Coleman was co-counsel to the petitioners in "McLaughlin v. Florida" (1964), in which the Supreme Court unanimously struck down a law prohibiting an interracial couple from living together. In 1969, he was a member of the U.S. delegation to the twenty-fourth session of the United Nations General Assembly. Coleman was also a member of the National Commission on Productivity (1971–1972). Coleman served in the boardrooms of PepsiCo, IBM, Chase Manhattan Bank, and Pan American World Airways. He was senior partner in the law firm of Dilworth, Paxson, Kalish, Levy & Coleman at the time of his appointment to the Ford Administration.