Rule 703 of the Federal Rules of Evidence permits expert witnesses to offer opinions based upon evidence that has not been offered in the proceedings. The Rule also sanctions the expert's basing her opinion on inadmissible evidence if that evidence is "of a type reasonably relied upon by experts in the particular field informing opinions or inferences upon the subject." In a recent Essay in this Review, Professor Carlson presents a helpful exposition of the confused evidentiary status of this otherwise inadmissible evidence. He correctly notes that the majority of courts refuse to allow the inadmissible evidence upon which the expert bases her opinion to come in as excess baggage with the opinion itself. The expert's reliance upon the inadmissible evidence does not change the evidentiary character of that evidence. For the limited purpose of explaining the expert's opinion, however, courts do permit the introduction of this otherwise inadmissible background information.
Thus, on the one hand, the jury may consider the facts or data upon which the expert based her opinion to assess the weight to be given to that opinion. Yet, on the other hand, the jury, when deciding whether to arrive at the same conclusion, cannot accept what the expert relied upon as true. In reaching its own conclusion, the jury can rely only upon the product of that evidence-the expert's opinion.' If this practice sounds like judicial double talk, it is. Professor Carlson, however, supports this result on two grounds. First,he contends that the introduction of the underlying facts would violate the hearsay rule.' Second, Professor Carlson justifies exclusion because of sixth amendment confrontation problems in criminal cases."
I disagree with Professor Carlson. With appropriate precautions, the introduction of the inadmissible facts or data upon which experts rely no more violates the hearsay rule's spirit than do the volumes of evidence that regularly are introduced through the numerous hearsay rule exceptions. And, although I am sympathetic to his confrontation concerns, recent developments suggest that no confrontation problem exists. More fundamentally, however, I oppose the view that Professor Carlson and the majority of courts support because that view is both illogical and unwise.
Paul R. Rice,
Inadmissible Evidence as a Basis for Expert Opinion Testimony: A Response to Professor Carlson,
40 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol40/iss3/3