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Questioning Forensic Evidence - A recently released NAS report raises a host of issues

  • 5/5/2009
  • Edward J. Imwinkelried
  • National Law Journal commentary

The July 28, 2008, edition of this column highlighted a pending U.S. Supreme Court case, Melen¬dez-Diaz v. Massachusetts, No. 07-591, which may have a major impact on the admissibility of expert testimony in federal court, especially in criminal cases. Of course, judicial decisions are not the only developments that can affect the future of expert testimony. In February of this year, the National Research Council of the National Academies of Science (NAS) released a long-awaited report, Strengthening Forensic Science in the United States: A Path Forward. Like the decision in Melendez-Diaz, that report could play a major rule in shaping the future treatment of expert evidence.

The NAS is a prestigious organization, and in the past it has released several reports that have exerted considerable influence over the admissibility of specific types of scientific evidence. In 1979, an NAS committee published On the Theory and Practice of Voice Identification, dealing with sound spectrography or "voiceprint." That report solidified the judicial opposition to the admissibility of that type of evidence. 1 Paul G. Giannelli et al., Scientific Evidence § 10.05 (4th ed. 2007).

In the 1990s, the NAS generated two reports on DNA evidence, one in 1992 and another in 1996. Those reports had a major impact on DNA practices, including effectively ending the use of multilocus probes. 2 Giannelli § 18.03[a].

A 2003 NAS document, titled The Polygraph and Lie Detection, strengthened the case for excluding polygraph evidence. 1 Giannelli § 8.03[c]. The NAS' 2004 report, Forensic Analysis: Weighing Bullet Lead Evidence, was highly critical of that technique for identifying the source of a particular bullet. The report presented a persuasive argument, and in 2005 the FBI discontinued the use of that technique. 1 Giannelli § 14.11. The question is whether the new report will have a similar impact.

In some respects, A Path Forward differs markedly from the prior reports. To begin with, rather than focusing on a particular type of expert testimony, the report addresses the broad domain of forensic science. Moreover, the new report takes a longer view. In 2005, Congress tasked the National Academies of Science to undertake a study assessing the future as well as the present resource needs of the forensic community. NAS report at S-1. The NAS' charge was to develop "recommendations for maximizing the use of forensic technologies and techniques to solve crimes, investigate deaths, and protect the public." Id. To that end, the report advances a number of forward-looking recommendations. For example, Recommendation No. 1 urges the creation of a National Institute of Forensic Science (NIFS). Id. at S-14. As conceived in the report, among other responsibilities, the NIFS would:

• "Establish...and enforc[e] best practices for forensic science professionals and laboratories."

• "Establish...standards for the mandatory accreditation of forensic science laboratories and the mandatory certification of forensic scientists and medical examiners/forensic pathologists." Id. at S-14.

The report also contemplates phasing out the coroner system and putting medical examiner offices in place in every jurisdiction in the United States. Id. at S-22. In the report, the NAS' primary agenda is a long-term one.

The report points out unique reliability of DNA evidence

However, in the course of constructing the policy argument for that agenda, the NAS commented on the current state of several important forensic disciplines. The report's initial summary sets the tone by stating flatly that, "[w]ith the exception of nuclear DNA analysis,...no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source." Id. at S-5. The report carries that theme through Chapter 5 dealing with a large number of forensic fields.

• Fingerprint analysis. Although fingerprint analysts have sometimes claimed that their technique has a "zero error rate," the report dismisses that claim as "scientifically [im]plausible." Id. at 5-12. The report emphasizes the large element of human interpretation in fingerprint analysis. Even positing the assumptions of the uniqueness and permanence of friction ridges, the report states that the question is whether in real world conditions using partial, distorted impressions, "anyone can reliably discern whether...two friction ridge impressions were made by the same person." Id. at 5-13. The report states that the variables relevant to that question have not been "characterized [or] quantified." Id.

• Toolmark and firearms identification. The report declares: "Because not enough is known about the variables among individual tools and guns, we are not able to specify how many points of similarity are necessary for a given level of confidence in the result. Sufficient studies have not been done to understand the reliability...of the methods.... [C]lass characteristics are helpful in narrowing the pool of tools that may have left a distinctive mark....[B]ut additional studies should be performed to make the process of individualization more precise and repeatable." Id. at 5-21.

• Microscopic analysis of hair. While there have been attempts to develop statistical estimates of the probability of a random match in hair characteristics, the report concludes that those approaches have "been shown to be unreliable." Id. at 5-23. In the NAS' view, "[n]o scientifically accepted statistics exist about the frequency with which particular characteristics of hair are distributed in the population." Id. at 5-25. The report acknowledges that, in the past, many courts have been receptive to testimony about microscopic hair comparisons. However, the report finds that the hypothesis that microscopy can individualize a hair source has "no scientific support." Id. at 5-26.

