702. Testimony by Experts


Section 702.    Testimony by Experts

If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify thereto in the form of an opinion or otherwise if

(a) the testimony is based upon sufficient facts or data,

(b) the testimony is the product of reliable principles and methods, and

(c) the witness has applied the principles and methods reliably to the facts of the case.


Introduction. This section, which is based upon Fed. R. Evid. 702 and Proposed Mass. R. Evid. 702, reflects Massachusetts law. There are two methods by which the judge may satisfy his or her duty as the gatekeeper to ensure that expert witness testimony is reliable: (1) the “Frye” test, i.e., general acceptance in the relevant scientific community, or (2) a Daubert-Lanigan analysis. Commonwealth v. Powell, 450 Mass. 229, 238, 877 N.E.2d 589, 595–596 (2007). See Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 585–595 (1993), and Commonwealth v. Lanigan, 419 Mass. 15, 24–26, 641 N.E.2d 1342, 1348–‌1349 (1994).

It is important to distinguish between the words used to express the principle of Massachusetts law set forth in this section and the application of the principle in specific cases. As the following notes indicate, the framework used under the Federal rules and in Massachusetts is the same, and each approach is specifically described as flexible. The principal difference is that in Massachusetts, the trial judge satisfies his or her gatekeeper responsibilities under Section 702(b) and (c) once the proponent of the evidence establishes that it is generally accepted by the relevant scientific community. See Commonwealth v. Patterson, 445 Mass. 626, 640–641, 840 N.E.2d 12, 23–24 (2005); Common­wealth v. Sands, 424 Mass. 184, 185–186, 675 N.E.2d 370, 371–372 (1997). Compare Commonwealth v. Lanigan, 419 Mass. at 26, 641 N.E.2d at 1349 (“We accept the basic reasoning of the Daubert opinion because it is consistent with our test of demonstrated reliability. We suspect that general acceptance in the relevant scientific community will continue to be the significant, and often the only, issue.”), and Canavan’s Case, 432 Mass. 304, 314 n.5, 733 N.E.2d 1042, 1050 n.5 (2000) (“Application of the Lanigan test requires flexibility. Dif­fering types of methodology may require judges to apply differing evaluative criteria to determine whether scientific methodology is reliable. In the Lanigan case, we established various guideposts for determining admissibility including general acceptance, peer review, and testing.”), with Daubert v. Merrell Dow Pharms., Inc., 509 U.S. at 594–595 (“The inquiry envisioned by [Fed. R. Evid.] 702 is, we emphasize, a flexible one. Its overarching subject is the scientific validity—and thus the evidentiary relevance and reliability—of the principles that underlie a proposed submission.”), and Kumho Tire Co. v. Carmichael, 526 U.S. 137, 141 (1999) (“[T]he test of reliability is ‘flexible,’ and Daubert’s list of specific factors neither necessarily nor exclusively applies to all experts or in every case.”). See also Kumho Tire Co. v. Carmichael, 526 U.S. at 150 (“Daubert makes clear that the factors it mentions do not constitute a ‘definitive checklist or test.’ [Daubert v. Merrell Dow Pharms., Inc., 509 U.S.] at 593. And Daubert adds that the gatekeeping inquiry must be ‘tied to the facts’ of a particular ‘case.’ Id. at 591.” [Quotation and citation omitted.]); Daubert v. Merrell Dow Pharms., Inc., 509 U.S. at 594 (“Widespread acceptance can be an important factor in ruling particular evidence admissible, and a known technique which has been able to attract only minimal support within the community[] may properly be viewed with skepticism” [quotation and citation omitted].).

