Halakhah su Levitico 21:7

Marriage between a person of Aharonic descent and a divorcée is expressly forbidden by Leviticus 21:7. As recorded by Shulḥan Arukh, Even ha-Ezer 6:8, marriage between a kohen and a female convert is also prohibited. The late Rabbi Moshe Feinstein, of blessed memory, is widely quoted as having ruled that ba'alei teshuvah, i.e., newly-observant young men, whose fathers were not observant may be permitted to marry divorcées or converts to Judaism despite the fact that they have held themselves out as kohanim. The reasoning, it is reported, is that the assumption of priestly descent on the part of such a person is derived entirely from his father's genealogical claim. Since the father was, and remains, non-observant, his testimony, it is claimed, as a matter of Halakhah, can be given no credence.

Exactly parallel to this is His, may He be exalted, saying "Let no one be found among you who passes his son or daughter through the fire, or who is an augur, a soothsayer, a diviner, a sorcerer. One who casts spells, or one who consults ghosts or familiar spirits, or one who inquires of the dead" (Deuteronomy 18:10-11)." For each one of these things is counted as a separate negative commandment; and they have nothing to do with the first of the two divisions of the second type. The proof about this is His saying, "a soothsayer, a diviner," in the middle; whereas each of them was already clarified to be a separate negative commandment. And that was His saying [this verse], after a soothsayer and a diviner were each also mentioned separately in another verse - and that was His saying, "do not divine and do not soothsay" (Leviticus 19:26). And just like soothsayer and diviner are separated, so too do they separate those before them and after them (in the verses in Deuteronomy), [to be] like soothsayer and diviner - as we explained, about bread, parched grain and fresh stalks. And someone besides us already erred about this topic - whether because his mind did not comprehend all of these things, or whether [because] he forgot them. So he counted His saying, "A harlot or a profaned woman they shall not marry; a woman divorced from her husband they shall not marry" (Leviticus 21:7), as one commandment. And it was already clarified in the Gemara, Kiddushin (Kiddushin 77a), that he is liable for each and every one [separately], even if it is [all included] in one woman - as we will explain in its place (Sefer HaMitzvot, Negative Commandments 161). And we can grant him an excuse for counting a harlot and a profaned woman as one commandment - as he thought it to be a general negative commandment. And in his thinking, His saying, "A harlot or a profaned woman they shall not marry," was for him, like His saying, "Do not eat any of it raw or boiled in any way." And he did not know that the one was to be separated and the other was not to be separated. And likewise did he not distinguish between His saying, "you shall not eat bread, parched grain and fresh stalks," and His saying, "he may not diminish her food, her clothing or her conjugal rights." However I will not attack him about this. Yet [regarding] his counting a divorcee together with a harlot and a profaned woman as one commandment - he has no argument for this at all. For it's - meaning the divorcee - being separate is clear. And that is His saying, "a woman divorced from her husband they shall not marry." Behold we have explained this great principle - meaning to say, the general negative commandment - and its questions. And we have informed you of those that are separated and those that are [limited] only to the general negative commandment, such that we are only liable for it once; and that the content which is separated is counted as several commandments and that which is not separated is counted as one commandment. And always place this principle in front of your eyes; for it is a great key in verifying the count of the commandments.

Another major problem exists with implementing hafka'at kiddushin today. The Gemara records many objectionable marriages that are binding, indicating that the Rabbis do not annul them. For example, Chazal do not annul the marriage of a kohein and a divorcee, although such a marriage is explicitly prohibited by the Torah (Vayikra 21:7).⁴See Teshuvot Binyamin Ze'ev (106) for a list of objectionable marriages where Chazal do not invoke hafka'at kiddushin. While criteria presumably exist to determine when marriages may be annulled, the Gemara never articulates them. The Rashba (Ketubot 3a) provides some insight: