Halakhic Midrash

Midrash halakha (Hebrew: הֲלָכָה‎) was the ancient Judaic rabbinic method of Torah study that expounded upon the traditionally received 613 Mitzvot (commandments) by identifying their sources in the Tanakh (Hebrew Bible), and by interpreting these passages as proofs of the laws' authenticity. Midrash more generally also refers to the non-legal interpretation of the Tanakh (aggadic midrash). The term is applied also to the derivation of new laws, either by means of a correct interpretation of the obvious meaning of scriptural words themselves or by the application of certain hermeneutic rules.

The Midrashim are mostly derived from, and based upon, the teachings of the Tannaim.

The phrase "Midrash halakha" was employed by Nachman Krochmal (in his "Moreh Nebuke ha-Zeman," p. 163), the Talmudic expression being "Midrash Torah" = "investigation of the Torah". These interpretations were often regarded as corresponding to the real meaning of the Scriptural texts; thus it was held that a correct elucidation of the Torah carried with it the proof of the halakha and the reason for its existence.

In the Midrash halakha three divisions may be distinguished:

The early halakha sought only to define the compass and scope of individual laws, asking under what circumstances of practical life a given rule was to be applied and what would be its consequences. The earlier Midrash, therefore, aims at an exact definition of the laws contained in the Scriptures by an accurate interpretation of the text and a correct determination of the meaning of the various words. The form of exegesis adopted is frequently one of simple lexicography, and is remarkably brief.

...
Wikipedia