Abstract
Impartiality of expert witnesses means that such experts operate within scientific principles and legal procedures. By doing so, they assist the trier of fact. There are two aspects to the requirements for the impartiality of expert witnesses: the individual perspective and the industry perspective. Each expert witness must follow individual standards, including avoiding irrelevant information affecting his or her opinions; applying reliable methods; employing reasonable analysis; and providing the findings in comprehensive reports (including a precise description of personal background and expert activity). They must also follow industry standards of forensic science regarding objective technical accessible demands, laboratory management and career management. Biased expert witnesses, however, will damage impartiality and impede the goal of assisting the trier of fact. Based on psychological theories such as dual process theory, authoritarian personality and intergroup threat, this paper classifies expert witness bias into four categories: (1) cognitive bias; (2) bias in the analytic process; (3) bias resulting from the position of the expert witness at trial; and (4) the social bias arising from social pressure or economic pressure. Because bias influences the relevance, credibility and impartiality of experts, steps should be taken to restrict certain categories of bias, which can be and must be controlled. Reflecting the differences between the Anglo-American legal system and the Chinese legal system, in China the bias of expert witnesses should be controlled in terms of actions, occupational management and independence of laboratories.
Meanings of impartiality of experts
The authenticators and authentication institutions engaging in proving scientific facts must abide by the laws and regulations, professional ethics, occupational disciplines, and technical operating standards (see Wang and zhang, 2013: 9). This paper concerns the standards of impartiality for experts and argues that experts should base their opinions only on the materials submitted to them, using the analytic methods and interpretive tools accepted by the peers in their field.
Some scholars argue that experts are expected to make their decisions as judges or juries, making their opinions standing in the middle (see Hu, 2014: 194 and Zhang, 2003: 380). But experts are not the triers of fact, because the information they rely on is usually provided by one side rather than by the two parties. While the task of experts is helping judges and juries find the truth, they are not the ones making the ultimate decisions. As a result, the experts cannot obtain all the materials because the experts are hired by one party. Even in inquisitorial systems, in which experts are not sponsored by the parties but instead by ‘the system’ (Malsch and Freckelton, 2009: 127) and therefore may obtain more all-around information, they still give their opinions based on information they obtained.
Impartiality is the core of forensic science
One of the roles of experts is to evaluate scientific findings and the results of analytical tests in the context of the relevant case circumstances. Because the forensic evidence is highly specialised, it is difficult for judges and juries, who are usually lacking in scientific and technical knowledge or experience, to understand. If expert witnesses are unfair, it is difficult for the trier of fact to identify the bias as well as to reach the truth.
The impartiality of expert witnesses requires that the expert should avoid the dispute between the two parties, and instead give his or her testimony exclusively based on the materials. Their opinions need to be evaluated by their peers directly and unambiguously.
To help the trier of fact discover the truth, experts must be impartial. Using scientific methods to analyse scientific evidence will help the trier of fact resolve unsolved issue. Forensic science plays an important role in solving key problems, such as such as helping the trier of fact to understand a fact in issue or the evidence, which are the cores of the cases and special knowledges (see Zhu, 2006: 15). So the answers are expected to be right, or at least should not be based on incorrect science. The expert testimony may only be the part of truth, which is beneficial to the commissioning party, but cannot be allowed to confuse the trier of fact. Because the judges, lawyers and both the sides may be the laymen, all of them lack the ability to discover errors in the expert’s opinion or methodology.
The equality of procedure requests the impartiality of experts. The equality of process means that both sides could hire the experts, helping them to find the truth based on the information they obtain. From this point of view, the gap between the opinions given by experts of the sides is normal and logical, because of the different information and materials they have and because of their adversarial standpoints. During cross-examination, judges or jurists can find the truth after considering the experts testimony of both sides, and evaluating which story is more credible depends on the decision of the trier of fact.
Standards of impartiality of experts
This paper examines the requirements for the impartiality of expert witnesses from two perspectives, that of perspective of individual experts and the industry perspective.
Requirements of perspectives of individuals
Each expert witness needs to follow the requirements for experts, including: avoiding irrelevant information affecting his or her testimony; applying reliable methods; using reasonable analysis; and providing comprehensive statements.
Cumulative information includes irrelevant or extraneous information and tendentious information. Extraneous information may confuse the experts, while tendentious information may lead to wrong decisions.
Reliable methods are central to the impartiality of experts. The primary function of experts is to use scientific knowledge, experience and technology that other people involved in the case are not familiar with to help those people know vital facts. As a result, applying reliable methods is the first requirement of expert witness impartiality. Furthermore, information about the case is the premise of the reliable methods.
