Of his life, few details are known, but, according to Grätz, he died before 1456. He was one of the foremost pupils of Jacob Moelin (Maharil), who ordained him in the rabbinate, and authorized him to officiate in Nuremberg. Weil, however, did not avail himself of this permission lest he should offend an older scholar, Solomon Cohen, who had been appointed rabbi of that city long before. This despite the fact that Weil himself ruled that a rabbi had no lifetime tenure (Responsa, No. 151). Indeed, this example illustrates two facets of Weil's personality - his deep humility and his deep-felt desire to avoid unnecessary confrontation and conflict. He generally signed his responsa "the little one, Jacob Weil".
Weil was later called to the rabbinate of Erfurt; and congregations far and near, recognizing him as an authority, addressed their problems to him. Among the rabbis who addressed questions to him are Rabbi Israel Isserlein (Maharya) and his student Rabbi Israel of Brno. Weil approved of the pilpulistic method only as an aid to study, but rendered legal decisions purely on the basis of logic (Responsa, No. 164).
Weil was especially severe on contemporary rabbis who regarded themselves as having peculiar privileges transcending the rights of the laity, declaring in a responsum (No. 163) that no rabbis of his time had any such prerogatives, and that, moreover, no man could be regarded as a scholar (Talmid Ḥakam) in the Talmudic sense. Despite his humility and his belief in the value of peace, when he felt that the need arose Weill did not spare his pen. After his father in law refused to repay the debt of a man who paid the ransom of his mother in law, Weill ruled that "since I am close to the case, it is my responsibility to take action and to nullify his evil decree (not to repay the debt) so that a mishap does not occur in Israel and the door is not closed on those who perform good deeds and the name of heaven is not desecrated ... and if he does not obey this strict ruling he is to be cursed and excommunicated and separated from all that is holy" (Resp. No. 148).
Of Weil's works only a collection of opinions and decisions, "She'elot u-Teshubot" (Venice, 1549), has been preserved. To this work was added an appendix entitled "Sheḥiṭot u-Bediḳot," containing regulations for slaughtering and for the examination of slaughtered cattle. These rules have been regarded as authoritative by later rabbis, have run through seventy-one editions, and have been the subjects of various commentaries and additions.
- Bernard Rosensweig Ashkenazic Jewry in Transition 1975, p. 11, "Chapter II – The Life of R. Jacob Weil. R. Jacob Weil was one of the leading authorities of his age"
- Steinschneider, Cat. Bodl. cols. 1258-1265;
- Benjacob, Oẓar ha-Sefarim, No. 99, p. 558; No. 385, p. 570;
- Fuenn, Keneset Yisrael;
- Michael, Or ha-Ḥayyim, No. 1061;
- Grätz, Gesch. viii. 309 et seq., 313 et seq.
- This article incorporates text from a publication now in the public domain: Singer, Isidore; et al., eds. (1901–1906). "Weil, Jacob". The Jewish Encyclopedia. New York: Funk & Wagnalls.