Health care politics are changing. They increasingly focus not on avowedly public projects (such as building the health care infrastructure) but on regulating private behavior. Examples include tobacco, obesity, abortion, drug abuse, the right to die, and even a patient's relationship with his or her managed care organization. Regulating private behavior introduces a distinctive policy process; it alters the way we introduce (or frame)political issues and shifts many important decisions from the legislatures to the courts. In this article, we illustrate the politics of private regulation by following a dramatic case, obesity, through the political process. We describe how obesity evolved from a private matter to a political issue. We then assess how different political institutions have responded and conclude that courts will continue to take the leading role.