Well-founded analysis is the bridge between the scientific conclusions and the truth. But it is hard to devise a legal standard to determine whether the analyses made by the experts are well-founded. Experts, who are proficient in their fields, help laymen to make decisions about the expert’s procedure, which means that where the analysis is not reasonable, this is a fact that laymen could not perceive without expert assistance. Because unjustified analyses may lead to unperceived erroneous conclusions, the analytic process needs to be well-founded and reliable.
In order to ensure that other people in the court can understand the testimony, comprehensive expert reports should be unambiguous. One of the functions of cross-examination is to helping the fact-finder to see flaws in the expert’s analysis and reach the truth. This also can bridge the gap between the expert testimony and other evidence, thereby constructing a whole story based on all the evidence that one side holds. As a result, expert opinions should be stated in court. Experts may give their statements in the courtroom, 1 or submit their reports to the court. 2 It does not matter what form they use for stating their comprehensive statements, experts should be asked to give their statements about all their findings, abiding by both the technology and the law to find which is beneficial to their clients.
Experts’ standards from the industry’s perspective
With the development of science and technology, some forensic analyses need laboratory experiments, such as the technology of DNA analysis. In these analyses, experts find results and give their conclusions after doing some experiments. Therefore, in addition to the impartiality of individual experts, the laboratory is another factor in achieving impartiality of experts. Industry standards for forensic science include objective, technically accessible demands; laboratory management; career management; and precise location of their occupation.
Some courts have imposed strict and systemic objective technical accessible demands, such as Rule 702 of the Federal Rules of Evidence (see Wang, 2012: 212–216). On the other hand, legal standards are another factor influencing on the impartiality of experts in China. Some fields request that the experts provide opinions using special methods, such as psychiatric testing or the evaluation of body impairment. The Guidelines for Examination for Body Impairment in Clinical Forensic Medicine adopts the Improvement of Boston Diagnostic Aphasia Examination to confirm whether a person has aphasia. 3 Besides this test, there are several other diagnostic methods. The most popular in China is the Chinese Rehabilitation Research Center Aphasia Examination (CRRCAE) (see Yan et al., 2010: 377). The guideline regulated by the Ministry of Justice of the People’s Republic of China adopts one of the methods and excludes the other methods, which prevents other methods from finding the truth. Different methods may lead to different conclusions. This guideline, therefore, does not provide the best objective, technical scientific information available.
Scientific experiment requires the equipment, reagents, samples and so on which are provided by the laboratory. Therefore, the proper management by the laboratory of all the elements in the operation could ensure that experts find the correct results. Polluted reagents and samples, or the broken link of protection of physical evidence, will tend to lead to erroneous results. Because of these concerns, the laboratory operating must be under a unified operation process, such as following the Accreditation Criteria for the Competence of Testing and Calibration Laboratories (ISO/IEC17025: 2005), 4 which standardises results from different laboratories. This means that research and experimentation in different laboratories should not be an element influencing on the expert opinions.
Pressure coming from the operator of the laboratory or from famous scholars may influence the impartiality of experts. If the expert gives the opposite view to the one the lab or prominent scholar expects, he or she may be under pressure. As we could not find all details of phenomena of mortality, the percentage of laboratories confirming the cause of death could not be 100 per cent. If senior administrators request the expert to find a specific cause of death, the forensic scientists have to follow such instruction. As a result, false reports are presented. Such a situation occasionally occurs in China.
Forensic science is characterised by a concern for public welfare, in both the legal process and in society, though it also makes profit for the practitioners in the field. The public welfare lies at the industry level, because of the function of helping the trier of fact to reach the truth and the order of the society. For the practitioners, locating their occupation precisely in terms of balancing public welfare and utility is the core of the impartiality of experts.
The factors that lead to bias in experts
Bias in experts could influence their impartiality, leading to the trier of fact making an unfair decision. Because the source of bias is the cornerstone of this problem, the nature of bias will be clarified first before discussing how to control bias in experts.
Psychologists define bias as a wrong attitude or a wrong cognitive system, primarily deriving from limited or wrong information (Li and Jia, 2013: 84). Bias is a tendency to be in favour of or against something or someone without knowing enough to be able to judge fairly (Longman Group, 1988: 117). Bias is characterised by judging without enough information, no matter whether the results favour one party or not. Fundamentally, bias in experts reflects the amount of distortion of information. Bias means that without knowing enough information, someone makes his or her decision regarding an individual or an event.
