The insanity defense: asking and answering the ultimate question

The authors address the main questions in the insanity defense debate: Should it be abolished? Should psychiatrists participate as expert witnesses? Is the profession damaged by such testimony? Is there a logical leap between providing psychiatric findings and providing an opinion to the ultimate question? Because the free will/determinism model underlying the current insanity defense positions can be used to argue either side of the debate, it does not supply any rational answers. The authors reframe the discussion, using a systems approach, and suggest answers to these questions that are in line with the clinical realities and on a firmer philosophic ground.     

Estimating Juror Accuracy,Juror Ability,and the Relationship Between Them

This article advances a method based on standard test theories and measurement models to determine correct verdicts for jury trials, and to estimate juror accuracy, juror ability, and trial difficulty (and the relationships among them). With five vignette cases and 1,318 juror eligible adults as the subjects, the model consistently identified verdicts that accorded with the judge’s instructions on the law as correct. With the correct verdicts, the strength of the relationship between juror accuracy and juror ability was found to be substantial. These findings suggest that the assumption of equivalent accuracy of jurors underlying the Condorcet’s jury theorem (Condorcet, Essai sur l’Application de l’Analyse a la Probabilite des Decisions Rendues a la Pluralite des Voix, Paris, 1785) may be untenable for general cases where jurors of diverse dispositions and abilities serve together; and that the role of juror ability in determining the accuracy of legal decisions could be more significant than that of attitudes and values because, unlike attitudes and values, ability could affect juror’s legal decisions regardless of the type of the case.     

Juror experience and jury verdicts

Most trial attorneys believe that repeated jury service produces several effects in jurors, one of the most important of which is an increased disposition toward conviction of criminal defendants. However, case law reveals a reluctance to accept the proposition that prior service per se would disquality a juror from sitting on an instant case because of actual or implied bias. The need for direct empirical investigation of the effects of prior jury service prompted the present study, which examined a complete docket of 175 consecutive criminal trials across onecalendar year in a state circuit court which required a 30-day term of its venire. The results indicated that as the number of jurors with prior jury experience increased there was a modest, but significant, increase in the probability of a conviction. Analysis of the relationship between initial verdicts and subsequent service disconfirmed the alternative hypothesis that attorneys deselected jurors on the basis of their first verdicts. Several parameters of experience were also related to foreperson selection. Implications for legal practice and for additional research are discussed.Support for this research was provided, in part, by National Science, Foundation grant No SES-8209479. A portion of this work was conducted while the senior author was a James McKeen Cattell Foundation Fellow.     

Juror interpretations of ambiguous evidence

In the context of a mock jury study, we tested the hypothesis that people's interpretations of ambiguous evidence depend on how (i.e., by whom) that evidence is introduced. Subjects watched a 45-min interrogation of a murder suspect who emphatically asserted her innocence but told an imperfect story. Before the tape, subjects read either the prosecution or defense lawyer's arguments concerning the suspect's interrogation performance; after the tape, they read counter-arguments from the opposing side. Results indicated that subjects high in the need for cognition (NC) were influenced more by arguments that preceded the evidence, whereas low-NC subjects were more influenced by arguments that followed the evidence. Theoretical and practical implications of these findings are discussed.     

Juror background characteristics and attitudes toward rape

Although numerous writers have discussed the importance of and link between juror characteristics and juror decisions in rape trials, anempirical investigation of the relationships between these characteristics and juror verdicts has not been made. Using data obtained from a sample of 896 citizens serving as mock jurors, the principal focus of the present research was on the correlations of jurors' background characteristics and their attitudes toward rape with their decisions in a simulated rape case. Results of the study showed that the jurors' background and attitudinal variables were associated with their decisions. In addition, the pattern of the correlations was quite stable as the characteristics of the case evaluated (in terms of defendant and victim race, victim physical attractiveness, victim sexual experience, strength of evidence presented, and type of rape committed) were found to have only negligible effects on these relationships. Other tests showed that only the attitudinal variables accounted for differences in the jurors' decisionsafter characteristics of the case had been considered. Further, as compared to background data, the jurors' views of rape were the most important predictor of their decisions. Implications of the role of jurors' views of rape in jurors' decisions in rape trials and the use of rape attitudes for selecting jury members in rape cases discussed.     

