§ 1. The party who considers himself or herself aggrieved, as well as the promoter of justice and the defender of the bond, have the right to introduce a complaint of nullity of the judgment or appeal against the sentence, according to cann. 1619-1640. § 2. After the time limits established by law for the appeal and its prosecution have passed, and after the judicial acts have been received by the tribunal of higher instance, a college of judges is established, the defender of the bond is designated, and the parties are admonished to put forth their observations within the prescribed time limit; after this time period has passed, if the appeal clearly appears merely dilatory, the collegiate tribunal confirms the sentence of the prior instance by decree. § 3. If an appeal is admitted, the tribunal must proceed in the same manner as the first instance with the appropriate adjustments. § 4. If a new ground of nullity of the marriage is alleged at the appellate level, the tribunal can admit it and judge it as if in first instance.
Source: Code of Canon Law (Vatican.va)