Cross‑Disciplinary Reliability and the Inadmissibility of “Shaking‑Only” Shaken Baby Syndrome / Abusive Head Trauma Testimony Under New Jersey’s Frye Standard

I. Introduction

The consolidated decision in State v. Darryl Nieves and State v. Michael Cifelli, 256 N.J. 451 (2025), marks a watershed moment in New Jersey’s law on expert scientific evidence and on prosecutions premised on Shaken Baby Syndrome / Abusive Head Trauma (SBS/AHT).

Writing for the Court, Justice Pierre‑Louis holds that, under the Frye “general acceptance” standard (still applicable to these older criminal matters), the State failed to demonstrate that expert testimony diagnosing SBS/AHT based on “shaking without impact” is sufficiently reliable to go to a jury. The central move in the opinion is to define the “relevant scientific communities” as including not only pediatric and clinical specialties but also the field of biomechanical engineering, and to insist on cross‑disciplinary general acceptance. Because the State showed broad medical support but did not show general acceptance in biomechanics that shaking alone can cause the classic “triad” of SBS/AHT findings, the Court bars this category of expert testimony in Frye‑governed cases.

The case arises from two prosecutions in which infants presented with subdural hematomas, retinal hemorrhages, and encephalopathy while in the exclusive care of their fathers. The same child abuse pediatrician, Dr. Gladibel Medina, diagnosed SBS/AHT and was poised to testify that, to a reasonable degree of medical certainty, the only explanation was that the children had been shaken by their caregivers. Defense motions led to a multi‑day Frye hearing in Nieves, exclusion of Dr. Medina’s SBS/AHT opinion there, and a follow‑on exclusion in Cifelli. The Appellate Division affirmed; the Supreme Court now does the same, and also upholds dismissal of the Nieves indictment for lack of admissible causation evidence.

Justice Wainer Apter, in dissent, accuses the majority of substituting judicial for scientific judgment, and of allowing a small group of biomechanical engineers to “veto” the consensus of every major medical society involved in diagnosing and treating AHT. She emphasizes that no other jurisdiction has excluded SBS/AHT testimony, and argues that whether SBS/AHT explains the injuries should be left to the jury after an adversarial contest between experts.

At its core, the decision extends and sharpens New Jersey’s recent line of cases (such as J.L.G. and Cassidy) that reevaluate long‑accepted forensic and clinical constructs through an evidence‑based lens, and it crystallizes a doctrinal rule: where a scientific theory is inherently multidisciplinary, its proponent must show general acceptance in each relevant community, not just in the clinical community that applies it.

II. Summary of the Opinion

A. Factual and Procedural Background

1. State v. Nieves

• D.J. was born extremely premature at 25 weeks, with a complex neonatal course including cardiac surgeries and retinal immaturity, but was ultimately discharged home to his parents in October 2016.
• In February 2017, at about 11 months chronological age (but developmentally delayed), he experienced three episodes of limpness / altered responsiveness while in the care of his father, Darryl Nieves. Each occurred during or around diaper changes.
• On the third episode, EMS transported him to Saint Peter’s University Hospital. Imaging revealed bilateral subdural collections with both old and new blood; ophthalmologic exam showed extensive, multilayered retinal hemorrhages in both eyes.
• A multidisciplinary workup (neurology, hematology, genetics, neuroradiology, pediatric ophthalmology, retinal specialist) reportedly found no alternative medical explanation. Child abuse pediatrician Dr. Medina diagnosed “abusive head trauma, as it occurs with a shaking event with or without impact.”
• Nieves was indicted for second‑degree aggravated assault and child endangerment.
• Defense moved for a Frye hearing to challenge the scientific reliability of SBS/AHT, specifically the theory that shaking alone, without impact, can cause the “triad” of subdural hematoma, retinal hemorrhages, and encephalopathy.

Judge Jimenez conducted a five‑day Frye hearing. The State called only Dr. Medina. The defense called:

• Dr. Joseph Scheller (pediatric neurology / neuroimaging),
• Dr. Julie Mack (radiology / pediatric radiology), and
• Dr. Chris Alan Van Ee (biomechanical engineering).