We know that bias may lead to unfair decisions. The next question is: Where did the bias come from? Psychology may give us some references and insights. In psychology, dual process theory insists that individual children are influenced by their parents and the community attitudes that they live in, before they realize attitudes of their parents and the community how to affect on themselves. These early social attitudes are stored in long-term memory, becoming the basis of their developing personal attitudes and views. As a result, the attitudes of their parents and the community they lived in can influence a person during their whole life (Chen, 2011: 20). If the experts have built a bias in their early ages, this bias which accompanies them could easily influence their testimony. And they may even not realise that they are not impartial.
Another factor resulting in bias is stereotype, which is relevant to portrayal of a group and arises from fixed beliefs or ideas (He and Liang, 2008: 760). In stereotype theory, the bias of language includes the description of positive or negative behavior of in-group and out-group members (Zebrowitz et al., 2010: 185–186). For example, different observers may describe a fight from different perspectives. Strangers tend to use the abstract descriptive vocabularies, describing violence and brutal tendencies, whereas those who are friends of the fighters tend to use specific language to describe it. The use of biased language is associated with two factors. One factor is encoding, which means people obtain same information or remember same events in different perspectives (see Wenneker Clemens et al., 504). This leads to extraction or storage of information that is more abstract or more specific. Another factor, the communication goals, relates to the retrieval and exchange of information. Individuals want or feel the need to convey a particular kind of information to others, which, based on the organisation of language and the goal of the communication, represents the standpoint of the person who describes a story, and the relation between that person and the object of the description. Psychology studies show that such coding factors affect descriptions automatically, transferring the belief of people who are describing events using unconscious stereotypes (see Wenneker Clemens et al., 504).
Authoritarian personality is a third source of bias in experts, as an authoritarian personality divides the world into two parts—we and they—and the gap between these two groups results in bias (Li and Jia, 2013: 85). According to this theory, expert will have some bias against the other party. The role adopted by scientist affects how scientists identify themselves within an adversarial judicial system; either as part of the prosecution or on behalf of the accused. This may introduce subconscious bias, with experts affecting their decisions especially where some ambiguity exists (see Langenburg et al., 2014: 17, citing Dror et al., 2005 and Charlton et al., 2010). As an expert, finding the ‘truth’ that is beneficial to his or her commissioning party may seem logical and inevitable. Just as the experts hired by the two sides may follow different procedures, so they may also tell different stories at the trial. The gap between the impartiality of the expert witness and their bias is clear.
The final cause of bias in expert witnesses is so-called ‘intergroup threat’. ‘Intergroup threat’ means that the resources of a group, including the behaviour, beliefs, values and other characteristics of the group members, are likely to threaten the existence, development and goals of other groups (Zhang et al., 2009: 473). When an intergroup threat occurs, members of this group will generate a bias against other groups, which is called ‘group bias’. Currently, psychological research mainly focuses on the negative attitudes generated by this type of bias. Study of expert bias is based on these psychological studies. As experts, they may have attitudes in both cases. This is why this paper insists on considering both negative and positive attitudes of intergroup threat.
The classification of expert bias
Based on psychological theories such as dual process theory, stereotype, authoritarian personality and intergroup threat, this paper classifies the bias of expert witnesses into four categories: (1) cognitive bias; (2) bias in the process of conclusion; (3) bias resulting from the position of expert witness in the trial; and (4) bias due to social pressure on the expert witness.
Cognitive bias
Cognitive bias includes confirmation bias, bias of science and technology, bias caused by profits, bias of location of expert occupation, and bias caused by experiences of experts.
Confirmation bias means that people test hypotheses by looking for confirming evidence rather than potentially conflicting evidence (see Balcetis and Dunning, 2006: 612). According to this theory, irrelevant information of decision-making should not let experts know, thereby preventing them from confirmation bias.
There are two types of confirmation bias that arise in science and technology. One is manifested in experts who excessively depend on particular scientific and technological methods to provide their conclusions. The other, conversely, is a bias against science and technology, which means that the experts depend on their personal professional experiences excessively without confirming their scientific reliability, or depend on unverified scientific methods.
Bias caused by profits leads experts to give their opinions against scientific principles or against their own professional experience of their field. As mentioned above, public welfare and utilitarian principles form the core of forensic science. If experts do not recognise both of these features and balance between them, they may excessively pursue the utilitarian, ignoring the public welfare, leading to cognitive bias.
The final element of cognitive bias is the bias caused by the individual experiences of experts. Experts’ own knowledge and their cognitive abilities will be influenced by their personal experiences, such as the attitudes of their parents, the community they lived in and their educational backgrounds.
