[Sidenote: Federal courts and judges.] [Sidenote: District attorneys and marshals.] The federal judiciary consists of a supreme court, circuit courts, and district courts.[28] At present the supreme court consists of a chief justice and eight associate justices. It holds annual sessions in the city of Washington, beginning on the second Monday of October. Each of these nine judges is also presiding judge of a circuit court. The area of the United States, not including the territories, is divided into nine circuits, and in each circuit the presiding judge is assisted by special circuit judges. The circuits are divided into districts, fifty-six in all, and in each of these there is a special district judge. The districts never cross state lines. Sometimes a state is one district, but populous states with much business are divided into two or even three districts. "The circuit courts sit in the several districts of each circuit successively, and the law requires that each justice of the supreme court shall sit in each district of his circuit at least once every two years." [29] District judges are not confined to their own districts; they may upon occasion exchange districts as ministers exchange pulpits. A district judge may, if need be, act as a circuit judge, as a major may command a regiment. All federal judges are appointed by the president, with the consent of the Senate, to serve during good behaviour. Each district has its _district attorney_, whose business is to prosecute offenders against the federal laws and to conduct civil cases in which the national government is either plaintiff or defendant. Each district has also its marshal, who has the same functions under the federal court as the sheriff under the state court. The procedure of the federal court usually follows that of the courts of the state in which it is sitting. [Footnote 28: See the second note on p.278.] [Footnote 29: See Wilson, _The State_, p. 554. I have closely followed, though, with much abridgment, the excellent description of our federal judiciary, pp. 555-561.] [Sidenote: The federal jurisdiction.] The federal jurisdiction covers two classes of cases: (1) those which come before it "_because of the nature of the questions involved_: for instance, admiralty and maritime cases, navigable waters being within the exclusive jurisdiction of the federal authorities, and cases arising out of the Constitution, laws, or treaties of the United States or out of conflicting grants made by different states"; (2) those which come before it "_because of the nature of the parties to the suit_," such as cases affecting the ministers of foreign powers or suits between citizens of different states.