Is there anything that actually prevents a Catholic marriage under circumstances such as this one? Of course Michael Schaivo was not charged nor convicted of murder, but the Pope himself came out against his actions.
As for the wedding dress, personally I think it is tacky as hell for someone who has been married once before to wear a white wedding dress. In this situation, it is just really awful. I don't know why they just didn't have the wedding at George Felos home.
Actually, there is quite a bit that prevents Schiavo from marrying in the Catholic Church.
Here's an article written by Canon Law expert Dr. Edward Peters in The Rock magazine.
When two people marry, there arises between them a "bond" of marriage, known in canon law as ligamen (Canon 1085). This marriage bond is what canonically prevents either spouse from marrying someone else for so long as the other spouse is alive, even if the couple has obtained a civil divorce from their marriage. Ligamen is the canonical enforcement of the familiar wedding words "till death do us part" and, with rare exceptions not applicable in a case like this one, only the death of one spouse can free the other from the bond of marriage.
Now, the Church has been around for a long time and she is, in Pope Paul VI's memorable phrase, "an expert in humanity." The Church has seen people try any number of ways around the demands of permanent Christian marriage, including even, the killing of one spouse in order to marry another. But while the death of a spouse, natural or otherwise, certainly ends the bond of the marriage that once existed, if that death was brought about by the surviving spouse, it is quite possible that canon law will step in to prevent the survivor from gaining by the misdeed and attempting another marriage in the Church. It does this by establishing on a killer spouse an impediment to marriage known as crimen (Canon 1090).
If you think you see in the Latin word "crimen" an ancestor of our English word "crime", you're right, for both terms are getting at what is, in the eyes of the Church at least, criminal behavior. According to Canon 1090, "One who, with a view to entering marriage with a certain person, brings about the death of one's own spouse or of the other person's spouse, invalidly attempts that marriage." Thus does the Catholic Church prevent someone from entering a marriage when, in order to be free to contract such a marriage, that person had brought about the death of a former spouse.
The impediment of crimen was present in the 1917 Code of Canon Law (see 1917 CIC 1075) and even before that it had been a part of ecclesiastical law for many centuries. Today's canon law on crimen is, in comparison with earlier law, much simplified, but reliable commentators on it such as Beal, Doyle, Kelly, and Hervada believe it means pretty much just what it says. Focusing our discussion, then, on factors suggested by the Schiavo situation, three things are required in order for the canonical impediment of crimen to apply.
1) The original parties must have been validly married. This fact that can be presumed, however, whenever there is a public celebration of a Catholic wedding.
2) At the time of the killing, the surviving spouse must have been intending to enter marriage with a specific person once free of the prior marriage bond. This is a question of fact to be determined on a case-by-case basis. Evidence such as positive statements about wanting to marry another or behavior consistent with future marriage plans, can be used to show this intention to marry. By the way, the fact that one might have multiple motives for wanting to cause the death of one's spouse (say, also the desire to save money on the disabled spouse’s health care), would not obviate the desire-to-marry motive.
3) The death of one spouse must be brought about by the surviving spouse. This does not mean, though, that the survivor spouse needs to have "struck the deadly blow". Commentators agree that a death brought about at the behest of the survivor qualifies for imposition of the impediment. Even if, therefore, spousal death came about with the approval a civil court and no civil liability could be attached to the instigator, one would still be burdened by the canonical impediment if, under the Church's moral analysis, one is found to have been morally responsible for the death of one's former spouse.
Once incurred, the impediment of crimen never ceases on its own. The mere passage of time will not erase it, not even if, sadly, after many years, people more or less forget about the dead spouse. Pastors cannot grant a dispensation from this impediment, nor can bishops. Even if a cleric is found to witness the wedding of one laboring under the impediment of crimen, such an attempt at marriage is null and of no effect in the eyes of the Church. Only the Apostolic See can dispense from the impediment of crimen (Canon 1078 § 2, n. 2), and commentators agree that the Holy See only very rarely considers such dispensations. Going back at least a hundred years, they can find no example of a dispensation from the impediment of crimen being granted where the fact of one's moral responsibility in the death of a former spouse is public knowledge.
In sum, if, in order to be free to marry a third party, one spouse succeeds in ending the other spouse's life, even through a civilly-approved death by euthanasia, and then goes on to attempt that marriage, such a person, besides facing other moral and even canonical consequences for the spousal death, attempts the subsequent marriage without the blessings of or recognition by the Catholic Church.
Of course, there are those who could say that anyone who is willing to kill a spouse in order to marry another is not likely to worry too much about what the Church thinks about their second wedding. There might be some truth in that, but the fact that some people are going to disregard moral and canon law in their decisions does not mean the Church cannot, or should not, enunciate clearly the rules are by which we should strive to live. The matrimonial impediment established under Canon 1090 is not, and is not intended to be, the Church's primary response to the threat of legalized euthanasia, but it is part of that response, and it would behoove us all to know that, in its way, it too strives to defend the innocent.
http://www.canonlaw.info/a_schiavo.htm