After reviewing extensive testimony and literature, the trial court:

• Found that SBS/AHT, as deployed here, was not supported by validated scientific testing and functioned more as a “final option” diagnosis reached by process of elimination than as an independently tested scientific theory.
• Held that there was no study showing that a human can generate, by shaking alone, forces sufficient to produce the triad in an infant without other injuries (particularly neck injury), and that biomechanical work to date failed to support that mechanism.
• Concluded that SBS/AHT testimony based solely on the triad, in the absence of physical evidence of trauma, was unreliable and highly prejudicial.
• Excluded Dr. Medina’s SBS/AHT causation opinion, and, as a result, dismissed the indictment for lack of admissible evidence on causation.

2. State v. Cifelli

• J.C. was also born prematurely. In late December 2016 and early January 2017, while in the care of his father, Michael Cifelli, he presented with vomiting, fever, seizure‑like episodes, and altered responsiveness.
• Hospital evaluation revealed fluid and blood around the brain requiring drainage, mixed‑age brain bleeds, significant retinal hemorrhages, an apparent macular abnormality, and a rapid increase in head circumference.
• As in Nieves, a multidisciplinary workup reportedly did not identify alternative explanations. Dr. Medina diagnosed SBS/AHT.
• Cifelli was indicted for aggravated assault and child endangerment; a parallel Title 9 (child abuse/neglect) case was ultimately dismissed.
• Judge Bucca initially denied a Frye hearing, finding SBS/AHT generally accepted. After the Appellate Division ordered a Frye hearing in Nieves, the parties agreed to hold Cifelli in abeyance and to be bound by the outcome in Nieves.
• After Judge Jimenez excluded SBS/AHT in Nieves, Judge Bucca adopted that ruling and barred Dr. Medina’s SBS/AHT testimony in Cifelli, but he did not dismiss the indictment.

3. The Appellate Division

The Appellate Division consolidated the State’s interlocutory appeals and:

• Affirmed exclusion of SBS/AHT testimony in both cases, holding that where a theory integrates multiple scientific disciplines, the proponent must show “cross‑disciplinary validation” – here, general acceptance both in pediatrics and in biomechanics.
• Held the State had shown general acceptance within pediatrics but not within biomechanics, and thus had failed the Frye reliability prong.
• Affirmed dismissal of the Nieves indictment, reasoning that without expert causation testimony, the State could not prove beyond a reasonable doubt how the injuries were caused; leaving causation entirely to juror speculation was impermissible.

4. Supreme Court Proceedings

The New Jersey Supreme Court granted certification in Nieves and leave to appeal in Cifelli, and granted extensive amicus participation from:

• State‑aligned amici: the Attorney General and DCPP, and a large coalition of pediatric and child abuse–related medical societies.
• Defense‑aligned amici: the Office of the Public Defender, the Innocence Network, biomechanical engineers, medical doctors skeptical of SBS/AHT, cognitive bias scholars, child‑welfare advocacy groups, and the Association of Criminal Defense Lawyers.

B. Holding and Disposition

Applying Frye and N.J.R.E. 702, the Court holds:

• The relevant scientific communities for SBS/AHT are both:
  • the medical/pediatric community (pediatrics, child abuse pediatrics, neurology, neuroradiology, neurosurgery, radiology, ophthalmology, etc.), and
  • the biomechanical engineering community.
• The State bears the burden to “clearly establish” general acceptance in all relevant communities. Degrees of relevance are not weighed.
• While the record shows broad support for SBS/AHT within much of the medical community, the State failed to establish general acceptance within biomechanics that shaking without impact can generate forces adequate to produce the triad in infants.
• Accordingly, Dr. Medina’s SBS/AHT “shaking‑only” causation opinion is inadmissible under Frye in these cases.

The Court therefore:

• Affirms exclusion of SBS/AHT expert testimony in both Nieves and Cifelli.
• Affirms dismissal of the indictment in Nieves, as the remaining evidence (caregiver presence plus injuries) would require purely speculative inference about causation.
• Leaves the Cifelli indictment intact, but without SBS/AHT testimony; the State must proceed, if at all, on other admissible evidence.

The majority carefully limits its holding to:

• Cases governed by Frye (i.e., those that originated and were adjudicated before Olenowski I adopted a Daubert‑like standard for criminal cases); and
• SBS/AHT theories based on shaking without evidence of impact as the mechanism producing the triad.

The Court expressly notes that if “new, reliable scientific evidence” emerges, the State may, in a future Daubert‑governed case, attempt to demonstrate that SBS/AHT “without impact” meets the reliability requirements adopted in Olenowski I.

