Expert Testimony

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Courts frequently look to the testimony of expert medical witnesses to assist them in the search for legal truth. In addition to Egyptian and Biblical references to forensic medicine, physicians in Greece and Rome functioned as expert witnesses. A physician testifying at the inquest into Julius Caesar's death stated that he found twenty-three stab wounds on the corpse but only one wound, a wound in the throat, that could have caused death. The Institutes of Justinian (529–533 c.e.) and the codices of Charles V, the Lex Bambergensis (1507), also made provisions for expert medical testimony (Landé; Clements and Ciccone). In the United States, physicians are called on to testify as expert witnesses in a variety of civil and criminal matters. The civil issues range from workers' compensation to child custody, from physical and emotional damages to malpractice. The issues in criminal cases range from cause of death to competence to stand trial, from deoxyribonucleic acid (DNA) typing to the insanity defense. This entry traces how a physician becomes involved as a medical expert witness, what the requirements of the role are, and the ethical issues that may arise.

Courts of law distinguish between fact witnesses and expert witnesses. Fact witnesses may be required to testify if they have some direct knowledge about the issue before the court, but may not express opinions. Expert witnesses have knowledge that goes beyond that of the ordinary citizen and agree to undertake the role of expert witness and are permitted to express opinions.

The difference between a "fact" and an "opinion" is the degree of concreteness of the description, or the difference in the "nearness or remoteness of inference" (McCormick, p.26). The courts and the public receive expert testimony with both admiration and suspicion. There is appreciation for the clarity provided, but fear that experts may control the legal outcome. This fear may be accentuated in a democratic society that mistrusts those with special knowledge. In 1986, the American Medical Association (AMA) took the position that "as a citizen and as a professional with special training and experience, the physician has an ethical obligation to assist in the administration of justice" (Council on Ethical and Judicial Affairs of the AMA, p. 138). The participation of the medical expert may be justified on the basis that a meaningful concept of justice requires empirical data on the function of the human organism in health and disease—data that the medical expert can provide (Ciccone and Clements).

The Expert-Witness Role

Expert-witness testimony in an adversarial legal system may lead to a battle of the experts, a battle that may be avoided if the court appoints an expert approved by both sides of a legal action. There are different models for the expert-witness role. In the first model, the court-appointed or "impartial expert" witness model, the expert witness is still subjected to cross-examination, yet has the implied endorsement of the court—the court would not hire an unqualified expert. However, the view that such an expert witness is neutral is a fallacy (American Academy of Orthopedic Surgeons) because the expert is necessarily an advocate for his or her opinion. In the second, the objective "expert-model," the expert is hired by or appointed to one party, but the expert's role is limited to a comprehensive examination of the evidence and formulation of an opinion, if possible. In the third, the "consultant" model, the expert functions as a consultant to the attorney. The expert provides an accurate statement of the examination conducted, the findings of the examination, and the opinion and reasoning used to arrive at the opinion, and provides assistance with trial strategy and cross-examination (Appelbaum). The ethical hazard of this model is that the expert may identify with the attorney's position and become an advocate.

In each model, the medical expert is expected to provide a clinical evaluation and a review of the applicable data in light of the legal question posed and in the spirit of honesty and striving for objectivity—the expert's ethical and professional obligation. This includes a thorough, fair, and impartial review and should not exclude any relevant information in order to create a view favoring either the plaintiff or the defendant (American Academy of Psychiatry and the Law). The treating physician, whom the court may compel to testify as a fact witness regarding contact with a patient, is frequently sought to provide expert-witness testimony. The legal system assumes that the treating doctor is more credible than a nontreating doctor. The treating physician has a specific therapeutic focus—the patient's health—that may not allow service as an expert witness. The treating physician may encounter a conflict of interest (e.g., maintaining the patient's confidentiality versus providing the court with information).

When taking on the functions and obligations of the expert-medical-witness role, the treating physician may, out of loyalty to the patient's best interests, act as an advocate for the patient. This distorts the obligation of the expert witness. On the other hand, if the treating doctor's expert testimony does not have the effect of adequately supporting the patient's position, the doctor-patient relationship may deteriorate as a result. Hence, the role of physician as advocate for the patient may be inconsistent with the role of physician as expert witness and pose the ethical issue of conflict of role obligation. This conflict should be avoided. When this is not possible, self-awareness of the possible conflict and awareness by the court of the conflict may minimize its effects.

The Ethics of Being a Medical Expert Witness

Medical professionals who undertake the role of expert witness are generally expected to have an unrestricted license to practice medicine, to be knowledgeable and experienced in the area in which they are functioning as a medical expert, and to have knowledge of the legal system. At the initial contact by the court or an attorney, the expert clarifies the question being asked and explores the relevant information about the case. The discussion of the question also permits the expert to be explicit about limitations of the evaluation he or she can offer. The expert witness must know the law that is relevant to the forensic question in the jurisdiction in which the expert may testify. The court or the attorney can provide the applicable statutes. Professional values require such obligations. In addition, legal consequences involving criminal and civil verdicts with ensuing penalties require this standard of obligation.

