by David Kim

he Supreme Court of New Jersey affirmed the exclusion of expert testimony regarding Shaken Baby Syndrome/Abusive Head Trauma (“SBS/AHT”) in cases alleging shaking without impact, holding that the State failed to demonstrate the necessary general acceptance under the Frye standard. The Court reasoned that because the diagnosis relies on biomechanical principles, it requires validation from both the pediatric medical community and the biomechanical engineering community, yet the State failed to establish that biomechanical engineers generally accept that shaking alone can cause the condition’s symptoms.

Background

To understand the scientific dispute at issue, the Court began its discussion by tracing the origins of the SBS/AHT hypothesis. The theory emerged in the early 1970s, primarily through the work of Dr. A.N. Guthkelch and Dr. John Caffey. Both researchers relied heavily on a 1968 study by Dr. Ayub Ommaya. Dr. Ommaya’s study did not involve testing on infants; rather, it subjected monkeys to whiplash simulations at speeds of 30 miles per hour to mimic rear-end car collisions. Dr. Caffey’s foundational studies, which popularized the “whiplash shaken infant syndrome” theory, relied on Dr. Ommaya’s data by analogy and on anecdotal evidence. Dr. Caffey did not conduct biomechanical experiments on infants to validate the theory. Decades later, in 2002, Dr. Ommaya published a follow-up paper questioning the use of his 1968 data as the basis for SBS/AHT theories, warning that the assumptions regarding infant brain and retinal injuries based on his study were “ambiguous or incorrect” and were made without reference to available biomechanical analysis.

The Nieves Case

The defendant, Darryl Nieves, is the father of D.J., who was born prematurely at 25 weeks in March 2016. In February 2017, when D.J. was 11 months old, he experienced three episodes of seizure-like behavior over approximately two weeks while in Nieves’ care. During the third episode, the parents called an ambulance, and D.J. was transported to Saint Peter’s University Hospital.

At the hospital, medical staff discovered that D.J. had bilateral retinal hemorrhages described as extensive, multilayered, too numerous to count, and extending to the periphery. D.J. also had bilateral subdural bleeding with both new and old blood present. These findings triggered a child abuse investigation.

Dr. Gladibel Medina, a child abuse pediatrician, evaluated D.J. and prepared a report after reviewing his medical history. A comprehensive medical evaluation involving specialists in neurology, genetics, hematology, neuroradiology, pediatric ophthalmology, and retinal medicine did not reveal any pathology to account for D.J.’s symptoms. D.J. had no reported accidental injuries, and his physical examination revealed no bruises, no spinal injuries, and no indication his head struck anything. Dr. Medina diagnosed D.J. with SBS/AHT “with or without impact” within a reasonable degree of medical certainty, though she conceded on cross-examination that there was no indication D.J.’s head had struck anything.

A Middlesex County grand jury indicted Nieves for second-degree aggravated assault and second-degree endangering the welfare of a child. Nieves moved for a Frye hearing to challenge the scientific reliability of the SBS/AHT hypothesis.

The Frye Hearing

The State presented Dr. Medina as its sole witness. She testified that doctors rely on a “triad” of symptoms to flag concern for SBS/AHT: subdural hemorrhages, severe retinal hemorrhages, and neurological presentation such as unresponsiveness, seizures, or altered mental states. Dr. Medina acknowledged there are no specific diagnostic criteria for SBS/AHT, only symptoms that may indicate the diagnosis. She testified that the established thresholds for intracranial injury from shaking derive from Dr. Ommaya’s 1968 study and that “everything else in biomechanics is based on those injury thresholds.” However, she admitted that controversy exists in the biomechanical community about whether shaking can generate forces sufficient to cause intracranial injury in infants. Significantly, Dr. Medina discussed studies by Dr. John W. Finnie (2010 and 2012) involving anesthetized lambs, acknowledging that in cases of vigorous shaking without impact, retinal hemorrhages were either minimal or non-existent in the test subjects.

The defense presented three expert witnesses. Dr. Joseph Scheller, a pediatric neurologist, testified that no biomechanical study has shown that humans can shake a baby with enough force to cause the triad of symptoms. Dr. Scheller also testified regarding a 2016 study by Dr. Natalia Callaway, which found that approximately 20% of healthy newborns have retinal hemorrhages, challenging the assertion that such hemorrhages are exclusive indicators of abuse. He opined that D.J.’s symptoms could be explained by subdural hygroma, a condition common in children born prematurely and concluded within a reasonable degree of scientific certainty that D.J. was not a victim of SBS/AHT.

