So, this is precisely why the code treats of those who are baptized into the Catholic Church, as the Church has the right and the authority to impose legal obligations for the conditions required to contract a valid marriage over and above the requirements of Divine Law. Church has no such authority over those who were not baptized in the Catholic Church, and that is precisely the reason why this legal requirement does not apply to non-Catholics. Conversely, the Church could at any time lift this requirement and declare that a Catholic could marry validly even in a civil ceremony. But the Church in her wisdom realizes what grave harm this would do to the Sacrament of Matrimony.
So it is incorrect to call them legal fictions. When the Church binds on earth, it is bound in heaven, and vice versa. It's the Church's actual law and it determines reality, and not merely a legal fiction. To use the term "fiction" suggests that such people are not REALLY married, but the Church is merely pretending that they are for the purposes of subsequent application of law. When the Church declares a sanatio, the couple do in fact become married in reality, reality being "in the eyes of God".
No, WRT
sanatio in radice, the Church is not saying that there is no marriage, rather, she is saying that there is a marriage now and henceforth, and that she will treat it as though there was a valid marriage from the beginning, even though from the time it was illicitly and invalidly contracted, up to the moment the
sanatio is promulgated, there was, in fact, no valid marriage. It is basically convalidation without requiring the spouses to renew their vows, i.e., retroactive validation. There could be any one (or more) of several reasons for so doing.
From The Catholic Encyclopedia (New Advent):
The dispensation called sanatio in radice consists in the revalidation of a marriage by reason of a consent formerly given, but ineffective at the time owing to some ecclesiastical impediment. When the impediment is removed, the consent is ipso facto ratified and no renovation is required. In such a case, it is requisite that the consent of both parties to the marriage had not ceased and that their wedlock had had the external appearance of a true marriage. Sanatio is resorted to when there is urgent reason for not acquainting the parties with the nullity of their marriage, or when one of the parties alone is cognizant of the impediment and the other cannot be informed without grave consequences, or when one party would be unwilling formally to renew a consent that is presumably existent. The pope has power to give the dispensation called sanatio in radice for all marriages which are invalid in consequence of an ecclesiastical impediment. Bishops generally have no such power, even when by particular indult they can dispense in diriment impediments. For the granting of sanatio in radice a special apostolic faculty is required. In the United States, the ordinaries may grant such dispensation, under certain limitations, when only of the parties to the marriage is aware of the impediment.I always liken it to the assertion made by some, that Ohio was never properly admitted to the Union in 1803, due to a procedural error, so in 1953, Congress retroactively made Ohio a state from the time of its putative 1803 admission up until that moment. The case can be made that from 1803 to 1953, without anyone realizing it, Ohio was not a state, but was, in fact, the sole remaining rump remnant of the Northwest Territory. It's entirely possible that without this, any laws passed by Congress, where Ohio's Senate and/or House votes would have made the difference between ratifying them and not ratifying them, would be invalid. That would be, as the saying goes, like trying to make fish soup into an aquarium, as opposed to making an aquarium into fish soup (which would be relatively easy by comparison).