Subjectivity and bias in forensic DNA mixture interpretation

The objectivity of forensic science decision making has received increased attention and scrutiny. However, there are only a few published studies experimentally addressing the potential for contextual bias. Because of the esteem of DNA evidence, it is important to study and assess the impact of subjectivity and bias on DNA mixture interpretation. The study reported here presents empirical data suggesting that DNA mixture interpretation is subjective. When 17 North American expert DNA examiners were asked for their interpretation of data from an adjudicated criminal case in that jurisdiction, they produced inconsistent interpretations. Furthermore, the majority of 'context free' experts disagreed with the laboratory's pre-trial conclusions, suggesting that the extraneous context of the criminal case may have influenced the interpretation of the DNA evidence, thereby showing a biasing effect of contextual information in DNA mixture interpretation.     

“Cannot Decide”: The Fine Line Between Appropriate Inconclusive Determinations Versus Unjustifiably Deciding Not To Decide

Inconclusive decisions, deciding not to decide, are decisions. We present a cognitive model which takes into account that decisions are an outcome of interactions and intersections between the actual data and human cognition. Using this model it is suggested under which circumstances inconclusive decisions are justified and even warranted (reflecting proper caution and meta‐cognitive abilities in recognizing limited abilities), and, conversely, under what circumstances inconclusive decisions are unjustifiable and should not be permitted. The model further explores the limitations and problems in using categorical decision‐making when the data are actually a continuum. Solutions are suggested within the forensic fingerprinting domain, but they can be applied to other forensic domains, and, with modifications, may also be applied to other expert domains.     

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.     

Reliable Gait Recognition Using 3D Reconstructions and Random Forests – An Anthropometric Approach

Photogrammetric measurements of bodily dimensions and analysis of gait patterns in CCTV are important tools in forensic investigations but accurate extraction of the measurements are challenging. This study tested whether manual annotation of the joint centers on 3D reconstructions could provide reliable recognition. Sixteen participants performed normal walking where 3D reconstructions were obtained continually. Segment lengths and kinematics from the extremities were manually extracted by eight expert observers. The results showed that all the participants were recognized, assuming the same expert annotated the data. Recognition based on data annotated by different experts was less reliable achieving 72.6% correct recognitions as some parameters were heavily affected by interobserver variability. This study verified that 3D reconstructions are feasible for forensic gait analysis as an improved alternative to conventional CCTV. However, further studies are needed to account for the use of different clothing, field conditions, etc.     

论声纹鉴定意见的表述形式

本文针对目前国内外讨论比较热烈的声纹鉴定意见表述问题进行了评述.首先介绍了实践中正在使用的听觉分析法、声谱比对分析法、声学分析法、听觉-声学分析法和说话人自动识别五种鉴定方法,指出了各种方法的优缺点;然后对现存的二元判决、可能性等级、似然比和英国立场声明四种鉴定意见表述形式进行了介绍和评析,通过分析发现,上述四种意见表述形式都存在一定的问题,实践中选择何种形式表述鉴定意见要综合考虑其科学性、逻辑性、现实性和可行性等多种价值选项;最后认为解决该问题的根本方法是各相关领域的专家应加强在鉴定方法上的合作性的基础研究.     

The Forensic Confirmation Bias: A Comparison Between Experts and Novices

A large body of research has described the influence of context information on forensic decision‐making. In this study, we examined the effect of context information on the search for and selection of traces by students (N = 36) and crime scene investigators (N = 58). Participants investigated an ambiguous mock crime scene and received prior information indicating suicide, a violent death or no information. Participants described their impression of the scene and wrote down which traces they wanted to secure. Results showed that context information impacted first impression of the scene and crime scene behavior, namely number of traces secured. Participants in the murder condition secured most traces. Furthermore, the students secured more crime‐related traces. Students were more confident in their first impression. This study does not indicate that experts outperform novices. We therefore argue for proper training on cognitive processes as an integral part of all forensic education.     

The Power of Contextual Effects in Forensic Anthropology: A Study of Biasability in the Visual Interpretations of Trauma Analysis on Skeletal Remains

The potential for contextual information to bias assessments in the forensic sciences has been demonstrated, in several forensic disiplines. In this paper, biasability potential within forensic anthropology was examined by analyzing the effects of external manipulations on judgments and decision‐making in visual trauma assessment. Three separate websites were created containing fourteen identical images. Participants were randomly assigned to one website. Each website provided different contextual information, to assess variation of interpretation of the same images between contexts. The results indicated a higher scoring of trauma identification responses for the Mass grave context. Furthermore, a significant biasing effect was detected in the interpretation of four images. Less experienced participants were more likely to indicate presence of trauma. This research demonstrates bias impact in forensic anthropological trauma assessments and highlights the importance of recognizing and limiting cognitive vulnerabilities that forensic anthropologists might bring to the analysis.     

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.     