Hearing. An evidentiary hearing is not always necessary to comply with Com­monwealth v. Lanigan, 419 Mass. 15, 641 N.E.2d 1342 (1994). See Palandjian v. Foster, 446 Mass. 100, 111, 842 N.E.2d 916, 925 (2006); Vassallo v. Baxter Healthcare Corp., 428 Mass. 1, 1–13, 696 N.E.2d 909, 909–918 (1998) (trial judge properly relied on affidavits and transcripts of testimony from other cases). However, as the Supreme Judicial Court noted, “we have not ‘grandfathered’ any particular theories or methods for all time, especially in areas where knowledge is evolving and new understandings may be expected as more studies and tests are conducted.” Commonwealth v. Shanley, 455 Mass. 752, 763 n.15, 919 N.E.2d 1254, 1264 n.15 (2010) (court acknowledged it was prudent for trial judge to conduct an evidentiary hearing in connection with expert testimony about dissociative amnesia because of “the evolving nature of scientific and clinical studies of the brain and memory”). To preserve an objection to expert testimony on grounds it is not reliable, a defendant must file a pretrial motion and request a hearing on the subject. See Commonwealth v. Sparks, 433 Mass. 654, 659, 746 N.E.2d 133, 137 (2001). A trial judge’s decision on whether expert witness evidence meets the Lanigan standard of reliability is reviewed on appeal under an abuse of discretion standard. See General Elec. Co. v. Joiner, 522 U.S. 136, 141–143 (1997); Canavan’s Case, 432 Mass. 304, 311–312, 733 N.E.2d 1042, 1048–‌1049 (2000).

Five Foundation Requirements. The proponent of expert witness testimony has the burden of establishing the five foundation requirements for the admission of such testimony under this section. See Commonwealth v. Barbosa, 457 Mass. 773, 783, 933 N.E.2d 93, 105 (2010) (explaining the five foundation re­quirements). First, the proponent must establish that the expert witness testimony will assist the trier of fact. See Commonwealth v. Francis, 390 Mass. 89, 98, 453 N.E.2d 1204, 1208–1209 (1983); Com­monwealth v. Rodziewicz, 213 Mass. 68, 69–70, 99 N.E. 574, 575 (1912). Second, the proponent must dem­onstrate that the witness is qualified as an expert in the relevant area of inquiry. See Commonwealth v. Frangipane, 433 Mass. 527, 535–536, 744 N.E.2d 25, 31–32 (2001); Commonwealth v. Boyd, 367 Mass. 169, 182, 326 N.E.2d 320, 328–329 (1975). Third, the proponent must demonstrate that the facts or data in the record are sufficient to enable the witness to give an opinion that is not merely speculation. See Sevigny’s Case, 337 Mass. 747, 751, 151 N.E.2d 258, 261 (1958). Fourth, the expert opinion must be based on a body of knowledge, a principle, or a method that is reliable. Commonwealth v. Lanigan, 419 Mass. 15, 26, 641 N.E.2d 1342, 1349 (1994). Fifth, the proponent must demonstrate that the expert has applied the body of knowledge, the principle, or the method in a reliable manner to the particular facts of the case. See Commonwealth v. Patterson, 445 Mass. 626, 645–648, 840 N.E.2d 12, 26–28 (2005); Commonwealth v. McNickles, 434 Mass. 839, 850, 753 N.E.2d 131, 140 (2001).

Each of these five foundation requirements is a preliminary question of fact for the trial judge to determine under Section 104(a), Preliminary Questions: Determinations Made by the Court. The trial judge has “broad discretion” in making these determinations. Commonwealth v. Robinson, 449 Mass. 1, 5, 864 N.E.2d 1186, 1189 (2007). In making these preliminary determinations, the trial judge may be required to resolve disputes as to the credibility of witnesses. Commonwealth v. Patterson, 445 Mass. at 647–648, 840 N.E.2d at 28. Expert witness testimony should not be deemed unreliable simply because there is a disagreement of opinion or in terms of the level of confidence among the experts. See Commonwealth v. Torres, 442 Mass. 554, 581, 813 N.E.2d 1261, 1282 (2004).