III. Analysis

A. Precedents and Doctrinal Background

1. The Frye Framework and N.J.R.E. 702

The decision is anchored in longstanding New Jersey doctrine on expert testimony:

• N.J.R.E. 702 requires that expert testimony:
  1. Concern a subject beyond the ken of the average juror,
  2. Be from a field “at a state of the art” such that the testimony is sufficiently reliable, and
  3. Be offered by a witness with sufficient expertise.
• At the time of the trial‑level proceedings here, the Frye reliability test applied: the science underlying the opinion must have “gained general acceptance in the particular field in which it belongs.”
• The proponent bears the burden to “clearly establish” general acceptance through expert testimony, scientific/legal writings, or judicial opinions (Harvey; Chun; Cassidy).
• The Court reiterates that because “scientific” evidence can be especially persuasive to juries, courts must insist on “an extraordinarily high level of proof” based on “prolonged, controlled, consistent, and validated experience” (Cassidy quoting Harvey).

New Jersey has repeatedly emphasized the trial judge’s “gatekeeping” role for expert evidence, particularly in criminal cases where liberty is at stake. The Court cites:

• State v. J.L.G., 234 N.J. 265 (2018), excluding most Child Sexual Abuse Accommodation Syndrome (CSAAS) testimony because it rested on untested clinical observations rather than objectively validated science, notwithstanding decades of courtroom use and acceptance by some clinicians.
• State v. Cassidy, 235 N.J. 482 (2018), requiring use of a NIST‑traceable thermometer in Alcotest calibration and underscoring that general acceptance cannot be shown merely by frequency of use or by avoiding scrutiny of underlying assumptions.
• State v. Chun, 194 N.J. 54 (2008), approving Alcotest breath‑test technology only after extensive technical review.

The Court situates Nieves/Cifelli squarely in this line: even if a technique or clinical construct has been widely used, its admissibility depends on whether the underlying science meets contemporary standards of reliability and general acceptance across the relevant disciplines.

2. Relevant Scientific Communities and Cross‑Disciplinary Validation

A key doctrinal move is the Court’s treatment of “relevant scientific communities”:

• Relying in part on State v. Pickett, 466 N.J. Super. 270 (App. Div. 2021), and State v. Olenowski (Olenowski II), 255 N.J. 529 (2023), the Court reiterates that:
  • There may be more than one relevant scientific community for a given technique.
  • Where a theory is inherently multidisciplinary, validation by a single community can be “too narrow”; cross‑disciplinary validation may be required.
  • The proponent must demonstrate general acceptance in each such community.
• In Olenowski II, for example, the reliability of Drug Recognition Expert (DRE) testimony had to be assessed with reference to both medicine and toxicology.

Applying this framework, the Court rejects the State’s contention that only the pediatric/clinical community is relevant for SBS/AHT. It notes:

• The modern SBS/AHT hypothesis was explicitly built on biomechanical concepts of rotational acceleration and whiplash, starting with:
  • Ommaya (1968): whiplash injury study in anesthetized monkeys, demonstrating that rotational displacement without direct impact can cause brain damage in high‑speed rear‑end collision analogs.
  • Guthkelch (1971) and Caffey (1972, 1974): extrapolating from that work to hypothesize that violent shaking of infants could cause subdural hematomas and retinal hemorrhages via tearing of bridging veins.
• As Dr. Medina herself testified, “what we know about shaking, and the established thresholds for intracranial injury comes from [Ommaya’s] study,” and “everything else in biomechanics is based on those thresholds.”
• The hypothesis that shaking alone (without head impact) can generate the triad is thus, by its nature, a biomechanical proposition about forces, accelerations, and tissue response, even if the diagnosis is made clinically.

The majority therefore holds:

• Biomechanical engineering is not merely “informative” or of “lesser importance” as the State argued; it is a co‑equal relevant community.
• A scientific community is either relevant or not – courts cannot grade its relevance and then discount its dissent.

This is the doctrinal pivot: the State cannot satisfy Frye by showing that many clinicians accept SBS/AHT if the underlying biomechanical claim – that shaking alone can cause the triad without other injuries – is not generally accepted in biomechanics.

