This chapter discusses the landmark Mono Lake litigation that finally reached the California Supreme Court, National Audubon Society vs. Superior Court – the case that turned the tide for the survival of Mono Lake, through public trust reasoning that would go on to foment a quiet revolution in environmental law. The chapter reviews the basic elements of the litigation, introducing the parties, their commanding legal avatars, and their overall positions before unpacking the specific arguments that made it to court. Then it highlights the most important doctrinal features of the landmark decision, including its affirmation that environmental values are protected by the public trust doctrine, its application of the doctrine to the upper reaches of the watershed, its assertion that public trust obligations extend over time, and its understanding of the legal nature of the doctrine itself. In casting the doctrine as a nonwaivable obligation to protect environmental values for future generations – a quasi-constitutional constraint on sovereign authority – the decision set the stage for its recognition as a tool of environmental law, and perhaps even a framework for environmental rights.