Educating Jurors about Forensic Evidence: Using an Expert Witness and Judicial Instructions to Mitigate the Impact of Invalid Forensic Science Testimony

Invalid expert witness testimony that overstated the precision and accuracy of forensic science procedures has been highlighted as a common factor in many wrongful conviction cases. This study assessed the ability of an opposing expert witness and judicial instructions to mitigate the impact of invalid forensic science testimony. Participants (N = 155) acted as mock jurors in a sexual assault trial that contained both invalid forensic testimony regarding hair comparison evidence, and countering testimony from either a defense expert witness or judicial instructions. Results showed that the defense expert witness was successful in educating jurors regarding limitations in the initial expert's conclusions, leading to a greater number of not-guilty verdicts. The judicial instructions were shown to have no impact on verdict decisions. These findings suggest that providing opposing expert witnesses may be an effective safeguard against invalid forensic testimony in criminal trials.     

The importance of forensic evidence for decisions on criminal guilt

Recent studies have found that the general public perceives forensic evidence to be relatively inaccurate and to involve high levels of human judgement. This study examines how important the general public finds forensic evidence by comparing decisions on guilt and punishment in criminal cases that involve forensic versus eyewitness testimony evidence and examining whether a CSI effect exists. Specifically, this experimental survey study utilized a 2 (crime type: murder or rape) × 4 (evidence type: DNA, fingerprint, victim eyewitness testimony, or bystander eyewitness testimony) ? 1 (no victim testimony for murder scenario) design, yielding seven vignettes scenarios to which participants were randomly assigned. Results indicate that forensic evidence was associated with more guilty verdicts and higher confidence in a guilty verdict. Forensic evidence did not change the expected sentence length and did not generally affect the ideal sentence length. However, for rape, respondents believed that the defendant should receive a longer sentence when forensic evidence was presented but forensic evidence did not alter likely sentence that respondents expected the defendant to receive. The results of this study did not support a CSI effect. Overall, this study suggests that forensic evidence – particularly DNA – has a stronger influence during the verdict stage than the sentencing stage.     

Jurors' Use of Hearsay Evidence: The Effects of Type and Timing of Instructions

To examine the effects of curative judicial instructions on jurors' perceptions of hearsay testimony, mock jurors (N = 180) were exposed to one of six versions of a trial that included proprosecution hearsay evidence accompanied by either disregard or limiting instructions, presented either immediately after the hearsay, at the end of the trial, or at both of these times. Also included were control conditions in which (1) the information was presented as nonhearsay (first-hand), (2) no hearsay was presented, or (3) the hearsay was presented without instructions. Results indicated that neither the hearsay nor the instructions, regardless of their form or timing, affected verdicts. In fact, findings revealed that participants may have disregarded the hearsay regardless of instructions heard. There was some evidence to suggest, however, that evaluations of other admissible evidence presented by the hearsay witness were negatively affected.     

Expert Testimony Regarding Child Witnesses: Does It Sensitize Jurors to Forensic Interview Quality?

Does expert testimony on forensic interviews with children help adults distinguish between poorly conducted and well-conducted interviews? This study evaluates the effects of social framework expert testimony regarding child witnesses in a case involving allegations of child sexual abuse. A 2 (Expert Testimony: present or absent) × 3 (Child Forensic Interview Quality: poor, typical, or good) × 2 (Child’s Age: 4- or 10-year-old) factorial design was used to examine whether expert testimony is prejudicial or beneficial to jurors (N = 463). The results revealed that, without expert testimony, mock jurors did not consider the forensic interview quality when reaching a verdict. However, with expert testimony, mock jurors were more likely to render guilty verdicts if the interview quality was good versus poor. Further expert testimony increased mock jurors’ knowledge about child witnesses. These findings suggest that expert testimony related to the impact of interview techniques on the reliability of children’s reports may assist fact-finders in evaluating child abuse cases.     

