A reader writes:

Are Sedevacantists excommunicated, outside the grace of the Church?  What I’m asking, I guess, are followers of the schismatic doctrine of Sedevacantism (and to a lesser extent, I suppose, that of SSPX) in mortal sin?

Excommunication is an ecclesiastical censure that has specific effects that are defined by canon law. These effects are found in Canon 1331, which can be read HERE. The effects listed do not include being "outside the grace of the Church." The latter could be interpreted in several ways, and I’m not entirely sure what is intended, but I can say that excommunication neither places a person outside the Church nor does it deprive him of grace.

It does, however, presuppose that the individual has committed a grave sin. That is why, as an excommunicate, he is not allowed to receive the sacraments until he repents, for it would be sacrilege for him to do so in what must be presumed to be a state of mortal sin.

The grave sin that sedevacanists (and those who have formally adhered to the schism of the SSPX) have committed is the sin of schism. Schism is both a sin and a canonical crime, and its definition as a canonical crime is as follows:

Can. 751 Heresy is the obstinate denial or obstinate doubt after the reception of baptism of some truth which is to be believed by divine and Catholic faith; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Supreme Pontiff or of communion with the members of the Church subject to him.

If a person commits the canonical crime of schism, as defined above, then he is liable for the penalty of excommunication:

Can. 1364 §1. Without prejudice to the prescript of can. 194, §1, n. 2, an apostate from the faith, a heretic, or a schismatic incurs a latae sententiae excommunication; in addition, a cleric can be punished with the penalties mentioned in can. 1336, §1, nn. 1, 2, and 3.

The fact that it is latae sententiae means that the excommunication doesn’t have to be declared by an ecclesiastical authority. It occurs automatically when the person commits the crime of schism.

But the way canon law is written, it is not enough to note that a person has outwardly committed a schismatic act and then conclude that he is necessarily excommunicated. Canon law contains a number of provisions that could keep the excommunication from taking its effect, or at least from taking effect automatically. Many of these are listed in canons 1323 and 1324.

You’ll note that one of these provisions is that a person is not subject to the penalty if they committed their offense through innocent ignorance, inadvertence, or error (1323 no. 2). This means that if a person (sedevacantist or otherwise) committed a schismatic act in one of these conditions then he would not be automatically excommunicated.

It is thus possible for one to commit an objectively schismatic act without incurring excommunication.

But assume that a sedevacantist can’t get out based on one of these exceptions in the law (either the three I named or the others), would he then incur excommunication?

Yes.

If a person maintains that the current Roman Pontiff (Benedict XVI) is not a valid pope then he thereby refuses submission to the Roman Pontiff. It is not enough to say, "I’m loyal to the office, I just don’t think that guy occupies it." You have to be in submission to the actual pontiff. You can’t be in submission to an office. If there is presently a Roman Pontiff (and there always is except in interregnums) and you ain’t in submission to him then you’re a schismatic.

You can also fail to be in submission to the Roman Pontiff in other ways, as the leaders of the SSPX were when they participated in episcopal ordinations contrary to a specific papal order–see John Paul II’s motu proprio, Ecclesia Dei. As the pontiff warned in this same document, those who formally adhere to this schism also incurred excommunication.

All of this deals with the canonical censure of excommunication, but we still have to look at the moral (as opposed to canonical) question: Are sedevacantists and other schismatics in mortal sin?

It depends. Any time anyone commits an objectively grave sin (and schism is one such sin) then they are potentially in mortal sin. Whether they are actually in mortal sin depends on whether they committed their offense with sufficient knowledge of its moral character and whether they gave it deliberate consent.

If a schismatic lacked sufficient knowledge of the moral character of what they were doing (e.g., they didn’t realize that being a Catholic was important or they didn’t realize that what they were doing was actually schimatic) or if they didn’t give deliberate consent to the act (e.g., because they were suffering from a severe psychological illness that prevented them from deliberately consenting to any of their actions) then they would not be in mortal sin. They would still have sinned gravely, but the sin would not be mortal.

On the other hand, if they had sufficient knowledge of the character of their act (and they have sufficient knowledge as long as they had enough knowledge that they should have known what they were doing was gravely sinful, so their ignorance wasn’t innocent) and they just up and did it anyway then their actions were mortally sinful and they will not go to heaven unless they repent.

As always, we can’t judge whether any particular person is in mortal sin, but those are the underlying principles.