A three-judge panel of the 9th U.S. Circuit Court of Appeals in San Francisco also upheld a lower court's ruling dismissing the defendants' claims that they were immune from punishment because they were government contractors.
Since 1990, more than 2,300 people have sued over health problems they believe were caused by exposure to radioactive emissions from south-central Washington's Hanford site over the years. The downwinder cases are largely based on the release of iodine-131, a radioactive byproduct of nuclear weapons production.

A judge dismissed six of the 12 initial "bellwether" cases. In 2005, juries rejected four more during two trials. Just two people, who suffered from cancer, won damages totaling $544,759 against the government and the contractors that managed the federal site at the time.

The appeals court on Tuesday overturned the verdicts against three plaintiffs, Wanda Buckner, Shirley Carlisle and Kathryn Goldbloom, who suffer from hypothyroidism, a condition that slows the body's metabolism.

The district court erred in ruling that the plaintiff's endocrinologist could not testify that he authored articles on I-131's effect on thyroid cells, because it deprived the jury of testimony from the doctor about the extent of his expertise regarding causes of thyroid illness, the appeals court ruled.

In addition, the defendants were allowed to impeach the doctor's testimony based on inadmissible hearsay of another doctor who did not testify, the court ruled.

"We thus have no choice but to reverse the verdicts against plaintiffs Goldbloom, Carlisle, and Buckner and remand for a new trial," Chief Circuit Judge Mary M. Schroeder wrote for the panel.

The court also overturned the ruling in favor of plaintiff Gloria Wise, who was awarded $317,251, on statute of limitations grounds. However, the appeals court remanded the case to district court to determine whether Wise had the information necessary to file a claim within the three-year statute of limitations.

That particular ruling is significant because it could mean the claims of hundreds of other plaintiffs will be time-barred, said Kevin Van Wart, whose Chicago law firm represents General Electric Co., E.I. DuPont de Nemours Co. and UNC Nuclear Inc.

Richard Eymann, a plaintiffs attorney, said he did not yet know how many other clients could have their cases dismissed as a result. Despite that potential impact, Eymann called the overall ruling a victory for the downwinders.

"We're hoping that the contractors and the government will get into serious settlement negotiations with us," he said.

The federal government created Hanford in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. Contractors operated reactors and other facilities that historical documents say resulted in intentional and accidental releases of toxic chemicals and radiation.

Residents only learned of the emissions when the government declassified thousands of documents in 1986.

People in Arizona, Nevada, Utah and the Marshall Islands have received compensation for being exposed to radiation during the atomic buildup. Downwinders at the Hanford site have had a more difficult time because health studies have offered differing opinions on whether they have suffered substantial or chronic exposures that threatened their health.

Iodine-131 concentrates in the thyroid, which regulates the body's metabolism. Most of the plaintiffs have thyroid conditions, such as cancer, hypothyroidism and hyperthyroidism. To succeed at trial, plaintiffs had to prove they were “more likely than not” harmed by radioactive iodine gases released during Hanford operations.

That can be difficult to prove, in part because thyroid disorders are not caused only by exposure to radiation. The plaintiffs' had asked the court to expand the test for causation when there are potentially multiple causes, such as radiation, smoking, genetics or pregnancy.

The appeals court rejected that request.

The court rejected the companies' claims that they were immune from punishment because they were government contractors. The district court already had rejected that claim, as well as claims that the defendants could be held liable for any I-131 emissions from the Hanford facility, which the appeals court rejected as well.

The government already indemnified the contractors under the Price-Anderson Act and must pay any damage awards.

The court denied an appeal by plaintiff Shannon Rhodes, whose claims were rejected by a jury, and upheld the $227,508 award for plaintiff Steve Stanton.

The court also denied an appeal to move to state court claims by other plaintiffs who do not yet have symptoms of any thyroid disease. They had previously sued the contractors for the costs of medical monitoring, but their claims were dismissed.

Van Wart called the last ruling particularly significant because it could have potentially involved thousands of additional plaintiffs.