This Article contributes to an emerging theoretical debate over the legitimate scope of public health law by linking it to a particular doctrinal debate in public nuisance law. State and local governments have been largely stymied in their efforts to use public nuisance litigation against harmful industries to vindicate collectively-held, common law rights to non-interference with public health and safety. The ways in which this litigation has failed are instructive for a broader movement in public health that is only just beginning to take shape. In response to evolving scientific understanding about the determinants of health, public health advocates are rapidly implementing new law and policy tools to alter our environments and behaviors in ways that improve health at the population level. Critics of this “new public health” movement seek to safeguard individual liberty by disconnecting the law and politics of public health from its science. They argue that modern health threats such as heart disease and diabetes are individual concerns not sufficiently public in nature to trigger doctrines that privilege state intervention over individual rights. Public health scholars engaged in this theoretical debate have overlooked a related doctrinal debate within public nuisance law in which courts have struggled to define the scope of “public rights,” including the right to non-interference with public health. In both debates, critics have rightly insisted that the public must be more than the mere aggregation of private interests. But the narrower conceptions of the public that critics have put forth fail to account for the full scope of the state’s authority and responsibility for public health. This Article stakes out a middle position by adopting the classically liberal view of public health law critics—that state interference with individual liberty requires robust justification—while also defining the public broadly so as to justify considerable state intervention under the banner of public health. Drawing on analysis of public nuisance litigation as a public health tool, I propose that epidemiological harms—which I define as those for which causation can be established at the population level, but not necessarily at the individual level—should be understood as public bads. This conception of the public provides a more robust justification for the new public health law movement that more firmly grounds it in the science of social epidemiology.