criminal trials without any meaningful scientific validation, determination of error rates, or reliability testing to explain the limits of the discipline. One recent judicial decision highlights the problem. In United States v. Green, Judge Gertner acknowledged that toolmark identification testimony ought not be considered admissible under Daubert.83 But the judge pointed out that “the problem for the defense is that every single court post-Daubert has admitted this testimony, sometimes without any searching review, much less a hearing.”84 Judge Gertner allowed the prosecution’s expert to describe the similarities between the shell casings at issue, but prohibited him from testifying that there was a definitive match. Obviously feeling bound by circuit precedent, the judge stated:

I reluctantly [admit the evidence] because of my confidence that any other decision will be rejected by appellate courts, in light of precedents across the country, regardless of the findings I have made. While I recognize that the Daubert-Kumho standard does not require the illusory perfection of a television show (CSI, this wasn’t), when liberty hangs in the balance—and, in the case of the defendants facing the death penalty, life itself—the standards should be higher than were met in this case, and than have been imposed across the country. The more courts admit this type of toolmark evidence without requiring documentation, proficiency testing, or evidence of reliability, the more sloppy practices will endure; we should require more.85

“[T]he undeniable reality is that the community of forensic science

generally admissible under Daubert, but excluded the specific testimony at issue, because the experts failed to properly document their basis for identification, and because an independent examiner had not verified the experts’ conclusions. Likewise, in United States v. Diaz, No. 05-CR-167, 2007 WL 485967, at *14 (N.D. Cal. Feb. 12, 2007), Judge Alsup allowed firearm identification testimony under Daubert, but prevented experts from testifying to their conclusions “to the exclusion of all other firearms in the world” and only allowed testimony “to a reasonable degree of certainty.” Cf. United States v. Glynn, 578 F. Supp. 2d 569 (S.D.N.Y. 2008), where Judge Rakoff precluded testimony that a bullet and shell casings came from a firearm linked to the defendant “to a reasonable degree of ballistics certainty,” because “whatever else ballistics identification analysis could be called, it could not fairly be called ‘science.’” However, the judge ruled that although inadmissible under Daubert, testimony that the evidence was “more likely than not” from the firearm was admissible under Federal Rule of Evidence 401. See also Green, 405 F. Supp. 2d 104, discussed in the text.


405 F. Supp. 2d at 107-08.


Ibid., p. 108.


Ibid., p. 109 (footnotes omitted). “The case law on the admissibility of toolmark identification and firearms identification expert evidence is typified by decisions admitting such testimony with little, and usually no, reference to legal authority beyond broad ‘discretion’ and an adroit sidestepping of any judicial duty to assure that experts’ claims are valid. Appellate courts defer to trial courts, and trial courts defer to juries. Later appellate courts simply defer to earlier appellate courts.” 4 Faigman et al., op. cit., supra note 1, § 34:5, p. 589.

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