Frank E.A. Sander, a longtime Harvard Law School professor known as a mentor to many and a pioneer in the field of alternative dispute resolution, died Feb. 25. He was 90 years old and lived in Cambridge, Massachusetts.

Sander served on the Harvard faculty from 1959 to 2006, authored numerous books on ADR, taught the topic at Harvard and had a profound impact on those who knew him, worked with him and learned from him.

“He was simply known as the 'Godfather of ADR' in the United States,” said friend Harry Mazadoorian of Kensington, Connecticut, a fellow ADR expert.

Mazadoorian was a student in a mediation course taught by Sander at Harvard in 1993, and recalled the scholar knew ADR inside and out and took many attorneys under his wing. “You always learned something from Frank. He seemed to know everybody involved in ADR,” he recalled.

Mazadoorian served on the editorial board of the Dispute Resolution Magazine for more than a decade while Sander was editor and remembered him as the captain of a tight ship. “He was a strict task master, and you went to that editorial board meeting well-prepared,” Mazadoorian said. “Frank would ask a lot of questions, and one of his favorite questions was, 'What is new in this? Has this been said before?'”

Chuck Doran, executive director of Boston-based Mediation Works Inc., said Sander will be remembered most for the “multidoor courthouse” approach, which he proposed during a conference in 1976. The idea developed into a collaborative process of assigning the most appropriate ADR methods to incoming cases and eventually caught the eye of federal Judge Griffin Bell, who later became President Jimmy Carter's attorney general. Under Bell's leadership, multidoor courthouses were established in cities around the world.

“Frank had this vision of the multidoor courthouse idea and he saw it come to fruition,” said Doran, who echoed Mazadoorian's comments about Sander's willingness to help other attorneys. “Given his credentials and influence, you would think he'd be inaccessible,” Doran said, “but the opposite was true. He answered his own phone and he always made himself available to me when I needed to talk to him.”

“Frank played a pre-eminent role in shaping that [ADR] important discipline, which has transformed our legal system,” said Harvard Law School Dean John Manning in a press release. “He was a beloved teacher and mentor to our students, a wise and selfless administrator at our school, and a cherished colleague and friend to faculty and staff.”

Born in Stuttgart, Germany, in 1927, Sander escaped Nazi Germany at age 11, coming to Boston via New York on one of the last passenger ships to leave England during World War II. He earned his law degree from Harvard in 1952, graduating magna cum laude and serving as treasurer of the Harvard Law Review. After law school he clerked for Chief Justice Calvert Magruder of the U.S. Court of Appeals for the First Circuit, and then for U.S. Supreme Court Justice Felix Frankfurter.

In 1966, he helped launch a Rockefeller Foundation-funded program that brought 40 African-American college juniors to Harvard Law School for the summer to excite them about legal careers. The program became a model for the Council on Legal Educational Opportunity, which has helped 10,000 lawyers of color graduate from American law schools.

Sander is survived by daughter Alison of Cambridge, Massachusetts; two sons, Tom of Lincoln, Massachusetts, and Ernest of New York City; and four grandchildren.