3. Earlier SBS/AHT Case Law

The Court acknowledges limited prior New Jersey authority:

• State v. Galloway, 133 N.J. 631 (1993): referenced “shaken baby syndrome” in passing in describing facts; did not analyze its admissibility.
• State v. Compton, 304 N.J. Super. 477 (App. Div. 1997): upheld SBS/AHT testimony where the mechanism involved shaking with impact; found general acceptance based on then‑current literature and out‑of‑state decisions. Compton did not address “shaking without impact” or biomechanical critiques that emerged later.

The Court then surveys national case law:

• Numerous decisions continue to admit SBS/AHT testimony (e.g., Clark v. State (Miss.), Nielsen v. State (Wyo.), Wolfe v. State (Tex.), Futrell (Ky.), various New York cases).
• Others recognize a growing scientific debate and grant new trials to allow juries to hear competing experts (Edmunds (Wis.), Del Prete (N.D. Ill.), Ackley & Lemons (Mich.), Roark (Tex.), Smith (Ga.), Bailey (N.Y.)).
• The Michigan Supreme Court’s recent decision in People v. Lemons, 22 N.W.3d 42 (Mich. 2024) is singled out: it holds that biomechanical testimony challenging SBS/AHT is admissible under Michigan’s Daubert‑like rule and describes SBS/AHT as “inherently grounded in biomechanical principles,” stressing that “the medical community is not the judge of the validity of biomechanical research.”

New Jersey thus becomes the first state high court to hold that, under a Frye standard and on a developed record, SBS/AHT “shaking‑only” testimony lacks sufficient cross‑disciplinary general acceptance to be admissible in criminal trials.

B. The Court’s Legal Reasoning

1. The Scientific Record on SBS/AHT “Shaking Alone”

The majority devotes substantial space (echoing the trial court) to the evolution of SBS/AHT science:

• Foundational biomechanical work and later recantation:
  • Ommaya (1968): high‑speed (≈30 mph) whiplash in monkeys shows rotational acceleration can cause subdural and subarachnoid hemorrhage without direct impact. Later, in 2002, Ommaya warned that extrapolating his findings to infant shaking was “improbable,” because no human shaking episode can reproduce those energy levels, and that key assumptions used in SBS/AHT literature (e.g., about short falls, retinal hemorrhages, and symptom timing) were “ambiguous or incorrect” and had been invoked “without reference to available biomechanical analysis.”
  • Guthkelch (1971): hypothesized that infant subdural hematomas without external trauma could result from shaking (“whiplash‑like” forces), after a small case series and a fluid‑filled flask experiment. In 2012, he too publicly questioned the scientific basis of SBS/AHT and warned against inferring abuse “from a finding of retino‑dural hemorrhage” alone.
  • Caffey (1972, 1974): coined “whiplash shaken infant syndrome,” relied heavily on anecdotal and historical cases, speculative comparisons between shaking and car crashes, and secondhand accounts (including a Newsweek article about an abusive nurse); explicitly acknowledged that evidence was “manifestly incomplete and largely circumstantial.” He did not perform biomechanical experiments.
• Subsequent biomechanical and animal studies:
  • Duhaime et al. (1987): retrospective review of 48 CHOP cases plus dummy experiments. All 13 fatalities showed blunt head trauma at autopsy, often not apparent clinically. Dummy shaking produced head accelerations well below thresholds derived from primate studies; short falls and impacts produced much higher accelerations. The authors concluded that severe “shaken baby syndrome . . . is not usually caused by shaking alone” and likely involves impact (e.g., shaking then throwing into a crib). Limitations: poor biofidelity of the dolls, especially the neck.
  • Prange et al. (2003): used an infant surrogate with a rigid wooden torso and hinged neck. Again found that even vigorous shaking generated lower angular accelerations than short‑distance falls or impacts. They wrote there was “no data to indicate that shaking alone can give rise to the injuries associated with SBS/AHT.” Limitations: unvalidated infant neck model; constrained head motion.
  • Cory & Jones (2003): showed that modest changes in surrogate design (center of gravity, neck type, padding) dramatically changed acceleration results; criticized the Duhaime model’s lack of biofidelity and concluded that her study could not “categorically” rule out shaking as a cause of fatal brain injury.
  • Jenny et al. (2017): used a more sophisticated test device with a segmented spine and multi‑axial neck. Reported angular accelerations up to ten times higher than Duhaime’s, illustrating how prior surrogate limitations depressed measured forces. Emphasized that infant injury thresholds remain unknown.
  • Finnie (2010, 2012 lamb studies): vigorously shook anesthetized lambs; some developed subdural hemorrhages and retinal pathology, and three lower‑weight lambs died before planned sacrifice. The authors concluded that shaking alone can be lethal and that absence of external head trauma does not rule out non‑accidental injury, but also cautioned that diagnosis of AHT “should be concluded with caution, unless there is other corroborating evidence of abuse or a convincing admission.” Lamb models, however, suffer from anatomical dissimilarities and stroke ethical limits similar to human experimentation.
  • More recent biomechanical literature cited by the Court (e.g., Schiks 2023, Davison 2022, Lloyd 2011) emphasizes that:
    • There is no consensus that shaking alone can exceed infant tissue failure thresholds.
    • Neck structures are more vulnerable than intracranial tissues; the levels of acceleration modeled for shaking suggest neck injury would often precede subdural/retinal injury, yet such neck injuries are frequently absent clinically.
• Confession studies:
  • The Consensus Statement and State‑aligned experts rely partly on caregiver “confessions” describing shaking without impact in cases with triad findings.
  • The Court is skeptical: confessions are not controlled scientific experiments; they may be false, coerced, or partial, especially where admitting to shaking but not impact seems strategically less incriminating. The “confession studies” (e.g., Starling et al.) themselves acknowledge limitations: descriptions may be incomplete and geared to legal sufficiency rather than biomechanical detail, making them weak bases for precise causation inferences.

