It is Catholic doctrine that the Pope, in virtue of his supreme vicarious power, can dissolve for the good of souls any natural, i.e. any non-sacramental, bond of marriage. A non-sacramental bond is one in which neither of the parties, or only one of the parties, is validly baptized as a Christian. The Pope can also dissolve a sacramental marriage [where both parties are validly baptized Christians] which has not been consummated. A dissolution, as opposed to a declaration of nullity, presupposes that the marriage bond is valid and that there are circumstances for the good of souls which justify the intervention of ecclesiastical authority to dissolve that bond. It is important to remember the difference between dissolution, which requires the active intervention of the executive power of the Church, and marriage nullity which is a judicial declaration that a marriage never existed in the first place. Unlike divorce, which claims to break any bond of marriage merely by the will of the parties and according to the criteria of civil divorce law, cases of dissolution can only be granted when strict conditions are in place. Moreover, the Pope cannot dissolve any sacramental marriage which has been ratified [i.e. in which the consent of both parties is valid] and consummated.
Cases of dissolution have a long and complex history and the Church makes reference to their usage even in Apostolic times, e.g. St. Paul (1 Corinthians 7, 12-16).
Cases of dissolution include the “Pauline Privilege” and the “Dissolution in Favour of the Faith.” Also included under the category of dissolution are the less common cases of “non-consummation”.