Bias in the process of drawing conclusions
The process of giving expert testimony involves making judgements and stating opinions. Furthermore, the stage of making the judgements could be divided into obtaining the test results through science, technology and other means, and analysis of the results and evaluation of the results (see Hume, 1981: 19–21). Therefore, bias in experts in the process of reaching their conclusion can be occur in various stages: accepting the case, obtaining the test results, analysis of the results, evaluating the results and providing expert testimony.
When at the stage of accepting a case, bias may be caused in experts by communication with their clients, especially if the clients are their acquaintances. For example, if the client is an officer of the community that the expert lives in, the identity of this officer means that the case happened in an area that the expert is familiar with. Although the identity of the client is irrelevant information, it may be inadvertently transmitted to the expert, which may lead the expert to know information that may trigger bias.
During the stage of obtaining the test results, bias in experts is mainly caused by bias of laboratory management and cognitive bias. Errors and the misunderstanding of results have a detrimental influence upon reaching the truth.
During the period of analysis, bias comes from the generalisation of experts, which is mainly reflected in choosing the information used to give the conclusion. This kind of bias is usually caused by stereotypes, especially the encoding stage, in which people tend to describe something from only one perspective (see Wenneker et al., 2005: 504).
Bias in experts that is presented in expert evaluations via expert testimony reflects the goals of communication. For instance, experts’ testimonies tend to favour their clients rather than stating everything they find based on the materials.
Bias resulting from the position of expert witnesses in the trial
When experts are sponsored by a party, such as the prosecution or the defendant, bias may arise. This paper divides the analysis of such bias into prosecuting party bias and bias of experts called by the defence.
The prosecuting party and the defence take opposite positions in the litigation. When representing them, experts tend to protect the interests of the group that hired them, which is inevitable in adversarial legal systems. Experts called by the defendants tend to suffer from bias caused by intergroup threat. The bias influences the impartiality of experts, because the expert hired by the defence wishes to help the accused find facts beneficial to the commissioning party.
Bias due to social effect on the expert witness
The three categories of bias of experts discussed above relate to the individual’s perspective. From an industry perspective, bias due to social effect on the expert witness is divided into bias in experts caused by laboratory management, bias caused by occupational pressure and bias caused by the social environment.
Some forensic analyses require laboratory experiments. If there is bias in the operation of the laboratory, then bias of the experts working in the laboratory is inevitable. Bias in laboratory management means problems in the management system, such as in the case of how to diagnose the aphasia. If the proper methods are not adopted, experts cannot use them to find the truth. And such bias is more serious than the bias of an individual expert, because it affects more experts and more cases.
The occupational pressure caused by the hierarchic system mentioned above may also lead to the bias of experts in their occupation. Occupational pressure may result in bias caused by misunderstanding of forensic results. This kind of bias may also stem from an intergroup threat.
Both the individual experts and the industry of forensic science occupy a special social environment. As a result, forensic science and its practitioners may have been influenced by the social environment, which leads to bias caused by social environment. The mistrust between people who are in the social environment makes it harder for the experts to take an ambiguous attitude when dealing with fields or problems that science has not solved.
Limiting bias
In order to maintain the impartiality of expert witnesses, it is necessary to control the level of bias in experts. Because experts’ bias influences the relevance of their expert testimony, the credibility of an expert witness, and the impartiality of experts, steps should be taken to restrict categories of bias that can and must be controlled. But which kinds of bias can be controlled? This question should be answered before discussing the process of controlling them.
Which kinds of bias can be controlled?
Experts’ biases can be classified into controllable and uncontrollable biases. For example, according to psychology, the effect of communication to describe words through affecting the target system is an unconscious transmission. Therefore, the coding factor of statements is not controllable. Based on the encoding method, bias of experts in the deduction stage is not controllable, or, at least, it is not controllable directly. Because of the deduction process presented by statements in the courts, bias in the deduction process can be controlled in the statements phase, rather than controlling it separately.
Which kinds of bias need to be controlled?
Biases that can be controlled can be divided into bias that should be controlled and bias that do not require control, as not all the kinds of expert bias influence the impartiality of experts or affect their ability to reach the truth. On the contrary, some kinds of bias contribute to constructing the story. For example, if the experts obtain more details of poisoning cases such as details regarding the crime scene, it is easy for them to confirm the type of the poison and how the poison came into the body of the victim. As a result, bias caused by that kind of information belongs on the list of biases that need not be controlled.
One way to control the bias of experts: Control the system of forensic science
However, when expert bias affects the impartiality of experts or affects their ability to reach the truth, some legal measures should be taken to control such bias. Controlling the system of forensic science includes establishing reasonable technical access mechanisms, establishing reasonable management systems and improving the selection and evaluation system of experts.
