Saul B. Horwatt, 79, a retired area electrical contractor who had been active in cultural, civic, and Jewish groups and who during the mid-1950s had been the defendant in noted cases involving the rights of former radicals, died of cancer June 14 at Arlington Hospital. He lived in McLean.

Mr. Horwatt, a native of Lithuania, came to this country in 1924. He was a graduate of the Jewish Theological Seminary in New York, and over the years had been a master electrician, labor organizer and trade journal editor. He had owned and operated the Metropolitan Electric Co. here for 33 years before retiring in 1983. He also had served on the board of the Washington Hebrew Congregation and had taught Yiddish at George Washington University.

In 1954, federal authorities attemped to revoke Mr. Horwatt's citizenship and deport him because he had once belonged to the Communist Party, an organization that advocated the overthrow of the United States government. These charges were brought during the years often identified with "McCarthyism," when any left-leaning departure from the political norm was investigated and individual rights were sometimes ignored in efforts to root out what some believed was the danger of a domestic communist threat to this country.

Mr. Horwatt spoke freely of his long-past association with the Communist Party, explaining that he joined the party in 1928 because of its support for Sacco and Vanzetti. The controversial execution of those two immigrant anarchists for murder and armed robbery drew world-wide protests because of what many believe to this day was a miscarriage of justice.

Mr. Horwatt said he had belonged to the Communist Party from 1928 to 1929 and again from 1933 to 1938. During those years, years of massive worldwide economic hardship, Communist and other radical parties rapidly gained adherents. Communist parties in Europe and America were advocating economic relief and racial equality, and not emphasizing violence.

Mr. Horwatt told a reporter in 1956, "The Communists are very clever at putting forth issues to attract people. Many people who join do so because they are interested in one particular issue . . . they don't think about the overall scheme."

In 1956, the federal goverenment abandoned its prosecution of Mr. Horwatt after U.S. District Judge Albert V. Bryan Sr. ruled in Mr. Horwatt's favor in federal court in Alexandria. The judge said that while Mr. Horwatt had been a Communist many years ago, "the court is not persuaded that Mr. Horwatt ever compassed or imagined the overthrow of the United States of America."

Judge Bryan went on to say that the court's conclusions were strengthened by the defendant's conduct as a citizen over the preceeding 16 years.

After the verdict, Mr. Horwatt told reporters that "I never lost faith in America. This whole thing, the way my friends have acted, my treatment at the trial, the outcome, has been a beautiful exhibition of how democracy works."

Before moving to the Washington area in 1941, Mr. Horwatt had lived in New York and Connecticut where he helped organize a local of the International Brotherhood of Electrical Workers. After moving here, he ran a business and devoted time to religious, cultural and civic affairs. He had been a technical adviser to Arena Stage.

In 1968 he did volunteer work for the Poor Peoples Campaign in Washington. He also helped organize minority apprentice programs in the International Brotherhood of Electrical Workers.

He had taught Jewish culture and Yiddish language courses at George Washington University, the Jewish Community Center of Greater Washington and the Northern Virginia Jewish Community Center. He had translated Yiddish literary works and had attended Yiddish cultural conferences in Israel.

Mr. Horwatt was a member of the Fairfax Electrical Board, the McLean Lions Club, the Washington Board of Jewish Education, and the Franklin Forest Neighborhood Watch Program in McLean. He was a founder and past editor of "Master Electrician," a trade journal.

Survivors include his wife, Lillian S., of McLean; two sons, Michael S., of Reston, and David A., of Los Angeles; a sister, Dora Pisetsky of Hartford, Conn., and four grandchildren.