R. Judah b. Asher (1270–1349), was born in Cologne, Germany. His father was R. Asher b. Jehiel (the Rosh), in whose yeshivah he studied; R. Jacob b. Asher was his brother. Because of his impaired eyesight, from which he suffered all his life, he did not succeed in compiling large works. In consequence of the violent anti-Jewish outbreaks of 1283 in Germany, R. Judah left his father's house and made his way to Spain, reaching Toledo in 1285 (this according to Schechter, but according to Abrahams, in 1305). When his parents reached Spain R. Judah renewed his studies under his father. In 1314 he signed a takkanah of his father, continuing a family tradition of tithing one's income for charity, a custom that his children also undertook to observe. He married first the daughter of his elder brother, R. Jehiel, and after her death, Miriam, the daughter of his second brother, R. Solomon.
In 1321 R. Judah was appointed his father's successor by the Toledo community, and on the latter's death in 1327 he immediately inherited his position as head of the bet din and of the Toledo yeshivah, serving until his death. He conducted his rabbinical office justly and impartially and was considered authoritative in his rulings. The Castilian government took account of his judgment even in non-Jewish cases. Taking into consideration the interests of the Jewish communities in Castile, he maintained that in principle the death sentence could be imposed but demanded restraint from the rabbis in imposing punishments and took care to preserve the legal autonomy of Jewish communities. From his responsa he appears to have tended toward stringency. The leaders of the Toledo community attempted to compel his bet din to give halakhic rulings only in conformity with the rulings of Maimonides, and to depart from them only where his father R. Asher had ruled accordingly in order to avoid differences of practice; R. Judah vehemently opposed them and threatened to resign his post, though he finally agreed to remain. Among his pupils were R. Menahem b. Aaron ibn Zerah, author of the Zeidah la-Derekh, and R. Machir, author of the Avkat Rokhel.
Among his' works may be mentioned Iggeret Tokhehah (ed. by Schechter, see bibl.) his testament to his children, which contains ethical sayings, an account of his family history, and instruction in the method of learning; apart from its ethical value it also has great historical importance, as it gives details of the social life of the Jews in the 14th century and the mutual relationship between the rabbi and the community in Spain. Also ascribed to him are "a confession" included in the Zeidah la-Derekh (4:5, chap. 17) and a commentary to tractate Shabbat, the last part of which is included at the end of his volume of responsa, and the Hukkat ha-Torah, consisting of an anthology of halakhot. The collection Ta'am Zekenim (ed. by A. Ashkenazi (1854) 64b–66a) contains a responsum by R. Judah "on the subject of metempsychosis and the reply of R. Asher b. Jehiel." Two piyyutim in his name have been preserved.
הסכמות: ר' יעקב יוסף ב"ר מרדכי עטטינגער, י אלול תר"ה;
ר' אלחנן ב"ר זנוויל ראזענשטיין, ברלין, יב אלול תר"ה;
ר' יעקב קאפיל ב"ב [באמברגר] הלוי, ווארמס, ח שבט תר"ו;
ר' יחיאל מיכל זקש, ברלין, כ אלול תר"ה;
ר' אהרן פולד, פראנקפורט דמיין, יט מרחשוון תר"ו;
Dr. Zunz, ברלין, 30 יוני 1846.