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.     

Children's testimony: Research findings and policy implications

Abstract

Traditionally the British legal system has taken a sceptical attitude toward the testimony of children, reflected in the competency requirement, the corroboration rule and the judicial caution. However, recent psychological research has suggested that children, properly interviewed, can provide invaluable testimony in securing convictions in cases of sexual or physical abuse. Research suggests that children's spontaneous accounts of events are generally accurate, and that suggestibility can be greatly reduced by appropriate questioning techniques. Partly as a result of such research, the legal hurdles surrounding children's evidence have been dismantled and procedural innovations, such as the use of the Videolink and videotaped interviews introduced. Empirical research demonstrates the success of the Videolink and a similar evaluation is planned for videotaped interviews. The latter has highlighted the need for a new research agenda which would include the impact of biased or repeated questioning, and requests to children from abusers to lie or keep secrets.     

Rape trauma syndrome

This article analyzes recent case law on the admissibility of rape trauma syndrome evidence. Because many rulings on the admissibility of this evidence have been based on judicial assumptions about human behavior, rather than on scientific evidence, we next describe psychological research relevant to concerns raised about its scientific reliability, helpfulness, and prejudicial impact. Following this review, we evaluate both the expert testimony provided and the judicial decisions in recent cases in light of current research. Finally, we provide suggestions for future psychological research that could 1 inform discussions of the admissiblity of rape trauma syndrome evidence.     

Juror common understanding and the admissibility of rape trauma syndrome evidence in court

Expert testimony on rape trauma syndrome has been used in sexual assault cases to corroborate the victim's complaint and to educate the jury. One of the primary arguments against the admissibility of this testimony is that it is not helpful because most jurors are adequately informed about rape and rape victim behavior. To test this assumption, a Sexual Assault Questionnaire (SAQ) was administered to experts on rape and post-traumatic stress disorder (PTSD) and two nonexpert comparison groups. Results indicated that the nonexperts were not well informed on many rape-related issues and were significantly less knowledgeable than the expert groups. The data also showed considerable consensus among the experts about the current scientific database on rape trauma. The implications of these results for the use of expert psychological testimony on rape trauma syndrome in court are discussed.     

Two conjectures about the issue of expert testimony

This article responds to concerns about expert testimony in experimental psychology by conjectur that disagreements about the propriety of the testimony are camouflaged arguments about the strength of psychological knowledge. Differences between proponents and opponents of expert testimony are about the state of psychological knowledge and certainty, rather than about the proper standard for psychologists to use when deciding whether to testify. A second conjecture is stimulated by the assumption that laypersons generally overvalue eyewitness testimony and that expert psychological testimony is a required corrective. The truth of this assumption rests on the debatable assertions that eyewitness identifications, without more, are potent sole determinants of trial outcome, and that lay juries need instruction from experimental psychologists about aspects of human behavior of which the jurors are definitive producers and consumers. One need not resolve these debates in order to understand that psychologists should not rely on the legal community to set the psychologists' standards for expert testimony. And psychologists, in considering their role as courtroom experts, should guard against a self-serving critique of the acumen of lay juries.     

论司法鉴定人资格

司法鉴定人制度是司法鉴定制度的核心,而明确司法鉴定人资格是完善司法鉴定人制度的前提。在对司法鉴定人的资质控制上我国一度处在规定不明,审查不清,制度混乱的状态,这也是导致许多案件所依据的鉴定结论反复出现矛盾的原因之一。通过比较国外相关制度,梳理我国现有制度的弊端,本文提出了完善我国司法鉴定人资格的若干建议。     

Barring ultimate issue testimony

This research focuses on one of the major changes wrought by the Insanity Defense Reform Act of 1984: the exclusion of expert mental health testimony on the “ultimate issue,” that is, testimony specifically addressing the expert's opinion that the defendant is sane or insane. Subjects in this research were presented with 1 of 10 variants of an insanity case in which experts testified for the defense, prosecution, both, or neither. The testimony was at one of three levels: diagnostic only, penultimate issue, or ultimate issue. Results showed that level of testimony had no effect on the verdict pattern. There was evidence to suggest that this effect may occur because jurors infer, and/or mistakenly recall, higher levels of expert testimony than was actually presented to them. In addition, general and specific constructs (Finkel & Handel, 1989) that predict verdict yieldedR ² values from .500 to .668 and were not significantly affected by the level of expert testimony. Implications of these findings are discussed.     

Is the Expert Admissibility Game Fixed?: Judicial Gatekeeping of Fire and Arson Evidence

Anecdotal evidence claims that in criminal cases, trial judges admit the prosecution's expert witnesses more readily than the defendants', and in civil cases the reverse is true; judges exclude plaintiffs' experts more often than civil defendants' experts. This occurs despite the fact that, with few exceptions, the same rules of admissibility apply to all parties and, in most jurisdictions, across criminal and civil cases. This article empirically tests this differential by reviewing judicial decisions to admit or exclude evidence holding the type of expert testimony constant, fire and arson evidence, across criminal and civil cases in the United States. The study examines the admissibility of fire and arson investigation experts in criminal and civil cases across all legal parties in fifty‐seven federal and state opinions in the United States. The findings offer empirical support of a bias in criminal cases and in civil cases which present expert witnesses at trial, and is less pronounced, but still evident, on appeal. Specifically, the role of the party that offers the evidence has a profound effect on whether arson evidence is admitted, even when factors around the judge's political affiliation, attorney experience, expert qualifications, and rules of evidence are taken into account.     

