Opinion ID: 1621727
Heading Depth: 1
Heading Rank: 6

Heading: whether the trial court erred in admitting probability statistics pertaining to the dna on the defendant's jacket

Text: ¶ 27. After asserting that the circuit court erred in admitting DNA evidence from his undershorts without any accompanying statistical data about the mixed sample thereon, Watts now asserts that it was error to admit probability statistics about the DNA evidence on his jacket. He contends that the State failed to show that there are current techniques used to calculate DNA population frequency statistics which are generally accepted by the scientific community and are neither arbitrary nor unreliable. He further asserts that the State failed to show that Dr. Tracey's strict application of the product rule to calculate population frequency statistics was a generally accepted technique in the scientific community. Rather, he urges this Court to require use of the more conservative ceiling principle. ¶ 28. The significance of a DNA match found between a suspect or a victim and genetic material recovered from the crime scene or other evidence is assessed through a population frequency analysis. That is, what is the likelihood that someone other than the suspect (or the victim) would possess DNA matching that found in the samples taken at the crime scene or from other evidence? As discussed in Issue II, we have found that population frequency statistics are admissible. Hull, 687 So.2d at 728. See also Crawford, 716 So.2d at 1045-46. ¶ 29. The Pennsylvania court, in Commonwealth v. Blasioli, 552 Pa. 149, 713 A.2d 1117 (1998), presents the most cogent explanation of the product rule, which states that the probability of a genetic profile occurring randomly is the product of the probabilities of each individual allele's occurrence in the general population. Id. at 1124. The statistical assessment performed after a match has been declared is called population frequency analysis. The object is to determine the overall likelihood that someone other than the suspect would possess DNA matching that in the sample obtained from the crime scene. The first step is to determine, for each matching allele, the likelihood that such an allele would appear in a randomly selected individual. This determination is made through the application of theoretical models based upon population genetics. Such models are generated by creation of a computer database containing DNA profiles obtained from the general population. The frequency of an allele obtained from a sample can be determined by calculating the probability that a matching allele would appear in a DNA sample obtained from an individual who was randomly selected from the database. To ameliorate theoretical problems associated with population substructures, discussed below, the Pennsylvania State Police laboratory database categorizes DNA samples according to three racial groups, and uses a process known as fixed binning. The probability of random matching is also reduced by choosing highly variable segments of the DNA, with dozens of individual alleles, so that individual allele frequency will be very low. Additional variations occur in the matching of the maternal and paternal alleles located at each locus, further reducing the probability of a random match. Once the probability of random occurrence is calculated for each individual allele, the individual probabilities may be combined to determine an overall probability of random matching across the genetic profile. In order to make this calculation, scientists have employed the product rule. The product rule states that the probability of two events occurring together is equal to the probability that the first event will occur multiplied by the probability that the second event will occur. Coin tossing is commonly used as an illustrationthe probability of a coin flip resulting in heads on successive tries is equal to the probability of the first toss yielding heads, fifty percent, times the probability of heads on the second toss, fifty percent, equaling twenty-five percent. As applied in DNA typing, the product rule states that the probability of a genetic profile occurring randomly is the product of the probabilities of each individual allele's occurrence in the general population. Such application can produce odds of up to one in 739 billion of a random profile match. Id. at 1122-24 (internal citations and footnotes omitted). ¶ 30. Watts bases his assault on the product rule on the National Research Council's 1992 Report which, while discussed by the expert witnesses when examined by his attorney, was never entered into evidence. See Underwood v. State, 708 So.2d 18, 26 (Miss.1998)(this Court decides cases on facts in the record, not assertions in the briefs). As Watts asserts, the 1992 NRC Report recommended the use of the more conservative ceiling principle and the interim ceiling principle. However, he fails to point out that the NRC's 1992 report did not constitute an outright rejection of the product rule. Instead, the NRC merely recommended that until data could be assembled from which to assess the impact of any significant population substructuring, the ceiling principle could be applied to impose an appropriate degree of conservatism. Blasioli, 713 A.2d at 1125. Since the publication of that report, three subsequent events have all but ended the controversy over use of the product rule. First, in 1993, the FBI conducted a survey of VNTR frequency data and determined that population frequency calculations based on the product rule were reliable, valid and meaningful, without forensically significant consequences resulting from population substructure as had been postulated by some scientists. Blasioli, 713 A.2d at 1125 (citing Laboratory Division, Federal Bureau of Investigation, United States Department of Justice, 1-A VNTR Population Data: A Worldwide Study 2 (Feb.1993)); Commonwealth v. Rosier, 425 Mass. 807, 685 N.E.2d 739 (Mass.1997); State v. Loftus, 573 N.W.2d 167, 174-75 (S.D.1997); State v. Copeland, 130 Wash.2d 244, 922 P.2d 1304 (Wash.1996). Based on the FBI study, Dr. Eric Lander, the leading opponent in the scientific community to use of the product rule declared that the DNA fingerprinting wars are over in his article, E. Lander & B. Budlowe, DNA Fingerprinting Dispute Laid to Rest, 371 NTURE 735, 735 (Oct. 27, 1994). Blasioli, 713 A.2d at 1125. Finally, in its 1996 Report, The Evaluation of Forensic DNA Evidence, the NRC noted that `[t]he ceiling principles were intended for VNTRs with many alleles, no one of which has a very high frequency [and t]hey are not applicable to PCR-based systems.' Rosier, 685 N.E.2d at 745( quoting 1996 NRC Report at 158). The 1996 Report concluded that both the ceiling and the interim ceiling principles were unnecessary and `[i]n general, the calculation of a profile frequency should be made with the product rule,' both for VNTR and PCR-based systems. Id. (quoting 1996 NRC Report at 5). ¶ 31. Based on these developments, courts which have considered the admissibility of statistical evidence based on the product rule have determined that the challenges to its use have been sufficiently resolved. Blasioli, 552 Pa. 149, 713 A.2d 1117; Loftus, 573 N.W.2d at 174; Rosier, 685 N.E.2d at 745; State v. Copeland, 130 Wash.2d 244, 922 P.2d 1304 (1996); Armstead v. State, 342 Md. 38, 673 A.2d 221 (Ct.App.1996); People v. Edgett, 220 Mich. App. 686, 560 N.W.2d 360 (1996); People v. Miller, 173 Ill.2d 167, 219 Ill.Dec. 43, 670 N.E.2d 721 (1996); State v. Morel, 676 A.2d 1347 (R.I.1996); Lindsey v. People, 892 P.2d 281, 292 (Colo.1995); State v. Dinkins, 319 S.C. 415, 462 S.E.2d 59 (1995); State v. Weeks, 270 Mont. 63, 891 P.2d 477 (1995); Taylor v. State, 889 P.2d 319 (Okla.Crim.App.1995); State v. Anderson, 118 N.M. 284, 881 P.2d 29 (1994); State v. Futrell, 112 N.C.App. 651, 436 S.E.2d 884 (1993). Given that the product rule has been accepted in the scientific community and found to be a reliable method of calculating population frequency data, we find that the trial court did not abuse its discretion by admitting the evidence.