[Dmitry Karshtedt] Abstract: Pharmaceutical companies often replace prescription drugs that are already on the market with modified versions that have the same active pharmaceutical ingredient. On the surface, such activity seems benign and perhaps even salutary. Nonetheless, antitrust litigation has revealed that firms sometimes modify existing drugs not because new formulations would demonstrably improve health outcomes, but principally because so-called secondary patents covering the new version of the drug enable them to maintain some effective market power over the active ingredient for which original, primary patent protection has expired. This “product-hopping” strategy runs counter to the goal of the legislative framework for regulating branded and generic drug approvals, which is to create appropriate incentives for discoveries that raise the quality of patient care and human health by providing a period of reward for the brand followed by timely and effectual generic entry.