Lead Opinion
In this аction brought under the Price-Anderson Act, 42 U.S.C. § 2210, we must decide whether Plaintiffs alleging they suffered cancer due to exposure to radiation from Defendants’ uranium mill have made a sufficient showing of causation under New Mexico law to survive summary judgment. We first determine the test for causation in this context, then evaluate whether the evidence submitted by Plaintiffs was sufficient to satisfy this test for summary judgment purposes.
This action was originally brought by several plaintiffs who alleged they or the decedents they represented suffered from a large variety of injuries and diseases as a result of exposure to radioactive аnd nonradioactive hazardous substances released from Defendants’ uranium milling facility in Cibola County, New Mexico. The district court entered a scheduling order requiring each plaintiff to produce expert affidavits making a prima facie showing of harmful exposure and specific causation for each alleged injury, but only three plaintiffs — the appellants in this action— did so. The district court dismissed the other twenty-five plaintiffs from the action with prejudice, and that dismissal is not contested in this appeal. As for the three Plaintiffs involved in this appeal, their experts opined these Plaintiffs’ exposurе to radiation from Defendants’ operations was a substantial factor contributing to each of them developing cancer. The district court concluded that New Mexico law required a showing of but-for causation and that Plaintiffs’ expert affidavits failed to meet that showing. The court therefore granted summary judgment to Defendants on Plaintiffs’ claims. This appeal followed.
We review the district court’s grant of summary judgment de novo, applying the same legal standard applicable to the district court. See Padhiar v. State Farm Mut. Auto. Ins. Co.,
In New Mexico, as is universally the case, a tort plaintiff must demonstrate the defendant’s actions caused the plaintiffs injury. Since 1892, New Mexico has generally required the plaintiff to make a showing of “that cause which, in natural
Plaintiffs first contend New Mexico’s uniform jury instructions make clear that but-for causation is not required in every case. New Mexico Civil Uniform Jury Instruction 13-305, in its description of causation, places brackets around the phrase “and if injury would not have occurred without it.” These brackets mean this phrase might “need to be adapted in accordance with the acts in each particular case.” 4 New Mexico Rules Annotated, 5 (2009). The commentary to the jury instructions, however, lists only two situations in which the but-for clause may be unnecessary or inappropriate: (1) cases involving alternative liability, such as the classic case of Summers v. Tice,
The first exception to but-for causation described in the commentary to the jury instructions applies to “the unusual circumstances” in which two or more defendants engage in simultaneous or nearly identical negligent acts but only one of these acts causes the injury complained of, thus making it difficult or impossible for the plaintiff to prove which defendant caused the harm. Roderick v. Lake,
The second exception described in the commentary to the jury instructions spe
Plaintiffs also argue that several New Mexico cases indicate a substantial factor test, rather than the but-for test, is appropriаte in circumstances where there are multiple potential contributing causes for an injury. However, the cases cited by Plaintiffs, with one possible exception, are fully consonant with the Restatement view of causation as we explained it in June. In our view, New Mexico cases using the phrase “substantial factor,” like the Colorado cases we discussed in June, do not create an alternative ground to but-for causation. See, e.g., Collins v. Perrine,
As for the one possible exception, Tafoya v. Seay Bros. Corp.,
Finally, Plaintiffs argue that the requirement to show but-for causation will cut off virtually all relief for toxic tort plaintiffs because an honest scientific expert will never be able to state as a concrete fact that a plaintiffs injury would not have occurred were it not for exposure to the defendant’s product. We note, however, that but-for causation in this context, as in other contexts, does not require proof to an absolute certainty. Although a plaintiff must prove but-for causation, the burden of proof in medical tort cases requires only “proof to a reasonable degree of medical probability,” Alberts v. Schultz,
We see no bаsis in New Mexico law for creating an exception to but-for causation simply because a case involves toxic torts, nor have Plaintiffs established any other basis for an exception to but-for causation in this case. We accordingly turn to the question of whether Plaintiffs made a sufficient showing of but-for causation to survive summary judgment.
Plaintiffs argue that causation is established through the following evidence: (1) Dr. Owen Hoffman’s calculation of each Plaintiffs’ “assigned share,” which reflects “the proportion of individuals in a heterogeneous population who are alike in all aspects of аge, gender, exposure history, and dose, who would not have been diagnosed with their cancer had they not been exposed” and is “an indirect statistical indicator of cancer causation for a given individual exposed to radiation” (Appellants’ App. at 111); (2) Dr. James Ruttenber’s testimony, based on the assigned share values calculated by Dr. Hoffman, that “a medical expert could consider radiation exposures from the Homestake mill to be a substantial contribution to the causes of the liver cancer, thyroid cancer, and bladder cancer of Plaintiffs Harriet
Notes
. In the case cited in the jury instruction commentary, for instance, the two defendants each shot in the plaintiff's direction at the same time while quail-hunting, and the plaintiff was struck by birdshot. See Summers,
. Although our opinion in June was based on Colorado law and we are applying New Mexico law in the instant case, we interpret New Mexico law to require the same showing of but-for causation that was required in June.
