Every judicial district has at least one district court judge, and most have from one to three district court judges. The number of judges can be changed by Congress when the need exists. Each judge may preside alone, or, when there are two or more judges, all may hold sessions of court at the same time.

The decisions made in federal district courts are reviewable by the court of appeals in each circuit. All the territory of the United States, Puerto Rico, Guam, and the Virgin Islands is divided into twelve judicial circuits.

These twelve circuits are further subdivided into judicial districts. Every state has at least one judicial district. All the territory of Idaho except Yellowstone National Park makes up one judicial district, for example. All of Yellowstone National Park is within the judicial district of Wyoming, including the parts of the park that are in Idaho. The number of districts in each circuit depends on the size of the area and the number of people living within it. Large states require more than a single district. California, New York, and Texas, for example, include four judicial districts. Judicial districts for large areas are further separated into divisions.

Federal law establishes the number of circuit judges and the place where court is held in each circuit. Congress can change both the number and location at any time, because the courts of appeals, like the district courts, are created by Congress. The Federal Courts Improvement Act of 1982 (Pub. L. 97-164, Apr. 2, 1982, 96 Stat. 25) created the United States Court of Appeals for the Federal Circuit, which hears appeals not based on regional boundaries like the other courts of appeal, but involving special topics, such as public contracts and patents, where the uniform application of legal principles nationwide is highly desirable.

The twelve regional courts of appeals hear appeals from the district courts and many decisions of federal administrative agencies. Cases are usually heard by three judges, but each circuit arranges to hear some cases en banc, with all the circuit judges of that circuit sitting together, hearing or rehearing the case and ruling by majority vote. A majority of the judges in regular active service in the circuit can order a case heard en banc at any time. This is usually done if the decision in the case is likely to have a significant effect on issues in pending cases, such as when the case involves an important question of constitutionality, jurisdiction, or the right to appeal.

The Court of Appeals for the Federal Circuit has appellate jurisdiction derived from the merger of the former Court of Claims and the Court of Customs and Patent Appeals in cases involving actions against the government, public contracts, and patents. It also hears appeals from the Court of International Trade, the Patent and Trademark Office, the Merit System Protection Board, and other agencies. This court is intended to provide for the uniform application and enforcement of law in cases that Congress deems should be treated uniformly, but which under the former appellate system were often decided differently from circuit to circuit. As a result of its topical appellate jurisdiction, the Court of Appeals for the Federal Circuit significantly reduces the number of appeals from such decisions to the Supreme Court.

The Supreme Court is empowered to hear cases on appeal that originate anywhere in the United States or its territories.