Dr. Julie Mack, an expert in radiology and pediatric radiology, testified that D.J.’s scans showed no signs of trauma – no soft tissue swelling, no skull fracture, and no brain abnormality. She testified that D.J.’s scans were consistent with Benign Enlargement of the Subarachnoid Space (“BESS”) or Benign External Hydrocephalus (“BEH”), conditions that can result in fluid collections and retinal hemorrhages without trauma. She stated there is no confirmatory test for SBS/AHT and that the premise that shaking alone could cause the described injuries was a heated controversy.

Dr. Chris Alan Van Ee, an expert in impact biomechanics and mechanical engineering, testified that the hypothesis that shaking alone can damage bridging veins without simultaneously injuring the neck cannot be scientifically supported. He explained that the angular accelerations created in shaking are less than those seen in even a one-foot fall and that biomechanical data shows that if someone shakes a child, neck injuries should occur first, yet D.J. exhibited no neck injury. He stated that no biomechanical study has definitively concluded that shaking can cause the injuries associated with SBS/AHT.

Following the hearing, the trial court barred Dr. Medina’s SBS/AHT testimony and subsequently dismissed the indictment against Nieves, finding insufficient evidence to prove causation without the SBS/AHT testimony.

In a related case, Michael Cifelli’s prematurely born infant, J.C., exhibited similar symptoms while in Cifelli’s care. Dr. Medina diagnosed J.C. with SBS/AHT. Following the ruling in Nieves, the trial court adopted that decision and barred Dr. Medina’s testimony. The Appellate Division consolidated the appeals and affirmed both trial court decisions, holding that the State failed to demonstrate general acceptance of the SBS/AHT hypothesis in the biomechanical community despite demonstrating general acceptance in the pediatric medical community.

Analysis

The Court began its analysis by reviewing N.J.R.E. 702, which governs the admission of expert testimony, providing that scientific knowledge may be admitted if it will assist the trier of fact and the witness is qualified as an expert. The proponent of expert testimony must establish three elements: (1) the subject matter is beyond the ken of the average juror, (2) the field of inquiry is at a state of the art such that an expert’s testimony could be sufficiently reliable, and (3) the witness has sufficient expertise to offer the testimony. State v. J.L.G., 190 A.3d 442 (N.J. 2018); State v. Kelly, 478 A.2d 364 (N.J. 1984).

During the relevant period, New Jersey courts applied the Frye standard to assess the reliability prong. Under Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), trial courts must determine whether the science underlying the proposed expert testimony has “gained general acceptance in the particular field in which it belongs.” Notwithstanding the emphasis on general acceptance, the underlying science “must have a ‘sufficient scientific basis to produce uniform and reasonably reliable results [that] will contribute materially to the ascertainment of the truth.’” State v. Chun, 943 A.2d 114 (N.J. 2008).

Reliability of expert testimony is paramount, particularly in criminal cases. As the Court observed, “[i]n evaluating the admissibility of scientific evidence introduced by the State in criminal cases, it is important to recognize that a high degree of reliability is necessary where the freedom, or even the life, of an individual is at stake.” Because labeling evidence as “scientific” or “expert” creates a danger that juries will accord excessive weight to unreliable testimony, “[g]eneral acceptance ‘entails the strict application of the scientific method, which requires an extraordinarily high level of proof based on prolonged, controlled, consistent, and validated experience.’” State v. Cassidy, 197 A.3d 86 (N.J. 2018).

The Court stated that the proponent of expert evidence bears the burden to “clearly establish” general acceptance through expert testimony, authoritative scientific and legal writings, or judicial opinions. J.L.G.; Cassidy. A key step in the court’s gatekeeping function is identifying the relevant scientific community. See State v. Pickett, 246 A.3d 279 (N.J. Super. Ct. App. Div. 2021). Importantly, “there might be more than one scientific community to consider,” and when multiple communities are relevant, the proponent must clearly establish general acceptance in all of them. “Cross-disciplinary validation” may be required “to determine reliability” when validation by a single scientific community is “too narrow.” Id. For example, in State v. Olenowski, 304 A.3d 598 (N.J. 2023), the court recognized that the relevant scientific communities for determining the reliability of Drug Recognition Expert testimony included both medicine and toxicology.