Against this backdrop, the majority finds the scientific foundation for the specific mechanism at issue – shaking without impact causing the triad as the sole basis for inferring abuse – to be seriously contested in biomechanics, even if widely accepted clinically.

2. Application of Frye to the Record

Two key factual/legal conclusions drive the result:

1. Identification of the mechanism at issue.
   • Although Dr. Medina’s written diagnosis used the formula “shaking with or without impact,” she conceded at the hearing that:
     • There were no external signs of impact on D.J. (no bruises, scalp swelling, skull fractures, or other trauma markers),
     • She had no evidence that D.J.’s head had hit anything, and
     • Her conclusion that a bridging vein had torn was an assumption, not something directly documented or supported by specific studies.
   • The Court therefore characterizes this as a “shaking without impact” causation theory for Frye purposes. (The dissent contests this framing, emphasizing that impact against a soft surface can leave no external marks and cannot be reliably excluded.)
2. No clear showing of general acceptance in biomechanics.
   • The majority notes the State’s own concession that “there exists some disagreement among biomechanical engineers generally regarding shaking alone as a mechanism of AHT,” and Dr. Medina’s acknowledgment of an ongoing controversy in the biomechanical literature.
   • The defense biomechanical expert, Dr. Van Ee, testified that:
     • Known head accelerations from modeled shaking are lower than those from relatively minor falls; and
     • Given the fragility of the infant neck, it is “unsupported by the data” to posit tearing of bridging veins without concurrent neck injury at the acceleration levels realistically achievable by a human adult.
   • Defense medical experts (Scheller, Mack) identified alternative medical explanations (e.g., prematurity‑related subdural hygromas, benign enlargement of the subarachnoid space / benign external hydrocephalus, vascular anomalies) and emphasized that:
     • Each element of the triad is non‑specific and has multiple non‑abusive causes.
     • The literature is affected by confirmation bias when SBS/AHT is used as both an inclusion criterion and outcome.
   • The Court finds that, taken together with the literature, this record shows:
     • No agreed‑upon biomechanical test or threshold demonstrating that humans can generate, by shaking alone, the forces needed to cause the triad in infants; and
     • No general acceptance among biomechanical engineers that such a mechanism has been validated.

Because Frye demands general acceptance in each relevant scientific community, the Court concludes that:

• The State failed to “clearly establish” general acceptance within biomechanics.
• Therefore, notwithstanding substantial clinical acceptance, the SBS/AHT shaking‑only causation theory does not satisfy Frye’s reliability prong.

3. Limits of the Holding and the Role of Other Evidence

The majority is careful to cabin its ruling:

• It does not hold that abusive head trauma is a fictitious construct or that all SBS/AHT testimony is inadmissible.
• It does not disturb prior cases (e.g., Compton) involving shaking with impact, or cases governed by Daubert‑like standards decided post‑Olenowski I.
• It explicitly acknowledges that:
  • Physical evidence of trauma (fractures, bruises, neck injuries, autopsy findings) and other evidence of abuse (e.g., eyewitnesses, admissions, pattern injuries) may still be presented to a jury.
  • Future scientific developments could support admission of SBS/AHT “without impact” testimony under the Daubert‑style test now in effect for new criminal cases.

