The US court system is called the adversarial system. The main duties of US courts are to resolve disputes, interpret the law, conduct judicial review, and in some cases make new law. The court system is hierarchical, with the Supreme Court at the top as the highest court of appeal. Lower courts include intermediate appellate courts and trial courts like district courts and municipal courts. Courts derive their authority from the US and state constitutions. They can also interpret laws passed by Congress, city councils, and administrative agencies. Through judicial review, courts ensure lower courts, legislatures, and executive bodies comply with the constitution.