Rule 705. Disclosing the Facts or Data Underlying an Expert'S Opinion

(a) Disclosure of underlying facts. Unless the court orders otherwise, an expert may state an opinion—and give the reasons for it—without first testifying to the underlying facts or data. But the expert may be required to disclose those facts or data on cross-examination.

(b) Objection. A party may object to an expert witness's testimony on the ground that the expert lacks a sufficient basis for expressing an opinion. Before the expert gives an opinion, counsel may be allowed to examine the expert about the facts or data underlying the opinion outside of the jury's presence. If there is evidence sufficient to support a finding that the expert lacks a sufficient basis for the opinion, the opinion is inadmissible, unless the party who called the expert witness first establishes the underlying facts or data.

Committee Notes

Maine Restyling Note [November 2014] Maine Rule of Evidence 705 is similar to its federal counterpart. The Maine version sets forth a procedure to test the factual basis for expert testimony before it is admitted, which has been included in the restyled version.

Federal Restyling Committee Note The language of Rule 705 has been amended as part of the general restyling of the Evidence Rules to make them more easily understood and to make style and terminology consistent throughout the rules. These changes are intended to be stylistic only. There is no intent to change any result in any ruling on evidence admissibility. The Committee deleted all reference to an "inference" on the grounds that the deletion made the Rule flow better and easier to read, and because any "inference" is covered by the broader term "opinion." Courts have not made substantive decisions on the basis of any distinction between an opinion and an inference. No change in current practice is intended.

Advisers' Note to former M.R. Evid. 705 (February 2, 1976) Subdivision (a) is designed to eliminate the necessity of a hypothetical question in eliciting expert testimony. Wigmore has said: "The hypothetical question, misused by the clumsy and abused by the clever, has in practice led to intolerable obstruction of truth." 2 Wigmore, Evidence § 686. The remedy is to allow the opinion to be given without prior disclosure of the underlying facts or data. The provision that prior disclosure of the underlying facts is not required does not mean that the expert is forbidden to disclose them on direct examination. The rule permits him to do so, even though facts not admissible in evidence may be included, as Rule 703 allows. The rule supersedes statements to the contrary in Warren v. Waterville Urban Renewal Authority, 235 A.2d 295 (Me. 1967). The court has discretion to require prior disclosure of the underlying facts, either on an objection that an inadequate foundation has been laid or for other reasons. In any event disclosure may be required on cross-examination. Tactically, of course, a party may prefer to disclose these facts on direct examination. Subdivision (b) reflects the awareness that a potential for serious abuse exists in the use of the technique permitted in subdivision (a). An expert may predicate his opinion on unreliable data and its weakness may not be revealed on direct examination. This may put the adverse party at a tactical disadvantage, forcing him to engage in blind cross-examination. Moreover, once the opinion is heard by the jury, it may well be that nothing done on cross-examination or by the court can eliminate the resulting prejudice. In civil cases if counsel has engaged in the pretrial discovery permitted by M.R.C.P. 26(b)(4), he should be equipped to challenge the basis of the opinion. This subdivision allows the alternative, however, of a voir dire examination before the opinion is admitted, so as to give a basis for its exclusion in an appropriate case.

Advisory Committee Note (February 15, 1993 Amendment) This amendment merely clarifies the language of Rule 705(a) that the disclosure of underlying facts referred to by the rule is disclosure in prior testimony in court, not pretrial disclosure during the course of discovery. The rule permitting an expert to give an opinion without first testifying to the underlying facts and data is not intended to limit or define the scope of required or permitted pretrial discovery of expert testimony.