Final answer:
There are twelve U.S. courts of appeals that review the decisions of the 94 district courts, which are the trial courts in the U.S. federal court system.
Step-by-step explanation:
There are twelve U.S. courts of appeals, also known as circuit courts, within the United States. These courts serve as intermediate appellate courts, reviewing decisions from the 94 U.S. district courts, which are the trial courts where federal cases are first heard. Each state has at least one district court, and the courts do not cross state lines. Some cases in district courts are heard by a jury under a single judge. The appellate courts oversee these trial courts, with a rotating panel of three judges who do not conduct trials but rather review the district courts' rulings within their circuit. Their decisions can be further appealed to the U.S. Supreme Court, the final court of appeal in the federal system. Additionally, there are specialized federal courts, such as bankruptcy courts and courts for international trade and federal claims, that handle specific types of cases. This system was established incrementally by Congress, exercising the power granted by Section 8 Clause 9 of the U.S. Constitution.