A HEAVY THUMB ON THE SCALE: THE EFFECT OF VICTIM IMPACT EVIDENCE ON CAPITAL DECISION MAKING*

The past several decades have seen the emergence of a movement in the criminal justice system that has called for a greater consideration for the rights of victims. One manifestation of this movement has been the “right” of victims or victims' families to speak to the sentencing body through what are called victim impact statements about the value of the victim and the full harm that the offender has created. Although victim impact statements have been a relatively noncontroversial part of regular criminal trials, their presence in capital cases has had a more contentious history. The U.S. Supreme Court overturned previous decisions and explicitly permitted victim impact testimony in capital cases in Payne v. Tennessee (1991) . The dissenters in that case argued that such evidence only would arouse the emotions of jurors and bias them in favor of imposing death. A body of research in behavioral economics on the “identifiable victim effect” and the “identifiable wrongdoer effect” would have supported such a view. Using a randomized controlled experiment with a death‐eligible sample of potential jurors and the videotape of an actual penalty trial in which victim impact evidence (VIE) was used, we found that these concerns about VIE are perhaps well placed. Subjects who viewed VIE testimony in the penalty phase were more likely to feel negative emotions like anger, hostility, and vengeance; were more likely to feel sympathy and empathy toward the victim; and were more likely to have favorable perceptions of the victim and victim's family as well as unfavorable perceptions of the offender. We found that these positive feelings toward the victim and family were in turn related to a heightened risk of them imposing the death penalty. We found evidence that part of the effect of VIE on the decision to impose death was mediated by emotions of sympathy and empathy. We think our findings open the door for future work to put together better the causal story that links VIE to an increased inclination to impose death as well as explore possible remedies.     

Comparing the effectiveness of <Emphasis Type="Italic">Henderson</Emphasis> instructions and expert testimony: Which safeguard improves jurors’ evaluations of eyewitness evidence?

Objectives

The New Jersey Supreme Court recently determined that jurors may not be able to effectively evaluate eyewitness evidence on their own. As a result, the Court proposed the use of judicial instructions to assist jurors (called Henderson instructions) and suggested the implementation of these instructions would reduce the need for expert testimony. We tested the efficacy of these instructions compared to alternative instructions and expert testimony.

Methods

We utilized a mock trial paradigm, randomly assigning 452 participants to 1 of 20 videotaped trial conditions that varied the quality of eyewitness evidence (both witnessing and identification conditions) and the type of safeguard presented during the mock trial.

Results

Jurors were sensitive to the quality of identification conditions on their own. Jurors were more likely to convict when identification conditions were good and less likely when identification conditions were poor. This relationship was mediated by eyewitness credibility ratings. Expert testimony resulted in skepticism by reducing the likelihood that jurors would convict regardless of the quality of witnessing and identification conditions. No variation of the instructions influenced verdicts.

Conclusions

While jurors were sensitive to the quality of identification conditions on their own, we observed no such effect for the quality of witnessing conditions, even with the aid of instructions and/or expert testimony. Both Henderson instructions and expert testimony may be insufficient for assisting jurors to effectively evaluate problematic witnessing conditions. Future research should examine the use of alternative safeguards.

     

Conduct and its Consequences: Attempts at Debiasing Jury Judgments

Jurors in negligence cases are supposed to judge a defendant by the reasonableness of his or her conduct and not by the consequences of that conduct. But several studies have shown that a cognitive heuristic known as hindsight bias can skew post hoc judgments of some prior behavior. Thus, jurors who must evaluate the actions of a defendant may be influenced inappropriately by the consequences of those actions. A complementary problem arises when jurors must evaluate the injuries incurred by the plaintiff. Here, jurors' knowledge about the defendant's allegedly negligent conduct can proactively influence their assessment of the plaintiff's injuries and determination of damages. The purpose of the present study was to examine the effectiveness of two procedural techniques intended to reduce or eliminate the impact of hindsight bias in negligence cases—multiple admonitions from a judge about the proper use of evidence—and bifurcation (actually withholding irrelevant evidence from jurors). We presented a re-enacted automobile negligence trial to 355 jury-eligible adults drawn from the community, varied the evidence and instructions that they heard, and measured liability judgments and damage awards from individual jurors both before and after deliberating, and from juries. Results showed that admonitions were generally ineffective in guiding jurors to the proper use of evidence but that bifurcation was relatively more effective. Deliberations had no curative effect on jurors' misapplication of evidence.     

