 In 1953, Gross joined the law firm of Curtis, Mallet-Prevost, Colt & Mosle; he would remain associated with the firm for the rest of his life.During the Army–McCarthy hearings, Gross represented Ralph Bunche, who was called before the committee, and Dag Hammarskjöld, who was threatened with being called before the committee.Beginning in 1959, Gross assisted the Tibetan government in exile and its leader the Fourteenth Dalai Lama as a lobbyist representing Tibet for the debate and vote about Tibet in the fall 1959 session of the United Nations.