Commonwealth v. Shu Feng Hsu (SJC-13855, September 9, 2026)

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SJC-13855

COMMONWEALTH vs. SHU FENG HSU.

Norfolk. April 6, 2026. – September 9, 2026.

Present: Budd, C.J., Gaziano, Kafker, Wendlandt, Georges, Dewar, & Wolohojian, JJ.

Homicide. Evidence, Expert opinion, Relevancy and materiality. Witness, Expert. Child Abuse. Jury and Jurors. Practice, Criminal, Jury and jurors.

Indictment found and returned in the Superior Court Department on January 11, 2019.

The case was tried before Douglas H. Wilkins, J.

The Supreme Judicial Court on its own initiative transferred the case from the Appeals Court.

Christopher DeMayo (Debra D. DeWitt also present) for the defendant.

Meagen K. Monahan, Assistant District Attorney, for the Commonwealth.

The following submitted briefs for amici curiae:

V. Marika Meis, of New York, Radha Natarajan, Nina Thacker, David R. Rangaviz, Sharon L. Beckman, Lisa M. Kavanaugh, & Katharine Naples-Mitchell for New England Innocence Project & others.

Thomas J. Carey, Jr., & Mark S. Brodin for Mark S. Brodin.

Mark Loevy-Reyes for Center for Integrity in Forensic Sciences & others. GAZIANO, J. The defendant, Shu Feng Hsu, was charged with murder in the first degree for the death of her eleven month old niece, Chloe Chen. Before trial, the defendant filed motions in limine to exclude expert testimony regarding abusive head trauma — a medical diagnosis describing injuries to the skull or brain of a young child due to inflicted blunt impact or violent shaking — and requesting a hearing pursuant to Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 585-595 (1993), and Commonwealth v. Lanigan, 419 Mass. 15, 24-26 (1994). Following a Daubert-Lanigan hearing, the trial judge allowed the motions in part and denied them in part, ruling that expert witnesses could testify that the victim showed symptoms "consistent with" abusive head trauma but could not testify that abusive head trauma "was the cause" of the victim's death. The judge also prohibited expert testimony that "short falls cannot cause [abusive head trauma]," among other restrictions. A Norfolk County jury convicted the defendant of the lesser included offense of involuntary manslaughter under the theories of battery and wanton or reckless conduct. The defendant appealed, arguing that the evidence was insufficient to support the conviction and that the judge abused his discretion by allowing the admission of expert testimony regarding abusive head trauma and short falls. We transferred the appeal to this court on our own motion and now affirm.1

Background. 1. Facts. Because the defendant challenges the sufficiency of the evidence, we summarize the evidence presented at trial in the light most favorable to the Commonwealth. See Commonwealth v. Latimore, 378 Mass. 671, 676- 677 (1979). a. The victim's death. In February 2018, the victim, an eleven month old girl, lived on the second floor of a home in Quincy with her parents and grandparents. The defendant and her husband, the victim's uncle, lived on the first floor of the home with their two year old daughter. The victim was generally a healthy child with no major illnesses. Several days per week, while the other adults in the household were at work outside the home, the defendant would watch her daughter and the victim. On the morning of February 15, 2018, the victim's grandmother and father cared for the victim. The grandmother watched the victim from 8 A.M. until she left for work between 9:30 and 10 A.M. The victim's father then watched her until

1 We acknowledge the amicus briefs submitted in support of the defendant by the New England Innocence Project, the Massachusetts Association of Criminal Defense Lawyers, the Boston College Innocence Program, the Committee for Public Counsel Services, the Criminal Justice Institute at Harvard Law School, and the Innocence Project; Mark S. Brodin; and the Center for Integrity in Forensic Sciences, Cyrille Rossant, Waney Squier, Jane Turner, Steven Gabaeff, and Judy Melinek. around 2 or 2:30 P.M., when he left the house to go to work and the defendant took over as the victim's caregiver in the first- floor apartment. Neither the grandmother nor the father observed any medical issues with the victim. Video recordings from surveillance cameras installed in the home, which were admitted in evidence at trial, show a healthy and active infant. She ate and watched television alongside the defendant in the living room, cruised in her walker, babbled, reached for objects, fed herself, and cried sporadically. Eventually, the defendant took her daughter and the victim to the defendant's bedroom for a nap. At around 4:20 P.M., approximately two and one-half hours after the defendant and the children went into the defendant's bedroom, a surveillance camera in the living room captured the sound of a baby intermittently crying for about five minutes. At around 4:25 P.M., the camera recorded the sound of eleven thuds occurring over the span of approximately one minute. The eleven thuds are interspersed with the sound of the baby crying. After the eleventh thud, the crying slowly stops and is replaced by coughing and gagging sounds. At 4:29 P.M., the defendant called 911. She told the 911 operator that the victim seemed "soft" and was having difficulty breathing. A Quincy police officer arrived at the home approximately six minutes later. He noticed the victim's breathing was shallow and that she appeared to be seizing. The officer did not recall if he observed a mark or a bruise on the victim's head. Paramedics arrived in an ambulance shortly thereafter. As the victim was placed in the ambulance, one paramedic noticed that the victim had a small bruise or abrasion on her forehead, and that she did not have a fever. The defendant told the paramedic that the victim had slept longer than usual that day and that she suffered multiple seizures in the moments before the defendant called 911. The victim was taken to Boston Medical Center. Upon the victim's arrival at the hospital, Dr. James Holsapple, the neurosurgeon who performed surgery on the victim, observed that she was unconscious and seizing and that her pupils were nonreactive. Holsapple did not observe a bruise on the victim's forehead or other conspicuous signs of trauma on her arrival. However, contemporaneous medical records indicate that the victim presented with a bruise on her forehead that may not have been recent. A computed tomography (CT) scan showed that the victim had an acute subdural hematoma2 covering most of the

