Over six decades, Mr. Lazarus helped Native American tribes across the country develop their democratic institutions, reclaim lands and exercise their sovereign powers. Arthur Lazarus Jr. was born on Aug. 30, 1926, in Brooklyn, to Arthur and Frieda (Langer) Lazarus. His father was a business consultant and one of the country’s first efficiency experts. His mother was an antiwar activist and advocate for conscientious objectors during World War II. Arthur grew up in Brooklyn, where he attended Poly Prep Country Day School. He went on to Columbia University, where he edited the student newspaper, The Columbia Spectator, and roomed with Allen Ginsberg, the future beat poet. He graduated in 1946 at age 19, having started college at 16 during World War II, when Columbia ran an accelerated program for undergraduates. He went to Yale Law School and graduated in 1949. He then joined what is now the Washington office of the law firm of Fried, Frank, Harris, Shriver & Jacobson, where he developed his interest in Indian law. He married Gertrude Chiger in 1956. She died in 2013. In addition to their son Edward, Mr. Lazarus is survived by another son, Andrew; a daughter, Diana; a sister, Margy Meyerson; and seven grandchildren.