Michael Nelson v. Matrixx Initiatives, Inc.

MEMORANDUM

Michael Nelson appeals from the district court’s orders excluding Nelson’s two expert witnesses on specific causation, and granting Matrixx’s motion for summary judgment. Because the parties are familiar with the facts and procedural history of this case, we repeat only those facts necessary to resolve the issues raised on appeal. We affirm.

• In a toxic tort case in California, a plaintiff must show both general causation, which is “that the substance at issue was capable of causing the injury alleged,” and specific causation, which is “that the substance caused, or was a substantial factor in causing, the specific plaintiffs injury.” Avila v. Willits Envtl. Remediation Trust, 633 F.3d 828, 836 (9th Cir.2011) (citing Jones v. Ortho Pharm. Corp., 163 Cal.App.3d 396 , 209 Cal.Rptr. 456, 462 (1985)). General and specific causation “must be proven within a reasonable medical probability based upon competent expert testimony.” Jones, 209 Cal.Rptr. at 460 .

Nelson offered Drs. Davis and Hwang as experts on the issue of specific causation, and both Drs. Davis and Hwang relied on differential diagnosis for their expert opinions that Nelson’s smell loss was caused by Zicam.…