In 2013, Pennsylvania law saw the final demise of any-exposure causation in asbestos litigation. Not so long ago—prior to the Pennsylvania Supreme Court's decision in Gregg v. V-J Auto Parts, 943 A.2d 216 (Pa. 2007)—asbestos plaintiffs routinely offered expert testimony that any exposure, no matter how minor, was sufficient to impose liability because "each and every breath" of asbestos-contaminated air was a "substantial factor" in causing illnesses such as mesothelioma. No longer.

In Gregg, the court, in the course of adopting a "frequency, regularity and proximity" test for asbestos product identification, somewhat unexpectedly addressed "each and every breath" expert testimony, holding that while such opinions were "common," "such generalized opinions do not suffice to create a jury question in a case where exposure to the defendant's product is de minimis, particularly in the absence of evidence excluding other possible sources of exposure." Such opinions were both bad law and bad science, "not fairly grounded in ... the underlying facts and ... not couched within accepted scientific methodology."

Gregg prompted many defendants to challenge these hitherto widely accepted expert opinions, both on legal grounds and as insufficiently grounded in science under Pennsylvania's Frye test for admission of expert testimony. In Betz v. Pneumo Abex, 44 A.3d 27 (Pa. 2012), the issue reached the Pennsylvania Supreme Court a second time, this time in the Frye context. In a test case in Allegheny County, an "each and every breath" opinion, specifically chosen for this purpose by the plaintiffs, was excluded, but the Superior Court reversed. The Supreme Court reversed and without dissent upheld the exclusion. Initially, the Superior Court had construed the scope of Frye too narrowly, according to the Supreme Court. Frye general acceptance analysis is appropriate whenever a "trial judge has articulable grounds to believe that an expert witness has not applied accepted scientific methodology in a conventional fashion in reaching his or her conclusions," according to the court in Betz.

On the scientific merits, the expert opinion in Betz was not based on the type of epidemiological evidence that scientists utilize:

"[The expert's] efforts to invoke case reports, animal studies and regulatory standards are also ineffectual in terms of substantial-factor causation, since the most these can do is suggest that there is underlying risk from the defendants' products."

De minimis causation opinions, such as those claiming "each and every breath" is a substantial factor, were contrary to the fundamental principle that the effects of exposures to toxic substances are dose-responsive. "Simply put, one cannot simultaneously maintain that a single fiber among millions is substantially causative, while also conceding that a disease is dose-responsive," the Betz court held. Thus, the trial court "was right to be circumspect about the scientific methodology underlying the any-exposure opinion." Because dose matters, an expert witness could not properly offer a causation opinion while having "no familiarity whatsoever with [the plaintiff's] individual circumstances," the court held.

Finally, as a matter of law, an "each and every breath" opinion was fundamentally at odds with the concept of "substantial factor" causation. Such opinions did "not consider the three factors [potency, intensity and duration] which ... need to be considered in trying to estimate the relative effects of different exposures," the court held.

"We do not believe that it is a viable solution to indulge in a fiction that each and every exposure to asbestos, no matter how minimal in relation to other exposures, implicates a fact issue concerning substantial-factor causation. ... The result, in our view, is to subject defendants to full joint-and-several liability for injuries and fatalities in the absence of any reasonably developed scientific reasoning that would support the conclusion that the product sold by the defendant was a substantial factor in causing the harm," the court continued.

Allowing expert testimony that assigned causal effect to de minimis exposures was legal as well as scientific error. "Discounting of the substantiality in exposure would be fundamentally inconsistent with Pennsylvania law," the court held.

One might have thought that Betz would have been the end of the argument, but the Superior Court continued to show considerable affinity to "each and every breath" causation opinions in asbestos cases. In Howard v. A.W. Chesterton, 31 A.3d 974 (Pa. Super. 2011), the court followed a pre-Betz decision and held that even "one or a de minimis number of asbestos fibers" could still be "a substantial factor in causing a plaintiff's injury." For a third time, the Pennsylvania Supreme Court accepted an appeal concerning "each and every breath" asbestos causation opinions.

Once Howard was before the Supreme Court, however, a most extraordinary thing happened. The plaintiff abandoned the arguments with which he had carried the day in the Superior Court and admitted error, "conced[ing] that the factual record fails to demonstrate regular and frequent enough exposures [to asbestos] to defeat summary judgment," as the court wrote in Howard v. A.W. Chesterton, 78 A.3d 605, 607 (Pa. 2013), quoting a brief from the plaintiff-appellee. Thus, the appeal in Howard nominally was "resolved upon mutual consent among the parties, who agree that the order of the Superior Court should be reversed."

The record revealed, however, that asbestos plaintiffs—and not just in Howard—were successful at getting the lower courts to ignore the holdings in Gregg and Betz and to continue with business as usual in asbestos litigation, allowing plaintiffs to proceed with de minimis causation theories that the Pennsylvania Supreme Court had twice rejected. Seemingly banking on the infrequency of Supreme Court discretionary review, plaintiffs would pursue the same arguments on appeal, but would concede error in the Supreme Court.

Even though error was conceded in Howard, the Supreme Court took the unusual step of issuing a published opinion that "reaffirm[s] several governing principles" stating precisely what Gregg and Betz forbade in asbestos litigation:

• The theory that each and every exposure, no matter how small, is substantially causative of disease may not be relied upon as a basis to establish substantial-factor causation for diseases that are dose-responsive.
• Relatedly, in cases involving dose-responsive diseases, expert witnesses may not ignore or refuse to consider dose as a factor in their opinions.
• Bare proof of some de minimis exposure to a defendant's product is insufficient to establish substantial-factor causation for dose-responsive diseases.
• Relative to the testimony of an expert witness addressing substantial-factor causation in a dose-responsive disease case, some reasoned, individualized assessment of a plaintiff's or decedent's exposure history is necessary.
• Summary judgment is an available vehicle to address cases in which only bare de minimis exposure can be demonstrated and where the basis for the expert's testimony concerning substantial-factor causation is the any-exposure theory.
• The content of expert discovery is specified in the Pennsylvania Rules of Civil Procedure, as may be supplemented by particular directives by courts of original jurisdiction.

No justice dissented. Justice Debra M. Todd concurred in the result only, unwilling to issue "proclamations" that she found "unmoored from any factual context."

That the court saw no need for "factual context" in rejecting de minimis expert causation opinions, however, is precisely what marks 2013 as the year that such opinions really became a thing of the past. As long as litigants could quibble about whether "each and every breath" expert testimony could be supportable under some set of facts, such opinions would continue to be offered. The advantages of such an approach—telling jurors that they need not worry about how much exposure any defendant's product caused—were simply too great. Howard has now provided the lower courts with clear, bright lines, a checklist of what plaintiffs experts may no longer do, with the implicit threat of summary reversal should they not be followed. Moreover, the Howard bullet points apply not just to mesothelioma, but to any and all dose-responsive diseases, a category that most statisticians would agree encompasses almost all conditions caused by exposure to toxic substances.

Reprinted with permission from the February 11, 2014 issue of The Legal Intelligencer. © 2014 ALM Media Properties, LLC. Further duplication without permission is prohibited. All rights reserved.

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