Derrick Bell, a legal scholar who saw persistent racism in America and sought to expose it through books, articles and provocative career moves — he gave up a Harvard Law School professorship to protest the school’s hiring practices — died on Wednesday in Manhattan. He was 80 and lived on the Upper West Side.

The cause was carcinoid cancer, his wife, Janet Dewart Bell, said.

Mr. Bell was the first tenured black professor at Harvard Law School and later one of the first black deans of a law school that was not historically black. But he was perhaps better known for resigning from prestigious jobs than for accepting them.

While he was working at the Civil Rights Division of the Justice Department in his 20s, his superiors told him to give up his membership in the N.A.A.C.P., believing it posed a conflict of interest. Instead he quit the department, ignoring the advice of friends to try to change it from within.

Thirty years later, when he left Harvard Law School, he rejected similar advice. At the time, he said, his first wife, Jewel Hairston Bell, had asked him, “Why does it always have to be you?” The question trailed him afterward, he wrote in a 2002 memoir, “Ethical Ambition,” as did another posed by unsympathetic colleagues: “Who do you think you are?”