• Document examination. The report has faint praise for this discipline: "Recent studies have increased our understanding of the individuality and consistency of handwriting...and suggest that there may be a scientific basis for handwriting comparison, at least in the absence of intentional obfuscation or forgery. Although there has been only limited research to quantify the reliability and replicability of the practices used by trained document examiners,...there may be some value in handwriting analysis." Id. at 5-30.

• Forensic odontology-bitemark analysis. The report states that "the majority of forensic odontologists are satisfied that bite marks can demonstrate sufficient detail for positive identification." However, the NAS has a very different view: "[N]o scientific studies support this assessment, and no large population studies have been conducted. In numerous instances, experts diverge widely in their evaluations of the same bite mark evidence." Id. at 5-37.

These comments pose several challenging issues for the courts. One question is whether the report should prompt additional Frye jurisdictions to rethink their standard for admitting scientific testimony. Will more jurisdictions abandon Frye's general acceptance test and shift to Daubert's empirical validity standard? Although most jurisdictions now follow some variation of Daubert (1 Giannelli § 1.14), a significant minority persist in adhering to Frye. Id. at § 1.16. Many of the techniques discussed in the NAS report are traditional methodologies that Frye jurisdictions routinely admit as generally accepted. The argument could be made that the NAS report is potent evidence that the Frye test is ineffective in separating the wheat from the chaff.

Assuming that the NAS report does not cause a particular Frye jurisdiction to convert to Daubert, the next question that naturally arises is whether the report will convince the courts to adopt a more restrictive attitude toward the forensic techniques that the report appears to criticize. As previously stated, in the past the NAS' issuance of reports has sometimes persuaded courts to change their stance on the admissibility of specific types of scientific evidence. That phenomenon is understandable. Under Frye, the dispositive issue is whether a clear majority of the specialists in the field accept the reliability of the theory or technique in question. "Forensic Science: The Role of the Hearsay Rule in Litigating Frye Challenges to the Admissibility of Scientific Evidence," 29 Crim. L. Bull. 158, 162-63 (March-April 1993). When a scientific organization as large and highly respected as the NAS raises questions about the reliability of an expert technique, that development arguably proves the existence of a major controversy that is the antithesis of the general acceptance required by Frye. Id.

Finally, what impact, if any, will the NAS report have on jurisdictions subscribing to the Daubert standard? At first blush, it might seem that, if the opponent invoked the NAS report to support a Daubert objection to the admissibility of testimony about a particular expert theory or technique, the proponent could rejoin that the report's contents are inadmissible hearsay. The passages in question in the report are undeniably assertive, and the opponent is offering the passages for the truth of the assertion, namely to establish that the empirical support for the technique is questionable. Fed. R. Evid. 801(a), (c).

However, that rejoinder is flawed. In Daubert, Justice Harry Blackmun expressly stated that Federal Rule of Evidence 104(a) on preliminary fact-finding governs the trial judge's ruling on the admissibility of the expert testimony. Daubert, 509 U.S. at 592 (1993). The last sentence of Rule 104(a) announces that when that statute controls, the judge "is not bound by the rules of evidence except those with respect to privileges." The hearsay rule is inapplicable to foundational testimony offered to establish or disprove foundational facts under Rule 104(a). State v. Cardone, 368 A.2d 952 (N.J. App. Div. 1976).

It is far too early to make any confident predictions about the eventual impact of the NAS report. The proposal for the NIFS may prove to be only wishful thinking. Likewise, it is possible that the report will have little or no impact on the courts' treatment of expert testimony. After all, Federal Rule of Evidence 702 is worded in the alternative: "scientific, technical or other specialized knowledge." That statutory language permits the proponent to argue that, even if the expert's technique falls short of qualifying as "scientific...knowledge," the judge should characterize the testimony as "technical" evidence and use a relaxed admissibility standard.

The Supreme Court's 1999 decision in Kumho Tire Co. Ltd. v. Carmichael, 526 U.S. 137 (1999), seems to foreclose that approach in federal court. However, the states remain free to interpret their version of Rule 702 in a different manner. E.g., State v. Fukusaku, 946 P.2d 32 (Hawaii 1997). The upshot is that the path forward may be neither straight nor short.
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Edward J. Imwinkelried is the Edward L. Barrett Jr. Professor of Law at the University of California, Davis School of Law. He can be reached ejimwinkelried@ucdavis.edu.

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