Midrash and the Foundations of Jewish Law, Lawrence H. Schiffman, From Text to Tradition: A History of Second Temple & Rabbinic Judaism, Ktav Publishing House, Hoboken, NJ, 1991.

During the exile, a feeling of patriotism and the desire to preserve the Israelite literary
heritage in the wake of the destruction of the ancestral homeland were probably
responsible for a new emphasis on the study of Israel’s scriptures. When Ezra returned to
Judea, he devoted himself to making the Torah the center of the religious life of his
people. But the Torah had one deficiency as a legal text. There were apparent
contradictions and inconsistencies between the legal rulings in its various sections. Now
something new was called for. How were the contradictions between laws on the same
subject to be handled? How were the multiple presentations of the same material to be
understood?

The duplications in the Torah begged to be interpreted. Thus was born the method
which later Hebrew termed midrash. Essentially, the exegetical (interpretative) technique
of midrash can be defined as the explanation of one biblical passage in the light of
another. In its earliest forms midrash dealt with matters of Jewish law, what the rabbis
later called halakhah. In the early Second Temple period, the new dependence on the
written law stimulated the development of the method of legal midrash. Its earliest record
is in the booksof Ezra and Nehemiah.

An example of the use of this technique in our period is the decision attributed to Ezra
to expel foreign wives. Returning exiles had married non-Israelite women of “the people
of the land” and children had been born to them. Ezra 9-1 presents a list of the nations
with which Israel had intermarried. The list is itself evidence of a midrashic
interpretation. Included are some nations with which the Torah had prohibited marriage
unconditionally and other nations that could marry Israelites only after a specific number
of generations according to other biblical sources. The technique of analogical midrash
led to the conclusion, based on Deut. 7-3 and 23-8–9, that the nations were all to be
treated alike; marriage with any of them was to be eternally proscribed. The expulsion of
the foreign wives was based on this exegetical conclusion.

Another example relates to the proper observance of Sukkot (Tabernacles). Leviticus 23
commands the building of the sukkah, and dwelling in it during the seven-day festival.
There is no mention of pilgrimage to the sanctuary. Deuteronomy 16 does not mention
the obligation of dwelling in sukkot but describes the festival as a pilgrimage. Legal
midrash led to the decision that the entire people was to assemble in Jerusalem and build
sukkot there. Thus it was possible to fulfill the commands of both codes and in this way
resolve the inconsistency.

Other decisions based on this technique are recorded in the covenant of Nehemiah 10.
These show beyond any doubt that the use of the midrashic method for the determination
of Jewish law in cases where the Pentateuch was either unclear or apparently
contradictory became the norm in the Persian period. It remained in use for the derivation
of new conclusions until well into the Middle Ages, and at the same time, as we will see,
often served as a means of justifying legal rulings already practiced on the basis of
ancient tradition.

To avoid confusion one point should be made very clear- the term midrash designates
both an exegetical method and a collection of literary materials based on midrashic
exegesis. Later on we will have occasion to discuss various midrashim of the latter sort. It
would be incorrect to conclude from the early dating of the technique of legal midrash that the contents of the collections to be examined later are of similar antiquity.