The judge has no authority to exclude the evidence because he or she disagrees with the expert’s opinion or finds the testimony unpersuasive. See Commonwealth v. Roberio, 428 Mass. 278, 281, 700 N.E.2d 830, 832 (1998) (“Once the expert’s qualifications were established and assuming the expert’s testimony met the standard of Commonwealth v. Lanigan, 419 Mass. 15, 641 N.E.2d 1342 (1994), the issue of credibility was for a jury, not the judge.”). When an expert’s opinion is based on the analysis of complex facts, the failure of the expert to account for all the variables goes to its weight and not its admissibility. Salvas v. Wal-Mart Stores, Inc., 452 Mass. 337, 359–360, 893 N.E.2d 1187, 1206 (2008). See id. at 351–360 (expert witness with doctorate in psychology and mathematics used statistical methods to evaluate large body of employee records to account for missing records and to opine that employer had wrong­fully deprived employees of compensation).

First Foundation Requirement: Assistance to the Trier of Fact. “The role of an expert witness is to help jurors interpret evidence that lies outside of com­mon experience.” Commonwealth v. Tanner, 45 Mass. App. Ct. 576, 581, 700 N.E.2d 282, 286 (1998). Thus, expert testimony may be excluded when it will not assist the jury. See Commonwealth v. Tolan, 453 Mass. 634, 648, 904 N.E.2d 397, 410 (2009) (trial judge has discretion “to preclude expert testimony on commonly understood interrogation methods”); Commonwealth v. Bly, 448 Mass. 473, 496, 862 N.E.2d 341, 360 (2007) (trial judge did not abuse his discretion in excluding expert witness testimony on the subject of cross-racial identification). Expert witness testimony also may be excluded because it is cumulative. See Anthony’s Pier Four, Inc. v. HBC Assocs., 411 Mass. 451, 482, 583 N.E.2d 806, 825 (1991). Expert witness testimony may be excluded because it does not fit the facts of the case. See Ready, petitioner, 63 Mass. App. Ct. 171, 179, 824 N.E.2d 474, 480 (2005) (concluding that a diagnostic test known as the Abel Assessment of Sexual Interest [AASI] was of no value to the fact issues facing the jury). See generally Section 403, Grounds for Excluding Relevant Evidence. Finally, expert witness testimony may be excluded as not probative of a material fact in dispute and thus of no assistance to the jury when it amounts to a mere guess or conjecture. See Kennedy v. U-Haul Co., 360 Mass. 71, 73–74, 271 N.E.2d 346, 348–349 (1971). See also Section 402, Relevant Evidence Generally Admissible; Irrelevant Evidence Inadmissible. There are circumstances, however, in which an expert witness’s opinion as to a possibility will have probative value. See Commonwealth v. Federico, 425 Mass. 844, 852, 683 N.E.2d 1035, 1040–1041 (1997). The trial judge has dis­cretion to determine whether expert witness testimony will assist the trier of fact. See, e.g., Commonwealth v. Francis, 390 Mass. 89, 95–102, 453 N.E.2d 1204, 1207–‌1211 (1983) (expert witness testimony on the reliability of eyewitness identification evidence).

Second Foundation Requirement: Qualifications of the Expert. “The crucial issue in determining whether a witness is qualified to give an expert opinion is whether the witness has sufficient education, training, experience and familiarity with the subject matter of the testimony” (quotations and citation omitted). Commonwealth v. Richardson, 423 Mass. 180, 183, 667 N.E.2d 257, 260 (1996). Qualification of a witness as an expert in accordance with Section 104(a), Preliminary Questions: Determinations Made by the Court, does not always require an explicit ruling on the record by the judge. However, if a formal ruling is made, it should be made outside the hearing of the jury. Id. at 184, 667 N.E.2d at 261.

“Whether an expert determined to be qualified in one subject is also qualified to testify in another, related subject will depend on the circumstances of each case, and, where an expert has been determined to be qualified, questions or criticisms as to whether the basis of the expert’s opinion is reliable go to the weight, and not the admissibility, of the testimony.”

Commonwealth v. Crouse, 447 Mass. 558, 569, 855 N.E.2d 391, 401 (2006) (noting that there must always be a first time for every expert witness). However, the trial judge, acting as the gatekeeper, must enforce boundaries between areas of expertise within which the expert is qualified and areas that require different training, education, and experience and within which the expert is not qualified. See Commonwealth v. Frangipane, 433 Mass. 527, 535, 744 N.E.2d 25, 31 (2001) (social worker qualified to testify as an expert witness that abused children may experience dissociative memory loss and recovered memory, but was not qualified to testify about how trauma victims store and retrieve or dissociate memories).

