Disputed cases concerning marriage are usually brought before the matrimonial court of a diocese.
This tribunal consists of a judge, a secretary or notary, and the Defensor Vinculi, or Defender of the Tie.
The cases which occur most frequently are those in which a "decree of nullity" is sought, a judgment that a certain marriage was and is invalid.
All decisions of the court, to be effective, must have the approval of the bishop.
An appeal from the diocesan court may be made to Rome; or, under certain restrictions, a case may be sent there directly.
In the Romani "Curia" or Court, the Congregation of the Holy Office has exclusive jurisdiction concerning the, Pauline Privilege, the impediment of disparity of worship and that of mixed religion; but it may refer cases to another Congregation, such as that of the Sacraments, or to the Tribunal of the Rota.
Any Catholic has the right to bring a case before the proper Roman Congregation or Tribunal, usually through a procurator or advocate.
New Catholic Dictionary