Michael Nelson v. Matrixx Initiatives, Inc.
592 F. App'x 591
9th Cir.2015Background
- Nelson sued Matrixx in California for loss of smell, alleging Zicam caused his anosmia.
- In California toxic-tort law, plaintiff must prove general causation (agent can cause injury) and specific causation (agent caused plaintiff’s injury) by competent expert testimony.
- Nelson proffered two experts (Drs. Davis and Hwang) who based specific-causation opinions on differential diagnosis.
- The district court excluded both experts because they failed to reliably rule in Zicam or reliably rule out common alternative causes (age and recent cold/virus).
- After excluding the experts, the court granted Matrixx summary judgment because Nelson had no admissible expert proof of specific causation, a necessary element.
- The district court also rejected Nelson’s attempts to shift the burden of proof, rely on FDA action, use third‑party medical histories, or recover the purchase price of Zicam.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Admissibility of experts on specific causation | Davis and Hwang’s differential-diagnosis opinions reliably show Zicam caused Nelson’s smell loss | Experts failed to reliably rule in Zicam or rule out common alternatives (age, viral infection) | Excluded experts as unreliable for specific causation |
| Sufficiency of proof after exclusion | Nelson argued other evidence or burden-shifting should allow the case to proceed | Matrixx argued plaintiff cannot prove required element without expert testimony | Summary judgment for Matrixx because Nelson lacked admissible expert proof of specific causation |
| Burden shifting on causation | Nelson sought to shift burden to Matrixx to disprove causation | Matrixx maintained plaintiff bears burden to prove causation | Court refused to shift burden to Matrixx |
| Reliance on regulatory action/third-party discovery | Nelson sought to rely on FDA action and third‑party medical histories to support causation | Matrixx opposed as insufficient to prove specific causation without reliable experts | Court precluded reliance on FDA action and third‑party medical histories as substitute for admissible expert proof |
Key Cases Cited
- Avila v. Willits Envtl. Remediation Trust, 633 F.3d 828 (9th Cir. 2011) (describing general and specific causation standards in California toxic‑tort law)
- Jones v. Ortho Pharm. Corp., 209 Cal. Rptr. 456 (Cal. Ct. App. 1985) (medical‑probability standard for causation requires competent expert testimony)
- Clausen v. M/V New Carissa, 339 F.3d 1049 (9th Cir. 2003) (properly conducted differential diagnosis can be admissible under Daubert)
- Claar v. Burlington N. R.R. Co., 29 F.3d 499 (9th Cir. 1994) (experts must do more than offer subjective beliefs; must reliably eliminate alternative causes)
- Daubert v. Merrell Dow Pharm., 509 U.S. 579 (1993) (general standard for admissibility of expert scientific testimony)