Unmodified Product Rule

In People v. Soto (1999) 21 Cal. 4th 512, the Supreme Court soundly rejected one of appellant's original claims on appeal, i.e., that use of the unmodified product rule was not validated by general consensus within the scientific community. After a detailed summary of expert testimony presented at two Kelly hearings and at trial, Soto discussed the decision in People v. Axell (1991) 235 Cal. App. 3d 836 1 Cal. Rptr. 2d 411, which confirmed general scientific acceptance of the product rule, and this court's 1992 decision in Barney, supra, 8 Cal. App. 4th 798, which concluded subsequent publications had undermined the rule's acceptance. (Soto, at pp. 526-537.) The court then reviewed significant developments after Barney, including: (1) a 1993 FBI publication of a worldwide study of VNTR frequency data, which concluded the unmodified product rule was reliable and free from error due to population substructuring (IA FBI, VNTR Population Data: a Worldwide Study (1993)); (2) a 1994 article in which Dr. Eric Lander, formerly a leading opponent of the product rule, concluded the rule offered "a reasonable best estimate" of random match probabilities (Lander & Budowle, supra, 371 Nature at pp. 737-738); (3) publication of the 1996 NRC Report, which reexamined the statistical issues and explicitly approved use of the product rule (1996 NRC Rep., supra, at pp. 2-4, 122); (4) a collection of articles, authored largely by defense expert witnesses, which criticized the 1996 NRC Report but expressed no disagreement with the product rule (e.g., Lempert, After the DNA Wars: Skirmishing with NRC II (Summer 1997) 37 Jurimetrics J. 439). (Soto, at pp. 537-539.) The Supreme Court then observed that a majority of other states "have concluded that the controversy over population substructuring and use of the unmodified product rule has been sufficiently resolved," and "extensive literature" had developed in peer-reviewed scientific journals to show that population substructuring does not significantly impact frequency estimates using the product rule. (Soto, supra, 21 Cal. 4th at pp. 540-541.) The court therefore concluded: "It is clear from the evidence in the record, the clear weight of judicial authority, and the published scientific commentary, that the unmodified product rule, as used in the DNA forensic analysis in this case, has gained general acceptance in the relevant scientific community and therefore meets the Kelly standard for admissibility." (Id. at p. 541.)