However, in the specific Frye-governed posture of Nieves and Cifelli, the absence of corroborating trauma and the contested biomechanical foundation require exclusion.

4. Causation and Dismissal of the Indictment in Nieves

Once SBS/AHT causation testimony is excluded, the Court agrees with the Appellate Division that the Nieves indictment cannot stand:

• The remaining evidence would show only:
  • D.J. suffered serious intracranial and retinal injuries, and
  • He was in Nieves’s care when symptom episodes occurred.
• Without expert testimony explaining how those injuries were inflicted and linking them to abusive conduct rather than to prematurity‑related or other natural conditions, any inference of criminal causation would be speculative.
• Permitting the case to proceed on a “Res ipsa”–style inference (“the child was injured while with the defendant, therefore the defendant must have abused him”) would impermissibly “shift or lighten” the State’s burden and risk conviction based on prejudice rather than proof beyond a reasonable doubt.

C. The Dissent’s Critique

Justice Wainer Apter’s dissent is extensive and forceful. Its main themes are:

• Frye as deference to scientific consensus:
  • Frye exists precisely because judges are not scientists; it directs courts to defer to the consensus of those “most qualified to assess the general validity” of a scientific method.
  • General acceptance does not require unanimity; there will always be “detractors to any scientific theory.” The relevant question is whether a theory is widely accepted in the disciplines that actually diagnose and treat the condition.
• Overwhelming medical endorsement of AHT:
  • Every major medical society involved in diagnosing and treating abusive head trauma – including the American Academy of Pediatrics and numerous radiology, neurosurgery, and ophthalmology societies worldwide – has explicitly endorsed AHT as a valid diagnosis.
  • The 2018 Consensus Statement is not the work of “a group of physicians,” but the product of a vetting process involving tens of thousands of clinicians through their professional organizations.
  • No major medical or scientific body has repudiated AHT; by contrast, in prior Frye rejections (Cavallo, Harvey, J.L.G., Cassidy) the challenged theories lacked any such institutional backing.
• Mischaracterization of the dispute:
  • The dissent stresses that AHT is a clinical differential diagnosis based on the totality of history, physical exam, imaging, labs, and exclusion of other causes – not a mechanical application of a “triad.”
  • It criticizes the majority for treating “SBS/AHT without impact” as a distinct diagnosis. In practice, absent a witnessed or videotaped event, clinicians often cannot know whether shaking was accompanied by impact on a soft surface. Lack of external signs of trauma does not equate to lack of impact, as Duhaime’s own autopsy series showed (impact signs only visible at autopsy in many fatal cases).
• Limits of biomechanical modeling:
  • Doll and animal models have profound limitations; we do not know actual infant injury thresholds, we cannot ethically experiment on infants, and neck and brain material properties are imperfectly known.
  • Later studies (Cory, Jenny, Finnie) undercut any categorical claim that shaking cannot cause the triad; if anything, they show that prior surrogate designs underestimated accelerations and that shaking can be lethal in some animal models.
  • Given these uncertainties, biomechanics cannot “disprove” AHT; at most, it shows gaps in mechanistic understanding that should inform, but not control, clinical judgment.
• Improper elevation of a small group of biomechanical engineers:
  • No biomechanical professional society has issued a consensus statement rejecting AHT; the record rests on a handful of individual experts and selected publications.
  • The majority’s approach allows this small cohort to override the considered judgment of vast clinical communities, in effect giving biomechanics a veto in a domain (medical diagnosis) where biomechanical engineers do not practice.
• Unrealistic evidentiary demands and consequences:
  • The dissent argues the majority implicitly demands randomized controlled trials or direct mechanical proof of bridging vein rupture – standards impossible and unethical to meet in this context, and not required for myriad other accepted diagnoses that rest on differential diagnosis rather than specific “confirmatory” tests (e.g., migraines, psychiatric disorders).
  • By making SBS/AHT “shaking‑only” testimony categorically inadmissible, the Court effectively precludes prosecutions and child‑protection actions where abusive shaking or shaking with impact on a soft surface is suspected but leaves no external stigmata.
  • The dissent would instead permit a full adversarial contest before the jury, allowing State and defense experts to debate the science and alternative causes case‑by‑case.