Medical experts can expect cooperation from the court or attorney in obtaining all the relevant legal, social, and medical documents. Medical experts should obtain consultations from others when there are important areas outside of the expert's knowledge. The medical expert must also be aware that the attorney may have a hidden agenda—understanding the hidden agenda may influence the expert's decision to accept or refuse the case. For example, when the evidence is not strong, is the prosecuting attorney's raising the question of competence to stand trial (CST) a way to keep the individual from being released? Is the defense attorney's request for an evaluation of CST a way to prolong the legal process so that prosecution witnesses may become difficult to locate, thereby weakening the district attorney's case? These are ethical questions the legal system must address, but medical experts who work with the legal system have a clinical obligation to avoid abuse of their role.

The individual who agrees to function as an expert witness is entitled to an expert witness fee, the terms of which should be clear and explicit at the time that the work is started. It is unethical for expert witnesses to make their fees contingent on the outcome of trials. In fact, there are advantages to the expert working with a retainer fee, against which the work of the forensic expert may be charged: (1) it diminishes whatever influence the examiner's concern for payment has on the quality of the work, and (2) if asked on cross-examination if the experts are being paid for their opinions, the experts are able to respond that in fact they were paid on a retainer basis for their time. Such arrangements avoid the ethical problem of experts being seen as "hired guns."

The informed consent of the individual to undergo a forensic medical evaluation should be obtained whenever possible. This includes a description of the purpose of the evaluation, the limits to confidentiality that may exist, and to whom a report will be made. The doctor-patient relationship includes, as one of its ethical requirements, the qualified obligation that the physician maintain confidentiality. The examinations conducted by the medical expert witness are usually outside the scope of the doctor-patient relationship; however, the bioethical obligations remain, and the physician must be aware of the bioethical obligation not to harm the individual unnecessarily by gratuitous disclosure of information. The disclosure of information must conform with the requirements of the law and the explanation made to the individual examined. In a legal context, the medical expert is bound not by rules of medical confidentiality, but by the rules of confidentiality that the legal circumstances require. It is expected that the medical expert witness will be aware of and abide by the specific rules of confidentiality applicable to work with the legal system. Informing the examinee may not be sufficient protection because the physician can create a relationship in which the examinee forgets the warning (Diamond). There are circumstances in medical-legal evaluations where consent is not required. The individual is then informed that the evaluation is legally required. However, if the individual chooses not to participate, the refusal will be included in any report or testimony.

Admission of Expert Testimony

The role of the expert witness is based on education, training, and experience that gives the expert knowledge in a particular discipline. The United States Supreme Court in Daubert v. Merrell Dow Pharmaceuticals (1993) described the limits of expert scientific testimony and endorsed the Federal Rules of Evidence (United States) that had broadened the admissibility of scientific testimony to include theories that were not widely held. The Daubert decision rejected the restrictive standard that permitted the judge to exclude expert testimony that the judge found was not "sufficiently established to have gained general acceptance in the particular field to which it belongs" (Frye v. United States, 1923). However, the U.S. Supreme Court also put limits on "the admissibility of purportedly scientific evidence" by requiring the trial judge to determine whether the reasoning or methodology underlying the testimony is scientifically valid and whether that reasoning or methodology properly can be applied to the facts in issue (Daubert v. Merrell Dow Pharmaceuticals, p. 2796). This gatekeeping function of the judge on expert scientific testimony may lead to judges who appoint their own experts to examine the experts put forward by opposing parties in the litigation.

Ethics and Medical Expert Testimony

The medical expert may be required to testify in perhaps one of ten cases that the expert is called upon to evaluate. It is this public role that causes the most discomfort and is the most sensationalized of all the expert's functions. The medical expert witness usually engages in this work as a part of a larger clinical practice. While some experts have given up clinical work, this is rare. Medical experts who have not actively engaged in their discipline or who have given it up may find their credibility questioned in court. Medical experts have the ethical obligation to inform the court or attorney hiring them of the status of their clinical practice. Prior to entering the courtroom, experts assist the attorney as well as they can "but only within the requirement of medical ethics" (Stone, p. 27). Each of the three models carries the ethical obligation that the expert be honest and, even when assisting an attorney, not become an advocate. The medical expert who is called to testify should require full and complete preparation from the attorney. Preparation for testimony, which almost always includes at least one pretrial conference between attorney and expert, is essential to adequate work in the courtroom.

