We examine the implications of the public trust doctrine in natural resource protection and conservation. A model of litigation and settlement among disputing parties suggests that the public trust doctrine introduces more costs and is more time consuming than would be the case with alternative approaches, such as the purchase of private rights through market transactions or application of eminent domain powers to reallocate the resource. Because the doctrine allows for uncompensated redistribution, it is resisted by current resource owners. Furthermore, by providing open standing to members of the public in challenging existing uses, public trust disputes encourage excessive demands, increasing the incidence of trial over settlement. This outcome is exacerbated if the plaintiffs derive utility from the ‘cause’ and provide litigation services at below-market rates, leading to greater investment in litigation. The costs of the public trust doctrine appear to have limited its application beyond the level anticipated by proponents. We present a case study of Mono Lake, part of the well-known 1983 litigation, National Audubon v. Superior Court to illustrate our arguments.