SAN FRANCISCO — The California Supreme Court has decided to delve into the murky and controversial debate over the reliability of DNA evidence, voting to review contradictory rulings on its admissibility.
The court's ultimate ruling will determine the standards for admitting DNA evidence, including ways of calculating the likelihood of a coincidental match. The ruling will be significant because it will help shape what juries are told before they evaluate the genetic evidence.
Although DNA evidence is expected to figure prominently in the O.J. Simpson trial, it is not clear how the California Supreme Court's ruling would affect a defense appeal if Simpson is convicted. Simpson's lawyers gave up the right to a separate hearing on DNA admissibility after Los Angeles Superior Court Judge Lance A. Ito ruled that such a hearing could not be held before the jury.
The state Supreme Court, which has been criticized for ducking the DNA controversy in the past, decided to issue a ruling in a Kern County case in which DNA results were the prime evidence against Sergio Venegas, convicted of raping a woman in a Bakersfield motel in 1989.
A Court of Appeal in Fresno recently reversed the conviction after questioning both the laboratory methodology used to find a match and the statistical analysis for calculating the odds of a coincidental match.
"There is no question that this will be an important decision in California because the (DNA) technology is something that is being utilized whenever prosecutors have enough of a sample to get a result," said Myrna Raeder, a professor at Southwestern University School of Law and an expert on the admissibility of DNA evidence. "I am delighted the California Supreme Court has decided to join the fray."
DNA evidence has been used to identify and convict suspects for years, but defense lawyers have repeatedly challenged its reliability. Courts of Appeal in California have reached contradictory conclusions in DNA cases, a prime reason why the state Supreme Court has been asked to settle the debate.
Much of the controversy has revolved around how to calculate the odds of a match. In the Kern County rape case, a method employed by the FBI found the DNA profile obtained from a semen sample could be shared by one in every 60,000 men in the general population and one in every 30,000 Latinos from the Southwest United States. A defense expert calculated the odds at 1 in 35 or, depending on the methodology, 1 in 378.
"The fight has always been about statistics," said Deputy Atty. Gen. Jo Graves, the state's lawyer in the Kern County case, "and that seems to me the real issue that the California Supreme Court is going to have to grapple with."
The Court of Appeal in Fresno ruled that the FBI's statistical analysis failed to meet generally accepted scientific standards. The court said admissibility hearings should be held to determine whether the methodology used by a particular laboratory was sound.
The California Supreme Court also voted Thursday to review two other rape cases that prompted appellate rulings upholding DNA evidence. The outcome of these will be determined by the ruling in the Kern County case.
"The court could simply approve the use of language that matches are generally very rare," said Raeder, "and give the defendant the right, if he or she chooses, to indicate what the statistics are."
In each of the cases, prosecutors used RFLP tests--Restriction Fragment Length Polymorphism--to link the suspect to the crime. That technology, which is being used in the Simpson murder case, has been presented in courtrooms since the late 1980s, with most courts around the nation favoring its admissibility.
RFLP tests are performed on fresh, well-preserved samples of blood or other human specimens. The tests are capable of pinpointing astronomical odds of a coincidental match. Another test, known as PCR, (polymerase chain reaction) can be performed on older, more degraded samples, but PCR is less definitive and more vulnerable to sample contamination. The California Supreme Court probably will take at least a year before ruling. The other DNA cases now before the court stem from the 1990 Los Angeles rape conviction of Henry Wilds and the 1991 Orange County conviction of Frank Lee Soto for attempted rape.