Considering forensic science: individual differences,opposing expert testimony and juror decision making

Two experimental studies examined the effect of opposing expert testimony on perceptions of the reliability of unvalidated forensic evidence (anthropometric facial comparison). In the first study argument skill and epistemological sophistication were included as measures of individual differences, whereas study two included scores on the Forensic Evidence Evaluation Bias Scale. In both studies participants were assigned to groups who heard: (1) no expert testimony, (2) prosecution expert testimony, or (3) prosecution and opposing expert testimony. Opposing expert testimony affected verdict choice, but this effect was mediated by perceptions of reliability of the initial forensic expert's method. There was no evidence for an effect on verdict or reliability ratings by argument skill or epistemology. In the second experiment, the same mediation effect was found, however scores on one subscale from the FEEBS and age also affected both verdict and methodological reliability. It was concluded that opposing expert testimony may inform jurors, but perceptions of the reliability of forensic evidence affect verdict, and age and bias towards forensic science influence perceptions of forensic evidence. Future research should investigate individual differences that may affect perception or bias towards forensic sciences under varying conditions of scientific reliability.     

Expertise in Fingerprint Identification

Although fingerprint experts have presented evidence in criminal courts for more than a century, there have been few scientific investigations of the human capacity to discriminate these patterns. A recent latent print matching experiment shows that qualified, court‐practicing fingerprint experts are exceedingly accurate (and more conservative) compared with novices, but they do make errors. Here, a rationale for the design of this experiment is provided. We argue that fidelity, generalizability, and control must be balanced to answer important research questions; that the proficiency and competence of fingerprint examiners are best determined when experiments include highly similar print pairs, in a signal detection paradigm, where the ground truth is known; and that inferring from this experiment the statement “The error rate of fingerprint identification is 0.68%” would be unjustified. In closing, the ramifications of these findings for the future psychological study of forensic expertise and the implications for expert testimony and public policy are considered.     

Meeting a Forensic Podiatry Admissibility Challenge: A Daubert Case Study

This article is an introduction to the United States Supreme Court's standard of admissibility of forensic evidence and testimony at trial, known as the Daubert standard, with emphasis on how this standard applies to the field of forensic podiatry. The author, a forensic podiatrist, provided law enforcement with evidence tying a bloody sock‐clad footprint found at the scene of a homicide to the suspect. In 2014, the author testified at a pretrial hearing, known as “a Daubert hearing,” to address the admissibility of this evidence in court. This was the first instance of forensic podiatry being the primary subject of a Daubert hearing. The hearing resulted in the court ordering this evidence admissible. The expert's testimony contributed to the suspect's conviction. This article serves as a reference for forensic podiatrists and experts in similar fields that involve impression evidence, providing evidentiary standards and their impact on expert evidence and testimony.     

Prediction of first ballot mock jury votes by the Analytic Juror Rater

Two scales of Abbott's (1987) Analytic Juror Rater (AJR) were used with 24 mock jurors to predict first ballot mock jury votes. Each participant observed one of two mock trial proceedings involving an actual second degree murder case. In a moot courtroom, they heard arguments from attorneys and witnessed examination of the defendant and actors portraying witnesses. The Cosmopolitan Lifestyle Scale of the AJR successfully predicted first ballot votes of participants (p<.02), while the Non-Authoritarian Scale showed a non-significant trend in the hypothesized direction. It was concluded that, in cases where evidence is not strong, the AJR may lend modest assistance to the attorney using peremptory challenge to eliminatevenire members who may be biased against a defendant.     

