This dissertation investigates the dynamics of law and legal change in the twelfth-century Norman Kingdom of Sicily; specifically, how ambitious local experts dislodged traditional legal regimes, consolidated power in judicial institutions, and centralized control of documentary culture. The first part of the dissertation traces how changes in the diplomatic, content, and personnel of local legal documents from the area around Salerno reveal larger-scale processes of legal consolidation by experts intent on perpetuating and expanding their authority. The main source base is a large corpus of unpublished archival documents from in and around the city of Salerno stored in the monastic archive of Cava. In light of these conclusions, the second part of the dissertation reevaluates the nature of royal power at the local level through an analysis of a diverse set of sources, including royal legislative texts, literary sources, and both published and unpublished documents related to the area around Salerno. Beginning the analysis from local documents eschews traditional narratives of legal change in the twelfth-century Norman Kingdom that prioritize royal legislation and legal administration. When viewed from the local perspective, royal power appears much more limited and dependent on local legal cultures that developed without significant influence from royal law.