Paul R. Rice

Publication Date


Document Type



In his article entitled Developing A Coherent Theory of the Structure of Federal Rule of Evidence 703, Professor Imwinkelried proposes a theory for the interpretation of Rule 703. He argues that a restrictive interpretation of the terms "facts or data" in Rule 703 would resolve the conflicts that have plagued that Rule. Professor Imwinkelried's proposal would exclude research data and other background facts from the definition of "facts or data." By his interpretation, when an expert is testifying to an opinion based on facts that have not been proven at the trial the expert witness may only rely on unproven case-specific facts--facts directly related to the cause of action. While I disagree with his interpretation of the scope of the terms "facts or data," that disagreement is unimportant to the serious problem with Rule 703 that should be addressed in a "coherent" theory. That problem is a deeper, more fundamental flaw in the logic of Rule 703 which Professor Imwinkelried passingly acknowledged, but chose to ignore.' This is the inconsistency in allowing expert witnesses to rely on facts that are not before the jury (both case-specific facts and scientific or background facts), and then pretending that those facts are not being accepted for truth when the jury accepts and relies upon the expert witness' conclusions.

Twitted by Professor Imwinkelried for having "been content to discuss [this] individual issue[], without endeavoring to develop a coherent theory of the structure of Rule 703, I would like to take this opportunity to further open myself to his criticism by advancing that narrow issue again and, hopefully, demonstrating that his "coherent" theory misses the point.

Professor Imwinkelried first argues that the validity of the scientific basis of expert witness testimony should be governed by Rule 703 because it was designed for that purpose. After all, the Rule is entitled "Basis of Expert Witness Testimony." While I personally agree that the basis of expert testimony should be controlled by the rule bearing that title, Rule 703 establishes a standard for judicial screening of an expert witness' basis only for facts or data, and that standard is applicable only when the facts or data considered by the expert in arriving at. his conclusion are not part of the factual record before the jury. Perhaps this is why the Supreme Court concluded that Rule 702, not Rule 703, controls the scientific basis of expert testimony.

Throughout the remainder of his article, Professor Imwinkelried identifies many of the disputes that exist about the interpretation of Rule 703, and explains how limiting the expert's reliance on inadmissible "facts or data" to "case-specific" facts or data, resolves those disputes. I believe that his limited interpretation of "facts or data" is unjustified. But more importantly, in focusing on those terms, he has lost sight of the more fundamental problem of the Rule's illogic. Before examining this disagreement and identifying the problem, however, the underlying rationale of Rule 703 should be clear.

Included in

Evidence Commons