Impact of Juror Attitudes about the Death Penalty on Juror Evaluations of Guilt and Punishment: A Meta-Analysis

This literature review summarizes the existing research examining how the attitude a potential juror has toward the death penalty impacts on the probability of favoring conviction. The summary of 14 investigations indicates that a favorable attitude toward the death penalty is associated with an increased willingness to convict (average r = .174). Using the binomial effect size display, this favorable attitude towards the death penalty translates into a 44% increase in the probability of a juror favoring conviction.     

Juror sensitivity to eyewitness identification evidence

A mock-jury study was conducted to examine juror sensitivity to eyewitness identification evidence. Subjects were 129 eligible and experienced jurors from Dane County, Wisconsin, who viewed a videotaped trial that involved an eyewitness identification. Ten factors associated with the crime and the identification (e.g., disguise of the perpetrator, retention interval, confidence of the witness) were manipulated. The results of this mock-jury study were combined with those of a previous study using the same experimental stimuli and procedures, but using undergraduates as subjects. This analysis showed that the confidence of the eyewitness was the most powerful predictor of verdicts (p<.05) and that differences between undergraduates and eligible jurors in their sensitivity to eyewitness evidence were negligible.     

Juror Sensitivity to the Cross-Race Effect

Black and White mock jurors' sensitivity to the cross-race effect was investigated by varying the race of the eyewitness in a simulated murder trial of a Black defendant. Participants heard an audiotape of a trial after which they rendered a verdict and rated the credibility of the witnesses. White participants found the prosecution witnesses (including the eyewitness) more credible, and the defense witness less credible, than did Black participants; they were also more likely to find the defendant guilty. The Black eyewitness was perceived as more credible than was the White eyewitness, but eyewitness race had no effect on verdict. These results are consistent with the literature indicating that jurors of different races reach different verdicts, and also that jurors are relatively insensitive to factors that affect eyewitness testimony, such as the cross-race effect.     

Effects of notetaking on verdicts and evidence processing in a civil trial

Examined the effect of notetaking on juror decision making and cognitive processing of evidence in a complex tort trial. Jury eligible participants either took notes during the trial and had access to those notes during decision making, took notes without access, or did not take notes. Those who took notes during the trial performed more competently than did nonnotetakers. Notetakers made correct distinctions in assigning liability and compensatory awards among four differentially worthy plaintiffs and recalled significantly more probative evidence than nonnotetakers. The almost identical performance of the notes-access group and the notes without access group suggests that notetaking had its impact at the encoding stage rather than at retrieval. We discuss possible motivational differences that may account for the results and constraints on generalizing the findings.This research was supported by National Science Foundation under grant No. SBR 9311922 awarded to Irwin A. Horowitz.     

Intoxicated Consent in Rape: Bree and Juror Decision-Making

The article examines the recent Court of Appeal judgment in Bree, in which the court considered the guidance that should be given to a jury when the complainant is intoxicated at the time of an alleged rape. As well as analysing the reasoning of the court in Bree, the judgment is placed in context by examining factors, such as social attitudes, that influence juror decision-making in rape cases. It also examines the suggestion made by the court in Bree that further law reform in this area would represent 'patronising interference' in the lives of women.     

Juror decision making,attitudes, and the hindsight bias

This study examines juror decision making in civil suits against police officers alleged to have engaged in illegal searches, using simulated case materials and mock jurors drawn both from adults called for jury service and a student subject pool. The experiment assesses the impact of a cognitive process (thehindsight bias) and of individual attitudes on awards and finds that both are related to juror decisions. We test a theoretical model that specifies that both attitudes and outcome knowledge exercise their influence upon the damage award decision by means of their impact on interpretation of testimony. Causal models of the decision-making process appear to support the role played by interpretation of evidence as a mediator between individual attributes and juror decisions.We are indebted to Reid Hastie, Tom Tyler, Phoebe Ellsworth, Jack Heinz, Robert Nelson, Rayman Solomon, and Bonnie Fisher for assistance with various aspects of the design, data collection, and analysis reported here. Financial support was provided by the American Bar Foundation, and the Center for Urban Affairs and Policy Research and the Dispute Resolution Research Center, both at Northwestern University.John D. & Catherine T. MacArthur Foundation.     