2 A subdural hematoma is an accumulation of blood in the space between the brain and the dura. See Commonwealth v. Millien, 474 Mass. 417, 421 (2016). The dura is the membrane between the skull and the brain. Id. at 421 n.4. Holsapple explained that "acute" indicates that the blood has "just come surface of the left hemisphere of her brain; the victim's brain had an eight millimeter midline shift, which meant that the middle of her brain was pushed over from its normal position by eight millimeters; and the left side of her brain was swollen. Based on the victim's critical injuries, Holsapple performed brain surgery approximately one hour and fifteen minutes after her arrival at the hospital. He found a large volume of high pressure, acute blood beneath the victim's skull. Holsapple was able to remove the subdural hematoma, but once it was removed, the victim became unstable, prompting emergency resuscitation efforts that caused additional brain swelling. The victim was subsequently transferred to the pediatric intensive care unit. She died on February 17, 2018. b. Investigation and arrest. On February 16, 2018, the day after the victim was taken to the hospital, the defendant participated in an interview with police. The defendant said that the victim cried a lot and had done so the previous day, but she denied that the crying frustrated her. The defendant told the interviewing officers that she had called 911 because the victim, who had been sleeping, suddenly clenched in a way that suggested she may be suffering from a seizure. The

out," and that subdural hematomas can occur in the absence of conspicuous scalp trauma or bruising. defendant denied touching, dropping, or shaking the victim, noting that if someone had struck her, there would have been a bruise or blood. The same day as the interview, police removed and seized memory cards from the surveillance cameras inside and around the defendant's home.3 The police arrested the defendant at her home on November 20, 2018, where, after searching for twenty minutes, they found her hiding in a bedroom closet. c. Commonwealth's expert witnesses. Dr. Anand Shah and Dr. Christina Stanley, medical examiners in the office of the chief medical examiner, performed the victim's autopsy. The autopsy revealed multiple injuries not attributable to medical intervention, including bruises on the victim's head, left forearm, and torso. Also discovered were multiple brain and

3 Although there was a surveillance camera in the defendant's bedroom, there was no memory card in the camera, so there are no video recordings available from that room. During the police interview, the defendant stated that she sold the memory card from the bedroom camera before February 15, 2018, although she could not remember to whom she sold it.

When the police went to the defendant's home, the living room camera's memory card was hidden inside a "little egg." The defendant told the police that she had removed the memory card from the living room camera at her husband's request and set it on the table, and that her two year old daughter grabbed the memory card from the table and hid it in the egg. retinal hemorrhages, and evidence of one brain hemorrhage that appeared to be weeks or months old.4 At trial, Shah directed the jury's attention to details in certain autopsy photographs. While showing the jury a photograph of the left side of the victim's face, Shah pointed to "areas of kind of red to blue, to purple bruising." He next showed a photograph of her outer left forearm and highlighted bruising that was "blue-purple in coloration and linear," and that there "look[ed] to be about three bruises." The next photograph showed "injuries of the left side of the [victim's] face" that Shah attributed to blunt force trauma, not medical intervention. Another photograph of the victim's face showed "bruising of [the] left cheek area" as well as "bruising around the left eyebrow" and "some bruising near the bottom of the left ear." Photographs of the right side of the victim's head showed "bruising of the right forehead" that had a "blue-purple discoloration."5 Shah testified that the victim's death was a

4 Holsapple had not found evidence of an old subdural hematoma during surgery.

5 On cross-examination, Shah acknowledged that a death notification report transmitted from Boston Medical Center indicated "no outward signs of trauma"; bruising to the victim's left ear may have been attributable to manipulation of the ear during surgery; and the victim developed a significant coagulopathy, which increased the probability of bruising due to medical intervention, especially where the victim was subject to ninety minutes of chest compressions. These concessions in Shah's testimony do not undermine our determination that the result of multiple significant blunt force impacts to the head that had been recently inflicted. Shah noted that the victim's blunt force injuries were not consistent with her bumping her head on a crib or a short fall of less than three feet. Similarly, Stanley, a neuropathologist, opined that the victim's subdural hematoma was the result of significant trauma. She testified that the subdural hematoma was inconsistent with a rebleed of the older hemorrhage, because the older hemorrhage was too thin to have caused the volume of bleeding that occurred. Dr. Kimberly Schwartz, a child abuse pediatrician and member of the Boston Medical Center child protection team, also testified at trial for the Commonwealth. Schwartz explained that abusive head trauma involves "injury to the brain or around the brain of a young child that is . . . not accidental." Schwartz reviewed the victim's medical records, spoke with the victim's parents and her medical team, and conducted a visual examination of the victim before completing a differential diagnosis6 of the victim's injuries. Schwartz concluded that the

evidence was sufficient when viewed in the light most favorable to the Commonwealth. See Latimore, 378 Mass. at 676-677.

