Conceptual decline has been one of the least examined forms of conceptual change. This essay explores some of the methodological and interpretive problems that have arisen through a study of the declining use of the concept of legal personhood in Anglo-American juridical discourse over the first half of the twentieth century. Such effort will generate a number of significant methodological questions: 1) How does identifying conceptual decline challenge an author-centered approach to a history of conceptual change? 2) How might the decline of a concept in one discourse affect the ways in which the term operates in other discourses; and how does the study of concepts operating across multiple discourses complicate the dichotomy between basic and technical concepts? 3) How might a once active, but now silent, concept continue to impact political discourse? Do lost concepts have an "afterlife"? The study of conceptual decline benefits from an interaction between Begriffsgeschichte and Cambridge School methods of studying conceptual change, while at the same time questioning some of the foundational assumptions of each approach.