On May 23, 2012, the Pennsylvania Supreme Court issued an opinion in the matter Betz v. Pneumo Abex LLC, No. 38 WAP 2010 (Pa. May 23, 2012) rejecting the same scientific methodology long used by plaintiffs’ expert pathologists in establishing legal or substantial-factor causation. The opinion was issued by way of a global Frye motion (Frye v. United States, 293 F. 1013 (D.C. Cir. 1923)) on behalf of three defendants who successfully challenged the admissibility of expert testimony on the basis that the methodology underlying the “any-exposure” theory is novel and scientifically invalid.


In February 2005, Charles Simikian commenced a product liability action against several defendants alleging that a career of hands-on occupational work with defendants’ automotive friction products caused him to develop mesothelioma. Defendants anticipated that the plaintiff’s expert would rely on the “each and every exposure” theory – that any exposure, no matter how small, contributes substantially to the development of asbestos-related diseases – and sought to preclude such testimony under Pennsylvania’s adherence to the Frye doctrine.

Plaintiffs retained John C. Maddox, M.D. as their primary causation expert whose report endorsed the any-exposure theory and concluded that “each exposure to asbestos is therefore a substantial contributing factor in the development of the disease.” In response, defendants proffered the report of occupational environmental epidemiologist M. Jane Teta who asserted that Dr. Maddox failed to follow proper scientific method in support of his conclusions. Dr. Teta posited that the “any-exposure theory” is inconsistent with the common understanding that the context and circumstances of exposure to toxic substances, including the critical component of dose, matter greatly in determining the risk of disease. Judge Colville of the Allegheny Court of Common Pleas sustained the Frye challenge and precluded plaintiffs from employing the any-exposure causative theory.

A Superior Court majority subsequently reviewed Judge Colville’s determination and reversed, relying in part on a liberal reading of Trach v. Fellin, 817 A.2d 1102, 1110 (Pa. Super. 2003), which supports the idea that experts may extrapolate, both upwards and downwards, from a sound scientific basis when forming opinions about the etiology of disease, and that this use of extrapolation, an idea on which Dr. Maddox in Betz relied heavily, is not an affront to Frye as “novel” science. The Supreme Court reversed, finding that Judge Colville did not abuse his discretion in his Frye determination.


Remaining defendants Ford Motor Company and Allied Signal, supported by a litany of amici, provided a compelling appellant defense. Broadly, appellants thought Daubert instructive – that fundamentally, scientific method is grounded in testing, and that Dr. Maddox’s expert opinion remains untested. Further, appellants attacked Dr. Maddox’s use of “extrapolation” logic – that no rational inference justifies large-scale downward toxicological extrapolations, characterizing the scientific validity of extrapolating from high to low dose exposures as “at best dubious.”

Dr. Maddox’s invocation of dosage quantity and intensity as considerable factors to weigh the relative effects of toxic exposure also played a part in Justice Saylor’s reversal. Essentially, it highlighted a fundamental and irreconcilable internal conflict in Dr. Maddox’s own conclusion – that “one cannot simultaneously maintain that a single fiber is substantially causative, while also conceding that a disease is dose responsive.”


The Betz opinion clearly vitiates a plaintiff’s use of the any-exposure theory as evidence of substantial causation in Pennsylvania forums.

Plaintiffs also long employed the any-exposure theory to circumvent frequency-proximity threshold requirements, generally stating that it is impossible to isolate any particular exposure to asbestos and opine as to those fibers’ causative effect alone, and therefore concluding that all exposures are considered to be substantially contributory to the contraction of an asbestos-related disease. Now plaintiffs will have to offer evidence that each defendant’s attributable exposure alone is substantially causative.

Additionally, it revalidates and breathes new life into Gregg v. V-J Auto Parts Company, 596 Pa. 274, 943 A.2d 216 (2007), a Pennsylvania Supreme Court case that the Betz Superior Court relegated to limited relevance in their analysis.