6 A differential diagnosis "is a standard scientific technique of identifying the cause of a medical problem by eliminating the likely causes until the most probable one is isolated" (citation omitted). Hick's Case, 62 Mass. App. Ct. 755, 761 (2005). victim's injuries were "consistent with abusive head trauma." She also opined that the victim's subdural hematoma was inflicted "[s]hortly before [the victim] presented to the hospital" and that the level of force necessary to inflict a subdural hematoma is force "not from . . . normal infant care." d. Defendant's expert witnesses. The defendant presented two expert witnesses. First, Dr. Janice Ophoven, a pediatric forensic pathologist, shared her expert opinion after reviewing the victim's case file, police and medical records, and autopsy reports. Ophoven testified that there was evidence the victim had sustained a prior head injury weeks or months before February 15, 2018, and opined that the victim "suffered a traumatic brain injury due to blunt-force trauma associated with chronic and acute subdural bleeding." She explained that "chronic" "means that it's been going on for a significant period of time," and noted that children with chronic subdural fluid can suffer an immediate collapse from falling and "banging their head on the crib or on the floor." Ophoven further testified that the victim went into cardiac arrest when doctors made the incision releasing the pressure in her brain, and that the significant amount of blood documented during the autopsy was due to surgical intervention rather than blunt force impact to the victim's head. Dr. John Galaznik, a pediatrician, similarly testified that the victim's injuries indicated preexisting subdural bleeding alongside some new bleeding, and that acute blood on a CT scan is not necessarily from the same day, but rather can be one to ten days old. He then opined that the victim's injuries could have been the result of rebleeding of a prior injury after a "trivial" impact or bump to the head, and that the bump could have occurred one to seven days before the victim was taken to the hospital. 2. Procedural history. On January 11, 2019, a grand jury indicted the defendant on a charge of murder in the first degree in violation of G. L. c. 265, § 1. In February 2023, the defendant filed two motions in limine to exclude expert testimony regarding abusive head trauma. After an evidentiary Daubert-Lanigan hearing, on March 6, 2023, the defendant's motions in limine were allowed in part and denied in part. A fourteen-day jury trial commenced the following day. At the close of the Commonwealth's case, the defendant moved for a required finding of not guilty, which the judge allowed with respect to murder in the first degree on a theory of deliberate premeditation but otherwise denied. The defendant then renewed her motion for a required finding of not guilty at the close of all evidence, which the judge also denied. The jury found the defendant guilty of involuntary manslaughter on theories of battery and wanton or reckless conduct. The defendant filed a motion for a required finding of not guilty after the discharge of the jury, which was denied. The judge sentenced the defendant to a term of from five to seven years in State prison. The defendant appealed, and we transferred the appeal to this court on our own motion. Discussion. On appeal, the defendant argues that (1) the evidence was insufficient to convict her of involuntary manslaughter, and (2) the trial judge abused his discretion in permitting expert testimony that the victim's injuries were "consistent with" abusive head trauma and that the victim's injuries were not consistent with a short fall. We begin with the sufficiency of the evidence. 1. Sufficiency of the evidence. In reviewing a sufficiency claim, we "determine whether, viewing the evidence in the light most favorable to the Commonwealth, any rational finder of fact could have found each of the elements of the offense beyond a reasonable doubt." Commonwealth v. Jones, 477 Mass. 307, 316 (2017), citing Latimore, 378 Mass. at 676-677. "A conviction may rest exclusively on circumstantial evidence," Jones, supra, and the inferences drawn by the jury from the evidence "need only be reasonable and possible and need not be necessary or inescapable" (citation omitted), Commonwealth v. Kelly, 470 Mass. 682, 693 (2015). "If, from the evidence, conflicting inferences are possible, it is for the jury to determine where the truth lies, for the weight and credibility of the evidence is wholly within their province" (citation omitted). Id. "Involuntary manslaughter is an unlawful homicide (1) where wanton [or] reckless conduct causes death, or (2) where an unintentional killing result[s] from a battery not amounting to a felony which the defendant knew or should have known endangered human life" (quotation and citation omitted). Commonwealth v. Simpson, 434 Mass. 570, 590 (2001). Wanton or reckless conduct is "intentional conduct that create[s] a high degree of likelihood that substantial harm will result to another person" (citation omitted). Commonwealth v. O'Brien, 494 Mass. 288, 297 (2024). The crime of assault and battery requires "the intentional and unjustified use of force upon the person of another, however slight" (citation omitted). Commonwealth v. Sheppard, 404 Mass. 774, 776 (1989). At trial, the jury were presented evidence that the victim was a healthy eleven month old on the morning of February 15, 2018. The victim's family members testified that the victim was behaving normally before she was left in the defendant's care, and video recordings from inside the home show the victim eating, interacting with family members, and cruising in her walker. The Commonwealth also presented evidence that the defendant was the victim's sole caretaker in the hours immediately before the 911 call. See Collazo v. Commonwealth, 483 Mass. 1025, 1027 (2020) (evidence warranted finding that defendant inflicted injuries on infant victim where jury could have found defendant was child's sole caretaker during key time period); Commonwealth v. Azar, 32 Mass. App. Ct. 290, 305 (1992), S.C., 435 Mass. 675 (2002), and 444 Mass. 72 (2005) (considering fact that defendant was child's sole caretaker before child's death in assessing sufficiency of evidence for conviction of murder in second degree). A video recording of the victim's home on the afternoon of February 15, 2018, which was played for the jury, captured the sound of a baby crying, followed by eleven distinct thuds, and then the defendant speaking on the telephone with the 911 operator. A paramedic who responded to the 911 call testified that, upon arriving at the home, the victim was unresponsive with her eyes rolled back, and that she had a visible bruise on her head.7 Given the difference in the victim's health before

