The federal court system has three main levels: district courts (the trial court), circuit courts (the first level of appeal), and the Supreme Court of the United States (the final level of appeal in the federal system). There are 94 district courts, 13 circuit courts, and one Supreme Court throughout the country.

Courts in the federal system work differently in many ways than state courts. The primary difference for civil cases (as opposed to criminal cases) is the types of cases that can be heard in the federal system. Federal courts are courts of limited jurisdiction—meaning they can only hear cases authorized by the United States Constitution or federal statutes. The federal district court is the starting point for any case arising under federal statutes, the Constitution, or treaties. This type of jurisdiction is called original jurisdiction or federal-question jurisdiction. Sometimes, the jurisdiction of state courts will overlap with the jurisdiction of federal courts—meaning that some cases can be brought in both courts. The plaintiff has the initial choice of bringing the case in state or federal court. But if the plaintiff chooses state court, the defendant may sometimes choose to remove the case to federal court.

Cases that are based entirely on state law may be brought in federal court under the court’s diversity jurisdiction. Diversity jurisdiction allows a plaintiff who is a resident of one state to file a lawsuit in federal court when the defendant is a resident of a different state. The defendant can also seek to remove a case from state court based on diversity jurisdiction. To bring a state law claim in federal court, all of the plaintiffs must be residents of different states than all of the defendants, and the amount in controversy must be more than $75,000.

Criminal cases may not be brought under diversity jurisdiction. States may only bring criminal prosecutions in state courts, and the federal government may only bring criminal prosecutions in federal court. And the principle of double jeopardy—which does not allow a defendant to be tried twice for the same charge—does not apply between the federal and state government. If, for example, the state brings a murder charge and does not get a conviction, it is possible for the federal government in some cases to file charges against the defendant if the act is also illegal under federal law.

In Texas, as in other states, the federal court system comprises three main levels: district courts, circuit courts, and the Supreme Court of the United States. Texas falls under the jurisdiction of several federal district courts and is part of the Fifth Circuit Court of Appeals. Federal courts have limited jurisdiction, meaning they can only hear cases involving federal law, the U.S. Constitution, treaties, or cases where the federal government is a party. Civil cases can be brought to federal court if they involve federal-question jurisdiction or diversity jurisdiction. Federal-question jurisdiction applies to cases arising under federal statutes, the Constitution, or treaties. Diversity jurisdiction applies when the plaintiff and defendant are residents of different states and the amount in controversy exceeds $75,000. Criminal cases, however, cannot be brought under diversity jurisdiction; they are prosecuted in federal court if they involve federal crimes and in state court for state crimes. The principle of double jeopardy does not prevent a defendant from being tried for the same act in both federal and state court if the act violates laws at both levels.