Opinion ID: 1375796
Heading Depth: 2
Heading Rank: 2

Heading: Expert opinions and scientific evidence

Text: The experts' testimony in the present case involved two types of evidence  scientific evidence on the procedures for determining a match between evidentiary DNA and opinion evidence concerning the experts' experience with random matches. The trial judge properly applied the Frye analysis and determined that evidence of a match is admissible. However, on the basis of the scientific evidence then available, the judge did not allow the experts to testify about the mathematical or statistical probability resulting from the match. Instead, the experts were allowed to offer evidence of their personal opinion. This testimony is governed not by the application of Frye but by Arizona Rules of Evidence 702 and 703. See State v. Roscoe, 145 Ariz. 212, 219, 700 P.2d 1312, 1319 (1984).  Frye -ing scientific evidence is necessary when application of a scientific technique is likely to have an enormous effect in resolving completely a matter in controversy. State ex rel. Collins v. Superior Court, 132 Ariz. 180, 199, 644 P.2d 1266, 1285 (1982), quoting M. UDALL & J. LIVERMORE, LAW OF EVIDENCE § 102, at 212 (2d ed. 1982). However, when the expert gives testimony that only helps a trier to interpret the evidence ... it will be received on a lesser showing of scientific certainty. Id. As we stated in Roscoe, [t]he weight of the evidence did not hinge upon the validity or accuracy of some scientific principle; rather, it hinged on [the expert's] credibility, the accuracy of his past observation ... the extent of the training ... and the reliability of his interpretations.... Roscoe, 145 Ariz. at 220, 700 P.2d at 1320; McCORMICK ON EVIDENCE § 203, at 871, nn. 27 and 28 (J.W. Strong et al., eds., 4th ed. 1992). The experts in this case did not testify to conclusions based on the application of Cellmark's statistics and database but only to their own experience. Having made the DNA examination according to recognized scientific principles and finding a match at three loci, the experts claimed that because of the unique nature of each person's DNA, they had never before seen a three-loci match from unrelated individuals. On the basis of their own experience, they believed such a random match would be very uncommon. The trial judge did not err in admitting this evidence of the experts' own work and experience and the opinions reached on that basis. See Ariz. R.Evid. 702 and 703.
The court of appeals suggested that although couched in terms of their personal experience, the experts' testimony effectively conveyed to the jury the then-impermissible random match probability statistics. We do not agree. Both witnesses explained why they had found a match both visually and numerically. They explained that the profiles matched over four probes, though one of the probe matches was rejected in the interests of accuracy and that the areas looked at by RFLP analysis are polymorphic and vary between individuals. This testimony fit within in the scientific evidence category and was permitted because it met the requirements of Frye. The prosecutor then turned to the experts' personal experience, developing their experience with the RFLP analysis and the pertinent literature to support their testimony that they had never personally seen or heard of a random match over three or four loci. However, it was also developed that such a match would be possible between identical twins or even brothers. Defendant chose not to cross-examine the experts on the basis for their opinions, instead focusing on the fact that only a small percentage of DNA differs from person to person, the possibility of laboratory error, bias, and environmental insults to the evidence DNA. As noted, this is the very type of opinion evidence discussed in Roscoe, which is not based on the application of scientific principle but, rather, on the observations and credibility of the witness. Thus, it need only meet the requirements of relevancy and not be substantially more prejudicial than probative. See Ariz.R.Evid. 401 and 403.
The court of appeals argued that Rule 703 might be used as a way to back-door otherwise unacceptable scientific evidence. Under the present state of our cases, however, because scientific evidence, as opposed to opinion evidence, must first meet the requirements of Rule 702 and Frye, we find this highly unlikely. Moreover, a search of cases within Arizona shows no such abuse of Rule 703. Rather, the alleged inadmissible evidence most often used under Rule 703 is hearsay, and we have clearly stated that such evidence is only admissible as a basis for expert opinion, not for any substantive value. See State v. Lundstrom, 161 Ariz. 141, 147-49, 776 P.2d 1067, 1073-75 (1989). The court of appeals also argued that for the defense to effectively cross-examine the experts about their assumptions was practically impossible without resorting to the precluded random match probability statistics. While we note that Defendant effectively and thoroughly cross-examined the experts on the problems that may have occurred to taint the match they declared, we also find nothing under Rule 703 that would have precluded cross-examination to establish that the opinions were based on application of an unrecognized scientific principle. It is well established in Arizona that the basis for an expert's opinion is fair game during cross-examination. See Ariz.R.Evid. 705; ARIZONA EVIDENCE § 24, citing State v. Swafford, 21 Ariz. App. 474, 486, 520 P.2d 1151, 1163 (1974) (The expert invites investigation into the extent of his knowledge, the reasons for his opinion including facts and other matters upon which it is based and which he took into consideration and may be subjected to the most rigid cross-examination concerning his qualifications and his opinion and its sources.). Moreover, had Defendant still desired to keep out the numbers that were the basis for the experts' opinions, he probably could have cross-examined the experts on the method of determining the significance of the match and the scientific controversy behind it without ever mentioning the exact numbers.