7 Even where there was some inconsistency between witnesses whether bruising appeared on the victim's head before her arrival at the hospital, the jury were entitled to credit testimony indicating its presence. See Commonwealth v. Miranda, 458 Mass. 100, 113 (2010), cert. denied, 565 U.S. 1013 (2011), S.C., 474 Mass. 1008 (2016) ("To the extent that conflicting inferences may be drawn from the evidence, it is for the jury to decide which version to credit"). That is especially true here, where the jury reviewed autopsy photographs of the victim and Shah, the medical examiner, opined that bruising on the victim's and after the sound of the eleven thuds, and the repetitive nature of the noises (interspersed with the baby's cries and culminating in coughing and gagging sounds), the evidence supported a reasonable inference that the defendant injured the victim. See Commonwealth v. Lacrosse, 494 Mass. 475, 503 (2024) ("the jury were required to ultimately decide what the surveillance video footage showed"); Commonwealth v. Forte, 469 Mass. 469, 482 n.23 (2014) ("Interpretation of the footage in relation to the witnesses' testimony was for the jury"). The jury heard expert testimony further supporting the reasonable inference that the victim's injuries were caused by recent, nonaccidental blunt force impact. Describing his observations from the autopsy, Shah opined to a reasonable degree of medical certainty that the victim died from blunt force head injuries caused by significant, repeated impact. While the jury reviewed autopsy photographs of the victim, Shah pointed to bruising on the left side of the victim's head and a bruise on the right side of her forehead. The jury "were well able to make their own evaluation of the mark[s] shown in the

head was not consistent with medical intervention. Moreover, regardless of whether the jury credited testimony on the existence of bruising before the victim received medical intervention, the jury could have credited Schwartz's testimony that abusive head trauma often manifests without external symptoms. photograph[s]." Commonwealth v. Kelly, 57 Mass. App. Ct. 201, 213 (2003). Shah also indicated that the victim's injuries were new, not old, and that they were not consistent with bumping her head on a crib or a short fall of less than three feet. Cf. Collazo, 483 Mass. at 1026 (among expert testimony establishing infant victim died due to injuries inflicted on him, medical examiner testified to autopsy finding of blood clot on victim's brain "that was not old enough to have formed a membrane"). Similarly, Stanley testified to a reasonable degree of medical certainty that the victim's subdural hematoma was caused by "significant trauma, shearing-type trauma." She explained that this trauma caused multiple veins between the victim's brain and dura to tear. When asked whether the victim's subdural hematoma could have resulted from a rebleed of an older hematoma, she stated that "it wasn't caused by that" and explained that "the . . . older hemorrhage . . . [was] just too thin to have a vessel in it that's big enough to cause that volume of bleeding." Schwartz testified that the victim's injuries were "consistent with abusive head trauma" to a reasonable degree of professional certainty. As to the victim's subdural hematoma, she opined that it was not consistent with a rebleed, and explained that the force necessary to inflict a subdural hematoma is generally force beyond that used in normal child care. And when asked whether the victim's subdural hematoma was consistent with a short fall from a sitting position, Schwartz answered, "No, I did not believe so" and that a subdural hematoma from a short fall "is not the same kind of size of subdural that we see in this case." The defendant's experts disagreed on a number of points. As previously noted, Ophoven testified that the victim suffered from chronic subdural bleeding and noted that a child with chronic subdural fluid could collapse from falling and bumping his or her head. She attributed the amount of blood found during the autopsy to surgical intervention rather than blunt force impact. Galaznik opined that the victim's injuries were caused by rebleeding of an older injury activated by a bump to the victim's head. He explained that this bleeding could have started days before the victim was taken to the hospital. While the medical experts provided contradictory theories of the victim's injuries, "the question whether to believe the experts [was] for the jurors." Commonwealth v. Kappler, 416 Mass. 574, 583 (1993). "This is particularly true of experts in the medical field, who regularly are permitted to testify on the basis of examination of records and other materials with respect to an issue in dispute." Commonwealth v. Cowen, 452 Mass. 757, 762 (2008). Here, where the defendant presented expert testimony offering an alternative theory for the victim's injuries, the weight of the competing expert testimony was a matter for the jury. See id.8 Setting aside the testimony of her own experts, the defendant argues that Holsapple's testimony on rebleeds "obviously undermined the Commonwealth's case." Specifically, while Holsapple testified that no old subdural hematoma was found during surgery, when asked whether the amount of blood was consistent with a rebleed, he acknowledged that "[i]t could be." But Holsapple subsequently qualified this statement by explaining that "rebleeds . . . tend not to be large acute subdurals of the type that [the victim] had but it is possible." The jury could have considered Holsapple's testimony together with the Commonwealth's experts' testimony and still reasonably concluded that the victim's injuries were not caused by a

