Originally published in the Encyclopedia Judaica, vol. 7 (1972), p. 1167.
HALAKHAH LE-MOSHE MI-SINAI (Heb. הֲלָכָה לְמשֶׁה מִסִּינַי; “a law given to Moses at Sinai”). As part of the Oral Law, a number of laws, possessing biblical authority but neither stated in Scripture nor derived by hermeneutical principles, are stated in rabbinic literature to be “laws given to Moses at Sinai.” The term occurs only three times in the Mishnah (Pe’ah 2: 6; Eduy. 8: 7; Yad. 4: 3) but is found frequently together with terms of similar import, in the other sources of rabbinic Judaism, particularly in the Talmud (such as—“there is a received halakhah”; “there is a received tradition”; or simply “received”). Similarly, according to the Jerusalem Talmud (Shab. 1: 4, 3b) the expression “in truth they said” also belongs to this category (however, see BM 60a and Rashi s.v. be-emet).
Among the laws said to have been given to Moses at Sinai are: the 18 defects which render an animal terefah (Hul. 42a); the duty of walking round the altar with willows and the feast of water drawing, both on the festival of Tabernacles (Suk. 34a); the underside and duct of the tefillin, the parchment of the tefillin, that the straps of the tefillin be black and the tefillin themselves square (Men. 35a), and that they should have a knot (Er. 97a); the minimum quantities of forbidden foods to constitute an offense and the rules regarding interpositions on the body which invalidate a ritual immersion (Er. 4a); that only half the damage is to be paid when damage is done by pebbles flying from under an animal’s feet (BK 3 b); and that doubtful cases of levitical defilement, if occurring in the public domain, are to be treated as pure (Hul. 9b). It will be seen that all these refer to long-established rules which could not have been known without a tradition to that effect. The medieval commentators point out that on occasion the term, halakhah le-Moshe mi-Sinai, is used of much later enactments and is not always to be taken literally, but refers to a halakhah which is so certain and beyond doubt that it is as though it were a halakhah given to Moses at Sinai (Asher ben Jehiel Hilkhot Mikva’ot, 1 (at the end of his Piskei ha-Rosh to Niddah) and his Commentary to Mishnah, Yad. 4: 3). In most cases, however, they explain it literally, i.e., that these halakhot were transmitted by God to Moses at Sinai Modern scholarship is skeptical on the whole question but it is clear that the rabbis themselves did believe in the existence of laws transmitted verbally to Moses.
Bibliography: Weiss, Dor, 1 (1904), index; W. Bacher, in: Studies in Jewish Literature. . . K. Kohler (1913), 56-70 (Ger.); H. Tchernowitz, Toledot ha-Halakhah, 1 (1934), 29-36; L. Strack, Introduction to the Talmud (1945), 9; J. Levinger, Darkhei ha-Mahashavah ha-Hilkhatit shel ha-Rambam (1965), 50-65 [L.J.]