has urged a more conservative mode of analysis. The FBI has countered that the research council's approach is too conservative and too defendant-oriented.
When the case went to trial, a Yale University professor of human genetics, testifying for the prosecution, estimated that the probability was "conservatively 1 in 4.5 million" that the DNA in sperm cells recovered from the victims belonged to someone other than Wilds.