Concurrence Opinion
concurring in part.
I agree that New Mexico law requires plaintiffs to demonstrate but-for causation, and that they did not create a genuine factual dispute on that issue. I accordingly join the majority’s discussion of the appropriate legal standard and concur in its judgment. I write separately to elaborate upon the manner by which plaintiffs in toxic torts cases can satisfy the but-for causation standard and to state my disagreement with the majority’s characterization of June v. Union Carbide Corp.,
I
Although I agree generally with the majority’s recitation of the facts, additional context is helpful in evaluating statements made by three of the plaintiffs’ experts. First, Dr. F. Owen Hoffman calculated an “assigned share” figure for plaintiffs Wilcox, Hartman, and Serna. He defined assigned share as “an empirical expression of the proportion of individuals in a heteroge-nous population who are alike in all aspects of age, gender, exposure history, and dose, who would not have been diagnosed with their cancer had they not been exposed.” Dr. Hoffman’s numbers were based on the dose of radiation each person’s diseased organ received from the defendants’ mine. At a 95% confidence interval, the assigned shares ranged from 0.5% to 41% for Hartman, from 0.073% to 25% for Serna, and from 3.3% to 80% for Wilcox. In other words, Dr. Hoffman could state with a relatively high degree of statistical probability that the chance
Second, Dr. Robert Peter Gale opined on the cause of Wilcox’s and Hartman’s cancers as follows:
Based on my consideration of all available data including, but not limited to, the arithmetic mean and 95% credibility interval of estimated assigned share, Plaintiffs Harriet Wilcox and Marcella Hartman were exposed to additional ionizing radiations as a consequence of Defendants’ operations. Such exposures are known to cause and/or contribute to the development of liver and bladder cancers. The arithmetic mean of ionizing radiation-related assigned share to each plaintiff from Defendants’ operations exceeds 10 percent. Assuming the medical records available to me are correct and complete and that no other parameter(s) unknown to me could, as a sole cause overwhelmingly explain each plaintiff having the cancer specified, I opine: to a reasonable medical probability exposure to ionizing radiations as a consequence of Defendants’ operations was a substantial factor contributing to each plaintiff developing сancer,
(emphasis omitted).
Finally, Dr. Inder J. Chopra separately considered the cause of Serna’s cancer. After examining Serna’s medical records, family and social histories, details of her exposure to radiation from the mine, and “other background risk factors” for cancer, Dr. Chopra opined, “Serna’s exposure to radioactivity was of sufficient magnitude, duration and intensity that, in my expert opinion, rendered it a substantial factor to her development of thyroid cancer.” He further averred that he “discovered no other overwhelming risk factors that may have caused Ms. Serna’s [canсer].”
II
A
The majority opinion treats the panel decision in June as controlling our application of the but-for causation standard. (Majority Op. 1170.) I disagree. The June majority ruled in favor of the defendants with respect to but-for causation on procedural, not substantive, grounds:
The problem for Plaintiffs is not that their experts failed to utter some magic words, such as “but for.” ... For all we know, the data would support but-for claims of some, or even all, Plaintiffs. The problem for Plaintiffs is that they did not make a timely argument that they had produced evidence of but-for causation, and they have never (not even in this court) contended that they have produced evidencе that [Defendants’] radiation was a necessary component of a causal set that probably would have caused the Plaintiffs’ ailments.
Unlike those in June, these plaintiffs have consistently argued that their proffered expert evidence satisfies New Mеxico’s but-for causation standard. The plaintiffs stated below that “[i]t is not necessary (nor is it possible) to opine that but for exposures [plaintiffs] would never have
B
We lack clear guidance from New Mexico courts with respect to the evidence required to meet the but-for causation standard in toxic tort cases. Tenth Circuit precedent similarly sheds little light on the issue. Faced with this lacuna, I would apply the principles fleshed out in Judge Holloway’s well-reasoned June partial dissent in evaluating such expert evidence.
In June, a medical expert (coincidentally, the same Dr. Chopra who provided sworn statements in this case) testified that the defendants’ uranium facility was “a substantial factor contributing” to the plaintiffs’ illnesses. Id. at 1254. But in June, Dr. Chopra went much further, explaining:
When I use in this particular case that radiation was a substantial factor contributing to occurrence of ... the illness that we are talking about, in my mind, I am thinking that if they had not been exposed to radiation, there is small or— probably they would not have — the disease would not have occurred in them.
Id. Moreover, he specifically opined that “[i]t is more probable than not that [the defendants’ uranium facility] of itself was a substantial contributing factor to each Plaintiffs thyroid disease, without which the Plaintiff’s respective thyroid disease would not have happened.” Id. (emphases and first alteration in original).
