Judicial Notebook

Recently some states have made it more difficult for professionals to be excused from serving on juries. A consequence of this change has been a growing concern over the influence these professionals may exert in jury deliberations by virtue of their specialized knowledge. Two cases illustrate the problem.

Case background

In May, the New York State Court of Appeals ordered a new trial for a homicide defendant convicted by a jury that included two nurses who called upon their medical knowledge in deliberating with other jurors. In People v. Maragh (2000 N.Y. LEXIS 899), the defendant was charged with beating his girlfriend to death. The prosecution presented evidence indicating that the cause of the woman's death was "blunt force trauma to the victim's liver and spleen, with massive internal bleeding." The prosecution argued that the defendant inflicted this trauma by repeatedly punching her in the abdomen. The defendant claimed that the victim suffered from seizures and died as a result of a venous air embolism. Expert testimony offered by the defense indicated that "autopsy results were consistent with death from an air embolism or other cardiac event" and that "the reported blood volume loss was inadequate to cause loss of consciousness or shock, let alone death."

After the defendant's conviction, two jurors came forward and testified that another juror, a registered nurse, had informed the jury that, contrary to the expert testimony for the defendant, "in her medical experience and estimation, the reported volume of the victim's blood loss could have caused ventricular fibrillation, which would result in death." There was also evidence that a second juror, also a nurse, "performed personal estimations of the blood volume loss and shared them with the rest of the jury." One of the lay jurors also testified that the jury's verdict had been directly affected by the nurses' opinions.

In ordering a new trial, the Court of Appeals held that while professional jurors may rely upon their professional knowledge in reasoning a case, they may not become unsworn witnesses by sharing their observations and reasoning with other jurors.

The New York court's decision followed a similar, though perhaps broader, ruling by the Appellate Court of Connecticut. In Connecticut v. Mills, (57 Conn. App. 356; 748 A.2d 891 (2000)), a psychologist was removed from the jury in a robbery prosecution that hinged largely on a questionable eyewitness identification of the defendant as one of the perpetrators. After hearing closing arguments, the psychologist-juror revealed to the court for the first time that 20 years earlier he had completed a dissertation dealing with "the effects of misleading information on eyewitness testimony and memory." Questioned by the judge, the psychologist-juror confided that he was unsure whether he could "refrain from revealing his specialized knowledge during deliberations." The psychologist was dismissed from the jury and the defendant was convicted.

In rejecting the defendant's claim that the psychologist had been improperly dismissed, the Appellate Court observed that: "The juror in this case could not assure the judge that he could keep his specialized knowledge private, [nor] that he would not use his specialized knowledge regarding identification during jury deliberations. It is within a judge's discretion to dismiss a juror where, as here, that juror possesses a specialized area of knowledge beyond the typical juror that may unduly influence jury deliberations."


In both cases, the problems caused by the specialized knowledge of the excluded professional jurors might have been obviated by careful questioning during the jury-selection process. Still, the question of who may serve on a jury and how they may use specialized professional knowledge remains. The New York court seems to have made it clear that professionals who serve on juries may utilize their special knowledge in deliberating as long as they do not share that knowledge with others on the jury. However, the Connecticut decision might be read as implying that a professional may not rely upon his or her own specialized knowledge in deliberating, regardless of whether that knowledge is shared with other jurors. That point is obscured somewhat by the psychologist-juror's unwillingness or inability to assure the court that he would not share his expertise with fellow jurors.

However, mandating that professionals not rely upon their own special knowledge and expertise at all when serving as jurors may be asking too much of the human mind. Certainly, such a rule would render it nearly impossible for psychologists to serve fairly on juries in the many cases where the state of mind of one or more individuals is a significant issue.

Further Reading

"Judicial notebook" is an effort by the Courtwatch Committee of APA's Div. 9, the Society for the Psychological Study of Social Issues, to encourage involvement by psychologists in judicial decision-making.