Richard Gardner, who in the late 1970s served as the American ambassador to Italy in a period of political violence there and concern in Washington about the Italian Communist Party’s growing strength, died on Feb. 16 at his home in Manhattan. He was 91. His daughter, Nina Gardner, said the cause was congestive heart failure.

While his profile was probably highest when he was posted to Rome, Dr. Gardner was also an adviser to Democratic presidential candidates and a distinguished law professor at Columbia University. One candidate he advised was Jimmy Carter, who on becoming president in 1977 appointed Dr. Gardner to the Rome post.