Ninth Circuit Improperly Lowers Admissibility Bar For Expert Causation Testimony

In Wendell v. GlaxoSmithKline LLC,¹ the U.S. Court of Appeals for the Ninth Circuit reversed a trial court order² that excluded expert testimony concerning the cause of a profoundly rare and deadly disease. The decision contravened multiple aspects of the U.S. Supreme Court's opinions on the admissibility of expert testimony and sets up a split among the federal circuits on the issue.

Background

Plaintiffs' son Maxx died in 2007 at age 21 from hepatosplenic T-cell lymphoma (HSTCL), an "exceedingly rare and aggressive" form of non-Hodgkin's lymphoma. In 1999, following a diagnosis of inflammatory bowel disease (IBD), Maxx was prescribed six-mercaptopurine (6-MP), an immunosuppressant of the thiopurine class that was not specifically approved for IBD but was widely used for that purpose. In 2002, doctors added to his drug regimen infliximab, marketed as Remicade® and one of a class of anti-TNF drugs approved for treatment of autoimmune disorders such as Crohn's