The Torah in Parashat Ki-Teseh (Debarim 23:2) commands that a man who is a “Pesu’a Daka” or “Kerut Shofcha” may not marry a Jewish girl. These terms refer to forms of damage caused to the reproductive organs that make a man infertile. A “Pesu’a Daka” is a man whose testicles were crushed, and a “Kerut Shofcha” is somebody whose member was cut.
The Sefer Ha’hinuch explains that the Torah forbade such a man from marrying a Jewish girl in order to disincentivize what was a common phenomenon in the ancient world. Men would volunteer to have their reproductive organs permanently damaged so that they could be appointed by the king to guard and care for the royal harem. We know this from Megilat Ester, which tells of King Ahashverosh’s “Sarisim” (eunuchs), the most famous of whom was Hegai, who was in charge of the young women brought to the palace for the king to choose a new queen. Men would have this done to them in exchange for the money and prestige that came with a job in the king’s palace. The Sefer Ha’hinuch writes that as we are a sacred nation, it is improper for a man to harm himself in this fashion. For this reason, the Sefer Ha’hinuch adds, this prohibition applies only if the damage to the reproductive organs were inflicted by the person himself or by somebody else. If this happened on its own, “Bi’ydeh Shamayim” (“at the hands of G-d”), then the man is permitted to marry. Since the purpose of the prohibition is to deter men from having this done to them, it applies only to situations which were caused by people, and not to those which occurred on their own.
This prohibition applies in all times and places, and, quite obviously, is relevant only to men. If a man with one of these conditions marries a Jewish girl and consummates the marriage, he has transgressed this prohibition and is liable to Malkut. The man is permitted to marry a female convert, or a gentile maidservant who was released and converted. According to the Talmud Yerushalmi, a man with one of these conditions violates this command by having relations with a Jewish girl, even outside the framework of marriage.