Obsolescence of environmental laws and regulations is unavoidable, and policies dealing with endangered species and ecosystem conservation often lag decades behind the relevant science. For example, endangered species laws and regulations and other conservation statutes typically fail to consider the interactions of strongly interacting species, probably because the importance of such interactions was not well understood when the laws were drafted. By failing to consider current knowledge, therefore, natural resource scientists and managers may be harming the species and systems they are charged with protecting. Most ecologists agree that the conservation of biodiversity is facilitated by maintaining population densities and distributions of strongly interactive species above estimable thresholds for ecological effectiveness. Assuming that conservation biologists and natural resource managers are “physicians to nature,” we therefore propose they are obligated to adhere to a doctrine of “best conservation practices based on the best science,” applying a more rigorous standard for the management of relatively interactive species than may be mandated by older statutes and effected by current practice and convention.