of Law at Oxford University, University College of London, McGill University, and University of Pennsylvania, and as a visiting professor at Harvard University School of Law and at New York University School of Law. In 1963, Elon was appointed head of the Institute for Research in Jewish Law at the Hebrew University, where he edited 10 volumes of The Annual of the Institute for Research in Jewish Law, as well as a digest of the response of the medieval authorities. From 1968 to 1971, he served as editor of the Division of Jewish Law of the Encyclopedia Judaica, and served as the editor of the Encyclopaedia Hebraica. He played a pivotal role in the Mishpat Ivri (Hebrew Law) movement. Among his many works, he authored the foundational Jewish Law : History, Sources, Principles - a monumental, three-volume book on Hebrew law for academic use and the training of Israeli law students. In 1955, he was appointed senior assistant to the Attorney General of Israel Haim Cohn, and from 1959 to 1966, Elon served as adviser on Jewish Law to the Israel Ministry of Justice, a job which included writing legal opinions based on Jewish law regarding every law proposed in Knesset. He was a member of numerous Israeli Public Inquiry committees, and he served on committees to prepare legal proposals in various fields of civil law. In 1979, Elon was awarded the Israel Prize for Hebrew law. Supreme Court of Israel In 1977, he was appointed to the Israeli Supreme Court. Elon's rulings often drew upon the principles of Jewish law; he sought to incorporate traditional Halakha into the corpus of Israeli civil law. Elon emerged as a prominent critic of former president of the Supreme Court Aharon Barak's judicial activism. Elon was involved in a number of important verdicts, including the acquittal of Nazi war criminal John Demjanjuk. Among Elon's prominent decisions were a ruling prohibiting registering the character of non-Orthodox conversions on Israeli identity cards, one ordering the return of a girl who had been transferred for adoption without her parents' consent, and the decision to order a local religious service committee to accept Leah Shakdiel as its first female member. In 1988, he ruled that active euthanasia ("mercy killing") was illegal, because it negated the values of the State of Israel as a Jewish state (Yael Shefer v. The State of Israel). In 1988, he was promoted