Physician Expert Witnesses Need Not Specialize in a Particular Disease to Consider it in Differential Diagnosis

    Physician Expert

    Court: Court of Appeals of Alaska
    Jurisdiction: Federal
    Case Name: Alison v. State
    Citation: 2019 Alas. App. LEXIS 94


    The appellant was convicted of second-degree murder after his infant daughter suffered a fatal injury while she was in his care. The state relied primarily on three medical expert witnesses to suggest that the probable cause of death could have been physical abuse.

    At trial, the appellant’s physician expert witnesses offered an alternative explanation for the deceased’s death: Ehlers-Danlos Syndrome (EDS). EDS is a neurogenetic disorder associated with collagen abnormalities and excessive bleeding. The victim’s mother had been diagnosed with a non-vascular version of the disorder after her death, which meant there was a 50% chance she had passed the disorder on to the victim. The child’s treating physician had also testified that they suspected the existence of an underlying genetic problem with the child.

    The trial court held that it would exclude all mention of the syndrome unless the appellant could present an expert on EDS or an expert who could have diagnosed the victim’s disorder to a ‘reasonable degree of medical certainty’. The court noted that in the absence of such testimony, the claim would only amount to speculation. In the trial court’s opinion, the appellant failed to do so and thus, could not use Ehlers-Danlos Syndrome as a defense in his case.

    The appeal alleged that the trial court erred in excluding this evidence and restricting the appellant’s questioning of the presented experts on this matter. The appeal further argued that this error impermissibly compromised the appellant’s ability to defend himself.


    The court noted that there were no eyewitnesses in the case. Furthermore, the state’s case had depended on the reliability of its experts, who had concluded that the victim’s death was most consistent with abuse. This was in direct contradiction with the testimony of the appellant’s experts, who had opined that Ehlers-Danlos syndrome was a probable cause of death. The court was of the opinion that in the face of such contradictory testimony, the jury should have been allowed the opportunity to understand the basis on which the expert opinions conflicted so heavily. This was important because of the circumstantial evidence that the appellant was a loving father who was very involved in the special needs that his child required.

    The court noted that the appellant was not required to present an expert on the syndrome because the requirement for expert witnesses was not to be experts in the particular areas on which they expressed opinions, but only to show that their opinion was based on methods used by experts in the field. The court believed that there was no need for an EDS expert to consider it as one of the factors when performing differential diagnosis to determine probable causes of death, and that the appellant did not require an expert to cross-examine the state’s witnesses on the impact the mother’s diagnosis would have had on their own differential diagnoses of the victim’s cause of death that they had conducted.

    The court opined that it was the state’s responsibility to prove its case beyond a reasonable doubt, and not his job to prove his innocence. The court noted that “whether the evidence offered tends to create a reasonable doubt as to the defendant’s guilt, not whether it establishes the guilt of the third party beyond a reasonable doubt,” citing Smithart v. State, 988 P.2d 583, 588 (Alaska 1999); and also Sanders v. State, 364 P.3d 412, 424-25 (Alaska 2015) (recognizing difference in evidentiary burden between evidence offered by the state against the defendant as opposed to evidence offered by the defendant). The court said that the existence of a possible alternative cause of death would have created a reasonable doubt in the case.

    The court noted that the trial court’s exclusion of any mention of the disorder did not allow the appellant’s experts to provide a medical basis of their opinion or to testify on the existence of an underlying genetic condition, while also infringing on his right to cross-examine the state’s witnesses by restricting his questioning them on the impact the syndrome would have had on their differential diagnosis.


    The court held that the trial court had erred in excluding all mention of the disorder and that the error was not harmless, as it affected the appellant’s ability to defend himself.