BERKELEY-- Stefan Riesenfeld, an internationally known expert in numerous legal fields and professor emeritus of law at the University of California, Berkeley, died Feb. 17. He was 90 years old. He died of heart failure at Alta Bates Hospital in Berkeley following a heart infection.

Riesenfeld was a recognized authority in countless fields of law including international law, comparative law, property law, creditors' remedies and bankruptcy, administrative law and legal history. During a career that spanned more than 60 years, Riesenfeld wrote or edited 32 books, 140 articles and 119 book reviews. He was also active in diplomatic relations for the United States government, serving as an academic legal advisor in the Panama Canal treaty negotiations, the recognition of Taiwan and the Iran hostage case. While in his 70s, he served two terms as Counselor on International Law in the U.S. State Department and represented the nation in three major cases before the International Court of Justice.

In 1946, he was called to Germany to serve as a civilian legal advisor with the U.S. Office of the High Commissioner. In that position, he worked on the preparation of the West German constitution, called the Basic Law of the Federal Republic of Germany. During his long career, he also wrote the statute for Hawaii's workers' compensation regulations and was actively involved in the development of human rights litigation in the United States.

"He was a very patriotic U.S. citizen," said Richard Buxbaum, a professor at UC Berkeley's School of Law (Boalt Hall) and Riesenfeld's long-time colleague. "He was thankful for his admission to the U.S. and proud of being able to serve this country."

Born in Breslau, Germany, Riesenfeld came to Berkeley in 1935 from the University of Milan, in Italy, to earn his law degree and to work as a research associate. He had moved to Italy in 1932 to escape the political climate in his native Germany. In 1940, he became a U.S. citizen.

When he arrived at UC Berkeley, Riesenfeld had two European law degrees and spoke three languages - French, German and Italian. Despite only learning English during his Berkeley law school years, Riesenfeld graduated from Boalt Hall right on time and near the top of his class.

Since 1935, Riesenfeld had spent only 14 years away from UC Berkeley - 11 of them teaching and studying at Harvard University and the University of Minnesota and three serving in the U.S. Navy during World War II. The work he did while teaching at Harvard earned him yet another law degree and, while teaching at the University of Minnesota, he found time to meet his wife and earn an undergraduate degree in electrical engineering.

Riesenfeld joined the UC Berkeley faculty in 1952. Although he officially retired in 1976, Riesenfeld continued to teach at Boalt Hall through December 1998. Despite his illness, Riesenfeld - one day before he died - finished grading blue books for a course on bankruptcy law he taught last semester.

"He was probably one of the best known of our faculty," said Boalt Hall Dean Herma Hill Kay. "To many people, especially in Europe, he personified the law school."

In the classroom, Riesenfeld never tolerated poor preparation on the part of students. He gave all of his lectures without using notes and expected his students to be ready to listen. He was famous for blurting out things like, "You have mashed potatoes for brains," or "I can explain it to you, but I can't understand it for you." This harsh but humorous style, along with the astounding amount of content he packed into each class session, attracted hundreds of students to his lectures each semester for 46 years.

"Because of his distinctive European accent and his genius, Riesenfeld was someone who made a very special impression on his students," said Kay.

"I have never known a teacher who, like Steve Riesenfeld, could be as tough a classroom instructor as any 'Paper Chase' caricature and yet, not only afterwards, but in the same setting, retain the affection and admiration of the students he was challenging," said Buxbaum. "Riesenfeld stories not only are the spark of most reunions; they are the glue that bonds 70-year-olds and 25-year-olds together."

He is survived by his wife, Phyllis Thorgrimson Riesenfeld, of Berkeley; two sons, Peter Riesenfeld of Rhode Island and Stefan Riesenfeld of London; and two grandsons.

A memorial service will be held at the Faculty Club on the Berkeley Campus on Wednesday, March 17 at 4PM.