This chapter sketches the philological and codicological work on Gratian’s Decretum and how that work is being employed in new ways. It begins by briefly touching on the collection’s wider dissemination as a way of placing it within an overall context of the Corpus iuris canonici. It then sketches the contributions of Stephan Kuttner and Peter Landau followed by the Redaktionsgeschichte of the text. The role the Decretum played in the transmission and fluidity of legal knowledge is analyzed through the lens of two case studies: Gratian’s balancing of the spiritual and secular roles of the feudal bishop, first, and, second, a unique case found only in one manuscript.