The Judicial Branch
The Judicial branch of the federal government interprets laws. There are three types of federal courts. The district courts, the Courts of Appeal, and the Supreme court.
The District courts.
The district courts are the only federal courts with original jurisdiction, meaning they are the first courts to hear a case. They are also the only courts to hold trials. There is at least one district court in each state and a total of 91 courts with 678 judges in the United States. On average they hear about 350,000 cases per year.
The Courts of Appeal
If you feel that the district courts made a mistake and as a result you didn't get a fair trial you can appeal to the Courts of Appeal. They do not determine guilt or innocence but can correct mistakes made by the district courts. There are 12 courts with 178 justices. They usually have a panel of 3 judges hear a case.
The Supreme Court
If the Courts of Appeal don't make the necessary corrections you can appeal again to the Supreme Court. However, they only hear less than 1% of the cases submitted to them. There are 9 justices on the Supreme Court. They are the highest court and their rulings are final unless they overturn them on a future ruling.
Types of Cases Tried in Federal Courts
There are only certain types of cases that are tried in federal courts. Some of these include: federal crimes, bankruptcy cases, crimes committed at sea, naturalization (supervision of people becoming citizens), and civil suits between residents of different states. The Supreme court also resolves conflicts between whole states.