Final answer:
Cases before the U.S. Courts of Appeals are usually heard by a three-judge panel. These intermediate appellate courts review the decisions of lower district courts and may precede an appeal to the Supreme Court.
The majority of U.S. cases, however, are heard in state courts.
Step-by-step explanation:
Cases brought before the U.S. Courts of Appeals, which are the intermediate appellate courts of the federal system, are usually heard by a panel of three judges. These courts review the rulings of trial (district) courts within their geographic circuit.
There are currently 179 judges authorized by Congress, serving across the thirteen appellate courts organized into 12 regional circuits and the nationwide Court of Appeals for the Federal Circuit. The appellate courts hear cases without a jury and often serve as a preliminary step before a case may be appealed to the U.S. Supreme Court.
When a case reaches the appellate level, the involved parties can present their arguments, but unlike trial courts, there are no new witnesses or evidence introduced.
The decision of these three-judge panels can be critical, often standing as final unless further appeal to the Supreme Court is granted through a process known as writ of certiorari, which requires the approval of at least four Supreme Court justices.
Despite the public focus on the Supreme Court, the vast majority of cases in the United States are heard at the state level. State courts may have their own appellate systems before cases reach their state Supreme Courts, which also handle a significant volume of the nation's casework.