Abstract
Certificate of need (CON) laws limit the supply of health care services in about two-thirds of U.S. states. The regulations require those who wish to offer new services or expand existing services to first prove to a regulator that the care is needed. While advocates for the regulation have offered several rationales for its continuance, the balance of evidence suggests that the rules protect incumbent providers from competition at the expense of patients, payors, and would-be competitors. In this article, I review the history of CON laws in health care, summarize the large literature evaluating them, and briefly sketch options for reform.JEL Classification: I11, I18, H75.