8 This is consistent with our most recent case law considering expert testimony on abusive head trauma. See Commonwealth v. Epps, 474 Mass. 743 (2016); Millien, 474 Mass. 417. In each case, we vacated the underlying conviction and remanded for a new trial where the Commonwealth had presented expert testimony on shaken baby syndrome or abusive head trauma, as the defendant was deprived of a substantial defense based on expert testimony that the child victim's injuries could have been caused by an accidental short fall. See Epps, supra at 748-749, 767-770; Millien, supra at 423-424, 434-438, 442. We reasoned that, given the "heated debate" surrounding these types of diagnoses in the medical community, the jury ought to have heard both sides of that debate, even where the defense experts fell within the minority on that debate, see Epps, supra at 755, 760, and regardless of who would have ultimately prevailed, Millien, supra at 418, 439. rebleed. See Commonwealth v. Hinds, 487 Mass. 212, 225 (2021), S.C., 494 Mass. 681 (2024) ("the determination of the credibility of [an] expert and the weight to be attributed to [an] expert's testimony" are questions for jury). Considering the evidence presented to them, the jury could have reasonably inferred that the victim's injuries were the result of the defendant inflicting blunt force on the victim, and that this constituted a battery that the defendant knew or should have known endangered the victim's life. See Sheppard, 404 Mass. at 776–777, 779 (affirming involuntary manslaughter conviction on theory of battery where defendant punched substantially smaller victim with sufficient force to cause victim's head to hit pavement, fracturing victim's skull). The jury also could have determined that inflicting blunt force on the victim created a high likelihood of substantial harm to the victim, thereby constituting wanton or reckless conduct. See Commonwealth v. Pease, 49 Mass. App. Ct. 539, 540-542 (2000) (affirming involuntary manslaughter conviction on theory of wanton or reckless conduct where defendant pushed victim, who fell and hit head, suffering cerebral trauma leading to death). 2. Expert testimony. The defendant next argues that the judge abused his discretion by admitting expert testimony regarding abusive head trauma and short falls. "The role of expert testimony is to assist jurors in interpreting evidence that lies outside their common experience" (citation omitted). Hinds, 487 Mass. at 217. A judge assesses the admissibility of scientific expert testimony under the Daubert-Lanigan standard, pursuant to which he or she must make "a threshold determination that the testimony is both relevant and sufficiently reliable to go before the jury" (quotation and citation omitted). Id. at 218. To determine reliability, a judge may weigh a nonexclusive list of factors, including "whether the scientific theory or process (1) has been generally accepted in the relevant scientific community; (2) has been, or can be, subjected to testing; (3) has been subjected to peer review and publication; (4) has an unacceptably high known or potential rate of error; and (5) is governed by recognized standards" (citation omitted).

Commonwealth v. Camblin, 478 Mass. 469, 475-476 (2017). However, a judge need not necessarily weigh each factor, as pursuant to the test established in Frye v. United States, 293 F. 1013, 1014 (D.C. Cir. 1923), "reliability can still be established by general acceptance alone, without regard to the other Daubert-Lanigan factors." Commonwealth v. Davis, 487 Mass. 448, 454 (2021), S.C., 491 Mass. 1011 (2023). See Commonwealth v. Rintala, 488 Mass. 421, 428 (2021). And if the proposed expert testimony satisfies this standard, the judge may still exclude expert testimony if its "probative value is substantially outweighed by the risk of unfair prejudice, confusion, or waste of time" (citation omitted). Commonwealth v. Chism, 495 Mass. 358, 375 (2025). See Mass. G. Evid. § 403 (2026). We review a judge's decision to admit or exclude expert testimony for abuse of discretion. See Rintala, 488 Mass. at 425. See also Chism, 495 Mass. at 375. "[A] judge's discretionary decision constitutes an abuse of discretion where we conclude the judge made a clear error of judgment in weighing the factors relevant to the decision, such that the decision falls outside the range of reasonable alternatives" (quotation and citation omitted). L.L. v. Commonwealth, 470 Mass. 169, 185 n.27 (2014). The proponent of the expert testimony "bears the burden of establishing . . . that the methodology or theory underlying the expert testimony is sufficiently reliable" (citation omitted). Rintala, supra at 426. Before analyzing the testimony at issue here, we begin by reciting the relevant procedural history. a. Procedural history. As previously noted, the defendant filed two motions in limine to exclude certain expert testimony. First, the defendant moved to exclude testimony at trial regarding abusive head trauma or shaken baby syndrome,9 and

9 As we have previously noted, because terms like "shaken baby syndrome" focus on a single injury mechanism — shaking — use of the term "abusive head trauma" has been recommended to requested a Daubert-Lanigan evidentiary hearing on the subject. As a basis for her motion, she argued that testimony regarding abusive head trauma and shaken baby syndrome was inadmissible under Daubert-Lanigan because, among other things, the theory "is no longer generally accepted in the relevant scientific community." Second, the defendant filed a supplemental motion in limine seeking to exclude use of the term "abusive" head trauma at trial. In her motion, she argued that an expert diagnosis using the word "abusive" would reach the ultimate issue of the defendant's guilt, impermissibly threatening the independence of the jury's decision. A Daubert-Lanigan hearing was held on the defendant's motions. At the hearing, the defendant's expert Galaznik and the Commonwealth's expert Schwartz testified. Galaznik opined that "there is no biomechanical, animal, or human experimental data" confirming that shaking would be "predicted to produce any primary brain injury, primary subdural bleeding, or primary retinal hemorrhaging in a . . . [twenty]-pound infant." He also testified that, according to research, a short fall of "as little as . . . two to three feet" could be "capable of inducing subdural bleeding and . . . the findings in this case."

more inclusively account for injuries inflicted on infants and children. See Millien, 474 Mass. at 423 n.7. Schwartz explained that abusive head trauma is a medical diagnosis that is identified through a differential diagnosis procedure. She also described a 2018 study finding that the short fall mortality rate for children under five years old is 0.48 per one million annually.10 On the day before trial, the judge issued his order allowing the defendant's motions in limine in part and denying them in part. The judge determined that abusive head trauma was generally accepted as a reliable medical diagnosis and that, therefore, expert testimony regarding abusive head trauma was admissible.11 However, he limited the expert witnesses to stating that the victim's injuries were "consistent with" abusive head trauma — not that abusive head trauma "was the cause" of the victim's injuries. Additionally, he prohibited the experts from testifying "that short falls cannot cause [abusive head trauma]." b. Abusive head trauma. We now consider whether the judge abused his discretion by allowing the admission of expert

10 See Choudhary et al., Consensus Statement on Abusive Head Trauma in Infants and Young Children, 48 Pediatric Radiology 1048, 1052 (2018).

