Appellate jurisdiction is the power of a court to review the decisions and change the outcomes of the decisions of previous, lower-level courts. The review process begins when a party or parties dissatisfied with the decision of the lower court appeal the decision to an appellate court.
Depending on the court and the type of case, appellate review may consist of an entirely new hearing on the matter (a trial de novo), or may be limited to a review of particular legal rulings made by the inferior tribunal (an appeal on the record).
The Supreme Court of the United States decides cases almost exclusively under its appellate jurisdiction. It can review most decisions of federal courts as well as the decisions of state courts involving questions of constitutionality or statutory law. Appellate jurisdiction is addressed in reference to the Supreme Court in Article III, Section 2 of the United States Constitution. Although the Supreme Court only exercises appellate jurisdiction over decisions of other courts, some U.S. courts may also review the decisions of non-judicial tribunals, such as administrative agencies.
A court exercising appellate jurisdiction can only decide issues of law and not of fact, since the finders of fact are the judges and the juries of the lower trial courts.