## Facts

- Gislaved Gummi AB (GGAB) manufactured rubber gaskets used in window and skylight production and applied talc as a lubricant.
- James Curtis Westberry worked at a Greenwood, South Carolina plant using the gaskets; in January 1994 he became a “gasket cutter,” repeatedly handling talc-coated gaskets at a cutting machine.
- Westberry testified he was exposed to high concentrations of airborne talc, received no warning about potential dangers, and wore no protective equipment.
- Soon after starting the gasket-cutter job, Westberry developed severe, persistent sinus problems, including hospitalization in July 1994 for a serious sinus infection.
- From September 1994 onward, Westberry underwent multiple sinus surgeries, including obliteration of his frontal sinuses.
- James and Connie Rena Westberry sued GGAB under South Carolina law on a products liability failure-to-warn theory, alleging talc inhalation from GGAB’s gaskets caused Westberry’s sinus disease.
- Westberry’s treating physician, Dr. W. David Isenhower, Jr., offered expert testimony that talc inhalation caused the condition, based primarily on differential diagnosis.
- A jury in the District of South Carolina found GGAB liable and awarded damages; GGAB appealed the admission of Dr. Isenhower’s causation opinion, and Connie Westberry cross-appealed seeking additur or a new trial on her damages.

## Issues

1. Whether the district court abused its discretion under Federal Rule of Evidence 702 and Daubert by admitting the treating physician’s medical causation opinion derived from differential diagnosis.
2. Whether the district court erred in denying Connie Westberry’s motion for additur or, alternatively, a new trial based on allegedly inadequate damages.

## Decision

- The Fourth Circuit affirmed the judgment.
- The court held the district court did not abuse its discretion in admitting Dr. Isenhower’s causation testimony because his differential diagnosis provided a sufficiently reliable basis under Rule 702 and Daubert.
- The court rejected the argument that the opinion was inadmissible due to the absence of precise quantitative exposure measurements, treating that point largely as affecting weight rather than admissibility on this record.
- The court affirmed the denial of additur or a new trial on Connie Westberry’s damages.

## Legal Principles

- A properly performed differential diagnosis is a generally accepted clinical methodology that can supply a reliable foundation for expert medical causation testimony under Federal Rule of Evidence 702.
- Daubert’s gatekeeping inquiry centers on the reliability of the expert’s principles and methods; disputes about the thoroughness of an expert’s differential diagnosis often go to weight and are tested through cross-examination and competing evidence.
- In toxic exposure cases, precise quantitative dose calculations are not an absolute prerequisite to admissibility when other evidence supports substantial exposure and the expert’s causation reasoning rests on accepted medical practice.
- Temporal relationship between exposure and onset or worsening of symptoms may support causation when combined with clinical evaluation and consideration of alternative causes.
- Appellate review of Rule 702 admissibility rulings is for abuse of discretion, giving substantial deference to the trial court’s evidentiary determinations.

## Conclusion

The Fourth Circuit upheld a verdict for plaintiffs in a failure-to-warn products liability action, holding that a treating physician’s causation opinion grounded in differential diagnosis was admissible under Rule 702 and Daubert despite the lack of precise exposure quantification, and it declined to disturb the jury’s damages award on cross-appeal.


Westberry v. Gislaved Gummi AB, 178 F.3d 257 (4th Cir. 1999)