CrimProf Blog

Editor: Kevin Cole
Univ. of San Diego School of Law

Thursday, February 1, 2018

Inwinkelried on Shaken Baby Syndrome, Battles of Experts, and Sufficiency of Evidence

This article addresses the ongoing dispute over the validity of Shaken Baby Syndrome (SBS). The proponents of SBS assert that even without an impact, the violent shaking of an infant by an adult can cause fatal brain injuries. The proponents rely on tens of case reports in which the infant died of brain injury and the evidence tended to show shaking but no striking. Many pathologists and pediatricians accept this theory. However, some biomechanical experts reject the theory. Their experiments indicate that without impact trauma, manual shaking of an infant cannot generate enough force to cause fatal brain injury. 

Although both sides of the dispute can point to empirical support, each side’s position is subject to doubt. In the case of the proponent’s theory, there are concerns about the accuracy of the case reports. A loving parent could easily repress the memory of an impact during the incident leading to his or her infant’s death, and a caregiver who had acted in bad faith would obviously have a motive to suppress the detail of the impact. In the case of the opponent’s theory, although the experiments can determine the force level generated by manual shaking, little is known about the brain injury threshold for infants. Medical ethics obviously preclude subjecting infants to the experiments that would be needed to validate an injury threshold.

Many courts admit both expert testimony about the SBS theory and testimony criticizing the theory. It is understandable that the testimony on both sides has been ruled admissible. In its celebrated 1993 Daubert decision on expert testimony, the Supreme Court commented that even admissible testimony might be “shaky.” The Advisory Committee Note accompanying the 2000 amendment to Federal Rule of Evidence 702 expressly states that sometimes testimony about “competing theories” will prove to be admissible under Daubert. 

Although many articles have been written about the admissibility of SBS and its critiques, to date no article has addressed the question of the legal sufficiency of SBS testimony. The question is certainly now timely; in a trilogy of decisions dated 2007, 2010, and 2011, the Supreme Court reversed the Ninth Circuit which had thrice ruled the evidence in an SBS case legally insufficient to sustain a conviction. The question not only concerns SBS; it also raises the broader question of the scope of the Supreme Court’s landmark 1979 legal sufficiency decision, Jackson v. Virginia. Some courts have read Jackson narrowly as contemplating that the judge conducting the sufficiency analysis will consider only the prosecution testimony. This article argues that Jackson mandates that the judge consider the defense testimony in the record as well as the prosecution evidence. In addition, the article contends that by restricting the judge’s inquiry to the contents of learned treatises admissible under Federal Rule of Evidence 803(18), an expanded Jackson analysis can be conducted without usurping the jury’s constitutional rule under the Sixth Amendment. Finally, the article applies this mode of analysis to the SBS controversy and concludes that given the current state of the empirical record, standing alone SBS testimony is legally insufficient to prove causation.

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