On February 1, 1956, Smith was one of five women named as plaintiffs in the federal civil suit, "Browder v. Gayle", challenging the constitutionality of the state and local bus segregation laws. On June 13, 1956, a three-judge panel of the United States District Court ruled that the laws were unconstitutional. The ruling was upheld by the United States Supreme Court on November 13 in a landmark decision, and in December it declined to reconsider. On December 20, 1956, the Supreme Court ordered Alabama to desegregate its buses and the Montgomery bus boycott ended.