Zafren was employed with the American Law Division, Congressional Research Service, at the Library of Congress, from 1967 to 1994, rising to the position of Specialist in American Public Law. He then became the Director of Legal Research at the Law Library of Congress until his retirement in 1998. He received a B.A. from Queens College; a J.D. from New York Law School; and a LL.M. from the George Washington University.