William vanden Heuvel, a public-minded lawyer and former diplomat who was an adviser to Robert F. Kennedy and an advocate of improving conditions for inmates in New York City jails, died on Tuesday June 16 2021 at his home in Manhattan. He was 91. In the Justice Department, from 1962-1964, Mr. vanden Heuvel was active in the civil rights struggle that would define Robert Kennedy’s tenure as the nation’s highest-ranking law enforcement official. Mr. vanden Heuvel was also among the trusted advisers who helped Kennedy plan his presidential campaign in 1968. Mr. vanden Heuvel served as Deputy US Permanent Representative to the United Nations from 1979 until 1981 and as US Permanent Representative to the European Office of the UN from 1977 to 1979. Former Senior Partner, now Of Counsel to the law firm of Stroock & Stroock & Lavan, he is also Senior Advisor to Allen & Company LLC, a New York investment banking firm. After completing the two-year curriculum at Deep Springs College, a junior college in California, he transferred to Cornell and graduated in 1950. He went on to earn a law degree there and serve as editor in chief of Cornell Law Review. His marriage in 1958 to the writer Jean Stein, who died in 2017, ended in divorce in 1969. He married Melinda Fuller Pierce, who survives him, in 1979. In addition to her and his daughter Katrina, from his marriage to Ms. Stein, Mr. vanden Heuvel is survived by another daughter from that marriage, Wendy M. vanden Heuvel; his stepchildren Ashley von Perfall and John vanden Heuvel Pierce; two grandchildren; and five step-grandchildren.