Impact of Defense-Only and Opposing Eyewitness Experts on Juror Judgments

Previous research shows that expert testimony on eyewitness memory influences mock-juror judgments. We examined the extent to which opposing expert testimony mitigates the impact of defense-only expert testimony. Participants (N = 497) viewed a video-taped trial involving an eyewitness identification and individually rendered verdicts and evaluated the evidence and the experts. We manipulated the Foils (unbiased vs. biased) and Instructions (unbiased vs. biased) of the lineup and Expert Testimony (no expert vs. defense-only expert vs. opposing experts). Expert testimony did not significantly influence juror judgments, but the opposing expert testimony diminished the credibility of the defense expert in the eyes of the jurors. Results point to the need for further research on conditions that qualify the impact of expert testimony.     

Goal Conflict in Juror Assessments of Compensatory and Punitive Damages

Recent tort reform debates have been hindered by a lack of knowledge of how jurors assess damages. Two studies investigated whether jurors are able to appropriately compartmentalize compensatory and punitive damages. In Study 1, mock jurors read a trial summary and were asked to assess compensatory and punitive damages in one of three conditions: (a) compensatory damages only, (b) punitive damages for the plaintiff, or (c) punitive damages for the state treasury. Results suggest that jurors who did not have the option to award punitive damages inflated compensatory damages via pain and suffering awards. Jurors were marginally more likely to award punitive damages when the plaintiff was the recipient. Mock jurors in Study 2 read a similar case summary and were asked to assess compensatory and punitive damages. Two factors were varied in Study 2: (a) egregiousness of the defendant's conduct, and (b) the recipient of any punitive damages (the plaintiff vs. a consortium of state funds). Jurors were more likely to award punitive damages when the defendant's conduct was more egregious and when the plaintiff was the recipient. The results suggest leakage between compensatory and punitive damage judgments, contrary to the law's mandate.     

Chaos in The Courtroom Reconsidered: Emotional Bias and Juror Nullification

A widespread presumption in the law is that giving jurors nullification instructions would result in "chaos"-jurors guided not by law but by their emotions and personal biases. We propose a model of juror nullification that posits an interaction between the nature of the trial (viz. whether the fairness of the law is at issue), nullification instructions, and emotional biases on juror decision-making. Mock jurors considered a trial online which varied the presence a nullification instructions, whether the trial raised issues of the law's fairness (murder for profit vs. euthanasia), and emotionally biasing information (that affected jurors' liking for the victim). Only when jurors were in receipt of nullification instructions in a nullification-relevant trial were they sensitive to emotionally biasing information. Emotional biases did not affect evidence processing but did affect emotional reactions and verdicts, providing the strongest support to date for the chaos theory.     

Life underWainwright v. Witt: Juror dispositions and death qualification

The current standard for determining juror qualification in cases in which the prosecution is seeking the death penalty was formulated by the U.S. Supreme Court in 1985 inWainwright v. Witt. This standard differs importantly from its predecessor, and requires that prospective jurors be dismissed if their views would prevent or substantially impair their ability to perform their functions as jurors. We assessed respondents according to the criteria imposed byWitt. We also measured independently prospective juror's abilities to perform the various specific tasks of a capital juror and their disposition to impose the death penalty automatically upon defendants convicted of murder punishable by death. Data from 148 respondents, selected randomly from juries on previously tried felony cases, indicated that 28.2% of those includable by theWitt standard would automatically impose the death penalty. Considering all respondents who would be erroneously included or excluded, a total of 36% of the sample showed inconsistencies with theWitt criterion. These findings are discussed in terms of jurors' difficulties in anticipating their roles as capital jurors.