The over-citation of Daubert in forensic anthropology

The 1993 US Supreme Court decision Daubert v. Merrell Dow Pharmaceuticals, Inc. presented new guidance for the judicial assessment of expert witness evidence and testimony in the determination of admissibility. Despite the rarity of admissibility challenges to forensic anthropology evidence, Daubert is frequently cited in published forensic anthropology research. This study undertook a qualitative thematic analysis of forensic anthropology articles published in the Journal of Forensic Sciences to assess why authors continue to cite Daubert and express concerns over potential exclusion. The results show a significant increase in the number of articles that cite legal admissibility standards over time (p < 0.001). Authors frequently cite these standards to contextualize their results within the Daubert framework or to justify the need for their research. Notably, many articles present Daubert as a constraining force, misinterpreting the guidelines as rigid criteria or that they require methods to be strictly quantitative. However, Daubert was intended to be a flexible tool for judges—not a standard or instruction for scientists. While it was reasonable to reflect on the scientific rigor of methods in the wake of the Daubert decision, a new perspective is warranted in which forensic anthropologists shift their focus from trying to “satisfy” admissibility guidelines to adopting quality assurance measures that minimize error and ensure confidence in analytical results, and developing and using methods that are grounded in good science—which is important regardless of whether or not the results are ever the subject of a trial.     

Effects of judicial instructions and juror characteristics on interpretations of beyond reasonable doubt

The standard of proof, beyond reasonable doubt (BRD), serves as a threshold for reaching verdicts in criminal cases. Past research has demonstrated that factors such as the wording of judicial instructions defining the standard can influence people's interpretation of it. In addition, there is some concern that instructions may not be effective for the wider jury-eligible population. In an experimental study involving members of the general public, we examined the effect of two commonly used judicial instructions (i.e. sure and firmly convinced) against a situation when BRD was undefined, on people's quantitative interpretations of BRD as well as on their self-reported understanding of the standard and confidence in applying it. We also explored the effect of juror characteristics (i.e. gender, age and education). Compared to when the standard was undefined, the sure instruction helped to reduce inter-individual variability in interpretations of BRD and the firmly convinced instruction increased people's understanding of the standard. However, neither instruction was effective in increasing confidence in applying the standard or in reducing observed individual differences. These findings underscore the importance of developing evidence-based judicial instructions that can benefit the broad jury-eligible population equally and in a variety of ways.     

Forensic Confirmation Bias: Do Jurors Discount Examiners Who Were Exposed to Task-Irrelevant Information?*†

Knowledge of task-irrelevant information influences judgments of forensic science evidence and thereby undermines their probative value (i.e., forensic confirmation bias). The current studies tested whether laypeople discount the opinion of a forensic examiner who had a priori knowledge of biasing information (i.e., a defendant's confession) that could have influenced his opinion. In three experiments, laypeople (N = 765) read and evaluated a trial summary which, for some, included testimony from a forensic examiner who was either unaware or aware of the defendant's confession, and either denied or admitted that it could have impacted his opinion. When the examiner admitted that the confession could have influenced his opinion, laypeople generally discounted his testimony, as evidenced by their verdicts and other ratings. However, when the examiner denied being vulnerable to bias, laypeople tended to believe him—and they weighted his testimony as strongly as that of the confession-unaware examiner. In short, laypeople generally failed to recognize the superiority of forensic science judgments made by context-blind examiners, and they instead trusted examiners who claimed to be impervious to bias. As such, our findings highlight the value of implementing context management procedures in forensic laboratories so as not to mislead fact-finders.     