Establishing reasonable technical access mechanisms
Establishing technical access mechanism is an effective measure to control the bias of expert witnesses. This can reduce the bias of other technologies, which experts are not allowed to use. In order to eliminate this kind of bias, more technology could be allowed to help experts reaching their conclusions. This could reduce the bias caused by different categories of technoloyies. Another reason to take this measure is the public welfare aspect of forensic science. These technologies may also help the trier of fact to reach the truth. It should be possible to allow experts to use these technologies rather than exclude them from the lawsuit because of bias.
Establishing reasonable management systems
Establishing reasonable management systems plays an important role in improving the management of experts, especially of those experts belonging to the investigation authorities in China. In China, investigation powers are implemented by the police, which characterized by both the judicial powers and administrative powers (see Li, 2011: 151). Experts who work for investigation departments, sometimes have to apply their opinions meeting their superiors’ requirements. Because of serious social panic, forensic experts must find out the cause of death of victims of murders, supplying some clues for investigators. But sometimes they could not find the reason as there is inadequate information to reach a conclusion. Laws and regulations should allow the experts to give ‘cause of death unclear’ as their conclusion. Only in this way can the expert testimony abide by both the law and scientific principles, and thus meet the requirement of impartiality for experts.
Establish a reasonable selection and evaluation system for experts
When the experts are selected and evaluated, there are several aspects that should be considered, including professional competence, professionalism, the expert’s ability to provide a statement and his ability to obtain new knowledge. These factors aim to control the bias of experts caused by the cognitive bias, community affection and so on before they are trained as experts.
A second way to control expert bias: Legal measures
Cross-examination
In the adversarial system, expert witnesses play a pivotal role in assisting the judges or juries to use forensic evidence. One underlying risk in this adversarial model is that it may result in unfairness because experts are biased in favour of their clients (see Lee, 1988: 480). Accordingly, lawyers can estimate whether the experts are impartial by posing questions during cross-examination (see Paciocco, 2009: 569). For example, lawyers could inquire about the experts’ situations in the procedure, their individual or professional prejudices, and the principles on which they based their conclusions. As a result, cross-examination is a significant and effective control of the bias of experts in an adversarial legal system.
Impeachment
Because bias in expert witnesses weakens the reliability of expert testimony, it could be offered as impeachment evidence against an expert witness who has given testimony. If an expert is found to be biased during cross-examination, the other side could be entitled to impeach the credibility of the expert in order to exclude his or her testimony.
A third way to control bias of experts: Ensuring the independence laboratories
Ensuring the independence of laboratories means that operating a laboratory follows the requirements for laboratory standards and is independent of administrative management. Supervision of a laboratory is another factor to consider in maintaining laboratory independence.
Laboratory management under industry standards is a prerequisite to ensuring the independence of a laboratory. The equipment, reagents and samples all influence the outcomes of experiments. As a result, the management of all these elements must comply with the ISO/IEC 17025, which can control expert bias caused by the laboratory methodology. Laboratory operation should depend on scientific principles and legal rules rather than administrative orders. Therefore, the management of laboratory is the cornerstone of ensuring the standardisation of the laboratory’s operation, which results in the independence of the laboratory.
The laboratory must also be independent of administrative management, to ensure that laboratories are administered by persons who are familiar with the laboratory’s operation. This management mode is conducive to the establishment of internal supervision mechanisms, which will improve the control of biases caused by technology, thereby preventing erroneous opinions presented in the court.
Conclusion
This paper has focused on how expert bias can diminish the reliability of expert testimony and has traced how such biases arise. Bias of expert witnesses results from individual expert’s problems as well as industry-wide biases. To avoid bias, expert witnesses should follow requirements of impartiality, including: avoiding redundant information affecting their judgments, applying reliable principles and methods, deducing opinions from facts or data reasonable, and stating their opinions comprehensively. From the perspective of the industry, standards of forensic science should include deliberate technological admission, standardised laboratory procedures and the precise location of their occupation.
To help experts remain impartial, the bias of expert witnesses should be controlled in terms of their individual actions, their professionalism and the independence of laboratories. To support their actions, the leading investigator should make sure that experts receive appropriate information. And the experts, through their professional training, should ensure that they analyse and give their opinions impartially. With respect to the independence of laboratories, operating under ISO/IEC 17025 will mean that the apparatus and operational methods are standardised. Operating laboratories standardised could avoid irrelevant information affecting on experts' decision-makings..
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.