Another important principle in our legal system is that of jurisdiction.
Jurisdiction is power, the power or authority of the court to decide a matter in controversy. The authority to compel witnesses to testify or command people to turn over documents or property, or to jail them for contempt. Jurisdiction is established in constitutions and by statute and is usually done geographically or by subject.
There are some matters over which a state or federal court has exclusive jurisdiction and some matters over which a state court has concurrent jurisdiction with the federal courts. Federal courts can, in some instances, decide questions of state law; state courts can, in some instances, decide questions of federal law. Sometimes it might be difficult to determine which matters are questions of federal, or state law, or both.
The final concept is the court structure. In general, there are trial courts and appellate courts.
When a case is appealed to an appellate court, both parties submit written briefs that contain a summary of the facts and arguments on the points of law involved, and the court may hear oral arguments by the attorneys. The court then issues an opinion which states the legal basis for the decision.
If the case is decided by an intermediate appellate court, the losing party may be able to appeal one more time. This second appeal is usually at the discretion of the higher court.