In this study, Kevin Mattison examines Deuteronomy's reworking of existing legal texts, arguing that Deuteronomy was designed to amend its main legal source, the Covenant Code (Exod 20:22-23:19). The model of amendment draws on existing models of replacement and supplementation in order to provide a more complete explanation of Deuteronomy's rewriting of the Covenant Code, which is characterized by a combination of presupposition, complementation, and contradiction. Internal revisions within the growing text of Deuteronomy exhibit a similar combination of these three factors. Deuteronomy's authors sought to amend the Covenant Code even as they continued to amend their own growing text. The author draws examples from laws governing sacrifice and slaughter (Deut 12:1-28), tithes and firstlings (Deut 14:22-29; 15:19-23; 26:12-15), and manslaughter and asylum (Deut 19:1-13).