Expert witnesses

SIGNIFICANCE: Testimony by expert witnesses can aid jurors in comprehending complex evidence; however, there are also risks that jurors may overvalue such testimony because of the professional positions of the witnesses or will completely dismiss the testimony because of its complexity.

In the second half of the twentieth century, case complexity within criminal and civil trials dramatically increased. As a result, reliance on expert witnesses and their role in the court system has also greatly increased. Within the adversarial trial system, the objective of expert testimony is to explain or clarify scientific, technical, or medical evidence for the benefit of the jury. Product liability, medical malpractice, antitrust, and many other issues arise in cases that require the testimony of an expert witness.

Rules and guidelines place limits on the types of witnesses who may be considered experts. It is the judge’s responsibility to decide, first, if the testimony of the expert will assist the jury in understanding the evidence or in determining a fact that is at issue. Second, guidelines help judges ensure that any testimony heard is from a witness who is appropriately qualified to speak on the subject. As more expert witnesses are brought into courtrooms to comment on various complex subjects, concerns arise that experts are merely “hired guns.”

Private Versus Court-Appointed Experts

One important issue to consider is how an expert witness is selected. Due to the adversarial nature of trials, each side may present an expert witness of its own choosing. Privately appointed experts have the potential of being biased in favor of the attorney who hired them. In addition, attorneys also have the opportunity to shop around until they find an expert who agrees to or is willing to present testimony in their favor. Privately appointed experts can be quite expensive, meaning that those with greater wealth may have an advantage in affording a helpful expert witness over those who lack financial resources.

An alternative to the privately appointed expert is the court-appointed expert. Although court-appointed experts are more common in other countries, some venues within the United States, such as family court in Texas, use them extensively. The benefit associated with using a court-appointed expert is that the witness is known to hold an objective position and is not perceived as having a hidden agenda.

Although approved of by judges and experts themselves, research has shown that attorneys are the least likely to favor using court-appointed experts. Not only do attorneys fear losing control over the trial process, there is also relatively less communication between court-appointed experts and attorneys. Court-appointed and privately retained experts both have their benefits and drawbacks; however, privately retained experts are most likely to be used in the criminal justice system in the United States. The next important issue to consider is how jurors perceive and evaluate expert witnesses and their testimony.

The Influence of Expert Testimony on the Jury

Once the judge has ruled on the admissibility of expert witness testimony, it becomes the jury’s responsibility to weigh and evaluate the testimony. An important issue that continues to arise is the potential confusion of jurors that may result from a “battle of the experts.”

Many court actors express apprehension at how the jury may interpret expert witness testimony. Some claim the intellectual incompetence of jurors will interfere with their ability to understand most expert testimony. This juror incompetence is said to result in one of two outcomes. In the first, jurors may simply rely on the superficial characteristics or credentials of the expert, taking the testimony for fact and not critically evaluating the testimony. In the second, the expert testimony and evidence may be too complex for jurors, and they will simply disregard it. In other words, there is a perception that jurors will either undervalue or overvalue the expert testimony.

Research has been able to assuage many of the concerns regarding jurors’ interpretations. Although studies have revealed that jurors do have difficulty understanding complex expert testimony, research has also shown that jurors not only critically evaluate the quality of an expert’s testimony, but also critically evaluate the credentials of the witness. In addition, difficulty in understanding and adequately evaluating expert testimony has been linked more often to the poor presentation of the evidence and testimony than to intellectual inadequacies among jurors.

Jurors themselves have revealed that they are not passive receptors, simply accepting expert testimony and complex evidence in an uncritical manner. To the contrary, jurors actively and critically evaluate and discuss complex evidence and testimony. Although there always stands a risk that jurors will misunderstand or undervalue complex expert testimony, it has been established that jurors take their responsibility quite seriously and adequately evaluate and integrate complex expert testimony. As science, medicine, and technology continue to advance, the role of the expert witness will continue to be relied upon to assist jurors in adequately comprehending important yet complex evidence.

Bibliography

Anderson, Patrick R., and Thomas L. Winfree, Jr. Expert Witnesses: Criminologists in the Courtroom. Albany: State University of New York Press, 1987.

Billings, Paul R., ed. DNA on Trial: Genetic Identification and Criminal Justice. Plainville, N.Y.: Cold Spring Harbor Laboratory Press, 1992.

"Court-Appointed Expert Witnesses." Cornell Law School, www.law.cornell.edu/rules/fre/rule‗706. Accessed 26 June 2024.

Freeman, Michael D. A., and Helen Reece. Science in Court: Issues in Law and Society. Brookfield, Vt.: Ashgate/Dartmouth, 1998.

Huber, Peter W. Galileo’s Revenge: Junk Science in the Courtroom. New York: Basic Books, 1991.

Lubet, Steve, and Elizabeth Boals. Expert Testimony: A Guide for Expert Witnesses and the Lawyers Who Examine Them, 3rd ed. Wolters Kluwer, 2014.