Simply, excommunication means being obliged not to receive Communion.
ANYBODY who commits a "mortal sin" is obliged not to receive communion (except in an emergency) unless he goes to confession and is absolved.
Some deeds are singled out. Having or procuring an abortion,for example, makes you excommunicated.
Here's one place where canon law is different from what we're familiar with. In such a case you are excommunicated latae sententiae -- automatically. You know what you did, you know the law (theoretically) so there's no need for a formal inquiry and declaration.
But you can also be officially declared excommunicated. That would be different. So if somebody says, "anyone who advocates or requires abortion is excommunicate," or even if a bishop, say the Bishop of San Francisco, asks a politician into his office and says,"You know, you really should not receive communion," it's not official. It is on the individual, and the divine penalty is on him too.
Also, there are misdeeds which automatically excommunicate and which require the Holy See (the pope or his agents) to lift the excommunication. A priest who breaks the seal of the confessional can only be readmitted to communion by the Holy See.
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The way the canons are written is unusual. The relevant canon, 912, says
Can. 912 Any baptised person who is not forbidden by law may and must be admitted to holy communion.SO that's like the default position. A minister of Holy Communion must assume, unless he KNOWS otherwise, that the person in front of him "may and must" receive.
SO, unless it's official, the minister has to assume that, however unlikely it may be, the person in front of him went to confession and was readmitted to the sacrament before he stood there and said, "Amen."
I don't know the official procedures for declaring someone excommunicate AND declaring the lifting of that status as "reserved." But it would take some sort of formal declaration not only that the person was excommunicated but that the excommunication could not be lifted by some random confessor. THEN the minister could deny the sacrament.
One way to look at this is that the canons bend over backwards to make provision for God's acting mercifully in the life of the sinner, and also that they are based on the idea that God knows what hes doing even when we don't.
My Dad was excommunicated.
He received a letter (do not remember who my Mom said it was from), that because he was marring my Mom and she was not only not Catholic but said she would not allow her children to be raised as Catholics, he was told “good bye” and his future children were all going to hell.
That was in 1945, so who knows what was going on at that time.
If it's all up to the individual, then Canon 915 has to be removed from Canon Law as totally absurd.
Canon 915 applies to and places expectations on the presiding clergy to enforce the rules of Canon Law and to do so, make sure those who are excommunicated or under interdict " . . . are not to be admitted to holy communion". The fact is, the Clergy have a responsibility to the Sacrament itself no matter what is contingent on the individual who may be excommunicated or under interdict.
All the talk about the individual presenting them self being the responsible party and everyone else is held harmless is a case of comparing apples to oranges. Canon 915 makes it clear that, no, the clergy are not to just assume that anyone who shows up should receive communion. They are responsible if they serve communion to someone who is excommunicated just as much as the individual who knows better unless it is absolutely impossible for the presiding priest to know whether or not they're excommunicated. Now, it is not in any way impossible for anyone in this forum to know that the likes of Biden and Peolsi and a host of others have never recanted their pro-abortion and other culture of death stands that defy Church Teaching, so it's absolutely absurd to say that the presiding priest can't be sure where they stand and should err on the side of allowing them to partake of communion.
All the focus on the individual is an attempt to sidestep the issue. The issue isn't whether scum like Biden and Pelosi are in deep do do for presenting themselves. They've excommunicated themselves, they know it, they did it by openly defying Church teaching and brag about having done so. What do they care about theoretically being in even worse shape after they present themselves since they don't accept Church Dogma and Doctrine anyway? They know that from the point of view of anyone who is Catholic they’re in deep do do in more ways than one. They have no intention of changing their ways, are not sincere Catholics who care what the Church teaches or believe that God is going to ever do a thing to them. They're not Catholic, get that through you're heads, they once were, they are not now.
The whole issue of their receiving communion arises from their publicly and non many occasions denying Church teaching. The objective reality of the situation is that they only show up for communion as a way to give the finger to the Church to add insult to injury. Those are the facts. It's silly or avoiding reality to pretend there is any reason whatsoever for anyone to believe they’re secretly repented and are worthy to receive communion. The presiding priest who is responsible for making sure people in exactly the situtation these two are in, " . . . are not to be admitted to holy communion", shouldn't admit them. There's no reason to believe they've repented any more than there would be to believe some guy with a Pentagram tattoo on his forehead and "Satan is Lord" tattooed on his arm has repented and is a Catholic worthy to receive communion. Without it becoming public knowledge that they've repented they have to be refused because it's public knowledge that they have excommunicated themselves by openly supporting abortion among other things.
The presiding priest is obligated to err on the side of caution and refuse them communion or Canon 915 is null and void noise and a waste of ink to print. Likewise, the references to the penalties the priest can expect if he doesn’t look over those presenting themselves and when he thinks some of those presenting themselves may be among those who, " . . . are not to be admitted to holy communion". Unless and until public figures like Pelosi and Biden very, very, publicly make it clear they no longer support abortion on demand, the ordination of women, queers marrying one another, and contraception, (for starters) just like they very publicly said they support those things no priest should permit them to receive. Canon 915 is clear and is written specifically to let the presiding preist know that people like Biden and Pelosi, " . . . are not to be admitted to holy communion". That's the rule and there's nothing contradicting that rule or making an exception saying they should be given the benefit of the doubt.
Either people who the clergy have reason to suspect are ineligible should be turned away, or it's absolutely dishonest and a shame on the Church to keep Canon 915 on the books when no priest is expected to abide by it. What, it’s a convenient rule they can use when they like and use against a priest that they can't find anything else on? Is it offically part of the smoke and mirrors Canon only included to impress the gullible? That’s what folks who argue it’s all up to the individual are boiling Canon 915 down to, a convenience for a Bishop who wants to find some reason to discipline a priest or a PR entry.
Anyone who publicly denies Church teaching is supposed to just as publicly state that they have repented and now accept Church Teaching before excommunication or interdict is lifted. Playing the, "how would the priest know" game doesn't float and IMHO is disingenuous.