Third Foundation Requirement: Knowledge of Sufficient Facts or Data in the Record. The basis of expert opinion may include the factors set forth in Section 703, namely: (a) facts observed by the witness or otherwise in the witness’s direct personal knowledge; (b) evidence already in the record or which the parties represent will be presented during the course of the proceedings, which facts may be assumed to be true in questions put to the witness; and (c) facts or data not in evidence if the facts or data are independently admissible in evidence and are a permissible basis for an expert to consider in formulating an opinion. See Section 703, Bases of Opinion Testimony by Experts; LaClair v. Silberline Mfg. Co., 379 Mass. 21, 32, 393 N.E.2d 867, 874 (1979). See also Department of Youth Servs. v. A Juvenile, 398 Mass. 516, 531, 499 N.E.2d 812, 821 (1986). This requirement means the expert witness

“must have sufficient familiarity with the particular facts to reach a meaningful expert opinion. The relevant distinction is between an opinion based upon speculation and one adequately grounded in facts. Although a trial judge has some discretion in making that distinction, it may be an abuse of discretion to disallow expert testimony which is based upon reasonably adequate familiarity with the facts.” (Citations omitted.)

Fourth St. Pub, Inc. v. National Union Fire Ins. Co., 28 Mass. App. Ct. 157, 161, 547 N.E.2d 935, 937–938 (1989). Contrast Commonwealth v. Talbot, 444 Mass. 586, 589, 830 N.E.2d 177, 180 (2005) (no error in excluding defense expert who was proffered to testify about the effects of hypoglycemic shock in view of the absence of any evidence that the defendant experienced such a condition at the time of the offense); Commonwealth v. Laliberty, 373 Mass. 238, 241, 366 N.E.2d 736, 739–740 (1977) (opinion concerning defense of lack of criminal responsibility not admissible absent evidence that defendant suffered from mental disease or defect at time of crime).

Fourth Foundation Requirement: Reliability of Principle or Method Used by the Expert. Both the United States Supreme Court, applying Fed. R. Evid. 702 in Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993), and the Supreme Judicial Court applying the common law in Commonwealth v. Lanigan, 419 Mass. 15, 641 N.E.2d 1342 (1994), agree on the fundamental require­ment that “[i]f the process or theory underlying [an] . . . expert’s opinion lacks reliability, that opinion should not reach the trier of fact.” Commonwealth v. Lanigan, 419 Mass. at 26, 641 N.E.2d at 1349. Both the Supreme Court and the Supreme Judicial Court require the trial judge to act as a gatekeeper to ensure that the expert witness testimony that is considered by the jury meets minimum standards of reliability. The variation between the two approaches is that Massachusetts law makes general acceptance the default position and a Daubert analysis an alternative method of establishing reliability. Under Fed. R. Evid. 702, Federal courts must consider five nonexclusive factors in assessing reliability, one of which is the traditional test that looked at whether the principle or method was generally accepted in the relevant scientific community. See Frye v. United States, 293 F. 1013 (D.C. Cir. 1923). “[G]eneral acceptance in the relevant community of the theory and process on which an expert’s testimony is based, on its own, continues to be sufficient to establish the requisite reliability for admission in Massachusetts courts regardless of other Daubert factors.” Commonwealth v. Patterson, 445 Mass. 626, 640, 840 N.E.2d 12, 23 (2005) (latent fingerprint identification theory). See Commonwealth v. Frangipane, 433 Mass. 527, 538, 744 N.E.2d 25, 33 (2001) (Lanigan hearing not necessary where qualified expert testimony has been accepted as reliable in the past in Massachusetts appellate cases). “Where general acceptance is not established by the party offering the expert testimony, a full Daubert analysis provides an alternate method of establishing reliability.” Commonwealth v. Patterson, 445 Mass. at 641, 840 N.E.2d at 23. These alternative, Daubert considerations include the ability to test the theory, existence of peer-reviewed publications supporting it, existence of standards for controlling or maintaining it, and known or potential error rates. See Daubert v. Merrell Dow Pharms., Inc., 509 U.S. at 593–594. “A judge may also look to his own common sense, as well as the depth and quality of the proffered expert’s education, training, experience, and appearance in other courts to determine reliability” (quotation and citation omitted). Commonwealth v. Pasteur, 66 Mass. App. Ct. 812, 826, 850 N.E.2d 1118, 1132 (2006). See also Commonwealth v. Powell, 450 Mass. 229, 239, 877 N.E.2d 589, 596 (2007) (holding a court may consider an appellate decision from a different jurisdiction).

