In 2017 a New York appellate court issued a landmark ruling rejecting an animal rights organization’s efforts to assign legal personhood status to chimpanzees in Matter of Nonhuman Rights Project, Inc. v. Lavery. This paper provides context for the ruling, and includes an amicus curiae brief the author filed in the case. The court discussed the amicus curiae brief in explaining its ruling, and a prominent animal law blog described the court’s decision as “citing to and relying on” the brief. The brief asserts and the court ruled that rights are broadly connected to humans’ norm of capacity for legal duties, and that because chimpanzees cannot bear legal duties they cannot be legal persons. Animal personhood litigation is in its infancy. The 2017 Lavery decision will be debated and cited for many years because the court directly embraced legal personhood’s foundational connection to the human community rather than dismissing the case on narrow grounds. This paper illuminates the reasoning behind the court’s decision and the argument that society should focus on evolving norms of human responsibility toward animals’ welfare rather than on the pretense of animal legal personhood.