In two federal asbestos cases, the plaintiffs' causation doctors were excluded because of the exposure proof under their opinions, not their medicine. In one, the experts could not point to a study tying an exposure that small to the disease. In the other, the court threw out the opinion that the product contained asbestos at all, and two physicians' causation opinions fell with it.
The rule
Federal Rule of Evidence 702 lets an expert testify only "if the proponent demonstrates to the court that it is more likely than not that" the testimony meets four tests, including that it "is based on sufficient facts or data" and that it "is the product of reliable principles and methods" (Rule 702(b) and (c)). The "more likely than not" language came in with the December 1, 2023 amendment. Both rulings below came earlier, in 2017 and 2018.
Toxic-tort cases have two causation questions. General causation asks whether the substance can cause the disease at all. Specific causation asks whether it caused this plaintiff's disease, given how the plaintiff was exposed. Both rulings turned on that second question, and on the exposure facts it depends on.
Ruling 1: the exposure was too small to tie to the disease
Rockman v. Union Carbide Corp., 266 F. Supp. 3d 839 (D. Md. 2017). Jeffrey Rockman got peritoneal mesothelioma, a cancer of the lining of the belly. He blamed it on chrysotile, a common form of asbestos, in a joint compound that workers used during three home repairs, in 1965, 1973 and 1976. He was a "bystander": he did not do the work himself. The court noted those projects spanned "no more than several weeks in total."
Two of his experts, Dr. Jerrold Abraham and Dr. Arthur Frank, said those exposures caused his cancer. The court excluded both opinions. It found that they "failed to support their specific causation opinions with “sufficient facts or data”" and had "conflated asbestos type and disease type in their analysis of the relevant scientific data." They could not point to any study linking this cancer to bystander exposure to chrysotile as brief and as distant as his.
A third expert, Dr. Arnold Brody, gave no opinion about Mr. Rockman. All three relied on the theory that "each and every" exposure to asbestos adds up and counts as a cause. The court found that theory is not the "product of reliable principles and methods" and excluded testimony based on it.
The case ended there. "Plaintiffs’ counsel acknowledged at this Court’s July 6, 2017 hearing that the Plaintiffs cannot survive summary judgment without the causation testimony of their experts." The court granted summary judgment for the defendants. It added that it would have done so even without excluding the experts.
Ruling 2: one expert's opinion fell, and two doctors fell with it
Hanson v. Colgate-Palmolive Co., 353 F. Supp. 3d 1273 (S.D. Ga. 2018). Sharon Hanson had pleural mesothelioma and ovarian cancer. Her husband, suing for her estate, blamed asbestos in Cashmere Bouquet body talc.
Her case rested first on Dr. Ronald Gordon, who said the talc contained asbestos. The court excluded that opinion. He had not recorded where on each sample grid he found each fiber he called asbestos, so the defense could not check his work. The court held that "omission of the location information is sufficient by itself to exclude Dr. Gordon's contamination opinion." It gave a second, independent reason: he skipped the final test step that tells talc apart from asbestos. The court also excluded his opinion that asbestos caused her mesothelioma.
Two physicians, Dr. Richard Kradin and Dr. Jacqueline Moline, gave the causation opinions. The defense's attack on Dr. Kradin's own medical reasoning did not win. On that, the court said: "Defendant's criticisms are more appropriate for cross examination." But both doctors depended on the excluded opinion. "Both physicians rely on Dr. Gordon's now excluded opinion CB talc contains asbestos. Without it, they have no basis for opining Mrs. Hanson's use of CB talc caused her cancer." The court excluded their causation opinions.
They could not fill the gap by citing older articles on talc either. The court found the question of asbestos in the talc was outside their expertise, and quoted an earlier decision: an expert "may not simply repeat or adopt the findings of another expert without attempting to assess the validity of the opinions relied upon." The court allowed the opinions of the three defense experts the plaintiff challenged.
Where the line falls
In both cases, the causation opinion broke at the exposure step. In Rockman, the alleged exposure was too limited for any study the experts cited to support. In Hanson, the only expert proof that the talc contained asbestos was excluded, and the causation opinions built on it went with it.
What to do
| If you offer the causation expert | If you oppose it |
|---|---|
| Prove the exposure first: the product contained the substance, by a method another lab could repeat, with the underlying data kept. | Ask for the data behind any testing. A result the other side cannot check is open to challenge. |
| Match the literature to this plaintiff: the same substance, the same disease, and an exposure of a similar length and closeness. | Test whether the literature matches how this plaintiff was exposed: how long, how close and to which form of the substance. |
| Don't rest the causation opinion on "each and every exposure" counting as a cause. | Look for the "each and every exposure" theory under any label. |
| Know which experts your physicians rely on. If one foundation opinion falls, find out what else falls with it. | Map which opinions rest on which. Excluding one foundation opinion can take several others down with it. |
Method: This is a pattern piece, not a count. It rests on two published federal district court rulings, read in full: Rockman v. Union Carbide Corp. (D. Md. 2017) and Hanson v. Colgate-Palmolive Co. (S.D. Ga. 2018). It shows how these two courts drew the line. It does not measure how often courts exclude toxic-tort experts. District court rulings do not bind other courts. Nothing here is legal advice.