Commonwealth v. Pytou Heang, 942 N.E.2d 927 (Mass. 2011)

1. Footnote 26: “At trial, after hearing most of [the expert’s] direct testimony . . . the judge . . . required the prosecutor to ask whetehr [the expert] could ‘exclude all other nine millimeter weapons that have six lands and six grooves with a right-hand twist . . . [a]s a matter of science.'” 2. In MA, “an evidentiary Daubert-Lanigan hearing is generally not required when [the courts] have previously admitted expert testimony of the same type . . . whether the appropriate methodology has been followed, or whether the quality of the evidence is sufficient to permit an opinion.” 3. Defendant contended that the judge erred in allowing the expert, on cross-examination, to tesity without the limitation required by the judge on direct examination (expert used the language like “virtually impossible” on cross-examination). The appellate court found no prejudicial error, “considerding the entirety of the witness’s testimony, the jury were adequately informed of the limitations.” 3. “In light of our ruling today and the findings of the NRC report, we offer the following guidelines to ensure that expert forensic ballistics testimony appropriately assists the jury in finding the facts but does not mislead by reaching beyond its scientific grasp. . . . First, before trial, the examiner must adequately document the findings or observations that support the examiner’s ultimate opinion, and this documentary evidence . . . shall be provided in discovery, so that defense counsel will have an adequate and informed basis to cross-examine the forensic ballistics expert at trial. Second, before an opinion is offered at trial, a forensic ballistics expert should explain to the jury the thoeries and methodologies underlying the field of forensic ballistics. . . . Third, in the absence of special circumstances casting doubt on the reliability of an opinion . . . the expert may offer that opinion to a ‘reasonable degree of ballistic certainty.'” 4. “The admission of an opinion to a ‘reasonable degree of ballistic certainty’ is similar to the manner in which our appellate courts permit other empirically based but subjective opinions to be presented. . . . The phrase, ‘reasonable degree of scientific certainty’ should be avoided because it suggests that forensic ballistics is a science, where it is clearly as much an art as a science.”

Nor did the judge abuse his discretion in allowing Trooper Lombard to offer his opinion only if he admitted on direct examination that he could not, as a matter of science, exclude every other nine millimeter firearm with six lands and six grooves with a right-hand twist. Given the absence of appellate guidance on this issue, the judge made a reasonable attempt to ensure *846 that the expert witness fairly informed the jury of his opinion as to a match and the limitations of that opinion.