Article III courts are federal courts in the United States, of various types including the Supreme Court, the District Court and the Court of Appeals. Article III of the U.S. constitution provides guidance in relation to these federal courts, most of which are located in large U.S. cities. They may also be known as constitutional courts.

The Supreme Court is a single court with national jurisdiction. There are ninety-four district courts across the fifty U.S. states, the District of Columbia and Puerto Rico. The District Courts act as the trial courts within the federal system, while the courts of appeals are the intermediate appellate courts. Another federal court is the Court of International Trade. The constitution gives the power to all federal courts to pass judgment on cases, which are carefully chosen for their suitability. Article III of the constitution also names the types of matters that may be dealt with in the federal courts. These include cases that involve litigation against the United States government, or a government officer. If a legal matter is determined to be unsuitable for the state court, the federal court will decide the case on its behalf. These are normally cases where the state court is not able to pass an impartial judgment, such as where a citizen of one state is suing a citizen of another state. The state court may not be able to reach a decision that is equally fair to both parties. Each case is judged on its individual merits in order to decide whether it should be heard in the state court or the federal court. If the case concerns a sum of money higher than $50,000, however, it will automatically be decided by the federal court.

If a particular case involves an ambassador, consul or person of equal public standing, the federal courts have the authority to deal with the matter. Cases that involve other citizens or governments of other countries are also deemed most appropriate for the federal courts. If a case relates to the constitution itself, its laws, congress laws, treaties or laws relating to the sea, rivers and lakes, the federal courts have the power to hear the matter. Similarly, the federal courts may also hear cases regarding business between states, such as contractual disputes. Cases involving the prosecution of terrorists, or dealing with other matters of national security, are heard in the federal courts.