Section 402A of the Restatement (Second) of Torts provides that a user or consumer injured by a defective product may seek redress from the product seller under a theory of strict liability. Nevertheless, Pennsylvania courts have held that not every entity with a role in putting a product into the hands of consumers is a "product seller" within the meaning of Section 402A. Entities like brokers, auctioneers, and second-hand markets have been exempted from the definition of "product seller."

The development of e-commerce has led Pennsylvania courts to consider whether online sales platforms are akin to brick and mortar retailers or more like the intermediaries that fall outside the scope of strict liability. In Oberdorf v. Amazon.com, 930 F.3d 136 (3d Cir. 2019), the plaintiff filed suit against Amazon alleging the product she purchased from a third-party vendor was defective. Although the U.S. District Court for the Middle District of Pennsylvania held Amazon was not a "product seller" within the meaning of Section 402A, the U.S. Court of Appeals for the Third Circuit disagreed, finding that Amazon qualified as a product seller, thus expanding the scope of strict products liability to include online sales platforms. Other courts have reached the same conclusion and expanded strict products liability to include e-commerce sites.