In making the reliability determination it is also important that

“[a] relevant scientific community must be defined broadly enough to include a sufficiently broad sample of scientists so that the possibility of disagreement exists, . . . and . . . trial judges [must] not . . . define the relevant scientific community so narrowly that the expert’s opinion will inevitably be considered generally accepted. In the context of technical forensic evidence, the community must be sufficiently broad to permit the potential for dissent.”

Commonwealth v. Patterson, 445 Mass. at 643, 840 N.E.2d at 25, quoting from Canavan’s Case, 432 Mass. 304, 314 n.6, 733 N.E.2d 1042, 1050 n.6 (2000). See id. at 313–316, 733 N.E.2d at 1049–1052 (holding that the requirement of reliability under Lanigan extends to expert opinions based on personal observations and clinical experience, including medical expert testimony concerning diagnosis and causation). The requirements of Lanigan, as amplified in Canavan’s Case, do not apply fully as to the standard of care in a medical negligence case. Palandjian v. Foster, 446 Mass. 100, 108–109, 842 N.E.2d 916, 923 (2006) (“How physicians practice medicine is a fact, not an opinion derived from data or other scientific inquiry by employing a recognized methodology. However, when the proponent of expert testimony incorporates scientific fact into a statement concerning the standard of care, that science may be the subject of a Daubert-Lanigan inquiry.” [Quotation and citation omitted.]).

The application of the Daubert-Lanigan factors in cases involving the “hard” sciences may not apply in the same way in cases involving the “soft” sciences. See Daubert v. Merrell Dow Pharms., Inc., 509 U.S. at 593–594; Com­mon­wealth v. Lanigan, 419 Mass. at 25–26, 641 N.E.2d at 1349. See also Mark S. Brodin, Behavioral Science Evidence in the Age of Daubert: Reflections of a Skeptic, 73 U. Cin. L. Rev. 867 (2005). The Supreme Judicial Court has stated as follows:

“Observation informed by experience is but one scientific technique that is no less susceptible to Lanigan analysis than other types of scientific methodology. The gatekeeping function pursuant to Lanigan is the same regardless of the nature of the methodology used: to determine whether ‘the process or theory underlying a scientific expert’s opinion lacks reliability [such] that [the] opinion should not reach the trier of fact.’ Com­monwealth v. Lanigan, 419 Mass. 15, 26 (1994). Of course, even though personal observations are not excepted from Lanigan analysis, in many cases personal observation will be a reliable methodology to justify an expert’s conclusion. If the proponent can show that the method of personal observation is either generally accepted by the relevant scientific community or otherwise reliable to support a scientific conclusion relevant to the case, such expert testimony is admissible.”

Canavan’s Case, 432 Mass. at 313–314, 733 N.E.2d at 1050. See, e.g., Commonwealth v. Shanley, 455 Mass. 752, 766, 919 N.E.2d 1254, 1266 (2010) (“[T]he judge’s finding that the lack of scientific testing did not make unreliable the theory that an individual may experience dissociative amnesia was supported in the record, not only by expert testimony but by a wide collection of clinical observations and a survey of academic literature.”).

