And cuм ex Apostolatus Officio certainly is still valid. It is cited in the 1917 code of canon law dealing with the issue of heretics holding office and is based in divine law not ecclesial law and therefore is true in perpetuity.
Pope St. Pius X: “None of the Cardinals may be in any way excluded from the active or passive election of the Sovereign Pontiff under pretext or by reason of any excommunication, suspension, interdict or other ecclesiastical impediment” (Vacante Sede Apostolica, 1904).
Pope Pius XII: “None of the Cardinals may, by pretext or reason of any excommunication, suspension, or interdict whatsoever, or of any other ecclesiastical impediment, be excluded from the active and passive election of the Supreme Pontiff” (Vacantis Apostolicae Sedis, 1945).
The problem with this seems to be "ecclesiastical impediment" as opposed to divine impediment.
From Nuvos Ordo Watch
http://www.novusordowatch.org/the_chair_is_still_empty.htmSalza Error #4: The Claim that Sedevacantism ignores the fact that the law of the Church allows even excommunicated cardinals to be elected Pope validly
Surprisingly enough, John Salza saw fit to repeat an old long-refuted argument against sedevacantism from Pope Pius XII’s constitution Vacantis Apostolicae Sedis, promulgated in 1945, regarding the election of a Pope. Salza quotes the Pope as follows:
None of the Cardinals may, by pretext or reason of any excommunication, suspension, or interdict whatsoever, or of any other ecclesiastical impediment, be excluded from the active and passive election of the Supreme Pontiff.
(Pope Pius XII, Apostolic Constitution Vacantis Apostolicae Sedis, 1945; qtd. in Salza, “Errors,” p. 3)
What may seem at first like a powerful strike against sedevacantism is easily refuted simply by drawing the proper distinctions, which Mr. Salza fails to do.
What the Pope is doing here is lifting all ecclesiastical censures, including that of excommunication, which any cardinal may be laboring under at the time of the conclave, for the purposes of allowing him to licitly elect the Pope – and licitly be elected himself. In other words, the Pope is saying that no one may bar from the conclave a cardinal who has any ecclesiastical penalty against him. Note that the emphasis is on the word “ecclesiastical.” The Pope, obviously, can only dispense from ecclesiastical penalties, not from divine ones, for he has no power to reinstate into the Mystical Body of Christ those who have been cut off from it by the divine law. (The same Pius XII alludes to this in his 1951 address to midwives, where he refers to the “natural law, from which . . . not even the Church has the power to dispense” [Pope Pius XII, “Address to Midwives on the Nature of their Profession,” Oct. 29, 1951;
http://www.papalencyclicals.net/Pius12/P12midwives.htm)]. Of course, if the Church has no power to dispense from the natural law, then, all the more so, she does not have the power to dispense from the divine law, either.)
What this means, quite simply, is that heretics, schismatics, and apostates are, of course, banned from a conclave, but not because they are excommunicated by the Church, but because they are not members of the Church to begin with, because of their heresy, schism, or apostasy. Put differently: The heretic is excluded from the valid election of the Pope not under the aspect of being ecclesiastically excommunicated, but under the aspect of being a heretic, i.e., a non-Catholic. Note that Pius XII’s legislation merely speaks of “any . . . ecclesiastical impediment.” However, being a non-Catholic is not per se an ecclesiastical impediment, it is, first and foremost, a divine impediment, and, naturally, not one the Pope has any power to dispense from. If the Pope, hypothetically, had wished to do the impossible and include even heretics as “licit” electors or recipients of an election, he would have said so – he would have written, “None of the Cardinals may, by pretext or reason of any apostasy, heresy, schism, excommunication, suspension, or interdict whatsoever, or of any other ecclesiastical or divine impediment, be excluded from the active and passive election of the Supreme Pontiff.” But of course, such a statement would have been absurd on the face of it, especially considering that, just as a “heretical Pope” is no Pope at all, neither is a “heretical cardinal” even a cardinal.
We recall here, as seen earlier, what Pius XII explicitly taught regarding apostasy, heresy, and schism in Mystici Corporis: “For not every sin, however grave it may be, is such as of its own nature to sever a man from the Body of the Church, as does schism or heresy or apostasy.” These three sins are such as to expel a man from membership in the Church by their very nature (meaning that they are in and of themselves incompatible with being a Roman Catholic) – not because of some ecclesiastical punishment, such as an excommunication. The reason why an apostate, then, is not a Catholic, is not because a bishop or a Pope has excommunicated him, but because the sin of apostasy is in and of itself incompatible with being a Roman Catholic, just as it is in and of itself incompatible for a triangle to have no angles.
Therefore, the fact that Pius XII lifted all excommunications from cardinals for the purposes of holding a licit conclave is irrelevant to the question of sedevacantism. Salza is merely demonstrating his ignorance on this point, failing to realize that Pius XII is speaking of Catholics who are excommunicated, not of non-Catholics. As this may be somewhat confusing for some, let me try to give an example of where this papal legislation would apply. Imagine a wayward cardinal who directly violates the seal of confession. By doing so, he incurs an automatic excommunication from which only the Pope can absolve him (see Canon 2369 §1). Let’s say that before the cardinal can reconcile with the Holy See and have his excommunication lifted, the Pope dies. Now what? Is the cardinal allowed to participate in the conclave, and could he even validly and licitly be elected Pope himself, even though he is under excommunication? Pius XII’s legislation says “yes.” That’s all we’re talking about. It has nothing to do with the ridiculous notion that someone can become Pope who denies the Catholic religion again and again in his words and actions.
For more on the argument from Pope Pius XII’s Apostolic Constitution Vacantis Apostolicae Sedis, please see this article:
http://www.traditionalmass.org/blog/2007/06/25/can-an-excommunicated-cardinal-be-elected-pope 
Topic: Cardinal Siri and the Dissent of Genoa (Read 12129 times)