 They also had to take the ironclad oath.In 1867 the United States Supreme Court held that the federal ironclad oath for attorneys and the similar Missouri state oath for ministers, teachers, and other professionals were unconstitutional, because they violated the constitutional prohibitions against bills of attainder and ex post facto laws.In March 1867 Radicals in Congress passed a law that prohibited anyone from voting in the election of delegates to state constitutional conventions or in the subsequent ratification who was prohibited from holding office under section 3 of the pending Fourteenth Amendment.