In several cases, the Supreme Judicial Court has relied on the discussion of forensic methods contained in a 2009 report by the National Research Coun­cil entitled Strengthening Forensic Science in the United States: A Path Forward 134–135 (2009) (NAS Report). See, e.g., Commonwealth v. Fernandez, 458 Mass. 137, 149 n.17, 934 N.E.2d 810, 820 n.17 (2010) (citing NAS Report that the “near universal” laboratory test for drug identity is the “gas chromatography-mass spectrometry” test); Commonwealth v. Barbosa, 457 Mass. 773, 788 n.13, 933 N.E.2d 93, 108 n.13 (2010) (citing NAS Report for proposition that nuclear DNA analysis is the standard against which many other forensic individualization techniques are judged). In Commonwealth v. Gambora, 457 Mass. 715, 724–727, 933 N.E.2d 50, 57–60 (2010), the defendant challenged the scientific basis of the latent fingerprint identification methodology known as ACE-V, which was criticized in the NAS Report. The Supreme Judicial Court observed that “[t]he NAS Report does not conclude that fingerprint evidence is so unreliable that courts should no longer admit it. The Report does, however, stress the subjective nature of the judgments that must be made by the fingerprint examiner at every step of the ACE-V process . . . .”

The Supreme Judicial Court has not addressed the standard to apply to evidence that meets the general acceptance test but is opposed on grounds that it is nonetheless unreliable. “Given that knowledge is constantly expand­ing, and that scientific principles are frequently modified in light of new discov­eries or theories, it is inconsistent with the reliability requirement to permit any theories or methods to be ‘grandfathered’ as admissible evidence.” M.S. Brodin & M. Avery, Massachusetts Evidence § 7.5.1, at 419 (8th ed. 2007).

Fifth Foundation Requirement: Reliability of the Application of the Principle or Method to the Specific Facts of the Case. See Commonwealth v. Colturi, 448 Mass. 809, 815–817, 864 N.E.2d 498, 503–504 (2007) (results of otherwise valid breathalyzer test is admissible to establish blood alcohol level at the time of the offense without expert witness testimony on the theory of ret­rograde extrapolation so long as the test was administered within three hours of the offense); Commonwealth v. McNickles, 434 Mass. 839, 847–850, 753 N.E.2d 131, 138–140 (2001) (disagreement among experts regarding the reliability of the application of a statistical method known as “likelihood ratios” to mixed samples of DNA evidence went to the weight, but not the admissibility, of the expert witness evidence); Smith v. Bell Atlantic, 63 Mass. App. Ct. 702, 718–719, 829 N.E.2d 228, 242–243 (2005) (even though expert witness was qualified and employed a reliable diagnostic method, her lack of knowledge of the details of the patient’s life called into question the reliability of her opinion and justified its exclusion in judge’s discretion).

Certitude of Expert Witness Opinion. In Commonwealth v. Heang, 458 Mass. 827, 942 N.E.2d 927 (2011), the Supreme Judicial Court explained that when an expert witness offers an opinion that is empirically based but subjective in nature, such as whether a cartridge or casing was fired from a particular firearm, it is not permissible for the witness to imply that the opinion has a statistical or mathematical basis. “Phrases that could give the jury an impression of greater certainty, such as ‘practical impossibility’ and ‘absolute certainty’ should be avoided. The phrase ‘reasonable degree of scientific certainty’ should also be avoided because it suggests that forensic ballistics is a science, where it is clearly as much an art as a science.” (Citation and footnote omitted.) Id. at 849, 942 N.E.2d at 946. In Heang, the Supreme Judicial Court provided the following examples of the degree of certitude that an expert witness may express when the opinion is empirically based but subjective in nature: for firearm or ballistics identification, a “reasonable degree of ballistics certainty,” Id. at 848–849, 942 N.E.2d at 946; for medical examiner and pathologist opinions, a “reasonable degree of medical certainty,” id. at 849, 942 N.E.2d at 945–946, citing Commonwealth v. Nardi, 452 Mass. 379, 383, 893 N.E.2d 1221, 1226 (2008); Commonwealth v. DelValle, 443 Mass. 782, 788, 824 N.E.2d 830, 836 (2005); for clinical diagnoses, a “reasonable degree of scientific certainty," Commonwealth v. Roberio, 428 Mass. 278, 280, 700 N.E.2d 830, 832 (1998); and for psychological opinions, a “reasonable degree of psy­chological certainty,” Commonwealth v. Wentworth, 53 Mass. App. Ct. 82, 86, 756 N.E.2d 1199, 1203 (2001). It may also be error for a fingerprint expert to state with absolute certainty that a particular latent print matches a known fingerprint. Commonwealth v. Gambora, 457 Mass. 715, 727–728, 933 N.E.2d 50, 60 (2010). In Heang, the court also noted that there are forensic disciplines that permit expert witness opinion to be expressed to a mathematical or statistical certainty. Commonwealth v. Heang, 458 Mass. at 849, 942 N.E.2d at 946, citing Commonwealth v. Mattei, 455 Mass. 840, 850–853, 920 N.E.2d 845, 854–856 (2010) (because it is possible to say to mathematical degrees of sta­tistical certainty that one DNA profile matches another, test results and opinions regarding DNA profile must be accompanied by testimony explaining likelihood of that match occurring in general population).


