The principle of "separation of powers" of the United States Government allows for an executive, legislative, and judicial branch. Article III of the Constitution establishes the judicial branch, but it is much briefer than the elaborate descriptions found in Articles I and II delineating the legislative and executive branches. The vagueness with which the founders treated the federal judiciary has allowed the function and structure of the branch to evolve and be interpreted by practice over the years. The highest court in the land, also known as the "court of last resort," is the Supreme Court which was established in Article III. The Supreme Court has a profound influence on the United States because of the pivotal role in plays in deciding constitutionality and affecting public policy. The members of the highest court and their function is tightly controlled and cautiously administered as befits such a potentially powerful office.

             The federal judiciary is comprised of three layers. At the bottom layer are the courts that are known as the "workhorses" of the federal judiciary. There are currently 94 of these district courts that have original jurisdiction in many kinds of cases. The district courts may hear civil and criminal cases, but "roughly 80 percent of them are civil cases" (Greenberg & Page 425). Such civil cases may be antitrust cases or disputes between citizens or states. The criminal cases "include violations of federal criminal laws, such as bank robbery, interstate drug trafficking, and kidnapping" (Greenberg & Page 425). .

             The next layer up from the district courts is an appellate layer. The U.S. Courts of Appeal are spread geographically into twelve districts across the United States. The U.S. Court of Appeals for the Federal Circuit is also a member of this level, bringing the number to thirteen. These courts only have appellate jurisdiction, which means that they only hear cases on appeal and no new evidence is presented to them.