The Role of the Expert Witness

Abstract

Scientists have become increasingly involved in the litigative process. Their role is to assist attorneys, judges, and jurors in understanding the complex scientific and technical issues with which they are confronted. This role, simply stated, is to inform and educate. To accomplish this mission, the scientist must be a genuine expert in his/her area of testimony and must also be expert in communicating clearly to persons who must be assumed to have no knowledge of the technical material and, in the case ofjuries, who have only grammar school education. There are two groups of people to whom the scientist addresses the information and education efforts. The first of these is the attorneys who have asked for assistance. It is not unusual for the scientist to spend more time educating them than studying the particular case and making calculations. This is critical because if the lawyers do not understand the scientific issues they cannot cross-examine properly; similarly, they cannot ask the correct questions of their own witnesses or argue the case to the judge or jury. The second group to whom correct information and education is critical is the judge and jury. An avoidance of technical terminology wherever possible and a bountiful use of simplified and concise charts, diagrams, and demonstrations are both essential. The adage that to teach requires detailed knowledge still holds, and teaching the truths of the science in junior high school terminology requires in-depth knowledge of the fundamentals. To be effective, the scientist witness must understand the issues of the case; otherwise it is not possible to be sharply focused in presenting the information needed in the trial. Certainly, the scientist witness has to have the credentials to be qualified as an expert, but once qualified, the emphasis is on accuracy, credibility, and clarity. Most scientists, engineers, and highly technical persons are generally unaware of the extent of the use of jargon in their usual conversations and of the lack of familiarity of the public with the most basic premises of radiation science. To be useful, discussions in the courtroom should be free of technical terms not previously defined and