[Question:]{.underline} Can a Catholic ever exchange valid marriage vows with a non-Catholic in the absence of a priest?
[Answer:]{.underline} Catholics know that the canonical form of marriage is required for validity, namely that they must exchange vows in the presence of their parish priest or a delegate. A Catholic who attempts marriage, even with a non-Catholic, without the canonical form, is not validly married in the eyes of God and the Church.
However, there is an extraordinary form of marriage (Canon 1098 in the 1917 Code and Canon 1117 in the 1983 Code), in which marriage vows are exchanged in the absence of the parish priest, when an obstacle exists to the exchanging of vows before the parish priest which lasts for more than one month. The priests of the Society marry validly those who refuse to participate in the Novus Ordo preparation for marriage and ceremonies, in virtue of this extraordinary form, and of supplied jurisdiction. The Canon permitting the use of the extraordinary form requests the presence of another priest if possible, or if this is not possible of at least two witnesses. It would be very imprudent for a couple of take advantage of this extraordinary form without the presence of a traditional priest, whose presence ensures the Church’s blessing and nuptial Mass, the civil requirements, adequate marriage preparation, and the keeping of precise records. However, it would not necessarily be invalid if they were to do so, in particular in mission countries in which traditional priests are absent for months at a time.
The situation with a mixed marriage is different. It requires dispensation from the impediment of mixed religion, which dispensation the couple manifestly cannot give themselves. Also, the Catholic who plans to enter into a marriage with a non-Catholic, is entering into a situation that compromises greatly the raising of children in the Faith, and is desperately in need of priestly guidance.
If the non-Catholic is not even baptized, the ensuing marriage will certainly be invalid, because the impediment of disparity of cult invalidates a marriage for which no dispensation is granted. However, if the non-Catholic is validly baptized, as is usually the case with a Protestant, the impediment is that of mixed religion. The absence of the dispensation or authorization makes the marriage in such a case illicit, but not invalid. Consequently, it might be theoretically possible for a mixed marriage in the absence of a priest to be valid, provided that the objective obstacle to the exchange of vows before the parish priest within one month is manifest. Since the Church only tolerates such marriage, and allows no blessings or nuptial Mass, there will not always be a serious obstacle to going to the Novus Ordo parish priest. If this obstacles does exist, it will be the refusal of the indifferentism promoted by the post-conciliar church in the marriage preparation. However, such a situation would be inappropriate, highly imprudent, and illicit. Such a couple would afterwards have to submit their case to a trusted priest for verification as soon as possible, and be willing to renew their vows before him at a later date in case of doubt.
Answered by Father Peter Scott, SSPX.