## Facts

- Steven Thomas, born in 1990, lived as a young child in Milwaukee residences built around 1900–1905, when lead-based paint containing white lead carbonate was commonly used.
- Thomas ingested deteriorated lead paint and lead-contaminated dust in those homes and suffered cognitive and neurological injuries consistent with childhood lead poisoning.
- Thomas sued multiple manufacturers alleged to have produced or marketed white lead carbonate pigment used in residential paint during the relevant period, along with landlords and an insurer.
- Because of the passage of time, the generic nature of white lead carbonate pigment as marketed, and missing historical records, Thomas could not identify the particular manufacturer whose pigment caused his injuries.
- The pigment manufacturers argued that risk-contribution liability should not apply beyond prior DES cases and that white lead carbonate was not sufficiently fungible to justify liability without product identification.

## Issues

1. Whether Wisconsin’s risk-contribution doctrine may apply to white lead carbonate pigment claims when the plaintiff cannot identify the specific manufacturer whose product caused the injury.
2. Whether white lead carbonate is sufficiently fungible in the relevant marketplace to justify risk-contribution liability.
3. Whether imposing proportionate liability without proof of specific causation violates due process, and how liability should be allocated among defendants.

## Decision

- The Wisconsin Supreme Court reversed the court of appeals and the summary judgment for the pigment manufacturers and remanded.
- The court extended Wisconsin’s risk-contribution doctrine beyond DES to white lead carbonate pigment used in residential paint.
- The court held that white lead carbonate was sufficiently fungible for risk-contribution purposes because it was functionally interchangeable in the marketplace for residential paint use.
- The court approved a burden-shifting approach: once the plaintiff makes specified threshold showings, each defendant may avoid liability only by proving it could not have caused the plaintiff’s injury (exoneration).
- The court held that liability may be apportioned according to each non-exonerated defendant’s share of the risk it contributed, commonly measured by market participation evidence during relevant time periods.

## Legal Principles

- A plaintiff who cannot identify the specific manufacturer may proceed under risk-contribution when product identification is practically impossible due to the product’s generic character and historical circumstances.
- Fungibility for risk-contribution turns on functional interchangeability in the relevant market use, not perfect chemical identity.
- The plaintiff must present evidence that: (a) the injury was caused by the product type (white lead carbonate pigment in residential paint), (b) the injury occurred in Wisconsin, (c) defendants manufactured or marketed the pigment for residential paint during the relevant period, and (d) specific identification is practically impossible.
- After the plaintiff’s threshold showing, the burden shifts to defendants to exonerate themselves by proving their product could not have been a source of the injury (including by time, place, or market non-participation).
- For non-exonerated defendants, damages may be allocated in proportion to each defendant’s contribution to the overall risk of harm, using evidence such as market share and the duration and volume of sales.
- Risk-contribution liability, as structured with participation limits and an exoneration opportunity, was held consistent with due process.

## Conclusion

The Wisconsin Supreme Court permitted childhood lead-poisoning plaintiffs to use risk-contribution liability against manufacturers of white lead carbonate pigment when specific manufacturer identification is not feasible, subject to threshold proof by the plaintiff, defendant exoneration opportunities, and proportionate allocation based on each defendant’s contribution to the risk.


Thomas v. Mallett, 701 N.W.2d 523 (Wis. 2005)