Abused Children. See Commonwealth v. Federico, 425 Mass. 844, 847–‌848, 683 N.E.2d 1035, 1037–1038 (1997).

Battered Woman Syndrome. The Legislature has concluded that battered woman syndrome evidence is of a kind appropriately presented to the fact finder by expert testimony. General Laws c. 233, § 23F, inserted by St. 1996, c. 450, § 248, which replaced G. L. c. 233, § 23E, repealed by St. 1996, c. 450, § 247, on the same subject, states that

“[i]n the trial of criminal cases charging the use of force against another where the issue of defense of self or another, defense of duress or coercion, or accidental harm is asserted, a defendant shall be permitted to introduce . . . evidence by expert testimony regarding the common pattern in abusive relationships; . . . the relevant facts and circumstances which form the basis for such opinion; and evidence whether the defendant displayed characteristics common to victims of abuse. Nothing in this section shall be interpreted to preclude the introduction of evidence or expert testimony . . . where such evidence or expert testimony is otherwise now admissible.”

Commonwealth v. Crawford, 429 Mass. 60, 67 n.15, 706 N.E.2d 289, 294 n.15 (1999).

Bloodstain Analysis. See Commonwealth v. Vasquez, 462 Mass. 827, 844–‌846, 971 N.E.2d 783, 798–799 (2012); Commonwealth v. Powell, 450 Mass. 229, 237–‌241, 877 N.E.2d 589, 595–597 (2007).

Capacity to Contract. See Sparrow v. Demonico, 461 Mass. 322, 327–‌330, 960 N.E.2d 296, 301–303 (2012).

Cause and Origin of Fire. See Commonwealth v. Goodman, 54 Mass. App. Ct. 385, 389–393, 765 N.E.2d 792, 794–797 (2002).

Computer Simulations. Evidence consisting of computer-generated models or simulations is treated like other scientific tests; admissibility is con­ditioned “on a sufficient showing that: (1) the computer is functioning properly; (2) the input and underlying equations are sufficiently complete and accurate (and disclosed to the opposing party, so that they may challenge them); and (3) the program is generally accepted by the appropriate community of scientists.” Commercial Union Ins. Co. v. Boston Edison Co., 412 Mass. 545, 549–550, 591 N.E.2d 165, 168 (1992).

Contribution of Alcohol to Personal Injury. See Baudanza v. Comcast of Mass. I, Inc., 454 Mass. 622, 631–633, 912 N.E.2d 458, 466–468 (2009).

Coprophilia (Sexual Fetish). See Commonwealth v. Lawton, 82 Mass. App. Ct. 528, 538–539, 976 N.E.2d 160, 170 (2012).

Dissociative Memory Loss. See Commonwealth v. Polk, 462 Mass. 23, 32–36, 965 N.E.2d 815, 824–827 (2012).

Dissociative Trance Disorder. See Commonwealth v. Montanez, 55 Mass. App. Ct. 132, 144–146, 769 N.E.2d 784, 795–796 (2002).

