The United States federal courts are a system of courts established by the U.S. Constitution to handle cases involving federal law, disputes between states, and cases involving foreign diplomats. This system includes the Supreme Court, which is the highest court in the country, as well as Courts of Appeals and District Courts. Federal courts operate separately from state courts and have jurisdiction over specific types of cases. They ensure that federal laws are interpreted and applied consistently across the nation, providing a vital check on the powers of the legislative and executive branches of government.