Exposure to harmful substances is a fact of modern life. These substances are everywhere—in the air we breathe, the food we eat, and the water we drink—and it is impossible to have zero exposure to all of them. For both science and law, however, the issue is not whether someone was merely exposed. Rather, it is whether the exposure was sufficient to cause the injury.

This fundamental rule of causation applies to every tort action—including asbestos cases—the Seventh Circuit held recently. The Seventh Circuit rejected the plaintiff’s expert’s causation theory that “each and every exposure” or the “cumulative exposure” may satisfy the plaintiff’s causation burden. The Seventh Circuit also made clear that courts cannot require a defendant to exclude a potential cause—disprove that exposure to its product could be a cause—because that impermissibly shifts the plaintiff’s causation burden onto the defendant. Krik v. Exxon Mobil Corp., No. 15-3112, 2017 WL 3768933 (7th Cir. Aug. 31, 2017).

As the Seventh Circuit summarized,

the principle behind the “each and every exposure” theory and the cumulative exposure theory is the same—that it is impossible to determine which particular exposure to carcinogens, if any, caused an illness. In other words, just like “each and every exposure,” the cumulative exposure theory does not rely upon any particular dose or exposure to asbestos, but rather all exposures contribute to a cumulative dose. The ultimate burden of proof on the element of causation, however, remains with the plaintiff. Requiring a defendant to exclude a potential cause of the illness, therefore, improperly shifts the burden to the defendants to disprove causation and nullifies the requirements of the “substantial factor” test.

Id. at *5 (emphasis added).

In Krik, the plaintiff developed cancer after smoking a pack and a half of cigarettes every day for 30 years. He also claimed occupational exposure to asbestos through his service in the U.S. Navy and later as a union pipefitter. The plaintiff sued scores of companies claiming that they were responsible for exposing him to asbestos and that the combination of smoking and asbestos combined to synergistically cause his lung cancer. After a two-week trial, the jury concluded that cigarette smoking was the sole proximate cause of the plaintiff’s cancer.

In support of his claim, the plaintiff proffered expert witness testimony that every exposure to asbestos contributes to the total cumulative dose and that the cumulative dose caused the cancer. Thus, according to the plaintiff’s theory, every exposure that contributes to the cumulative dose is a “substantial factor” in causing the injury. The defendants challenged the admissibility of this causation theory in pre-trial motions, and the district court held that plaintiff “had not established that the ‘any exposure’ theory was sufficiently reliable to warrant admission under Rule 702 and the Supreme Court’s seminal case on the admissibility of expert witness testimony, Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).” Id. at *1.

During trial, the plaintiff tried to skirt the district court’s ruling and introduce the same causation theory, this time packaging it as a “cumulative exposure” theory. In excluding the expert witness testimony, the district court held that the “each and every” theory and the “cumulative exposure” theory were virtually identical, and equally lacking in scientific merit. Indeed, the theory was “not tied to the specific quantum of exposure attributable to the defendants, but was instead based on his medical and scientific opinion that every exposure is a substantial contributing factor to the cumulative exposure that causes cancer.” Id. at *2.

In affirming the district court, the Seventh Circuit explained that the plaintiff’s “each and every exposure” theory and “cumulative exposure” theory were scientifically and legally bankrupt, and would nullify the substantial factor causation test. The Seventh Circuit joined the Ninth and Sixth Circuits that “such a theory of liability would render the substantial-factor test essentially meaningless. Allowing causation to be established through testimony like the expert’s would ‘permit imposition of liability on the manufacturer of any asbestos-containing product with which a worker had the briefest of encounters on a single occasion.’ This is precisely the sort of unbounded liability that the substantial factor test was developed to limit.” Id. at *6 (quoting McIndoe v. Huntington Ingalls Inc., 817 F.3d 1170, 1177 (9th Cir. 2016) and citing Lindstrom v. A–C Prod. Liab. Tr., 424 F.3d 488, 493 (6th Cir. 2005)).

The Seventh Circuit also held that the district court had properly excluded the so-called “Helsinki Criteria” as substantive evidence or as a foundation for inadmissible causation testimony. The “Helsinki Criteria” was a set of consensus principles announced at an international public policy conference in 1997 that includes the proposition that “[c]umulative exposure on a probability basis should thus be considered the main criteria for the attribution of a substantial contribution by asbestos to lung cancer risk.” The “Helsinki Criteria” were not admissible, however, as substantive evidence or as foundation for otherwise inadmissible causation testimony—a ruling that is consistent with the decisions of many other courts across the nation. Id. at *6-7.

The Seventh Circuit went on to reject the plaintiff’s arguments about any possible “juror investigation.” During jury selection, the prospective jurors were asked if they knew any of the parties or potential witnesses. After the jury was sworn, one juror advised the trial court that she and the plaintiff might have attended a birthday party together for a friend that happened to be in the same union as the plaintiff. The plaintiff told the district court that he did not know the juror’s friend and did not think he was at the party. One defendant then hired an investigator to find the “friend” who had the birthday party. The investigator found the man, and confirmed that the plaintiff was not at the party. Neither the court, nor the plaintiff’s counsel, learned about the investigation until after the jury’s verdict. The Seventh Circuit concluded, “[f]or this case, however, we need not rule about the propriety of such a practice because we have determined that there was no prejudice to Krik and that the investigation could not have altered the course or outcome of the trial. The investigator questioned [the juror’s] friend and not [the juror]. [The juror] herself notified the court about the birthday party, thus indicating that she recognized that it might be relevant, and decreasing the chance that its revelation would bring about any embarrassment or surprise for her. As the district court noted, the ‘nature of the investigation was relatively benign and there is no proof that prejudice was reasonably likely.’” Id. at *9.

At bottom, the Seventh Circuit answered two critical questions that thousands of parties face every year in Illinois asbestos cases. First, does a defendant ever have the burden under Illinois law of “disproving” the allegation that exposure to its product was a substantial contributing factor in causing the plaintiff’s injury? Second, are the plaintiff’s “each and every exposure” theory and “cumulative exposure” theory admissible to prove causation under Illinois law? The Seventh Circuit answered both questions, “No.” 

The authors are counsel of record for one of the defendants in the case.