“Those who vote for abortion have already unofficially excommunicated themselves. That is how it works.”
That is a theological speculation. You will be hard-pressed to prove it definitively from Canon Law, the Catechism, or other binding teaching.
In the Church's application of law, benefits are applied broadly and penalties applied narrowly. Thus, all those who knowingly, purposefully, and directly aid in the procurement of a specific completed abortion are excommunicated latae sententiae (automatically). However, it's a stretch to say that a politician who supports legalized abortion on demand is directly aiding in any specific completed abortion.
This is especially true in light of the fact that the application of excommunications latae sententiae must be made through a narrow interpretation of the law, rather than a broad one.
Now, one could otherwise argue that these politicians are excommunicated for heresy. Heretics are also excommunicated latae sententiae. However, one would need to surmount two hurdles to make that case. The first is that one would need to show that being a pro-abort politician is heresy. I think, personally, that that is the case, but my theological opinion + a buck or two will get you a cup of coffee. I'm unaware of any formal, official pronouncement by the Church on that topic.
But assuming that being a pro-abort politician is heresy, the next hurdle is that one must be a formal heretic to be excommunicated latae sententiae. Being a material heretic (unknowingly, unwittingly, or without obstinance, holding views that are heretical) doesn't get you excommunicated. Otherwise, everyone who had forgotten the particulars of the doctrine of transubstantiation from their catechism 40 years ago, and mistakenly mixed up some of the particulars with the heresy of consubstantiation would be excommunicated from the Church.
That means, pretty much, that some competent ecclesiastical authority would have to make the judgment that someone holds heretical views, knowingly holds them, understands the nature of their heresy and understands the true teaching of the Church, and holds their views obstinately, that is, in the face of direct correction by competent ecclesiastical authority.
Ms. Pelosi could wind up in this situation, as her bishop has summoned her to be instructed and corrected. If she refuses the doctrinal correction of her bishop, it would be difficult to justify failing to pronounce her a formal heretic.
But it's a more problematic thing to say that pro-abort “Catholic” politicians are excommunicated latae sententiae merely by virtue of their political position on the subject.
They are, however, whether excommunicated or not, very bad Catholics. And the bishops have already said generally, pro-abort Catholic politicians should not receive the Blessed Sacrament. What remains is for the bishops to grow a backbone and name specific pro-abort Catholic politicians and ask them not to come to Holy Communion.
sitetest
I thought the root of the “unofficial” excommunication was the fact that the Church teaches that anyone who partakes of communion in a state of grave sin, partakes in blasphemy. The Priest warns the parishioners that to partake unworthily is anathema, and reminds them to refrain from falsely “communing”.
Excommunication is being cut off from the communion of saints - by oneself or by an outside authority (i.e. the Bishops). Is that a misunderstanding?
Note: I proffer my opinion in the hopes of learning, not arguing! I’m a pentecostal married to a Catholic, and I’ve spent some time and effort to understand my wife and kids’ church - even though I don’t believe it is the right church for me.