If an expert testifies at trial, his or her opinion is evidence in the case, and, like any other evidence, may be relied upon by a testifying expert. What if the initial expert does not testify? This arises in a number of ways. The first expert may be unavailable (it is surprising how frequently the word ‛deceased“ pops up in this area); he or she may be an assistant to the testifying expert (common when large consulting firms are retained); or the initial expert’s opinion may be barred by the pretrial order, simply because there are too many experts and the Court has limited the number who may testify.

It was the last scenario that confronted District Judge Louise W. Flanagan in Bouygues Telecom, S.A. v. Tekelec, 2007 U.S. Dist. LEXIS 10786 (E.D.N.C. Jan. 31, 2007). The Court had limited the plaintiff to five experts and then found that an excluded report had been adopted in the reports of two of the remaining experts. The Bouygues Court identified two scenarios in which one expert would be permitted to rely on the opinion of another, non-testifying expert:

(1) In accordance with Fed.R.Evid. 703: ‛[E]xpert opinion which relies upon the information or opinion of others is acceptable, provided it is the sort of opinion reasonably relied on by experts in the relevant area of expertise.“

(2) When the other expert is an assistant, and essentially an amanuensis, of the testifying expert: ‛‘An expert witness is permitted to use assistants in formulating his expert opinion, and normally they need not themselves testify.... Analysis becomes more complicated if the assistants aren't merely gofers or data gatherers but exercise professional judgment that is beyond the expert's ken.... A scientist, however, well credentialed he may be, is not permitted to be the mouthpiece of a scientist in a different specialty’“ (quoting Dura Automotive Sys. of Indiana, Inc. v. CTS Corp., 285 F.3d 609, 612-614 (7th Cir. 2002)).

The Bouyges Court disallowed the reliance in this case, which it clearly perceived to be an attempted end run around its pretrial order: ‛The purpose of expert testimony is to aide the fact-finder, through explanation of complicated or technical areas which require specialized knowledge and understanding.... While this function undoubtedly can lead to the adoption or incorporation of the ideas, information, and analysis of others with expertise in the same field, it does not lead to the conclusion that an expert with a perhaps overlapping, yet admittedly different, area of expertise should be permitted to merely adopt and incorporate verbatim another's ‘expert’ opinion.“

Compare the recent opinion of the Court of Federal Claims permitting one expert to rely on the report of another expert, in Banks. v. United States, 2007 U.S. Claims LEXIS 30 (Ct. Cl. Feb. 12, 2007).

Two other salient but unrelated holdings of Bouygues:

• In a civil action, a qualified expert may testify as to the knowledge, state of mind, motive or intent of an adverse party where that state of mind derives from the party’s participation in a technical field or industry — in this case, that ‛‘reasoning about [defendant's] knowledge can be properly drawn from ... [its] own statements, documentary evidence and testimony referred to in the course of this analysis,’ and that the basis for [the expert’s] conclusions are ‘reasonable interpretations of what a person within the telecom field would know’“ (brackets in original).

• The Court relied on Rule 704(b)’s limitation to criminal cases in concluding that such state-of-mind testimony may be admitted in a civil action even though it touches on an ultimate issue.

• Following the same line of reasoning, the Court permitted the plaintiff’s expert to testify as to the credibility of the defendant’s communications to the plaintiff.