In Christine Elizabeth Hayes’ book Introduction to the Bible, in the chapter about Deuteronomy, she points out instances where the writer revises the laws given in Exodus and Leviticus likely to fit his beliefs and the circumstances of his time. That is clearly evident in the revisions to how slaves and sacrifices are to be handled. The following paragraphs were extracted from her book per the citation that follows them.
Weinfeld (“Deuteronomy,” 177) notes that when Deuteronomy contains laws found also in P, it sometimes presents them in a more rational or desacralized manner—thus D’s treatment of sacrifice differs from that of P, as will be shown below. Rather than assuming a direct literary relationship between the two, scholars tend to view large sections of P and D as representing different and roughly contemporaneous streams of ancient Israelite tradition—each containing preexilic and exilic layers.
In short, close textual analysis and comparison leads Weinfeld and many others to conclude that the editors of Deuteronomy updated and revised earlier laws, particularly as reflected in the Covenant Code, in keeping with the circumstances of the eighth through sixth centuries. Deuteronomy thus exemplifies a phenomenon that occurs at several critical junctures in Israel’s history—the modification and rewriting of earlier laws and traditions in light of new circumstances and ideas. As such, Deuteronomy is itself an implicit authorization of the process of interpretation. To the extent, then, that we think of the biblical corpus as a canon, it is a canon that allows for the continued unfolding or development of the sacred tradition. The idea of an evolving or flexible canon may seem at odds with modern intuitions about the nature of sacred canons—which are generally thought to be fixed, static, and authoritative precisely because unchanging. But such a view does not capture the reality of the biblical corpus. In Israelite culture, texts representing sacred revelation were modified, revised, updated, and interpreted in the process of transmission and preservation. Indeed, it was precisely because a text or tradition was sacred and authoritative that it was important that it adapt and speak to new circumstances.
Elizabeth Hayes, Christine. Introduction to the Bible (The Open Yale Courses Series) (pp. 176-177). Yale University Press. Kindle Edition.