D. Likely Impact and Broader Significance

1. Immediate Effects in New Jersey Criminal and Child‑Protection Cases

• Frye‑governed criminal cases: For older criminal matters still governed by Frye, prosecutors will be unable to present SBS/AHT expert testimony that attributes the triad to shaking alone (without corroborating evidence of impact or other trauma) as the mechanism of injury.
• Title 9 / DCPP proceedings: Although the opinion addresses criminal evidence rules, the underlying skepticism about SBS/AHT “triad‑only” diagnoses is likely to be invoked in civil child‑protection matters as well, at least as to weight and reliability of such opinions.
• Causation proofs: Prosecutors and DCPP will need to rely more heavily on:
  • Direct evidence (eyewitnesses; admissions with corroboration),
  • Corroborative physical trauma (fractures, bruises, neck injury, autopsy findings), and
  • Robust exclusion of alternative medical explanations.
• Defensive strategy: Defense counsel in pending cases will likely cite Nieves/Cifelli alongside J.L.G. to challenge SBS/AHT and similar quasi‑syndromic constructs, pushing courts to scrutinize clinical consensus against underlying empirical validation.

2. Prospective Under the Daubert‑Like Standard (Olenowski I)

For new criminal cases, New Jersey has replaced Frye with a Daubert‑inspired standard (Olenowski I). While the Court in Nieves/Cifelli does not apply Daubert, it signals:

• The door is open for the State to attempt, in a future Daubert hearing, to justify SBS/AHT “shaking‑only” testimony by satisfying factors such as testability, peer review, known or potential error rates, and general acceptance.
• However, the analytic posture the Court adopts here – especially the insistence on cross‑disciplinary scrutiny and on objective biomechanical support for mechanistic claims – will likely inform Daubert analyses as well.

Practically, any future Daubert challenge to SBS/AHT in New Jersey will need to:

• Directly grapple with and not simply cite away the biomechanical criticisms and limitations identified in this opinion.
• Distinguish between:
  • Using SBS/AHT as a broad descriptor of an injury pattern consistent with abuse, and
  • Testifying that the triad alone, in the absence of other evidence, proves shaking as the only cause.

3. Influence on Other Forensic and Clinical “Syndromes”

The decision reinforces a trajectory visible in J.L.G. and Cassidy:

• Courts will not treat consensus within a clinical community – especially where based primarily on case series, impressions, and differential diagnosis – as sufficient if there is no objective experimental foundation.
• When a theory’s core claims are mechanistic or physical (e.g., about forces, patterns, or probability), courts may insist on validation in the corresponding physical sciences (biomechanics, statistics, computer science) instead of seeing those disciplines as secondary.
• This has potential implications for:
  • Pattern evidence (bite marks, comparative bullet lead, some aspects of bloodstain pattern analysis),
  • Algorithmic DNA mixture interpretation (as in Pickett),
  • Emerging digital forensics tools (e.g., proprietary software), and
  • Other behavioral or clinical syndromes invoked in court (e.g., some “profiles” or accommodation syndromes).

4. National Landscape and Possible Spillover

Because this is the first state Supreme Court to find SBS/AHT “shaking‑only” expert testimony inadmissible under Frye, the decision will likely:

• Be cited by defense counsel and innocence organizations in other jurisdictions as persuasive authority to:
  • Seek new trials in SBS/AHT convictions resting solely on triad‑based causation, and
  • Press appellate courts to require more rigorous scientific validation of SBS/AHT mechanisms.
• Be distinguished by prosecution‑aligned courts as limited to New Jersey’s cross‑disciplinary reading of Frye and to a particular record.

How strongly other courts follow New Jersey’s lead may turn on:

• Local standards (Frye vs Daubert),
• Existing precedent on SBS/AHT, and
• How deeply those courts engage with the biomechanical and empirical critiques articulated here.