11 The judge discussed all five Daubert-Lanigan factors in his order. However, because general acceptance in the relevant community alone continues to be sufficient to determine reliability, see Rintala, 488 Mass. at 428, we only focus on his findings pertaining to this factor. testimony regarding abusive head trauma. In his decision, the judge concluded that abusive head trauma "is generally accepted by physicians and the medical community" as a diagnosis that does not turn upon the presence of a specific set of symptoms or observations but is instead reached through a differential diagnosis.12 In reaching this conclusion, the judge relied on guidance from various organizations and peer-reviewed consensus statements designating abusive head trauma as a valid medical diagnosis.13 However, the judge also expressed concerns about

12 The judge rejected the characterization of abusive head trauma as requiring a "triad" of symptoms, noting a 2018 study describing the use of this term as misleading, given the complex nature of the diagnosis. See Millien, 474 Mass. at 418 (abusive head trauma presents as "triad" of symptoms — subdural hematoma, retinal hemorrhages, and encephalopathy). See also Choudhary et al., supra at 1060 ("The term 'triad' is a legal convention that falsely mischaracterizes a complex [abusive head trauma] diagnosis process").

13 In his findings, the judge noted that he relied on statements by the American Academy of Pediatrics, the American Academy of Ophthalmology, the American Association of Neurological Surgeons, the Centers for Disease Control and Prevention, and other comparable organizations. See American Association of Neurological Surgeons, Shaken Baby Syndrome (Apr. 2024), https://www.aans.org/patients/conditions-treatments/ shaken-baby-syndrome [https://perma.cc/KZ5B-X6HT]; American Academy of Ophthalmology, Abusive Head Trauma/Shaken Baby Syndrome (2015); Narang et al., American Academy of Pediatrics, Policy Statement, Abusive Head Trauma in Infants and Children (2020); Public Health Agency of Canada & Canadian Paediatric Society, Joint Statement on Traumatic Head Injuries Due to Child Maltreatment: An Update to the Joint Statement on Shaken Baby Syndrome (2020); Royal College of Paediatrics & Child Health, Child Protection Evidence: Systematic Review on Head and Spinal Injuries (Aug. 2019); Centers for Disease Control and Prevention, About Abusive Head Trauma (May 2024), https://www how the jury would understand the term "abusive," which could suggest that an action was "violent" or "cruel," or that the actor had a particular state of mind. Further, the judge noted that whether abuse had actually occurred was a factual question committed to the jury. Yet, the judge recognized that "[p]rohibiting use of the term would be hard to implement, because the medical witnesses on both sides naturally have used and will use it, the term describes a specific body of knowledge, there is no obvious, medically accepted alternative, and there is a great likelihood that witnesses accustomed to using the term will do so inadvertently even if ordered to avoid it." Accordingly, he limited experts to testifying that the victim's injuries were "consistent with" abusive head trauma, not that abusive head trauma caused the victim's injuries. The judge did not abuse his discretion by admitting testimony that the victim's injuries were "consistent with"

.cdc.gov/child-abuse-neglect/about/about-abusive-head- trauma.html [https://perma.cc/VG83-P356]; Choudhary et al., supra; Narang et al., Acceptance of Shaken Baby Syndrome and Abusive Head Trauma as Medical Diagnoses, 177 J. Pediatrics 273 (2016); Narang et al., A Daubert Analysis of Abusive Head Trauma/Shaken Baby Syndrome — Part II: An Examination of the Differential Diagnosis, 13 Hous. J. Health L. & Pol'y 203 (2013); Narang, A Daubert Analysis of Abusive Head Trauma/Shaken Baby Syndrome, 11 Hous. J. Health L. & Pol'y 505 (2011); Parks et al., Centers for Disease Control and Prevention, Pediatric Abusive Head Trauma: Recommended Definitions for Public Health Surveillance and Research (Apr. 2012). abusive head trauma. On this record, the judge properly determined that abusive head trauma is generally accepted as a valid medical diagnosis in the relevant medical community.14 According to the consensus statements presented by the Commonwealth, numerous national and international medical societies and organizations recognize abusive head trauma as a valid medical diagnosis. See Choudhary et al., Consensus Statement on Abusive Head Trauma in Infants and Young Children, 48 Pediatric Radiology 1048, 1049, 1052 (2018) (reviewing "[fifteen] major national and international professional medical societies' and organizations' consensus statements confirming the validity of the [abusive head trauma] diagnosis"). The Commonwealth also presented literature indicating that physicians widely recognize abusive head trauma as a diagnosis. For example, in one 2016 survey of children's hospital physicians with over 600 respondents, ninety-three percent of

