The 1983 Code of Canon Law provides an exception to certain of the Church’s laws regarding marriage for those who have "defected from the Church by a formal act." For example, they don’t need permission for mixed marriages (i.e., marrying a non-Catholic Christian), they don’t need to be dispensed for disparity of cult (i.e., marrying a non-baptized person), and they don’t need to observe the Catholic form of marriage.
Unfortunately, the 1983 Code–which introduced the idea of formal defection from the Church being relevant here–does not tell us what counts as formal defection. As a results, canonists have done their best to try to figure out what Rome means by this, and there’s been a kind of consensus develop in the commentaries regarding what a person needs to do in order to formally defect.
Basically, you’d need to decide to leave the Church (i.e., to decide to defect from it) and execute this decision by some kind of formal act, such as sending a letter to your bishop or getting baptized in another church.
Thus the green CLSA commentary (which is pretty typical on this point of what you find in other commentaries) says:
The following may be considered to have defected from the Catholic Church by a formal act: those who have made a public declaration of their abandonment of the Catholic faith, either in writing or orally before two witnesses, and those who have formally enrolled by some external sign in another Christian church or another religion [commentary on c. 1117].
Unfortunately, this is now wrong.
The reason it’s now wrong is that the Holy See (specifically, the Pontifical Commission for the Interpretation of Legislative Texts, which is the competent dicastery in this matter) has just issued a document clarifying what is needed for a person to have formally defected from the Church.
And before I get started,
HERE’S SOME COMMENTARY FROM ED PETERS.
Now. . . .
The upshot is that in order to formally defect one must:
1) Decide to leave the Church (which supposes an act of heresy, apostasy, or schism),
2) Put this decision into effect ("realize" it),
3) Manifest this decision externally by submitting it in writing to the Ordinary (normally the bishop) or one’s pastor, and
4) Get the Ordinary or pastor to agree that you really have performed the act of will to leave the Church described above and thus committed heresy, apostasy, or schism.
It is then to be noted in the parish baptismal register that you have so defected.
Now, as is obvious, this is waaaaaay stricter than commentators have been thinking up to this point.
It also has the effect of reducing to basically zero the number of people who will have formally defected in the sense necessary to trigger the exemptions from the Church’s marriage laws.
In fact, it reduces the number of people falling under the exemption so far toward the vanishing point that it is not clear why an exception should be made in the first place.
People who have decided to leave the Church are simply not going to go through the required procedure very often.
People who are really serious about leaving the Church will simply leave and that will be it. What do they care if the Catholic Church regards their marriages as valid or not?
Further, even if people do go through the procedures, bishops and pastors are not going to grant their consent very often. (Many will just blow off the request: "Oh, you don’t really mean it. You’re just doing this because you want to get married outside the Church. You’ll be back, and I don’t want the hassle of having to slap you with the canonical penalties that would be entailed if I concluded that you have committed the canonical crime of heresy, apostasy, or schism. Excommunicating you and branding you a heretic, an apostate, or a schismatic would even hinder your reconciliation with the Church, and I don’t want to do that.")
The people who have left the Church will then attempt marriage outside the Church without a formal defection and–because they are still bound to observe the Catholic form of marriage–their marriages will be invalid.
The current document seems to be almost directly contrary to the
original intent of the law, which was to provide a way for those who
have defected from the Church to not have their marriages end up automatically invalid.
What the effect of the document will be–for practical purposes–is to virtually abolish the exemptions contained in the Code of Canon Law for those who formally defect since almost nobody will meet the stipulated criteria now.
Of course, Rome has the power to make this change. It’s Rome’s authority that creates the requirement for Catholics to observe the Catholic form of marriage to begin with, since this is a matter of merely ecclesiastical law. And Rome can decide who (if anyone) it wants to exempt from those requirements.
But this is a striking change from what has been understood up to this point, and it will have the effect of increasing the number of invalid marriages and correspondingly the number of annulments and convalidations that have to take place.
Personally, I consider this to have been a poor way of handling the situation. If the above is really what the Holy See intended its law to mean then it either should have (a) written the law more clearly to spell out what it wants in the first place or (b) issued an authentic interpretation on this point back in 1983 when the Code went into effect, so that we wouldn’t have had a contrary interpretation (that was eminently reasonable based on the words of the law) develop in the community of canonists.
In other words: If that’s what they meant then they should have told us almost a quarter century ago!
As a result of doing this at this late date, there is a pastoral problem that has been created. To wit: Lots of people left the Church by what appeared at the time to be a formal act (e.g., getting baptized in the Mormon church) and got married without observing Catholic form and then they came to their senses and came back to the Church and some of them were told, "Oh, you don’t need to get a convalidation. You had formally defected."
If the above-linked document is judged to be retroactive then guess what: Those people do need a convalidation and they’re not validly married to each other right now!
The number of such people may be small, but that’s still a real pastoral problem that this delayed clarification of the law will have created.
The good news is that, at least if the Code is given a sensible reading, the problem should not arise, because Canon 16 ยง2 provides that:
An authentic interpretation put forth in the form of law has the same force as the law itself and must be promulgated. If it only declares the words of the law which are certain in themselves, it is retroactive; if it restricts or extends the law, or if it explains a doubtful law, it is not retroactive.
Any clearheaded reading of the document from the PCILT would show that it does not "only declare the words of the law which are already certain in themselves" for there is nothing in the relevant canons about having to request in writing and then get your bishop or pastor to agree to your request.
Instead, the new document would seem to "restrict[] or extend[] the law or . . . explain[] a doubtful law" and so it should not be retroactive.
It should only binds those from here on out who wish to exercise the Church’s exemptions from canonical form on grounds of formal defection.
But it’s still an awful sloppy way to handle the law.

