## Facts

- Roger G. Nelson was prescribed and took Cordarone (amiodarone), a prescription anti-arrhythmic drug manufactured and sold by defendants American Home Products Corporation and Wyeth-Ayerst Laboratories Company.
- Nelson developed optic-nerve injury and ultimately lost his eyesight while using Cordarone.
- The Nelsons sued in a diversity products-liability action, asserting that Cordarone caused the injury and that defendants were liable (including on failure-to-warn theories).
- Defendants disputed causation and moved for summary judgment, arguing plaintiffs lacked admissible evidence that Cordarone caused Nelson’s optic neuropathy rather than an idiopathic or alternative cause.
- Plaintiffs’ causation proof relied principally on expert opinions drawn from (i) case reports and adverse event reports, (ii) labeling changes and “Dear Doctor” communications describing a “possible association” between Cordarone and optic neuropathy, and (iii) temporal sequence between drug exposure and onset of symptoms.

## Issues

1. Whether plaintiffs’ expert opinions on causation, grounded largely in case reports/adverse event reports, manufacturer and regulatory communications, and temporal association, were admissible under Federal Rule of Evidence 702 and *Daubert*.
2. If the causation opinions were inadmissible, whether plaintiffs could survive summary judgment on causation, an essential element of their products-liability claims.

## Decision

- The court granted defendants’ motion for summary judgment.
- The court found plaintiffs’ causation expert testimony inadmissible under Rule 702/*Daubert* because the methodology did not reliably support an inference that Cordarone caused Nelson’s injury.
- The court held that labeling changes and warning letters describing a “possible association” were not proof of causation and could not substitute for a reliable scientific basis.
- The court treated case reports and adverse event reports as insufficient, without stronger scientific support, to establish causation.
- The court rejected temporal sequence (“after taking the drug, the injury occurred”) as inadequate to show causation and found plaintiffs’ differential-diagnosis reasoning did not reliably rule in Cordarone as the cause.
- With no admissible causation evidence, plaintiffs failed to create a genuine issue of material fact; defendants were entitled to judgment as a matter of law.

## Legal Principles

- Summary judgment is appropriate when there is no genuine dispute of material fact and the movant is entitled to judgment as a matter of law; once the movant identifies an absence of evidence on an essential element, the nonmovant must produce evidence sufficient for a reasonable factfinder to find in its favor.
- In complex pharmaceutical injury cases, causation generally must be proven through admissible expert testimony.
- Under Rule 702 and *Daubert*, expert causation testimony must rest on reliable methodology and fit the facts; opinions that primarily rely on temporal association, anecdotal reports, or regulatory/manufacturer warnings may be excluded as unreliable.
- Manufacturer labeling changes and “Dear Doctor” letters that describe reported events or a “possible association” are regulatory cautionary statements and do not, without reliable scientific support, establish that a drug more likely than not caused a plaintiff’s injury.
- Case reports and adverse event reports, standing alone, typically do not establish causation because they lack controls and do not reliably rule out alternative explanations.

## Conclusion

The court excluded plaintiffs’ drug-causation expert testimony as methodologically unreliable and, because causation could not be shown without admissible expert proof, granted summary judgment for defendants on all claims.


Nelson v. Am. Home Prods. Corp., 92 F. Supp. 2d 954 (W.D. Mo. 2000)