The legal process by which decisions of a lower court are reviewed is known as the appellate process. Appellate procedures will vary greatly from one jurisdiction to the next. In the United States, when a legal decision is overturned through the appellate process, the court may reverse the lower court decision entirely or in part, or may reverse and remand the case back to the power court for further proceedings.
The United States court system is divided into the state court systems and the federal court system. Within each distinct system, there are lower trial courts, appellate courts, and a supreme court. Both civil and criminal cases may be eligible for appeal from a trial court to the appellate court. Criminal defendants have an automatic right to an appeal upon conviction in a trial court. Criminal cases may appealed to either the state appellate court or the federal courts, or both in some cases.
When a case is appealed, the appellate or higher court will review the record of the case and the briefs in support of the parties' positions. In most cases, the court will only review the case for substantial errors made by the lower court giving deference to the lower court's findings of fact. In some select situations, the lower court case will be reviewed de novo, or without giving deference to the lower court on findings of fact.
When a case is overturned by an appellate or supreme court, the court has two basic options. It may decide that the error was so egregious that it cannot be remedied by sending the case back to the lower court. In that case, the higher court will reverse the decision of the lower court signifying the end of the case, unless a higher court may be appealed to after the decision is overturned. The court may also remand the case back to the lower court for further proceedings. In many cases, this means a new trial.
When a criminal conviction or sentence is overturned in a higher court, if the court reverses the lower court ruling entirely, then the defendant is free and cannot be recharged or retried. The conviction must be erased from his official criminal record. If the case is remanded back to the lower court, then the prosecutor has the option to retry the case or dismiss the charges. If the prosecutor decides to retry the case, then the defendant must defend the charges all over again. When a sentence is overturned, the higher court may simply adjust the defendant's sentence, or they may send that case back to the lower court for another sentencing hearing.