Rabbi Moshe Tendler, a singular authority on medical ethics in the Jewish world, died Sept. 28 at a hospital in Rochelle Park, NJ. He was 95.

Rabbi Tendler was both a master of the Torah and a trained microbiologist. In articles, three books, speeches, and frequent legislative testimony, Rabbi Tendler made influential statements on a number of controversial issues — the clinical definition of death, organ transplantation, permissible circumcision techniques, stem cell research and more — that shaped how the larger Jewish community addressed these questions.

Rabbi Tendler’s more than 80-year association with Yeshiva University began when he entered its Talmudical Academy, a high school. He later took up rabbinical studies at the university’s Rabbi Isaac Elchanan Theological Seminary. Drawn to biology from childhood, Rabbi Tendler, while studying at Yeshiva, simultaneously took evening courses at New York University. There he received a bachelor’s degree in biology and then a master’s degree before eventually earning a doctorate at Columbia.

Yeshiva hired him as a biology instructor in 1952, and within a few years, he was appointed assistant dean in charge of student affairs. He was later named a rosh yeshiva at the seminary, a title given to the school’s leading teachers and one he held at his death. He lectured from his hospital bed by Zoom until five months ago, his son Mordecai said.