Strengthening Forensic Science in the United States A Path Forward (2009) / Chapter Skim
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3 The Admission of Forensic Science Evidence in Litigation
3 The Admission of Forensic Science Evidence in Litigation
Pages 85-110
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From page 85... ...
No judgment is made about past convictions and no view is expressed as to whether courts should reassess cases that already have been tried. The report finds that the existing legal regime -- including the rules governing the admissibility of forensic evidence, the applicable standards governing appellate review of trial court decisions, the limitations of the adversary process, and judges and lawyers who often lack the scientific expertise necessary to comprehend and evaluate forensic evidence -- is inadequate to the task of curing the documented ills of the forensic science disciplines.
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From page 86... ...
. Moreover, in almost every instance, scientific evidence tests the abilities of judges, lawyers, and jurors, all of whom may lack the scientific expertise to comprehend the evidence and evaluate it in an informed manner. Nowhere are these dilemmas more evident than in decisions pertaining to the admissibility of forensic science evidence proffered in criminal trials.
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From page 87... ...
These questions are significant: The goal of law enforcement actions is to identify those who have committed crimes and to prevent the criminal justice system from erroneously convicting the innocent. So it matters a great deal whether an expert is qualified to testify about forensic evidence and whether the evidence is sufficiently reliable to merit a fact finder's reliance on the truth that it purports to support.
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From page 88... ...
The court rejected the evidence, stating: Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recog nized, and while courts will go a long way in admitting expert testimony deduced from a well‑recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs. The Frye decision held that the lie detector test was unreliable because it had not gained "general acceptance" in the relevant scientific community.
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From page 89... ...
The first version of Federal Rule of Evidence 702 provided that: If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or educa tion, may testify thereto in the form of an opinion or otherwise.12 In place of Frye's requirement of general scientific acceptance, mere "assistance" to the trier of fact appeared to be "the touchstone of admissibility under Rule 702."13 After the promulgation of Rule 702, litigants, judges, and legal scholars remained at odds over whether the rule embraced the Frye standard or established a new standard.14 There was also much controversy surrounding the application of Rule 702 in civil cases. Most notably, Peter Huber popularized the now well-known phrase "junk science" to criticize the judiciary's acceptance of unreliable expert testimony in support of tort claims.15 Huber's study was sharply criticized,16 but it nonetheless spurred a debate over the use of expert testimony in the courts.
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From page 90... ...
The district court held that the expert testimony proffered by the plaintiffs was inadmissible, because their scientific evidence was not sufficiently established to have general acceptance in the field to which it belonged.20 The court of appeals, citing Frye, affirmed the judgment of the district court, declaring that expert opinion based on a methodology that diverges significantly from the procedures accepted by recognized authorities in the field cannot be shown to be generally accepted as a reliable technique.21 The Supreme Court reversed, holding that the trial court had applied the wrong standard in assessing the expert testimony proffered by the plaintiffs. The case was then remanded for further proceedings.
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From page 91... ...
Kumho Tire importantly held that Rule 702 applies to both scientific and nonscientific expert testimony; the Court also indicated that the Daubert factors might be applicable in a trial judge's assessment of the reliability of nonscientific expert testimony, depending upon "the particular circumstances of the particular case at issue." 526 U.S.
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From page 92... ...
2000) (holding trial courts are not compelled to conduct pretrial hearings in order to discharge the gatekeeping function under Daubert as to expert testimony)
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From page 93... ...
the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.37 The commentary accompanying the revised rule38 recites the "Daubert factors" and then goes on to explain that: Courts both before and after Daubert have found other factors relevant in determining whether expert testimony is sufficiently reliable to be con sidered by the trier of fact.
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From page 94... ...
does not distinguish between scientific and other forms of expert testimony. The trial court's gatekeeping function ap plies to testimony by any expert.
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From page 95... ...
Judicial dispositions of Daubert-type questions in criminal cases have been criticized by some lawyers and scholars who thought that the Supreme Court's decision would be applied more rigorously to protect the rights of accused parties: [Daubert] obligated trial court judges to assume the role of "gatekeepers" and to exclude proffered scientific evidence unless it rested on scientifically valid reasoning and methodology.
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From page 96... ...
Federal appellate courts have not with any consistency or clarity imposed standards ensuring the application of scientifically valid reasoning and reliable methodology in criminal cases involving Daubert questions.46 This is not really surprising. The Supreme Court itself described the Daubert standard as "flexible." This means that, beyond questions of relevance, Daubert offers appellate courts no clear substantive standard pursuant to which to review decisions by trial courts.47 As a result, trial judges exercise great discretion in deciding whether to 45 Ibid., p.
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From page 97... ...
If a defendant's challenge is rejected and is followed by an acquittal, no appeal ensues and the matter is over. Reported opinions in criminal cases indicate that trial judges sometimes exclude or restrict expert testimony offered by prosecutors;50 reported opinions also indicate that appellate courts routinely deny appeals contesting trial court decisions admitting forensic evidence against criminal defendants.51 But the reported opinions do not offer in any way a complete sample of federal trial court dispositions of Daubert-type questions in criminal cases.52 48 Gen.