THE EMERGING FORENSIC ROLE FOR WORK PRODUCT REVIEW AND CASE ANALYSIS IN CHILD ACCESS AND PARENTING PLAN DISPUTES

An emerging forensic service is that of conducting a work product review of a court‐appointed child custody evaluator's evaluation and report. If the reviewer determines there are serious deficiencies in the work product, then the reviewer will provide consultation to the retaining attorney and expert testimony. The reviewer usually is in a hybrid role of consulting/advising the retaining attorney, testifying, and educating the court. Ethical issues in providing forensic services and rebuttal testimony as a reviewer are discussed. Both reviewers and evaluators have a duty to be objective and balanced in their analyses of data and issues. Both types of experts should strive to be helpful to the court and try to serve the best interests of children. Ethical nuances involving review work are discussed. Evaluator and reviewer share the same dataset. Evaluators need to take care to keep a high quality case record with legible interview notes. Reviewers provide a monitoring function for the court or a function of forensic quality control so the court will not be misled by expert testimony of evaluators that is based on flawed data collection and/or analysis. A list of questions is presented for reviewers to use in scrutinizing the quality of the custody evaluation. A list of questions is presented for examining the quality of the reviewer's own work product. The importance of a case analysis and use of conceptual frameworks by evaluators and reviewers is discussed.     

鉴定人的责任负担

鉴定人是司法鉴定活动的决定性因素。鼓励专家参与法庭服务与约束专家独立、客观实施鉴定这一对矛盾需要通过制度的合理设置达到一定的平衡状态,以适合诉讼活动的开展。鉴定人的责任负担是体现对鉴定人实施鉴定活动进行约束的主要手段,也是我国进一步深化司法鉴定体制改革不可回避的重要内容之一。     

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.     

Naturalistic decision making in forensic science: toward a better understanding of decision making by forensic team leaders

This study uses the naturalistic decision-making (NDM) perspective to examine how Dutch forensic team leaders (i.e., the officers in charge of criminal forensic research from the crime scene until the use of laboratory assistance) make decisions in real-life settings and identifies the contextual factors that might influence those decisions. First, a focus group interview was conducted to identify four NDM mechanisms in day-to-day forensic decision making. Second, a serious game was conducted to examine the influence of three of these contextual mechanisms. The results uncovered that forensic team leaders (i) were attracted to obtain further information when more information was initially made available, (ii) were likely to devote more attention to emotionally charged cases, and (iii) used not only forensic evidence in the decision making but also tactical, unverified information of the police inquiry. Interestingly, the measured contextual influences did not deviate significantly from a control group of laypeople.     

Identifying and measuring juror pre-trial bias for forensic evidence: development and validation of the Forensic Evidence Evaluation Bias Scale

Abstract

Previous research has provided support for the impact of juror pre-trial bias on judicial decision making, particularly in cases where the evidence presented at trial is of weak or ambiguous probative value. In an effort to identify whether a pre-trial bias for forensic evidence exists, the Forensic Evidence Evaluation Bias Scale (FEEBS) was developed and tested. The results of a principal components analysis suggested that two distinct constructs were being measured, corresponding to a pro-prosecution and pro-defence bias toward forensic evidence. In a second validation study, scores on these two subscales were compared with other existing juror bias measures (Juror Bias Scale and Belief in a Just World) and in a mock juror decision making task only the pro-prosecution subscale of the FEEBS predicted the perceived strength of forensic evidence. A partial mediation model is presented which explains the relationship between this bias and verdict preferences. The implications of this potential juror bias are discussed in the context of real juries, the CSI Effect (which refers to anecdotal claims that jurors are biased by the popularity of fictional representations of forensic science on television) and peremptory challenges, as well as future research directions.     

司法精神病鉴定基本问题研究

近年来我国刑事司法实践中曝光的若干典型个案凸显精神病鉴定的混乱状况。实证调研发现,精神病鉴定自身的特征——对象的复杂性、过程的回溯性、知识背景的跨学科性、手段的有限性与结论的主观性,影响到其客观性与可信度。目前精神病鉴定存在的问题主要包括启动难、鉴定过程中医学与法学学科错位、诉讼权利保障机制欠缺、强制医疗制度带有行政化特征以及鉴定体制改革引发的问题。应当在坚持职权主义启动模式的基础上,对部分死刑案件增设强制启动机制,增设申请启动鉴定的上诉途径,细化启动考量标准;司法精神病专家与法律职业群体之间应当重新分工;应当增设被鉴定人由于鉴定导致人身自由被剥夺的法定强制措施以及在专家辅助人的帮助下对鉴定意见的质证权;强制医疗程序应当进行司法化改造并通过社会化途径加强执行能力;在鉴定管理体制上,应当取消现有鉴定主体限于医院的规定,恢复等级化的体系设置并建立鉴定人准入与培养机制。     

Weakening forensic science in Spain: from expert evidence to documentary evidence

An amendment in 2002 to the Spanish Code of Criminal Procedure converted into documentary evidence the expert reports prepared by official laboratories aimed at determining the nature, weight, and purity of seized drugs. In most cases, experts are spared from appearance before the courts. This is likely to be extended to other forensic fields. After an overview of criminalistic identification in current forensic science, the objectivity and reliability concepts used by jurists and scientists are considered by comparing the paradigm of individualization with that of likelihood. Subsequently, a detailed critical study is made on the above-mentioned Spanish legal reform, and a comparison is made with the decision on the Melendez-Diaz v. Massachusetts case as ruled by the Supreme Court of the United States. Although the reform is in compliance with the Spanish Constitution, it is at odds with science, in particular regarding the logic underpinning the scientific evaluation of evidence.     

