When I lived in Cincinnati (1973-1975), I was on the Beit Din both for conversion and divorces (Gittin). An unusual case came before us. A couple came for a "get". After the ceremony, the woman turned to the Beit Din, and said "now I want a letter that I am not Jewish". We looked at her in surprise. "My husband's mother hated me, and said that she would never accept our marriage. I told her that I would show her, and have her own Orthodox rabbi marry us. I converted just to spite her. I have witnesses that I was in Church the Sunday before and the Sunday after my conversion". Rabbi Scharfstein, the head of the Beit Din, refused to issue such a letter. It is abundantly clear in our sources, that although we check out a convert's motives before hand, if we failed to do so, or if we were duped, the conversion stands. On the one hand, this situation underscored the weakness of individual rabbis doing conversions. There had been an agreement between the Orthodox rabbis in Cincinnati that all conversions and divorces would go through Rabbi Scharfstein's central Beit Din. But this woman's conversion had been performed by an individual Modern Orthodox rabbi who USUALLY worked through the Beit Din, but did not this time. He apparently knew that there was something "fishy" about the woman, and that Rabbi Scharfstein would refuse to perform the conversion. One could only guess at what pressures the rabbi had been under to perform a conversion that he apparently knew was unacceptable. On the other hand, there was zero basis for declaring her conversion invalid. So how did we get to the current situation of conversions being routinely invalidated retroactively; sometimes even decades after the event? Sometimes, there is basis for such an action. If it can be shown that one of the members of the Beit Din was invalid, that would make the conversion invalid, according to the accepted practice of requiring a Beit Din, (although it is unclear in the Talmud if this is an actual requirement, even ex post facto. In a saner time, the conversion would have been redone as a stringency). But what invalidates one from being on a Beit Din? In the Talmud, it would only be a public sinner. RAMBAM introduces a new factor; heretical beliefs. This is unknown in Talmudic sources, and goes unmentioned in the Shulchan Aruch. This view opens up a Pandora's Box. What exactly constitutes heresy? I will here remind you of the view of certain rabbis that owning a Smart Phone not only invalidates one from being a witness or a judge (Dayyan), but even from being counted in a minyan! How far do we go? RAMBAM's definition of heresy, is itself declared heresy by some of his colleagues! But a controversial 1972 event changed the rules for all. I have discussed in an earlier series the very tragic issue of Mamzerut; usually translated "bastardy", but actually meaning the issue of a union of inscest or adultery. The children of such a union may never marry a Jew (with certain limited exceptions). A cause celebre in the early '70s in Israel, was the case of the Langer twins. Before WW II, a Jewish woman married a man who was not of Jewish background. The man insisted he had converted. The woman said that he had only had himself circumcised. During the war, they lost contact with each other, and each assumed the other to be dead. They both survived, and wound up in Israel. Each remarried, and had started a family. When this situation was discovered, the Rabbinate declared the woman's second marriage to be adulterous, and her two children to be mamzerim. This stirred up great resentment in the secular community. Rabbi Shlomo Goren, Chief Rabbi of the IDF, said "If I were Chief Rabbi of Israel, I would find a solution". At that time, Chief Rabbis reigned for life. A new law was put into place, limiting the Chief Rabbis' tenure to ten years. The Chief Rabbis Unterman and Nissim were ousted. Rabbis Goren and Yosef were installed. Within days, Rabbi Goren had convened a special secret Court. The man was asked to recite the Shema. He was unable to do so. Rabbi Goren declared his belief that the man had never converted. He added that the Talmud makes the (enigmatic) statement that "all who marry or convert, do so with the consent of the rabbis". No one is quite sure of the meaning of this statement. Rabbi Goren interpreted it to mean that the rabbis could undo a marriage or conversion. He decalred the conversion of the woman's first husband, if it had happened at all, to be null and void. He also declared her marriage invalid, even if the conversion had been done. The two children, a young man and a young woman, were married to their fiances the next day, with Golda Meir acting as the "parent", giving the bride and groom away. This action of Rabbi Goren sent shock waves throughout the rabbinic world. His fellow Chief Rabbi opposed both the action and the manner in which it had been done. Those members of the Supreme Rabbinic Council who leaned in the direction of the Hareidi world, resigned their positions. The Chief Rabbinate was no longer taken seriously in many circles. Ironically, the idea that a rabbi could retroactively decalre a conversion invalid, was taken up by some Hareidi Batei Din, especially in the U.S., but by the 1990s in Israel as well (although not the idea of declaring a marriage invalid, which would solve the agunah problem for thousands of women.) Suddenly, for those who take the idea seriously that, contrary to all known sources, a conversion could be undone, a convert would always live under the threat of finding him or her self suddenly a non-Jew once again, if one rabbi or another is unhappy with something they have done.. In my opinion, this approach is without halalchic merit. I would still regard such a person as Jewish. I constantly see well meaning, but uneducated, Jews writing Facebook messages that conversions can be undone,. This would come as a shock to all rabbis before 1973, as well as non-political rabbis today. This is part of the conversion crisis. This is politics.