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From page 98... ...
In addition, plaintiffs and defendants, equally, are more likely to have access to expert witnesses in civil cases, whereas prosecutors usually have an advantage over most defendants in offering expert testimony in criminal cases. And, ironically, the appellate courts appear to be more willing to second-guess trial court judgments on the admissibility of purported scientific evidence in civil cases than in criminal cases.53 plaintiffs, those defendants usually win, but when criminal defendants' proffers are challenged by the prosecution, the criminal defendants usually lose." D
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From page 99... ...
modern courts or lawyers are more literate about science than they were in the past.54 Unlike many forensic techniques that were developed empirically within the forensic community, with little foundation in scientific theory or analysis, DNA analysis is a fortuitous byproduct of cutting‑edge science. From the beginning, eminent scientists contributed their expertise to ensuring that DNA evidence offered in a courtroom would be valid and reliable,55 and by 1996 the National Academy of Sciences had convened two committees that issued influential recommendations on the use of DNA technology in forensic science.56 As a result, principles of statistics and population genetics that pertain to DNA evidence were clarified, the methods for conducting DNA analyses and declaring a match became less subjective, and quality assurance and quality control protocols were designed to improve laboratory performance.
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From page 100... ...
Among existing forensic methods, only nuclear DNA analysis has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between an evidentiary sample and a specific individual or source. Indeed, DNA testing has been used to exonerate persons who were convicted as a result of the misapplication of other forensic science evidence.58 However, this does not mean that DNA evidence is always unassailable in the courtroom.
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From page 101... ...
In addition to alleged defects in laboratory reports and sampling procedures, trial courts routinely consider whether experts possess the necessary qualifications to testify and, more generally, whether expert testimony is sufficiently reliable to be admitted under Daubert and Federal Rule of Evidence 702. However, in published opinions addressing expert testimony based on drug identification, federal appellate courts rarely reverse trial 62 See supra text accompanying note 54; see also Gov't of V.I.
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From page 102... ...
All of this explains why the task of evaluating the reliability of expert testimony is uniquely entrusted to the district court under Daubert, and why we give the district court considerable leeway in the execution of its duty. That is true whether the district court admits or excludes ex pert testimony.
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From page 103... ...
It also transformed their admissibility standard into a Daubert permissive one, at least for that subcategory of expertise.71 This is a telling critique, especially when one compares the judicial decisions that have pursued rigorous scrutiny of DNA typing with the decisions that have applied less stringent standards of review in cases involving fingerprint evidence. In holding that fingerprint evidence satisfied Daubert's reliability and relevancy standards for admissibility, the Fourth Circuit's decision in Crisp noted approvingly that "the Seventh Circuit [in United States v.
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From page 104... ...
When forensic DNA first appeared, it was sometimes called "DNA fingerprinting" to suggest that it was as reliable as fingerprinting, which was then viewed as the premier identification science and one that consistently produced irrefutable results. During the effort to validate DNA evidence for courtroom use, however, it became apparent that assumptions about fingerprint evidence had been reached without the scientific scrutiny being accorded DNA.
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From page 105... ...
19, 2007) (holding that the ACE‑V methodology of latent fingerprint identification was "a subjective, untested, unverifiable identification procedure that purports to be infallible" and therefore ruling that fingerprint evidence was inadmissible)
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From page 106... ...
Judicial Dispositions of Questions Relating to Other Forensic Disciplines Review of reported judicial opinions reveals that, at least in criminal cases, forensic science evidence is not routinely scrutinized pursuant to the standard of reliability enunciated in Daubert. The Supreme Court in Daubert indicated that the subject of an expert's testimony should be "scientific knowledge" -- which implies that such knowledge is based on scientific methods -- to ensure that "evidentiary reliability will be based upon scientific validity." The standard is admittedly "flexible," but that does not render it meaningless.
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From page 107... ...
Thus, even if inclined to mount a Daubert challenge, they lack the requisite knowledge and skills, as well as the funds, to succeed.80 The reported decisions dealing with judicial dispositions of Dauberttype questions appear to confirm this assessment. As noted above, the courts often "affirm admissibility citing earlier decisions rather than facts established at a hearing." Much forensic evidence -- including, for example, bite marks81 and firearm and toolmark identifications82 -- is introduced in 80 Neufeld, supra note 44, at S109, S110.
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From page 108... ...
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.
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From page 109... ...
. This only reinforces the importance of careful analysis of expert testimony in this case.
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From page 110... ...
. In many forensic areas, effectively no research exists to support the practice."92 As the discussion in this chapter indicates, the adversarial process relating to the admission and exclusion of scientific evidence is not suited to the task of finding "scientific truth." The judicial system is encumbered by, among other things, judges and lawyers who generally lack the scientific expertise necessary to comprehend and evaluate forensic evidence in an informed manner, trial judges (sitting alone)
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