Appellate courts compose the middle level, and trial and specialized courts compose the base level.
These courts are often called the guardians of the Constitution. It is their job to interpret and apply laws to resolve disputes between parties, thus protecting the rights and liberties outlined in the Constitution. The basic structure of the federal court system can be best understood as a pyramid. At the top sits the Supreme Court, the highest court in the land. Beneath the Supreme Court are the 13 United States Courts of Appeals and the U.S. Court of Appeals for the Armed Forces.