Oregon Supreme Court opens gate to scientific expert testimony

This week the Oregon Supreme Court reversed the Court of Appeals and allowed the admission of a medical expert's testimony on the causation of an alleged injury.  In Marcum v. Adventist Health System/West, plaintiff had received an injection of contrast dye in her hand in anticipation of undergoing an MRI. The technician injected the dye into the surrounding tissues instead of the vein, and plaintiff suffered immediate and ongoing symptoms, including pain, swelling and discoloration of plaintiff's hand.  At the ensuing trial, plaintiff's expert sought to testify that the dye injection caused plaintiff's injuries. 

In its "gatekeeping" role, the trial court considered the seven factors for admissibility of scientific evidence, excluded the testimony, and entered a directed verdict for defendant.  Those factors are:  (1) the technique's general acceptance in the field; (2) the expert's qualifications and stature; (3) the use which has been made of the technique; (4) the potential rate of error; (5) the existence of specialized literature; (6) the novelty of the invention [if one is involved]; and (7) the extent to which the technique relies on the subjective interpretation of the expert.  The Court of Appeals affirmed, stating that the expert failed to identify a scientifically valid cause of the injury.

The Oregon Supreme Court concluded that the trial court should have allowed the testimony.  The Court noted that while some of the admissibility factors pertain to techniques and tests, the key issue in this case was causation.  Justice Thomas Balmer, writing for the Court, discussed at length the case of Jennings v. Baxter from 2000, which allowed the use of a "differential diagnosis"---the inclusion of all potential causes, followed by the elimination of all but the posited cause---to prove causation.  While some of the factors in the instant case weighed in favor of exclusion (novelty, lack of a mechanism to explain causation, lack of published studies and rate of error), the Court determined that the nature of plaintiff's injury (sudden, immediate, localized), coupled with the "differential diagnosis" evidence proffered by her expert, weighed in favor of opening the gate to this plaintiff.  Accordingly, the Court reversed and remanded to the Court of Appeals for further consideration of other unresolved issues.  You can find the Oregon Supreme Court's opinion here.