Marking the fifteenth anniversary of Lucas v. South Carolina Coastal Council—the modern U.S. Supreme Court's seminal regulatory takings decision—this Article surveys Lucas's impact upon regulations that restrict wetland filling, sprawling development, and the emission of greenhouse gases. The Lucas Court set forth a new categorical rule of governmental liability for regulations that prohibit all economically beneficial use of land, but also established a new defense that draws upon the states' common law of nuisance and property. Unexpectedly, that defense has taken on a life of its own—forming what this Article calls the new nuisance doctrine. As this Article explains, nuisance is new in at least two important ways. First, it has taken on a new posture, evolving from defense, to offense, to catalyst, for legislative change. Second, nuisance has taken on new substance, triggered in part by Lucas's explicit recognition that "changed circumstances or new knowledge may make what was previously permissible no longer so."