This dissertation takes as its point of departure two fundamental insights about the scriptural text and Judaism in the late Second Temple period that have been proven beyond doubt by the scrolls discovered in the Judaean Desert. First, it is evident that an exegetical process was operative in the scribal transmission of the biblical text in varying degrees and to various ends. Second, legal matters were clearly among the foremost questions occupying exegetes at this time. To what extent, then, has reflection on legal exegetical issues found articulation in extant textual variants from the Second Temple period? When, where, how, why, and to what extent did Jewish scribes deliberately alter the scriptural text for legal-exegetical purposes? What 'rules' applied, and were they the same as governed non-legal material? What were the underlying exegetical (or theological, or sociological) motives, rationales, and justifications for this scribal behavior? A synoptic picture of all extant, deliberate, legal variants is an essential prerequisite for answering these questions in a precise, empirically sound way. The present dissertation offers a specific contribution toward these larger ends by collecting and analyzing all examples of a single type of variant--namely, major textual pluses--preserved in extant witnesses to pentateuchal legal texts from the period. Three types of expansions are studied: (1) cases in which 'new' material is inserted into the biblical text, (2) cases of exegetical pastiche (a combination of locutions borrowed from elsewhere in biblical law), and (3) cases of 'simple transfer,' in which the wording of a parallel verse is imported unchanged for interpretive purposes. These expansions function primarily to solve exegetical problems, to clarify or specify scriptural wording, and to articulate scriptural implicature. They are therefore important for understanding the role of scripture and the development of canon in the period. The analysis of these cases offers important data for better understanding the pluriformity of the pentateuchal text in the period, for assessing the character and scope of scribal exegesis in the transmission of biblical law, and for charting the unclear literary boundaries between scriptural transmission and exegetical rewriting in the period.