Effects of Experiencing the Eyewitness Identification Procedure on Juror Decisions

Mistaken eyewitness identifications are believed to contribute to a preponderance of wrongful convictions, underscoring the need to identify methods to help decrease the likelihood of false convictions based on eyewitness testimony. The present study tested the hypothesis that providing jurors with first-hand experience with eyewitness identification procedures could help further sensitize them to the limitations of eyewitness testimony. Eighty college students watched a videotaped mock trial in which the prosecution’s sole evidence was eyewitness testimony. In a 2 × 2 randomized factorial design, we manipulated whether participants heard expert psychological testimony (henceforth referred to as expert testimony) on the limitations of eyewitness identification and whether they experienced an eyewitness identification procedure. As predicted, experiencing the eyewitness identification procedure had a significant impact on juror decisions, suggesting that this procedure could further help reduce the likelihood of wrongful convictions.     

Contribution to the Development of Guidelines in the Analysis of Biological Evidence in Sexual Assault Investigations

This investigation intends to study materials and techniques used for biological evidence collection in sexual assault cases and is divided into two stages: in stage one, methods for biological evidence collection (the single swab (including three variants) and the “double swab technique”) were compared; in stage two, swabs’ component material was compared. The sampling was composed of 42 heterosexual couples who provided mock samples. The collection methods in which the whole swab is covered by evidence presented significantly better outcomes (p < 0.001), such as the “double swab technique.” Additionally, nylon swabs proved to present significantly better features regarding the capacity of sample elution, providing significantly higher amounts of DNA (p ≤ 0.034). This study provides guidelines for better collection of biological evidence regarding the collection method using a swab and the proper swab material to utilize.     

Impact of hypnotic testimony on the jury

In the past decade, the forensic use of hypnosis to enhance the memories of victims, witnesses, and defendants has sharply increased. A great deal of controversy surrounds this issue. Some commentators argue that testimony derived from hypnosis should not be allowed as evidence because of its inherent unreliability and the unduly powerful impact it may have on a jury. In the present research, we used a jury simulation technique to study the impact that a hypnotically refreshed witness has upon jurors' decision making. A major finding is that jurors view hypnotic testimony with a certain amount of skepticism. In some respects, its impact is comparable to that of testimony based on delayed recall, and rarely does it have the impact of testimony from an immediate report. In addition, jurors' judgments about hypnotically refreshed testimony affected the way they evaluated other evidence at trial: Jurors who learned that a prosecution witness had been hypnotized were less believing ofother prosecution witnesses than were jurors not exposed to hypnotic testimony. The forensic application of these findings is discussed.This research was supported by a grant from the National Science Foundation, Law and Social Sciences Program. We thank Jane Goodman, Doug Leber, Bonnie Sawnson, Russ Wade, Karen Guest, Jonna Barsanti, Don Kline, Elaine Sullivan, and David Kuykendall for their help at various stages of the project.     

Whole Plastome Sequences of Two Drug-Type Cannabis: Insights Into the Use of Plastid in Forensic Analyses

DNA is one of the fastest growing tools in forensic sciences, increasing reliability in forensic reports and judgments. The use of DNA has increased in different areas of the forensic sciences, such as investigation of plant species, where plastid DNA has been used to elucidate and generate evidence in cases of traceability of genetically modified and controlled plants. Even with several advances and the practice of using DNA in forensic investigations, there are just few studies related to the identification of genetic tools for the characterization of drug and nondrug-types of Cannabis. Herein, the whole plastomes of two drug-type Cannabis are presented and have their structures compared with other Cannabis plastomes deposited in the GenBank, focusing in the forensic use of plastome sequences. The plastomes of Cannabis sativa “Brazuka” and of the hybrid Cannabis AK Royal Automatic presented general structure that does not differs from the reported for other C. sativa cultivars. A phylogenomic analyses grouped C. sativa “Brazuka” with the nondrug C. sativa cultivars, while the hybrid Cannabis AK Royal Automatic placed isolated, basal to this group. This suggests that the analysis of plastomes is useful toward genetic identification of hybrids in relation to C. sativa.