In court, medical expert witnesses are not advocates for either side in the litigation, but may advocate their opinion. The most effective role of the expert witness is that of teacher—that is, one who elucidates the nature of the evaluations and the reasoning used to arrive at his or her opinions. The expert should present credentials without exaggeration. The expert should be prepared to present specific perspectives or bias and identify value components that are always present in interpretations of the data. If the issue before the court presents an ethical dilemma for the expert, whether as a result of personal belief or from concerns about societal harm that his or her opinion may cause, the expert has the obligation to avoid involvement in such cases. The requirement of truthfulness on the part of the medical expert witness requires that relevant information not be kept secret (Rappeport). In addition, there are limitations that occur in medical examinations, and these limitations of reviewed materials (e.g., completeness of the examination or knowledge of that area of medicine) may require the expert to qualify an opinion or, at times, to decline to provide an opinion to a particular question.

The attorney who retained the medical expert will call and question the expert with direct examination. This usually begins with eliciting the expert's credentials; the questions present the expert's education, training, experience, and other information that chronicle the achievements of the expert to the court. Using the Daubert directives, the judge may rule to exclude the expert. Medical-expert witnesses are expected to present their testimony—avoiding jargon—with sufficient clarity so that those lacking expertise can understand the findings and follow the reasoning. The attorney who has retained the expert can be expected to emphasize his or her ability and the brilliance of the conclusions. The cross-examining attorney, both in speech and gesture, will often attempt to convey to the court that the expert witness lacks credibility and that his or her conclusions are worthless.

The expert may be presented a hypothetical question, which is a conflation of assumptions and proven facts into an organized account of a situation. The hypothetical question calls for expert witnesses to assume the information in the question to be fact. Then experts are asked if they have an opinion derived from those facts and, if they do, to state that opinion. The hypothetical question is used because there is a dispute about the facts, and the hypothetical question allows the court to hear the expert's opinion without deciding if the facts in evidence are true.

The expert witness has rights in the courtroom and may ask the judge to clarify when material that is asked for is privileged. The expert witness may ask for clarification of a question or refuse to answer questions the expert does not understand. Experts may and should say that they do not have a response to the question, if in fact they do not have one. Experts, when asked a yes or no question, can ask the judge whether the answer can be qualified. If on crossexamination this is not permitted, on subsequent redirect examination the attorney who retained the expert may ask for further clarification. The expert has a right to complete an answer and should protest if interrupted. Expert witnesses, as contrasted with fact witnesses, may refresh their recollections using written notes and records.

The courtroom, the most visible portion of the adversarial system with its "battle of the experts," is viewed by some critics as a three-ring circus. Even when expert witnesses agree substantially, small differences may be exaggerated by an attorney and held up as proof that the entire discipline has nothing to offer the courts. If expert witnesses are expected to provide absolute certainty, the witnesses will inevitably be clowns in the courtroom. However, the opinion of the expert witness, as with a medical diagnosis, is a probability statement and as such, is the best conclusion given the analysis of the data. This conclusion may certainly be open to question. Although the credibility of the expert witness is important, the courtroom belongs to the attorneys. The weight given to the testimony of the expert is markedly influenced by the courtroom skill of the attorneys involved. Do the faults of the legal system outweigh its benefits and is there an alternative, superior system for arriving at legal verdicts? This is a question better considered in an analysis of the adversarial system.

At a trial, the ultimate issue is the question about which the jury or judge must arrive at a verdict (e.g., did the defendant's negligence cause the injury to the plaintiff?). It has been suggested that the medical expert respond only to questions about the medical condition and avoid responding to the ultimate issue, which some have called either a leap in logic (American Psychiatric Association [APA] Statement on the Insanity Defense) or the application of medical reality to a legal procedure. It is contended that the ultimate issue is an issue of social and moral policy and, therefore, is beyond the province of scientific inquiry. While there are circumstances when the information does not permit the medical expert to arrive at an opinion, the fact that the question has been framed in a legal context may make it appropriate for the expert to express an opinion. This opinion need not usurp the role of the trier of fact.


Much of society's ambivalence toward expert witnesses is derived from society's unrealistic hopes and fears of expert witnesses. The hope that the expert will have secret skills, which provide special access to absolute truth, imbues the expert role with unrealistic authority and certainty. This expectation of expert witnesses is not consistent with the reality of scientific expertise that allows for probable conclusions. The fear that the expert will take over the legal process and subvert justice is also exaggerated. The legal system has rules of procedure that limit the influence of the expert witness. Functioning within the boundaries of science and governed by ethical guidelines, experts are not oracles whose conclusions are not open to question, but witnesses who can provide the legal system with useful information.

j. richard ciccone (1995)

bibliography revised

SEE ALSO: Confidentiality; Conflict of Interest; DNA Identi-fication; Law and Bioethics, Law and Morality; Malpractice, Medical


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