Expert testimony in child sexual abuse cases

We presented participants with syndromal, witness credibility, or anatomically detailed doll evidence to determine (a) whether these different types of expert evidence exert differential influence on participants' judgments and (b) whether the influence of this evidence could be better explained by the relative scientific status or the probabilistic qualities of the research presented. Additionally, we investigated whether a strong or weak cross-examination of the expert would be more successful in discrediting the information provided in the expert's testimony. Findings suggest that participants are less influenced by expert testimony based on probability data (i.e., syndromal evidence) than by expert testimony based on case history data (i.e., credibility of anatomically detailed doll evidence). Participant responses did not differ as a function of the strength of the cross-examination of the expert. As expected, women were more likely to respond in a pro-prosecution direction than were men. Implications for the use of expert evidence in child sexual abuse cases are discussed.     

THE SCIENTIFIC BASIS OF PSYCHOLOGICAL TESTING

The legal standards for admissibility of expert testimony have recently been raised following several U.S. Supreme Court decisins. Although forensic mental health experts have relied on psychological testing as a method of data collection for many years, the scientific basis of such testing has traditionally gone unquestioned in court. Given the increased scrutiny currently being applied to expert testimony, it is more important now than ever for attorneys, judges and forensic experts to understand the scientific principles underlying psychological tests. In this article, the scientific principles of validity and reliability are explained, and scientifically acceptable methods for the forensic use of psychological testing are discussed. The application of recent case law to several well-known tests is described.     

Social science in court

This article discusses the role of social science in legal proceedings with special attention to the ethical situation of the expert psychologist asked to testify about the reliability of an eyewitness identification. It argues that in this area as in others one cannot discuss the ethics of expert psychological testimony without attending to the quality of the research and theory on which the testimony is based. It also identifies as considerations that bear on the propriety of such testimony the information the fact finder is likely to receive in its absence and the factual guilt of the defendant. The paper goes on to discuss the relationship between law and social science more generally. It argues that ultimately courts do and should have the last word regarding the place of social science in legal proceedings.     

Jurors' knowledge of battered women

An increasing number of psychologists with expertise in the area of battered women are participating in the legal system as expert witnesses and occasionally testify on behalf of a battered woman who has injured or killed her partner. Testimony about the battered woman syndrome has been offered to help the jury understand why the defendant reasonably perceived that she was in danger of harm. One of the requirements of expert testimony is that it be beyond the common understanding of the jury. Many commentators assume that jurors are uninformed or misinformed about battered women and, thus, that expert testimony is necessary to educate them. This study evaluated what jurors know about violent relationships. Approximately 300 jurors read scenarios about spousal violence and answered a questionnaire dealing with circumstances surrounding such abuse. Results suggest that on certain dimensions of spousal violence, jurors are aware of empirical research findings. On other dimensions, jurors are less well-informed and could potentially benefit from the testimony of an expert.     

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.     

Can experts help jurors to evaluate eyewitness evidence? A review of eyewitness expert effects

Courts occasionally permit psychologists to present expert evidence in an attempt to help jurors evaluate eyewitness identification evidence. This paper reviews research assessing the impact of this expert evidence, which we argue should aim to increase jurors' ability to discriminate accurate from inaccurate identifications. With this in mind we identify three different research designs, two indirectly measuring the expert's impact on juror discrimination accuracy and one which directly assesses its effect on this measure. Across a total of 24 experiments, three have used the superior direct methodology, only one of which provides evidence that expert testimony can improve jurors' ability to discriminate between accurate and inaccurate eyewitness identifications.     

Ten years in the life of an expert witness

American Courts are experiencing increased use of expert testimony based upon psychological research. Ten years ago, I began testifying about my own research on human perception, recollection, and eyewitness accounts. The growing acceptance of this testimony percipitated a backlash from some psychologists. This essay describes the chronology of these events, and their relevance for the more general use of psychological research as evidence in court.     

Psychopathy,expert testimony,and indeterminate sentences: Exploring the relationship between Psychopathy Checklist‐Revised testimony and trial outcome in Canada

Purpose. Psychopathy, as measured by the Hare Psychopathy Checklist‐Revised (PCL‐R), has the potential to inform judges attempting to preventatively detain Canada's highest risk offenders. However, studies examining the stigma of the psychopathy label give reason to exercise caution when expert witnesses introduce PCL‐R scores into their testimony. Methods. Judges' written or oral judgments were gathered from a publically available database in Canada. Dangerous offender hearings (N = 136) were examined to determine how factors within expert witness testimony were related to sentences of indeterminate or determinate length. Results. Results show a trend for PCL‐R scores to be related to trial outcome. Specifically, psychopathy diagnoses were correlated to experts' ratings of treatment amenability which were in turn related to trial outcome. In addition, experts tended to show partisan allegiance in the way they scored offenders on the PCL‐R. Conclusion. Discussion advocates a measure of caution when using PCL‐R testimony in an adversarial court context. Further research clarifying the role psychopathy plays in court decisions is also encouraged.     

Courtroom testimony by psychologists on eyewitness identification issues

This article makes two major points in regard to expert psychological testimony on eyewitness identification. First, the attention devoted by psychologists to eyewitness identification issues is far out of proportion to the incidence of trials involving eyewitness identifications of criminal defendants; furthermore, the often-expressed concern over wrongful convictions is probably misplaced. Second, the experimental methods used in studies of eyewitness performance are fundamentally unsuited for drawing conclusions about actual witnesses. Hence, there is not an adequate scientific foundation for expert psychological testimony on eyewitness identification. Archival research is perhaps the most promising approach to the study of the criminal justice system.     

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.