A Favor of the Faith Case is also known as the “Petrine Privilege” because it allows the pope, as the Successor to St. Peter, to dissolve a marriage in a situation in which only one party in a valid marriage is unbaptized. By definition, this means that, in the eyes of the Church, the marriage is not sacramental (to be sacramental both parties must be baptized). This type of case is not found in the Code of Canon Law, but developed after the promulgation of the Code of Canon Law in 1917.
The implementation of this procedure is reserved to The Pope. It involves the circumstance where one of the parties in the marriage is unbaptized and the other is baptized. Either party wants to become Catholic or wants to marry a Catholic. This marriage can be dissolved, permitting the person to become Catholic or to marry a Catholic. Thus, the Pope may act in favor of the Christian faith.
For the difference between the Pauline Privilege and the Privilege of the Favor of the Faith (Petrine Privilege), please click here.