Gold versus platinum: Do jurors recognize the superiority and limitations of DNA evidence compared to other types of forensic evidence?

Abstract

In a series of studies, the authors examined (a) public perceptions concerning forensic scientific evidence, (b) the relative influence attributed to DNA evidence compared to other forms of forensic identification evidence, and (c) the impact of cross-examination addressing the limitations of DNA testimony. In Studies 1 and 2, both undergraduate students and representative jurors rated DNA as the most accurate and persuasive type of evidence compared to other types of forensic evidence. This finding was consistent across samples of individuals with varied exposure to media coverage of scientific evidence. Experimental results further revealed the strong influence of DNA evidence in verdict decisions regardless of the type of crime or whether the evidence was incriminating or exculpatory. In Studies 2 and 3, DNA-based expert testimony demonstrated strong effects on juror decisionmaking even after cross-examination. These effects were mitigated to some extent in Study 3, however, by the interaction of the reliability of DNA evidence and the focus of cross-examination. The implications regarding the use of DNA and other scientific evidence for public policy and practice in legal decisions are discussed.

Lay understanding of forensic statistics: Evaluation of random match probabilities, likelihood ratios, and verbal equivalents.

“…Because DNA evidence has tremendous credibility (Lieberman, Carrell, Miethe, & Krauss, 2008), whereas shoeprint comparison is less well known, we also expect (Hypothesis 3) that DNA evidence will produce larger shifts in estimates of the chances of guilt than shoeprint evidence even when the statistics that the expert uses to characterize the strength of the evidence are the same. And because the log scale may make it easier to express high and low values and thereby facilitate shifts in judgment in response to the forensic evidence, we expect (Hypothesis 4) that people's judgments will be more responsive to forensic science evidence (greater shifts in estimated chances of guilt), when these judgments are elicited on the log scale than when elicited as statements of odds.…”

Firmament or Folly? Protecting the Innocent, Promoting Capital Punishment, and the Paradoxes of Reconciliation

“…192-212). The calculation and reporting of statistical probabilities frequently are controversial (Kaye, 2009;Perlin, Kadane & Cotton, 2009;Thompson, 2009) and can be misunderstood by juries (Lieberman, Miethe, Carrell, & Krauss, 2008). In short, "DNA analysis does not and cannot answer questions of guilt or innocence with epistemological certainty" (Aronson & Cole, 2009, p. 627).…”

The Effect on Mock-Juror Decision-Making of Power-of-Speech Within Eyewitness Testimony and Types of Scientific Evidence

“…Compared with other types of scientific evidence, research has consistently found DNA to be the most authoritative evidence type for mock-jurors, and DNA has been associated with more guilty verdicts than fingerprint or hair evidence (Lieberman et al, 2008). DNA may be considered the gold standard of scientific evidence, and common media representations of its credibility may bias perceptions of its value.…”

“…They found that both strong and weak physical evidence was more influential than strong and weak EWT. In addition, Lieberman, Carrell, Miethe, and Krauss (2008) compared the contribution of various evidence types including DNA, fingerprints and EWT to mock-juror verdicts. Across two crimes, DNA was found to be the most influential and EWT the least.…”