IV. Complex Concepts Simplified

To clarify the technical issues in the opinion, the following concepts are central:

• Shaken Baby Syndrome (SBS):
  • Historical term used to describe a constellation of brain and eye injuries believed to result from violent shaking of infants.
  • Now generally subsumed within Abusive Head Trauma.
• Abusive Head Trauma (AHT):
  • Medical diagnosis for inflicted intracranial injury in infants/young children.
  • Encompasses multiple mechanisms: shaking alone, shaking with impact, or blunt impact alone.
  • Clinically made through a multidisciplinary evaluation and exclusion of other diseases/accidents.
• The “Triad” of SBS/AHT:
  • Subdural hematoma: bleeding between the dura (outer brain covering) and the brain surface, usually from tearing of bridging veins.
  • Retinal hemorrhages: bleeding in the layers of the retina; in AHT, often extensive, multilayered, and extending to the periphery.
  • Encephalopathy: global brain dysfunction, manifested as seizures, unresponsiveness, apnea, or altered mental status.
  • Historically, presence of the triad in infants with no plausible accident has been treated by many clinicians as strongly indicative of abuse; the opinion challenges reliance on the triad alone as proof of shaking‑only abuse.
• Biomechanics:
  • The application of mechanical principles (forces, motion, energy) to biological structures.
  • In this context, it studies whether and how external movements (e.g., shaking, falls, impacts) generate internal forces that can damage infant brains, eyes, necks, and veins.
  • Uses surrogates (dummies, animal models, computer simulations) to estimate accelerations and tissue responses.
• Frye Standard:
  • Pre‑Daubert test for scientific evidence: the theory or technique must have “gained general acceptance” in the relevant field(s).
  • Focuses on consensus within scientific communities rather than on a factor‑by‑factor reliability analysis.
  • Still applies in New Jersey to older criminal matters decided before Olenowski I.
• Daubert‑Like Standard in New Jersey (Olenowski I):
  • For current and future criminal/quasi‑criminal cases, New Jersey uses a reliability test modeled on Daubert v. Merrell Dow:
    • Testability, peer review/publication, known or potential error rates, standards, and general acceptance are factors.
  • Gives judges broader discretion to examine methodological soundness beyond mere consensus.
• Differential Diagnosis:
  • The process physicians use to determine the most likely cause of a patient’s condition:
    1. List all plausible causes that could explain the signs and symptoms (“rule in”).
    2. Systematically exclude causes that do not fit, based on tests, history, and observations (“rule out”).
  • AHT is typically diagnosed this way, by excluding plausible accidents and medical diseases.
• Benign Enlargement of the Subarachnoid Space (BESS) / Benign External Hydrocephalus (BEH):
  • Conditions where extra fluid accumulates around the brain in infants, sometimes associated with prematurity and male sex.
  • May predispose infants to subdural collections with minimal trauma and can present with seizures or developmental delay.
  • Defense experts pointed to these as alternative explanations for D.J.’s findings.
• Bridging Veins:
  • Veins that traverse from the brain’s surface to the dural venous sinuses, draining blood from the brain.
  • A key hypothesized mechanism in SBS/AHT is that rotational forces tear these veins, causing subdural hemorrhages.
  • The Court notes that direct biomechanical proof of bridging‑vein rupture from shaking alone in human infants is lacking.

V. Conclusion

State v. Nieves and State v. Cifelli reflect New Jersey’s continued insistence that expert evidence in criminal cases be grounded not only in clinical consensus but in demonstrably reliable science, particularly when that evidence is likely to dominate the fact‑finder’s understanding of causation. The Court:

• Defines SBS/AHT as a multidisciplinary theory whose reliability must be judged with reference to both clinical and biomechanical communities.
• Holds that, on the record presented and under the Frye standard, the State failed to show general acceptance in biomechanics that shaking without impact can cause the triad of subdural hematoma, retinal hemorrhages, and encephalopathy in infants.
• Bars such “shaking‑only” causation testimony in Frye‑governed criminal trials and dismisses an indictment that depended on that testimony to establish causation.

In doing so, the Court aligns SBS/AHT “shaking‑only” evidence with other once‑accepted but now‑disfavored forensic constructs (such as broad CSAAS testimony), and it elevates cross‑disciplinary scrutiny as a central feature of expert admissibility analysis. At the same time, it leaves room for future scientific advances, under a Daubert‑like standard, to support more nuanced or better‑validated approaches to diagnosing abusive head trauma.

The dissent underscores the stakes on the other side – the risk that excluding widely accepted medical diagnoses from the courtroom will impede protection of vulnerable children and undervalue the lived experience of clinicians. That debate, between deference to medical consensus and insistence on cross‑validated empirical foundations, is likely to continue, both in New Jersey under the new Daubert‑style regime and in jurisdictions nationwide wrestling with the proper role of SBS/AHT in the criminal courts.