Federal courts are not allowed to intervene in a legal dispute indiscriminately. This authoritative text lays out the constitutional source of federal authority and the limits to its application, focusing on federal questions and diversity. Jurisdictional problems and jurisdictional amount are discussed, as well as admiralty, sovereign immunity, abstention, injunctions against suit, and civil rights removal. Also includes coverage of three-judge courts, trial location, and the law applicable in federal courts.