Eli Katz, a Yiddish scholar who as a young UC Berkeley professor in the '60s resisted a McCarthyite loyalty test and won a victory for academic freedom, died at Alta Bates Medical Center in Berkeley on July 22 of complications from his third stroke. He was three weeks from his 78th birthday.

The U.S. government's fear of subversion and hunt for Communist Party infiltrators in the '50s victimized hundreds of intellectuals, and Professor Katz was summoned to testify before the House Un-American Activities Committee.

Professor Katz, the son of Jewish immigrant union activists in New York, had participated in a student strike as an undergraduate at City College of New York in 1949 and all his life held strong views against racism, imperialism and colonialism.

He refused to answer any questions about his political beliefs and associations.

In the '50s, Professor Katz had moved to the West Coast and enrolled at UCLA to pursue doctoral studies in Yiddish. Yiddish, a German dialect, was the language spoken by his Eastern European-born parents, and it was in danger of dying as a result of the Nazis' genocide of European Jews during World War II.

Professor Katz earned a doctorate with a focus on medieval Yiddish and in 1963 was appointed an assistant professor in the German department at UC Berkeley. McCarthyism was fading but apparently not dead: Professor Katz swiftly faced another loyalty quiz, this time by Berkeley's chancellor.

Again, he refused to discuss his political beliefs and associations.

"Eli told me he had refused to answer those questions when asked by HUAC," recalled a close friend, Sonoma State economics Professor Victor Garlin, "and that he would continue to refuse to answer those questions because they were irrelevant to his qualifications as a professor."

As a result, he was let go at the end of the academic year.

Professor Katz took his case to the Academic Senate Committee on Privilege and Tenure. The committee decided the chancellor had been wrong and persuaded the university, which was under pressure from the burgeoning Free Speech Movement on campus, to reinstate Professor Katz.

He got his job back in 1966 and served as an assistant professor until 1970. He then moved to Sonoma State, where he was a faculty member until retiring as a full professor in 1992.

His stand re-established the principle of academic integrity for the UC Berkeley faculty. It also gave him the freedom to fulfill his vocation as a Yiddish scholar.

He produced more than 20 publications, and became a widely respected scholar, translator and teacher until a stroke severely impaired his ability to speak in the last year of his life.

"Mr. Katz had a distinguished career because he successfully confronted the effort to dismiss him from academic life," Garlin wrote in an e-mail.

Professor Katz's best-known books are a scholarly edition of "The Book of Fables, the Yiddish Fable Collection of Reb Moshe Wallich" and a translation of stories by I.L. Peretz, a Yiddish writer of the late 19th and early 20th centuries.

Professor Katz taught a popular Yiddish class at UC Berkeley Extension and led a Yiddish-language reading group under the auspices of Lehrhaus Judaica in Berkeley.

"Eli was a very important figure in the world of Yiddish," said Barbara Epstein, a UC Santa Cruz professor. "He was considered nationally and internationally an expert on Yiddish linguistics and very important teacher of Yiddish. Eli was one of a small number of people trying to keep Yiddish alive."

Professor Katz is survived by his wife, Dr. Helena Leiner of Berkeley; his children, Jeremy of Oakland; Mia of Bremen, Germany; Daniel of Paris; and Paola of Berkeley; his stepson, Lawrence Brickman of Brooklyn, N.Y.; granddaughters Hilary and Julia of Oakland, and Lisa, Daphne and Esther of Paris; and his sister and brother-in-law, Rosalind and Fred Scheiner of Roslyn Heights, N.Y.

There will be a private burial at Mountain View Cemetery in Oakland. Plans for a memorial service are pending.