This Note discusses the regulatory regime developed by the Food and Drug Administration (FDA) to ensure generic drug quality through premarket approval. The Hatch-Waxman Act effectively created the contemporary generic drug industry in 1984, and today, this industry saves the United States billions of dollars in medical costs. The legal-scientific concept of “bioequivalence” is central to the Hatch-Waxman regime, and its meaning has developed through statutory, regulatory, an advisory pathways in Congress and at the FDA. In this Note, I argue that the FDA’s current approach to promulgating standards for bioequivalence—largely based on guidance documents—threatens the agency’s ability to sustain comprehensive and authoritative regulation in the future. Guidance documents and petition responses are not subject to public input according to the standards of the Administrative Procedure Act (APA), and may create confusion among regulated entities and trouble for consumers. Nevertheless, courts repeatedly have deferred to the FDA’s choice of policymaking form and have found challenges under the APA to be nonjusticiable for lack of standing and ripeness. I argue that this deference should be attenuated and justiciability should be restored, not because generic drugs approved under the current regime are demonstrably dangerous to patients, but because systematic foreclosure of public input and judicial oversight is an unsustainable regulatory approach.