14 We note that courts in other jurisdictions have likewise found that abusive head trauma is a generally accepted diagnosis. See, e.g., Nielsen v. State, 2018 WY 132, ¶ 32 (abusive head trauma "has long been recognized as a clinically valid medical diagnosis" [citation omitted]). See also Commonwealth v. Fernandez, 458 Mass. 137, 150–151 (2010) ("judges may rely on the decisions of other courts as one factor when evaluating the general acceptance of scientific evidence"). But see State v. Nieves, 262 N.J. 161, 238-239 (2025) (in cases of child abuse from shaking without impact, expert testimony regarding shaken baby syndrome and abusive head trauma not sufficiently reliable to go before jury). surveyed physicians indicated that abusive head trauma is a valid evidence-based diagnosis. See Narang et al., Acceptance of Shaken Baby Syndrome and Abusive Head Trauma as Medical Diagnoses, 177 J. Pediatrics 273, 273 (2016). And further, abusive head trauma is diagnosed "like any other medical diagnosis, by considering all the information acquired via clinical history, physical examination, and laboratory and imaging data." Choudhary et al., supra at 1052. Although the defendant provided literature describing the shortcomings of abusive head trauma and shaken baby syndrome diagnoses,15 these sources do not undermine the judge's determination that abusive head trauma is a generally accepted medical diagnosis. First, "[u]nanimity of opinion among the

