Haw. Rev. Stat. § 705
The expert may testify in terms of opinion or inference and give the expert's reasons therefor without disclosing the underlying facts or data if the underlying facts or data have been disclosed in discovery proceedings. The expert may in any event be required to disclose the underlying facts or data on cross-examination.
HRS § 705
RULE 705 COMMENTARY
The difference between this rule and Fed. R. Evid. 705 is that the latter rule eliminates the need for prior disclosure "unless the court requires otherwise"; the present rule eliminates the need for prior disclosure so long as "the underlying facts or data have been disclosed in discovery proceedings."
The traditional approach, in cases where the expert lacked firsthand knowledge of the underlying facts, was to permit the opinion testimony only after the basis was specified in a hypothetical question derived strictly from evidence already admitted in the action. The hypothetical question has been subject to extensive criticism on the grounds that it is unnecessarily time-consuming, that it encourages bias, and that it often is confusing to the jury. See, e.g., Barretto v. Akau, 51 H. 383, 463 P.2d 917 (1969); McCormick §§14, 17. The general practice of incorporating into the hypothetical question the entire body of relevant data adduced by prior testimony often results in a formulation of formidable length and density. In a recent Hawaii case, the question alone took up five pages of the transcript, Cozine v. Hawaiian Catamaran, Ltd.,49 Haw. 77, 108,412 P.2d 669, 689 (1966). This is by no means a record. In an early California case, the hypothetical question took up 83 pages of transcript, with an additional 14 pages of objections. McCormick §14 n. 95.
The intent of this rule and of Fed. R. Evid. 705 is to eliminate the burdensome and outmoded necessity of formulating a hypothetical question in every instance in which an expert bases his opinion upon other than firsthand knowledge, and to render prior disclosure of underlying data discretionary with the court except in those relatively rare instances where discovery proceedings have not yielded the underlying material. In practice, such instances should be limited to situations where experts are obtained while the trial is in progress, given the continuing duty to disclose discovery material imposed by HRCrP 16(c)(2) and HRCP 26(e)(1)(B). In such instances prior testimonial disclosure, which need not be in hypothetical form, is required in order to allow the adversary to judge whether the basis lacks sufficient trustworthiness to qualify under Rule 703.
For similar provisions, see Cal. Evid. Code §802; Kans. Code Civ. Proc. §§ 60-456, 60-457; Uniform Rule of Evidence 705.
Rule 703 and this rule do not foreclose expert witness from revealing, during direct examination, contents of material reasonably relied upon, though hearsay, to explain basis of opinion, provided expert actually relied on material as basis of opinion, materials are of type reasonably relied upon by experts in field in forming opinions on subject, and materials do not otherwise indicate lack of trustworthiness.85 Haw. 336,944 P.2d 1279. Mentioned:74 Haw. 141, 838 P.2d 1374.