Distributing Heroin. See Commonwealth v. Miranda, 441 Mass. 783, 792–‌795, 809 N.E.2d 487, 495–497 (2004).

DNA. See Commonwealth v. Dixon, 458 Mass. 446, 453, 938 N.E.2d 878, 884–885 (2010) (“[a] properly generated DNA profile is a string of code that exclusively identifies a person’s hereditary composition with near infallibility”); Commonwealth v. Mattei, 455 Mass. 840, 847–852, 920 N.E.2d 845, 852–856 (2010) (evidence that DNA test failed to exclude the defendant “without accompanying evidence that properly interprets that result creates a greater risk of misleading the jury and unfairly prejudicing the defendant than admission of a ‘match’ without accompanying statistics”).

Extrapolation. Extrapolation evidence to determine the weight of drugs is permissible, and any objections to its admissibility should be raised by way of pretrial motion. Commonwealth v. Crapps, 84 Mass. App. Ct. 442, 445–449, 997 N.E.2d 444, 448–450 (2013).

Fingerprints. See Commonwealth v. Patterson, 445 Mass. 626, 641–655, 840 N.E.2d 12, 24–33 (2005). Cf. Commonwealth v. Gambora, 457 Mass. 715, 724–725, 933 N.E.2d 50, 58–59 (2010) (considering report by National Research Council, Strengthening Forensic Science in the United States: A Path Forward 102–104, 136–145 (2009)).

Firearm Identification (Forensic Ballistics). See Commonwealth v. Heang, 458 Mass. 827, 847–848, 942 N.E.2d 927, 944–945 (2011) (adopting “guidelines” for the admissibility of expert firearm identification testimony that [1] require documentation of the basis of the expert’s opinion before trial, which the Commonwealth must disclose to the defense in discovery; [2] require an explanation by the expert to the jury of the theories and methodologies underlying the field of forensic ballistics before offering any opinions; and [3] limit the degree of certitude that the qualified expert may express about whether a particular firearm fired a specific projectile or cartridge to a “reasonable degree of ballistic certainty”).

Gunshot Residue. See Commonwealth v. Johnson, 463 Mass. 95, 107–‌108, 972 N.E.2d 460, 470–471 (2012); Commonwealth v. Pytou Heang, 458 Mass. 827, 851, 942 N.E.2d 927, 947 (2011).

Personality Testing. See Ready, petitioner, 63 Mass. App. Ct. 171, 172–‌179, 824 N.E.2d 474, 476–480 (2005).

Posttraumatic Stress Disorder. See Commonwealth v. Anestal, 463 Mass. 655, 658 n.5, 978 N.E.2d 37, 41 n.5 (2012); Commonwealth v. Crawford, 429 Mass. 60, 67, 706 N.E.2d 289, 294 (1999).

Retrograde Extrapolation. See Commonwealth v. Senior, 433 Mass. 453, 458–462, 744 N.E.2d 614, 618–621 (2001).

Susceptibility to Suggestiveness. See Commonwealth v. Soares, 51 Mass. App. Ct. 273, 280–282, 745 N.E.2d 362, 368–370 (2001).

Valuation of Real Estate. See Correia v. New Bedford Redev. Auth., 375 Mass. 360, 362–367, 377 N.E.2d 909, 911–914 (1978) (expert wit­ness may use the depreciated reproduction cost method to form an opinion as to the value of real estate when the judge finds that there is a justification for the use of this disfavored approach).

For examples of cases applying this section, see M.S. Brodin & M. Avery, Massachusetts Evidence §§ 7.4–7.6 (8th ed. 2007); 3 M.G. Perlin & D. Cooper, Mottla’s Proof of Cases in Massachusetts §§ 83:6–83:25 (3d ed. 1995 & Supp. 2007); W.G. Young, J.R. Pollets, & C. Poreda, Annotated Guide to Massachusetts Evidence § 702 (2011 ed.).

Jury Instructions. See Commonwealth v. Hinds, 450 Mass. 1, 12 n.7, 875 N.E.2d 488, 496 n.7 (2007).

Cross-Reference: Section 703, Bases of Opinion Testimony by Experts.

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