Editor’s note: The author appeared for amicus curiae Product Liability Advisory Council in the Pa. Supreme Court decisions discussed in this article.

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.