Bases of Opinion Testimony by Experts
The facts or data in the particular case upon which an expert bases an opinion or inference may be those perceived by or made known to the expert at or before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence. Facts of data that are otherwise inadmissible shall not disclosed to the jury by the proponent of the opinion or inference unless the court determines that their probative value in assisting the jury to evaluate the expert's opinion substantailly outweighs their prejudicial effect.
As amended effective December 1, 2000.
The rule adopted by Congress is the rule proposed by the Supreme Court. Gender-neutralizing amendments were made to this rule in 1987.
Advisory Committes Note
Facts or data upon which expert opinions are based may, under the rule, be derived from three possible sources. The first is the first-hand observation of the witness, with opinions based thereon traditionally allowed. A treating physician affords an example. Rheingold, The Basis of Medical Testimony, 15 Vand. L. Rev. 473, 489 (1962). Whether he must first relate his observations is treated in Rule 705. The second source, presentation at the trial, also reflects existing practice. The technique may be the familiar hypothetical question or having the expert attend the trial and hear the testimony establishing the facts. Problems of determining what testimony the expert relied upon, when the latter technique is employed and the testimony is in conflict, may be resolved by resort to Rule 705. The third source contemplated by the rule consists of presentation of data to the expert outside of court and other than by his own perception. In this respect the rule is designed to broaden the basis for expert opinions beyond that current in many jurisdictions and to bring the judicial practice into line with the practice of the experts themselves when not in court. Thus a physician in his own practice bases his diagnosis on information from numerous sources and of considerable variety, including statements by patients and relatives, reports and opinions from nurses, technicians and other doctors, hospital records, and X rays. Most of them are admissible in evidence, but only with the expenditure of substantial time in producing and examining various authenticating witnesses. The physician makes life-and-death decisions in reliance upon them. His validation, expertly performed and subject to cross-examination, ought to suffice for judicial purposes. Rheingold, supra at 531; McCormick §15. A similar provision is California Evidence Code §801(b).
The rule also offers a more satisfactory basis for ruling upon the admissibility of public opinion poll evidence. Attention is directed to the validity of the techniques employed rather than to relatively fruitless inquiries whether hearsay is involved. See Judge Feinbergs careful analysis in Zippo Mfg. Co. v. Rogers Imports, Inc., 216 F. Supp 670 (S.D.N.Y. 1963). See also Blum et al., The Art of Opinion Research: A Lawyers Appraisal of an Emerging Service, 24 U. Chi. L. Rev. 1 (1956); Bonynge, Trademark Surveys and Techniques and Their Use in Litigation, 48 A.B.A.J. 329 (1969); Zeisel, The Uniqueness of Survey Evidence, 45 Cornell L.Q. 322 (1960); Annot., 76 A.L.R. 2d 919.
If it be feared that enlargement of permissible data may tend to break down the rules of exclusion unduly, notice should be taken that the rule requires that the facts or data "be of a type reasonably relied upon by experts in the particular field." The language would not warrant admitting in evidence the opinion of an "accidentologist" as to the point of impact in an automobile collision based on statements of bystanders, since this requirement is not satisfied. See Comment, Cal. Law Rev. Commn, Recommendation Proposing an Evidence Code 148-150 (1965).
Advisory Committee's Note to Amendment effective December 1, 2000
Rule 703 has been amended to emphasize that when an expert reasonably relies on inadmissible information to form an opinion or inference, the underlying information is not admissible simply because the opinion or inference is admitted. Courts have reached different results on how to treat inadmissible information when it is reasonably relied upon by an expert in forming an opinion or drawing an inference. Compare United States v. Rollins, 862 F.2d 1282 (7th Cir. 1988) (admitting, as part of the basis of an FBI agent's expert opinion on the meaning of code language, the hearsay statements of an informant), with United States v. 0.59 Acres of Land, 109 F.3d 1493 (9th Cir. 1997) (error to admit hearsay offered as the basis of an expert opinion, without a limiting instruction). Commentators have also taken differing views. See e.g., Ronald Carlson, Policing the Bases of Modern Expert Testimony, 39 Vand.L.Rev. 577 (1986) (advocating limits on the jury's consideration of otherwise inadmissible evidence used as the basis for an expert opinion); Paul Rice, Inadmissible Evidence as a Basis for Expert Testimony: A Response to Professor Carlson, 40 Vand.L.Rev. 583 (1987) (advocating unrestricted use of information reasonably relied upon by an expert).
The amendment governs only the disclosure to the jury of information that is reasonably relied on by an expert, when that information is not admissible for substantive purposes. It is not intended to affect the admissibility of an expert's testimony. Nor does the amendment prevent an expert from relying on information that is inadmissible for substantive purposes.
Nothing in this Rule restricts the presentation of underlying expert facts or data when offered by an adverse party. See Rule 705. Of course, an adversary's attack on an expert's basis will often open the door to a proponent's rebuttal with information that was reasonably relied upon by the expert, even if that information would not have been discloseable initially under the balancing test provided by this amendment. Moreover, in some circumstances the proponent might wish to disclose information that is relied upon by the expert in order to "remove the sting" from the opponent's anticipated attack, and thereby prevent the jury from drawing an unfair negative inference. The trial court should take this consideration into account in applying the balancing test provided by this amendment.
This amendment covers facts or data that cannot be admitted for any purpose other than to assist the jury to evaluate the expert's opinion. The balancing test provided in this amendment is not applicable to facts or data that are admissible for any other purpose but have not yet been offered for such a purpose at the time the expert testifies.
GAP Report--Proposed Amendment to Rule 703
The Committee made the following changes to the published draft of the proposed amendment to Evidence Rule 703:
2. The words "in assisting the jury to evaluate the expert's opinion" were added to the text, to specify the proper purpose for offering the otherwise inadmissible information relied on by an expert. The Committee Note was revised to accord with this change in the text.
3. Stylistic changes were made to the Committee Note.
4. The Committee Note was revised to emphasize that the balancing test set forth in the proposal should be used to determine whether an expert's basis may be disclosed to the jury either (1) in rebuttal or (2) on direct examination to "remove the sting" of an opponent's anticipated attack on an expert's basis.