Source: Michael Fishbane's Biblical Interpretation in Ancient Israel (New York: Oxford, 1988) 194.
Fishbane states the following about Numbers 15's interpretation of Leviticus 4:
"Clearly [in Numbers 15] YHWH is not the speaker, for he is referred to in the third person in the relative clauses of vv. 22b and 23b; nor is Moses the speaker, and for the same reason. The speaker is thus neither YHWH nor Moses but...a preacher of the law of YHWH as given to Moses. That this preacher did not simply preach the law of Lev. 4 is clear in the explanations which are added, the expansion of the law to include the stranger, and the addition of provisions dealing with intentional transgressions and an entire ideology pertaining thereto. But nowhere does the preacher adjust his legal traditio--revolutionary as it is--to a divine speaker's words or authority; and nowhere does he make use of the preaching authority of Moses, as does the deuteronomist repeatedly."
I think Fishbane is saying here that the author of Numbers 15:22-31 respects the divine authority of the traditum, Leviticus 4. Consequently, he does not try to rewrite it, but rather he presents himself as a human interpreter. This may be true, but Fishbane's acknowledgement that Deuteronomy takes another track shows that not everyone saw the traditum as totally authoritative. Deuteronomy may have been trying to replace what came before by offering a new Torah. What's that say about how he viewed the old Torah? Deuteronomy resembles the pseudepigraphical writings, which use older traditions while offering something novel. Scholars have contended that Jubilees, for instance, was intended to replace the Torah.
But the fact that not everyone views the traditum as authoritative does not mean that no one does. So Fishbane may be right to note that different interpreters interact with sources in different ways. Some try to interpret them, and some try to replace them.
Tomorrow, I may tackle child sacrifice.