In Judge Holloway’s view, which I share, Dr. Chopra’s use of the phrase “substantial factor” was immaterial. He could have used any term whatsoever to speak about causation; the incantation of magic words is not required, providеd that an expert’s opinion roughly corresponds to the legal concept of but-for causation. Dr. Chopra’s testimony in June is a good example of the type of evidence that clears this hurdle. In addition, a plaintiff can prevail by adducing evidence suggesting that a defendant’s polluting activities worsened or hastened the plaintiffs illness. Cf. Tafoya v. Seay Bros. Corp.,
But in this case, plaintiffs did not produce such evidence. Drs. Gale and Chopra did not define what they meant by the term “substantial factor.” As the expert testimony in June makes quite clear, “substantial factor” is not a term of art from which sine qua non causation can be inferred; instead, it takes on a meaning that can differ depending on the “particular case.”
When their opinions are read as a whole, neither Dr. Gale nor Dr. Chopra concludes that plaintiffs’ cancers would not have arisen but for them exposure to defendants’ radiation. Dr. Gale merely opined that defendants’ mining operations were a substantial factor leading to Wilcox’s and Hartman’s cancers, “[ajssuming” that no other fаctor “could, as a sole cause overwhelmingly explain each plaintiff having the cancer specified.” Similarly, Dr. Cho
Of course, an expert need not opine that the defendants’ actions were the sole cause of the injury. As a general rule, a plaintiff demonstrates but-for causation by showing that his injury would not have been sustained absent the defendant’s negligence, and there can be multiple but-for causes of a plaintiffs injury. See Restatement (Second) of Torts § 432. But the statements submitted to the district court do not claim that plaintiffs’ cancers probably would not have occurred but for defendants’ actions. Further, the experts’ referenсe to Dr. Hoffman’s mean assigned share values— all below 50% — suggests that they did not intend the term “substantial factor” to be the functional equivalent of but-for causation. Even Dr. Chopra’s supplemental affidavit, submitted after the causation issue was squarely raised, does not support such an inference.
Ill
In toxic tort cases, the causation issue presents a difficult hurdle for plaintiffs and their experts. But that hurdle is not insurmountable. As Judge Holloway’s considered partial dissent in June demonstrates, an expert need not revert to legalisms or rule out all other potential causes of a plaintiffs injury. Instead, the totality of аn expert’s testimony must convey that he or she believes the plaintiff probably would not have gotten sick — or the illness would have been later-developing or less severe — but for the defendant’s negligence. Unfortunately for Wilcox, Hartman, and Serna, their experts conveyed no such belief. Therefore, I join the majority in affirming the district court’s grant of summary judgment to the defendants.
. I agree with the majority that, in all respects relevant to this case, New Mexico law related to but-for causation is equivalent to Colorado law as considered in June. (Majority Op. 1170 n. 2.)
Concurrence Opinion
concurring.
I write separately because my reading of the record reveals that Plaintiffs have waived any argument that the but-for standard of causation does not apply. Although I have no reason to question the majority’s view that the New Mexico Supreme Court would apply the but-for standard rather than the substantial-factor test, I would not reach Plaintiffs’ argument on this point and offer no definitive opinion on the matter here. Instead, I would hold that the but-for standard is the applicable causation standard in this case — Plaintiffs having waived any argument to the contrary — and would proceed directly to the question of whether Plaintiffs offered sufficient evidence under that standard to survive summary judgment. On that question, I agree fully with the majority’s reasoning and its ultimate conclusion that Plaintiffs did not offer sufficient evidence.
On appeal, Defendants contend that Plaintiffs did not argue before the district court that the substantial-factor test applied. I agree. In opposing Defendants’ motion for summary judgment, Plaintiffs did not ask the district court to apply the causation standard that they now advance on appeal — viz., the substantial-factor test. Rather, Plaintiffs contended that the but-for standard applied and urged the district court to hold that their evidence satisfied that standard. For example, they stated that “New Mexico requires both a showing that an event is a contributing factor and a cause without which an injury would not have occurred, or more commonly, ‘but for’
Because Plaintiffs did not argue before the district court that the substantial-factor test governed the determination of whether Plaintiffs’ cancer was caused by radiation that Defendants emitted, we should not consider Plaintiffs’ attempt for the first time on appeal to convince us to apply that test. See Tele-Commc’ns, Inc. v. Comm’r,
Because I would hold Plaintiffs to their waiver, I would proceed directly to the second question on appeal — whether Plaintiffs experts’ affidavits made a sufficient showing of but-for causation to survive summary judgment. I agree fully with the majority’s conclusion that they did not do so.
. In asserting that but-for causation was the proper causation standard under New Mexico law, Plaintiffs cited to Tafoya v. Seay Brothers Corp.,
. I do not find Plaintiffs’ response to Defendants' assertion of waiver to be persuasive. Plaintiffs merely state that "Plaintiffs clearly argued that their experts' opinions satisfied the substantial factor test and more.... Plaintiffs vigorously argued that the expert opinions satisfy the New Mexico but-for test, but in doing so, Plaintiffs likewise amply argued that the same evidence satisfies the slightly more relaxed substantial factor test.’’ Aplts. Reply Br. at 4. That does not comport with my reading of Plaintiffs’ arguments before the district court.