Expert testimony is common in tort litigation, especially on issues of standard of care and cause-in-fact. Rule 704 of the Federal Rules of Evidence and its state counterparts abolished the prohibition of testimony on ultimate issues, leading to the possibility of expert testimony on the often crucial issue of proximate cause. The situation is easy to imagine. After counsel has qualified an expert witness and elicited an opinion that the particular act or omission "caused" the injury in question, counsel might very well be tempted to inquire whether the witness has an opinion as to whether the act or omission was a "proximate" or"legal" cause of the accident. Or, counsel may merge the two lines of inquiry and ask whether the act or omission "proximately resulted" in the accident or injury to the plaintiff. The inquiry seems harmless. The term "proximate" is commonly understood to mean only "near" or"close to." The question is not innocuous, however. The issue of expert testimony on the question of proximate cause implicates several restrictions on expert testimony that survive the broad permission of Rule 704, and touches upon the serious issue of the proper roles of expert and fact-finder in the application of law to facts. The few published cases that have considered the issue of expert testimony on proximate cause are split.' The question arises far more often, however, than is indicated by the relative scarcity of reported decisions.
This Article addresses the usefulness and propriety of expert testimony on the issue of proximate cause. After briefly defining the concept of proximate cause, this Article argues that expert testimony on proximate cause is inadmissible under Rule 704, despite the general admissibility of testimony on ultimate issues. In addition, opinion on proximate cause is inadmissible because it fails to clear the separate hurdles of Rules 702' and 4036 of the Federal Rules of Evidence. A technical expert on standard of care or actual cause is not qualified to opine on the issue of proximate cause and thus fails the expertise test of Rule 702. Furthermore, even the testimony of a genuine expert on the issue of proximate cause should be excluded because such testimony fails the helpfulness test of Rule 702. Finally, expert testimony on the issue of proximate cause is inadmissible under Rule 403 because its probative value is substantially outweighed by the possibility that such testimony will confuse the issues and mislead the jury.
Daniel J. Steinbeck, William M. Richman, and Douglas E. Ray,
Expert Testimony on Proximate Cause,
41 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol41/iss2/2