The Court’s Application of Governing Law to Present Case

The Court first addressed the threshold question of identifying the relevant scientific communities. Tracing the history of SBS/AHT theory, the Court observed that its starting point was Dr. Ommaya’s 1968 whiplash study, which tested acceleration and deceleration of monkeys’ brains during simulated rear-end car collisions. Although Dr. Ommaya’s study did not concern head trauma in infants from shaking, it became the foundation for subsequent SBS/AHT diagnoses. Drs. Guthkelch and Caffey later relied on Dr. Ommaya’s study in conceptualizing SBS/AHT theory.

Given this history, the Court found “particularly odd” any attempt to relegate biomechanics to secondary status. The Court reasoned that the scientific community upon which SBS/AHT’s very foundation rests cannot be deemed less relevant than the medical community that now diagnoses the condition, “a diagnosis that quite possibly would not have existed if not for a biomechanical study and the field of biomechanics in the first place.” The Court rejected the State’s argument that the biomechanical community was “not of coequal importance,” noting that the State proffered no biomechanical expert testimony on its behalf.

The Court emphasized that a scientific community is either relevant or not for purposes of determining admissibility; degrees of relevance are not weighed. Were the Court to accept that biomechanical engineering was relevant but “not that relevant,” the question would arise regarding how much relevance to afford that community. Such an approach would be unworkable, according to the Court. Citing the Michigan Supreme Court’s observation in People v. Lemons, 22 N.W.3d 42 (Mich. 2024), the Court ruled that it is “untenable” to divorce the diagnosis of SBS/AHT from its origin in biomechanics. Accordingly, the Court concluded that both the medical/pediatric community and the biomechanical engineering community are relevant scientific communities for purposes of SBS/AHT expert testimony.

Turning to whether the State met its burden, the Court ruled the State failed to establish general acceptance in the biomechanical community regarding whether shaking without impact can produce the triad of symptoms. The Court noted that Dr. Ommaya himself published a 2002 study criticizing researchers’ reliance on his own work, cautioning that the assumptions upon which pediatric brain and retinal literature had been based were “ambiguous or incorrect” and were used in differential diagnosis “usually without reference to available biomechanical analysis.” Dr. Guthkelch similarly questioned the scientific foundation of SBS/AHT in 2012, calling for “civility in scientific discourse” given the divisiveness interfering with the pursuit of truth.

The Court found significant that the State itself acknowledged “some disagreement among biomechanical engineers generally regarding shaking alone as a mechanism of AHT.” Dr. Medina also testified that controversy exists in biomechanics focused on whether shaking can generate forces sufficient to cause intracranial injury in infants. Each defense expert testified that no biomechanical study has shown that shaking alone results in the symptoms associated with SBS/AHT.

While acknowledging that humans cannot be used as test subjects in potentially dangerous experiments, the Court reasoned that such limitations “should not give way to assumptions in making an SBS/AHT diagnosis for which significant criminal liability follows when no other evidence of abuse is present.”

Conclusion

The Court held that both the medical/pediatric community and the biomechanical engineering community constitute relevant scientific communities for purposes of Frye analysis and that the State failed to establish general acceptance in the biomechanical community. The research, studies, and testimony presented at the Frye hearing reflected a lack of consensus among biomechanical engineers regarding whether shaking alone can cause the triad of symptoms. While the State demonstrated acceptance among many in the medical community, it failed to satisfy its burden as to the biomechanical community. The Court emphasized that its holding does not foreclose future prosecutions where physical evidence of trauma or abuse exists, nor does it preclude future showings of reliability under the Daubert standard should new scientific evidence emerge.

Accordingly, the Court affirmed the exclusion of expert testimony diagnosing SBS/AHT based on shaking without impact. See: State v. Nieves, 2025 N.J. LEXIS 1149 (2025).

Editor’s note: Anyone with an interest in Shaken Baby Syndrome/Abusive Head Trauma, especially without impact, is strongly encouraged to read the Court’s full opinion.

Subscribe today

Already a subscriber? Login