Sometimes, one side of a case, called a party in legal terms, thinks the trial court made the wrong decision. When that happens the party can ask the appellate court to hear the case. This process, called an appeal, takes place after a case is decided by a trial court. The party who lost at trial and is bringing the appeal is called the appellant. The party who won at trial and is responding to the appeal is called the appellee.
The appellate court has the power to reverse (overrule) the decision of the trial court. It does this by reviewing the written record from the trial court, called the transcript, along with the written arguments presented by each side. Occasionally the court asks the parties to appear in person for oral arguments as well. During the appellate process, the judges review the case for legal mistakes that are important enough to change the decision entered by the trial court.
Appellate courts base their decisions on a legal review of the written record from the trial and on the legal argument supplied by the appellant and appellee. An appellate court does not hear live witnesses or decide the facts of the case. Appellate courts limit their review to legal issues. For example, the appellate court will not decide if Susie Witness was lying when she testified in the trial court, but the appellate court will decide if it was legally proper for the trial court judge to allow the jury to hear what Susie Witness had to say during the trial.
As a result of a criminal appeal, the appellate judges can reverse a conviction, reduce a sentence or order a new trial. In a civil case, the judges can reverse the judgment or reduce a damage (money) award. The appellate court explains the reason for its decision in a written opinion. In some cases, if serious errors were made, the appellate court may even order that a new trial be held.