Role of the Scientific Expert Witness

Court testimony may be required of anyone involved in the investigative process. Expert witnesses are used to provide relevant information from their specific role in the investigation, have more knowledge on a subject than the average person, and are able to provide the court with opinions based on their experience. The triers of fact then determine guilt or innocence based on a variety of evidence. Evidence is information provided through testimony, materials, or documentation. So what exactly is an expert witness? An expert witness, according to Federal Rules of Evidence 702 (1988), is “one who by reason of education or specialized experience possesses superior knowledge respecting a subject about which persons having no particular training are incapable of forming an accurate opinion or deducing a correct conclusion”. Knowledge and expertise on a particular case (i.e., officers, detectives, and crime scene personnel) or on a specific evidence (i.e., laboratory scientist) constitutes a forensic scientist as the expert. Law has defined the role of an expert as an impartial educator who assists the triers of fact by providing specialized knowledge to help decide the outcome of a case (Frankel, 1989). The expert is also an instrument of the lawyer and court, making that person a witness. Forensic experts are used to provide scientific and technical information within their area of expertise to judges and juries, also referred to as the triers of fact. Experts have an ethical obligation to define their area and level of expertise and should not testify beyond that level of expertise. Expert testimony is based on facts and honesty. Expert witnesses should provide a simple statement of their education, an evaluation of the relevant evidence, and a presentation of their findings in court. Experts must be willing to volunteer information that may be ethically, though not legally, required (Frankel, 1989). In addition, experts must point out the nature of scientific findings and acknowledge contradictory evidence when it exists. Scientists have an ethical obligation to inform the lawyers of the limitations of the scientific evidence. Juries tend to give a disproportionate amount of weight to expert testimony due to the CSI effect, so experts should not abuse the authority they have in the courtroom. Experts hold a position in the gray area of working in a court of law while exhibiting nonlegal expertise.

Academics and the legal system do not usually coexist in comfort. The laws of science and the rules of evidence have little in common. In theory, academia functions on the principle of collegiality. In theory and reality, the American legal system is adversarial. The average academic entering the legal system is in a tremendous culture shock. (Goff, 2000)

Should scientists accommodate the law when in the courtroom? This perception may be interpreted in a number of ways. First, is this statement implying that scientists should act unethically if that is the precedent set by the court? Next, is the statement implying that experts are brought into the court as pawns of the lawyers? Finally, is the statement specifically referring to the scientists’ testimony, demeanor, or scientific nature? Alan Goldman states that scientists should “accept limitations on their authority to act on direct moral perception....” However, it has also been stated that “if the law has made you a witness, remain a man of science; you have no victim to avenge, no guilty or innocent person to ruin or save. You must bear testimony within the limits of science” (Saviers, 2002). When scientists enter a courtroom, they must be careful in what they say and how they say it. It is the job of those in the adversarial system to discredit the experts’ testimony and, at times, even the experts themselves to make the best case for their client. Jurors should exhibit caution and not overweigh evidence and information provided by experts.

Though expert witnesses do not have formal rules for testifying, there are some common informal rules to follow. Experts should not discuss the case with anyone outside of court. One may not know the suspects, victims, family members, friends, investigators, or opposing council, so it is best not to risk providing information that could negatively impact the case. Experts should avoid advocacy and defensive or argumentative responses. These actions may feel natural when conducting business in the adversarial system; however, by preventing natural instincts, the experts will reinforce their credibility with the court and the triers of fact. Expert witnesses should immediately stop talking if the judge or lawyer interrupts. If yes-no questions need clarification, the experts should request permission to answer in greater detail than the original question required. Experts cannot avoid questions if they believe the answer will support the opposing side; the worst thing forensic experts do for their credibility is to show bias or hesitate to give an objective answer (Shiftman, 2000). Written reports should be thorough, concise, readable, and objective; should not fail to provide requested details; may contain reviews of relevant literature, statistics, and resources used; and, finally, should present an opportunity for the expert to provide all necessary information without the common interruptions that occur in a courtroom. Reports should also include information regarding the work conducted by anyone other than the expert. Experts should not volunteer information without being asked, should not guess answers, and should not generalize. The experts’ testimony is less effective when it is presented in a generalized manner, although some attorneys may push the experts into such a method of response. An ethical dilemma is created as a result and should be avoided. It is acceptable, and at times expected, that experts will respond to questions with the answer, “I do not know”; qualification as an expert does not make someone an expert on all topics. Expert testimony may cite the opinions of authors and base answers off standard information found in scientific books and journals. Experts should assure that they fully understand questions before answering, recognize the weaknesses of their opinions, and prepare for questions regarding those possible weaknesses. Examples of weak opinions include those based on prior testimony in the case where new technologies or methods have developed since the previous testimony. The most important rule for ethical expert witnesses is to present opinions truthfully after all information is collected and examinations are completed (Model Rules of Professional Conduct, 2002). These are just some of the informal rules that prepare a scientist to present expert testimony for the judicial system.

Expert witness testimony may have a significant impact on juries because it is considered highly credible. It is important that the information provided by experts measures up to the jury’s expectations of reliability. Scientists should avoid junk science, evidence that is not consistent with generally accepted scientific views. Daubert criteria have helped to eliminate this issue in court and are discussed further in Chapter 6. Experts receive criticism if their testimony is speculative, includes facts not exhibited by the evidence, is not relevant, is common knowledge, or is based on inadmissible information. The jury may have difficulty processing evidence when both the prosecution and the defense have experts who are highlighting differing facts. Conflicting testimony by two expert witnesses happens; it may occur because the focus is on different measures, interpretations vary, the experts use different approaches, or the scientists were trained in different schools of thought. Most commonly, the differences may be traced back to the lawyers’ line of questioning, which is meant to favor their client. Even if expert opinions conflict, it does not necessarily make one more right or wrong. It is possible that both points are valid based on specific research. Literature serves as a guide, but in the truth of science, facts are meant to be challenged. Science is ever changing, which is how uncertainty in science becomes an obstacle for expert witnesses. The adversary process does not allow for the exchange of information between experts when facts conflict, which is needed to help overcome uncertainty. If witnesses could communicate with the opposing expert, they may receive clarity regarding the origin of their differences in opinion. Additional drawbacks for the expert witnesses include the risk of damage to their reputation if the opposing council attempts to discredit them, contradictory information provided by opposing experts that may make science look divided and unreliable, fees charged by private experts that encourage bias (or the perception of bias), and the lack of fees for public experts that may create problems of witnesses undermining information. Other issues aside, expert testimony comes with a great responsibility for the scientist. Expert witnesses are one tool lawyers use to formulate a case on behalf of their client. The differences between science and the law, which will be discussed in Chapters 6 and 7, make the process of expert testimony difficult; however, scientists must remain impartial and speak to only what information the evidence and testing have provided. Expert witnesses are held in high esteem by the jury, so it is important to provide information accurately and authoritatively.

 
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