15 See Bache et al., Open Letter on Shaken Baby Syndrome and Courts: A False and Flawed Premise (2015), http://www .argumentcritique.com/special-edition.html [https://perma.cc /WRB3-3D9W] (scientific basis for shaken baby syndrome diagnosis is disputed); Findley et al., Shaken Baby Syndrome, Abusive Head Trauma, and Actual Innocence: Getting It Right, 12 Hous. J. Health L. & Pol'y 229 (2012) (describing ongoing debates regarding shaken baby syndrome and abusive head trauma diagnoses); Guthkelch, Problems of Infant Retino-Dural Hemorrhage with Minimal External Injury, 12 Hous. J. Health L. & Pol'y 201 (2012) (raising various problems with shaken baby syndrome and abusive head trauma diagnoses, including how terms imply mechanism of injury and theory of perpetrator's intent that are not necessarily accurate); Tuerkheimer, The Next Innocence Project: Shaken Baby Syndrome and the Criminal Courts, 87 Wash. U. L. Rev. 1 (2009) (describing scientific debate regarding whether shaking alone can cause symptoms associated with shaken baby syndrome diagnosis). relevant scientists is not essential even under the general acceptance test." Commonwealth v. Shanley, 455 Mass. 752, 765 (2010), quoting Lanigan, 419 Mass. at 27. Second, the "judge ha[d] 'broad discretion' to weigh [the Daubert-Lanigan] factors and to apply varying methods to assess the reliability of the proffered testimony." Camblin, 478 Mass. at 476, quoting Palandjian v. Foster, 446 Mass. 100, 111 (2006). Such discretion was properly exercised here, particularly where the defendant's sources primarily dispute the possibility that shaking alone can cause the injuries associated with abusive head trauma. See, e.g., Bache et al., Open Letter on Shaken Baby Syndrome and Courts: A False and Flawed Premise (2015), http://www.argumentcritique.com/special-edition.html [https://perma.cc/WRB3-3D9W] ("The scientific basis for the assertion that these injuries are the consequence of deliberately inflicted violent shaking is highly contentious"). But the diagnosis of abusive head trauma encompasses multiple mechanisms of head and brain injury, including shaking, blunt impact, or a combination of causal mechanisms. See Commonwealth v. Millien, 474 Mass. 417, 423 n.7 (2016) (term "abusive head trauma" meant to encompass multiple mechanisms of injury). See also Parks et al., Centers for Disease Control and Prevention, Pediatric Abusive Head Trauma: Recommended Definitions for Public Health Surveillance and Research 10 (Apr. 2012) ("abusive head trauma is defined as an injury . . . due to inflicted blunt impact and/or violent shaking"). The judge thus did not abuse his discretion in determining that abusive head trauma is generally accepted by the medical community. Next, the defendant argues that Schwartz's testimony regarding abusive head trauma was inadmissible because it did not assist the jury pursuant to Mass. G. Evid. § 702(a). She contends that the jury needed no expert assistance to understand the link between blunt force impact and the victim's injuries, where the medical examiner had already testified that the victim died from multiple blunt force impacts. We disagree. An expert's testimony must "help the trier of fact to understand the evidence or to determine a fact in issue." Mass. G. Evid. § 702(a). See Commonwealth v. Ridley, 491 Mass. 321, 326 n.5 (2023). "This condition goes primarily to relevance." Id. at 326, quoting Daubert, 509 U.S. at 591. "To be relevant, the proposed evidence need only have a tendency to make a material fact more or less probable than it would be without the evidence." Hinds, 487 Mass. at 219. Here, an expert opinion concerning the mechanism likely to have caused the victim's injuries was relevant and helpful to a lay juror who would not understand the significance of injuries such as subdural hematomas or midline shifts. Schwartz's testimony on abusive head trauma provided important context for the jury to weigh when assessing key issues in the case. She described how quickly symptoms of abusive head trauma manifest in young children, whether abusive head trauma symptoms are possible without any external signs of trauma, and the differences between adult and children's brains that make these injuries possible. She also provided background on the level of force necessary to inflict a subdural hematoma — one of the injuries associated with abusive head trauma — by explaining that the required force is beyond that used in "normal" infant care. Schwartz's medical expertise thus assisted the jury in understanding the victim's injuries and held important probative value. Cf. Commonwealth v. Roderiques, 462 Mass. 415, 428 (2012) ("When medical expertise is necessary to aid understanding evidence, experts may testify as to the cause of a victim's injuries"); Commonwealth v. Colin C., 419 Mass. 54, 60 (1994) (information concerning behavioral characteristics of sexual assault and sexual abuse victims "may aid [the jury] in reaching a decision"). The defendant further contends that the judge erred in admitting testimony about abusive head trauma because the word "abusive" "comes close to an opinion on the ultimate issue of guilt." While an expert may not provide an opinion on the defendant's innocence or guilt, Roderiques, 462 Mass. at 428, "[t]here is no prohibition on an expert testifying to an opinion that touches the ultimate issue in a case," Commonwealth v. Goddard, 476 Mass. 443, 446 (2017). See Mass. G. Evid. § 704. Schwartz's testimony stayed within these confines. She testified that the victim's injuries were consistent with abusive head trauma — requiring force beyond "normal" child care — and were not consistent with an accidental short fall. In so opining, "[h]er analysis was confined to the mechanism by which the injuries were suffered but did not speculate as to the circumstances or ultimate responsibility for those injuries." Roderiques, 462 Mass. at 429. And she "never offered an opinion as to the defendant's ultimate innocence or guilt." Id. See id. at 428-429 (no abuse of discretion in allowing expert to opine that baby's injuries were "not accidental" and that certain injuries "could not have been caused by a man stepping on the child while asleep in a recliner"). When such testimony approaches an ultimate issue of guilt, "the probative value of the opinion must be weighed against the danger of unfair prejudice" (citation omitted). Goddard, 476 Mass. at 447. See Mass. G. Evid. § 403. As discussed above, Schwartz's testimony held significant probative value, as it provided context regarding the timing, symptoms, and force associated with the victim's injuries. On the other side of the scale, there was also a risk of prejudice here. As the judge noted, particularly where "abusive" is an emotionally charged word that approaches the ultimate opinion, there was a risk that the jury might use it as a proxy for culpability. See Commonwealth v. Rodriguez, 437 Mass. 554, 561 (2002) (discussing possibility that designation of witness as expert could cause jury to defer to expert's opinion). Given this risk of prejudice, the judge imposed appropriate limits to mitigate any prejudicial effect from testimony regarding abusive head trauma. In his order, he prohibited experts from stating that abusive head trauma was the cause of the victim's injuries and instead confined them to stating that the injuries were "consistent with" abusive head trauma. This prevented expert witnesses from encroaching on the jury's ultimate responsibility of determining the defendant's guilt. Cf. Commonwealth v. Wilson, 441 Mass. 390, 400-401 (2004) (judge properly admitted expert testimony that hypothetical facts were "consistent with" possession of marijuana with intent to distribute); Commonwealth v. Colon, 64 Mass. App. Ct. 303, 312 (2005) (expert may opine that child's vaginal injuries were "consistent with" penetration). Moreover, the defendant had multiple opportunities to cure any potential prejudicial effect through cross-examination of the experts and by providing expert testimony describing the shortcomings of an abusive head trauma diagnosis. See Commonwealth v. Mason, 485 Mass. 520, 535 (2020) (risk of prejudice from witness's testimony mitigated on cross- examination). Cf. Millien, 474 Mass. at 423-424, 430, 433-434 (defendant prejudiced by counsel's failure to seek funds to retain expert witness, who could have challenged Commonwealth expert's opinion that victim's head injuries were caused by violent shaking rather than short fall). And in the final jury charge, the judge instructed the jury that, although they could weigh expert testimony in their fact finding, they were required to reach their own conclusions on the defendant's guilt or innocence. See Commonwealth v. Stokes, 440 Mass. 741, 751 (2004), S.C., 460 Mass. 311 (2011) ("We presume the jury follow the judge's instructions"). Accordingly, the judge did not abuse his discretion in admitting testimony that the victim's injuries were "consistent with" abusive head trauma. c. Short falls. Finally, we examine the judge's ruling on expert testimony pertaining to short falls. The judge concluded that there is no general acceptance of the theory that accidental short falls can never cause symptoms consistent with abusive head trauma, pointing to studies in the record that at least supported such a scenario as a rare possibility. See Commonwealth v. Epps, 474 Mass. 743, 759-760 (2016) (discussing medical and scientific debate whether accidental short falls can cause such injuries). Consequently, the judge's order prohibited testimony "that short falls cannot cause [abusive head trauma]." The defendant argues that the judge's order was violated when Shah and Schwartz testified that the victim's injuries were not consistent with a short fall. When asked whether the victim's injuries "would likely be caused by a short fall less than three feet," Shah responded that the victim's injuries "would not be consistent with that short [of a] fall." Similarly, Schwartz opined that the victim's subdural injury could not be caused by a fall from a sitting position. In both instances, this expert testimony reflected specific analysis of the victim's injuries, whereas the order prohibited testimony that short falls, in general, cannot cause abusive head trauma. The experts' testimony thus did not violate the order. Conclusion. For the foregoing reasons, we conclude that the evidence was sufficient to convict the defendant of involuntary manslaughter. Further, we determine that the judge did not abuse his discretion by admitting expert testimony that the victim's injuries were "consistent with" abusive head trauma.

Judgment affirmed.