Evaluating expertise in forensic anthropology

The medicolegal system relies on the ability of experts and non-experts alike to make judgments about expertise and use those judgments to reach consequential decisions. Given the lack of standard criteria, mandatory certification, or licensure for establishing expertise required to practice forensic anthropology and testify as an expert witness, we sought to understand how individuals assess and identify expertise in forensic anthropology by using a social science tool called the Imitation Game. This tool assesses immersion in a specific area of study via discourse, with the premise that some individuals lacking expertise themselves imitate or attempt to pass as experts. For this project we recruited volunteers with varying expertise in forensic anthropology to participate in interviews which asked questions about the practice and structure of the discipline. Those interviews were transcribed, anonymized, and evaluated by other recruited individuals with varying expertise in forensic anthropology. Results found that judges who were experts in forensic anthropology performed better than non-expert judges in determining who was not an expert in forensic anthropology based on their anonymized responses; however, nearly half of the non-experts were still able to pass as experts in forensic anthropology. The difficulties in assessing expertise based on discourse interactions demonstrates the value and need for well-defined credentials and mandatory certification to practice forensic anthropology. This study demonstrates that accurately identifying expertise in forensic anthropology may be challenging for both experts and non-experts, especially when relying solely on interactional expertise rather than formal assessments of competency which directly elucidate contributory expertise.     

Expert Disagreement in Bitemark Casework*

Abstract: Bitemark cases continue to raise controversy due to the degree of expert disagreement which is frequently seen. Using a case mix of 49 bitemark cases from 2000 to 2007 each injury was independently assessed for its forensic significance using a previously described bitemark severity scale. Following the assessment, the mean value for the bites was categorized according to the crime type, the degree of expert agreement, and the judicial outcome. Results suggest that bitemarks found in child abuse cases have statistically significantly lower forensic value than those in other crime types, that bites where there is mutual agreement between experts will have higher forensic value than those where there is disagreement at trial, and that cases in which DNA has provided an exoneration will demonstrate similar quality to those where a conviction was secured. Forensic odontologists should carefully assess bitemark evidence and ensure that it meets certain minimums in relation to the presence of class and unique features before undertaking an analysis.     

浅谈高坠案的现场勘查与法医学检验鉴定要点

高坠案是司法实践检案最常见的类型之一.高坠案的性质有他杀、自杀和意外,多见于后两者.但受高坠案发的突然性、现场多无人在场、很少有可靠的痕迹物证等客观条件限制,使得高坠案的性质判断极其困难.以基层司法实践检案研究为背景,从对高坠现场的坠落起点、坠落空间、水平移行距离、坠落终点进行客观仔细的勘查,全面系统的法医检验鉴定,深入详细的调查走访等多个方面进行全面的阐述和介绍.     

迈向“过程导向信任”的刑事死因鉴定争议解决机制

中国当今刑事鉴定争议频发。其中当事人与办案机关鉴定冲突最剧烈、不满手段最多样,且其社会影响最大者,目前主要聚集在部分死因鉴定领域。该类鉴定争议既滋生过度重复鉴定,更促使部分当事人上访、闹事,一度还以此衍生出暴力性群体事件。死因鉴定争议的发生,主要源于影响鉴定意见可信性的一系列因素,而非仅因为、甚或主要基于鉴定意见的客观可靠性。因此,为重塑中国刑事死因鉴定的公信力,必须走向从实践出发的法律研究与制度建构立场,以回应办案部门创建、并亟须理论提炼与立法改良的“过程导向信任”的鉴定争议解决机制。其关键措施,是通过死因鉴定程序的开放性与当事人双方（包括其聘请的法医专家）的充分参与性,从而实现鉴定意见的可信性或当事人可接受性;并以此领域的鉴定争议解决为突破口,进行鉴定制度改革,以提升中国整个刑事司法鉴定的公信力与可信性。     

浅议鉴定文书对立统一的语言特点

鉴定文书作为一种司法文书，要保证其法律的严肃性、公正性；同时它又是一种类似科学报告的特殊文书，要具有科学性、客观性。目前讨论大多停留在原则层面上，对具体制作语言要求涉及不多。其实，只要正确地处理好文书语言的中立性与预断性、准确性与模糊性、简略性与详解性以及针对性与相关性等四者间对立统一的特点，司法鉴定就很好地履行法律所要求的客观“翻译”工作．同时也降低鉴定人的风险责任。