## Facts

- The United States built and operated the Hanford Nuclear Reservation in Washington to produce plutonium during and after World War II.
- The government contracted with private companies, including E.I. DuPont de Nemours & Co. and later other contractors, to design, construct, and operate facilities at Hanford.
- Plutonium production emitted radionuclides, including radioiodine (I-131), associated with thyroid injury; government “recommendations” for exposure existed but were not enforceable standards.
- Individuals and putative classes alleged that airborne releases of radioactive materials and inadequate warnings or protections caused thyroid cancer, hypothyroidism, and related illnesses in surrounding communities.
- The Price–Anderson Amendments Act of 1988 centralized “public liability actions” arising from nuclear incidents in federal court and supplied a federal cause of action incorporating state substantive standards absent conflict.
- After extensive consolidated proceedings, the parties used a bellwether trial with twelve selected plaintiffs; six claims were dismissed pretrial and six were tried to a jury.
- The district court rejected a complete “contractor immunity” defense, permitted strict-liability submission on an abnormally dangerous activity theory under Washington law, and instructed the jury that plaintiffs had to prove cause-in-fact (but-for) causation.
- The jury found for two plaintiffs and awarded roughly $550,000 total damages; the remaining trial plaintiffs did not prevail.
- Plaintiffs who lost challenged the causation instruction; contractors appealed the denial of contractor immunity and the strict-liability/abnormally dangerous activity rulings.

## Issues

1. Whether the jury should have been instructed on a “substantial factor” standard rather than but-for cause-in-fact causation for alleged radiation-related injuries under Washington law as applied in a Price–Anderson public liability action.
2. Whether Price–Anderson preserves or implies a broad federal common-law contractor immunity that categorically bars liability for contractors operating under federal direction and specifications.
3. Whether plutonium production with radioactive emissions at Hanford could be treated as an abnormally dangerous activity supporting strict liability under Washington law, and whether alleged limits in contemporaneous risk knowledge defeat that classification.
4. Whether other instructional and evidentiary rulings warranted disturbing the bellwether verdicts.

## Decision

- The Ninth Circuit largely affirmed the district court’s rulings and the bellwether verdicts.
- The court upheld the cause-in-fact (but-for) causation instruction and rejected plaintiffs’ request for a relaxed “substantial factor” instruction.
- The court rejected contractors’ claim of broad contractor immunity, holding Price–Anderson did not create a categorical federal common-law immunity for Hanford contractors.
- The court upheld submission of strict liability based on the determination that Hanford plutonium production and associated emissions could qualify as an abnormally dangerous activity under Washington law.
- The court left intact the defense verdicts for the non-prevailing plaintiffs and the damages awards to the two prevailing plaintiffs.

## Legal Principles

- In a Price–Anderson “public liability action,” state substantive tort standards generally supply the rules of decision unless displaced by a conflicting statutory requirement.
- Under Washington law in this setting, plaintiffs must prove cause-in-fact (but-for) causation; scientific uncertainty does not itself replace that requirement with a general “substantial factor” standard.
- Probabilistic, epidemiological, and dose-related evidence may be considered by the factfinder within a cause-in-fact framework, but the plaintiff still must establish factual causation for the individual injury.
- Price–Anderson does not confer a sweeping federal common-law contractor immunity that categorically shields government contractors from public liability actions; contractors remain subject to incorporated state-law duties and defenses and statutory protections actually provided by Congress.
- Large-scale plutonium production with radioactive releases may be deemed an abnormally dangerous activity under Washington law, supporting strict liability where the risk of severe harm cannot be eliminated by reasonable care; incomplete historical knowledge of specific harms does not automatically preclude that classification.

## Conclusion

The Ninth Circuit affirmed the bellwether trial outcome, holding that plaintiffs had to prove but-for causation under Washington law as incorporated by Price–Anderson, that Hanford contractors were not entitled to a categorical federal contractor immunity, and that strict liability could proceed on an abnormally dangerous activity theory for plutonium production and radioactive emissions.


In re Hanford Nuclear Reservation Litig., 534 F.3d 986 (9th Cir. 2008)