Section 705. Disclosure of Facts or Data Underlying Expert Opinion
The expert may testify in terms of opinion or inference and give reasons therefor without prior disclosure of the underlying facts or data, unless the court requires otherwise. The expert may in any event be required to disclose the underlying facts or data on cross-examination.
NOTE
This section is taken nearly verbatim from Proposed Mass. R. Evid. 705, which the Supreme Judicial Court adopted in Department of Youth Servs. v. A Juvenile, 398 Mass. 516, 532, 499 N.E.2d 812, 821 (1986).
The rule is aimed principally at the abuse of the hypothetical question. It does not eliminate the availability of the hypothetical question, but only the requirement of its use. . . . The thrust of the rule is to leave inquiry regarding the basis of expert testimony to cross-examination, which is considered an adequate safeguard.
Id., quoting Advisory Committees Note on Proposed Mass. R. Evid. 705. Under Massachusetts law, for purposes of direct examination, there is a distinction between an experts opinion on the one hand and the hearsay information that formed the basis of the opinion on the other, holding the former admissible and the latter inadmissible. Commonwealth v. Greineder, 464 Mass. 580, 584, 984 N.E.2d 804, 808 (2013). However, on cross-examination, the opposing party may choose to elicit the hearsay basis for an opinion offered on direct examination. See Commonwealth v. Nardi, 452 Mass. 379, 387–395, 893 N.E.2d 1221, 1228–1234 (2008). In Commonwealth v. Barbosa, 457 Mass. 773, 785787, 933 N.E.2d 93, 106–108 (2010), the Supreme Judicial Court stated the direct examination of an expert on facts not in evidence
is limited to the experts opinion and matters of which the expert had personal knowledge, such as her training and experience, and the protocols generally accepted in her field of expertise. Only the defendant can open the door on cross-examination to testimony regarding the basis for the experts opinion, which may invite the expert witness to testify to facts or data that may be admissible in evidence but have not yet been admitted in evidence.
Accord Commonwealth v. Leng, 463 Mass. 779, 783785, 979 N.E.2d 199, 205 (2012); Commonwealth v. Nardi, 452 Mass. 379, 387395, 893 N.E.2d 1221, 12281234 (2008).
Cross-Reference: Article VIII, Introductory Note.
Limitation on Cross-Examination. Under certain circumstances, the requirement that the expert disclose underlying facts or data on cross-examination may be limited by Section 403 considerations. See Commonwealth v. Anestal, 463 Mass. 655, 668669, 978 N.E.2d 37, 4749 (2012). In Anestal, the court held that
[o]nce the Commonwealth sought to inquire over objection about this prior bad act evidence, it was incumbent on the judge in the sound exercise of his discretion to ascertain whether the evidence was probative and, if so, whether that probative value was substantially outweighed by the danger of unfair prejudice to the defendant.
Id. at 669, 978 N.E.2d at 48. This inquiry should take place at sidebar, or the judge should conduct a voir dire. Id. at 669 n.20, 978 N.E.2d at 49 n.20.
