||Novellae and expositions on Hilkhot Pesah of the Shulhan Arukh, subsequently included in the large edition of the Shulhan Arukh.
R. Jacob b. Joseph Reischer (also known as Jacob Backofen; c. 1670–1733), was born in Prague, R. Reischer studied under R. Aaron Simeon Spira, rabbi of Prague, and was known as a prodigy in his early youth. Afterward he studied under R. Spira's son, R. Benjamin Wolf Spira, av bet din of the Prague community and rabbi of Bohemia, whose son-in-law he subsequently became. His brothers-in-law were R. Elijah Spira and R. David Oppenheim. R. Reischer's surname, borne by his grandfather and uncles (see introduction to his Minhat Ya'akov), derives from the fact that his family came from Rzeszow, Poland, and not, as has been erroneously stated, because he served as rabbi of that town.
While still young, he became dayyan of the "great bet din of Prague." He was appointed av bet din of Ansbach, capital of Bavaria, and head of its yeshivah in 1709, and in 1715 av bet din of Worms. There, students flocked to him from all parts of Europe. He had, however, opponents who persecuted him. About 1718, he was appointed av bet din and head of the yeshivah of the important community of Metz. There, too, he did not find peace. He related that in 1728 "malicious men, as hard as iron, who hated me without cause, set upon me with intent to destroy me by a false libel, to have me imprisoned." His first work, Minhat Ya'akov, was published, while he was still young, in Prague in 1689. In the course of time he was accepted by contemporary rabbis as a final authority (Shevut Ya'akov, vol. 1, no. 28; vol. 3, no. 61), and problems were addressed to him from the whole Diaspora, e.g., Italy, and also from Erez Israel (ibid., vol. 1, nos. 93 and 99). He made a point of defending the rishonim from the criticism of later writers, and endeavored to justify the Shulhan Arukh against its critics. But there were also those, particularly among the Sephardi rabbis of Jerusalem, who openly censured his habit of criticizing rishonim and aharonim (ibid., vol. 1, no. 22), and criticized him in their works. His replies to these criticisms were not always couched in moderate language. The main target of his criticism was R. Joseph b. David of Breslau, author of Hok Yosef (Amsterdam, 1730).
R. Reischer was also the author of the following works: Minhat Ya'akov (Prague, 1689) - part 1 is an exposition of the Torat ha-Hattat of R. Moses Isserles, and part 2, entitled Torat ha-Shelamim, is an exposition of Hilkhot Niddah of the Shulhan Arukh together with expositions and supplements to the Kunteres ha-Sefekot of R. Shabbetai b. Meir ha-Kohen and responsa; a second edition, entitled Solet le-Minhah ve-Shemen le-Minhah (Dessau, 1696), contained the glosses of his son, R. Simeon; Shevut Ya'akov, responsa in three parts - part 1 (Halle, 1710) also contains "Pe'er Ya'akov," the residue of his novellae on the Talmud which were destroyed by fire in 1689, part 2 (Offenbach, 1711) contains a revised edition of the laws of migo and sefek sefeka ("double doubt"), which had been published separately in Prague in 1689, and part 3 (Metz, 1789) contains his "Lo Hibbit Aven be-Ya'akov," a reply to the attacks on his first works; Iyyun Ya'akov (Wilhelmsdorf, 1729) is a commentary on the aggadot in Ein Ya'akov of R. Jacob ibn Habib, and on Avot.