One witness to conversion - Igrot Moshe Yoreh Deah 3:112

Rav Moshe Feinstein was asked in 1974 about a conversion case where only one of the three members of the beit din actually saw the טבילה due to space constraints. Was this טבילה valid or did the woman need to go again in order to validate her conversion? Rav Moshe stated unequivocally that the conversion was valid, on a number of grounds:

1) Even though we say that one witness is not valid in the face of a חזקה, and in this case the חזקה would be that the woman is not Jewish, the fact is that in this case we say איתרע חזקתה - her חזקה is defective, due to the fact that she had accepted the mitzvot and made all of the many preparations for going to the mikveh and would not have gone through all of that if she was not planning on following through.

2) Tosafot in Gittin allow a witness to a גט to say בפני נכתב if he only heard the writing take place, even if he did not actually see it. In this case as well, if the people can say that they heard her dunk but did not see her, they can be accepted.

3) It could be that the beit din function not as witnesses but as judges. As such, they do not need to actually see her dip into the mikveh. It could be that there role is to instruct her to do so and may not even need to be present. This is based on Ramban, who writes that if the beit din instruct a person in mitzvot and the person accepts them and then the beit din instructs him to go and get a brit mila and go to the mikveh and he does so - even not in their presence - then his conversion is valid.

4) Even if they have to be present for the טבילה, it could be that their presence is ceremonial in nature (similar to their presence by סמיכה for פר העלם דבר של ציבור) and thus their not seeing the action does not invalidate the conversion.

Tevila for a Giyoret - Igrot Moshe Yoreh Deah 3:111

Rav Moshe Feinstein was asked about a woman who wanted to convert but was physically unable to bend or crouch in the water, and thus would not be able to immerse her entire body in the mikveh at once. Given the strict nature of the requirement of mikveh in the context of conversion, Rav Moshe ruled that she would have to find a mikveh that was deep enough to cover her entire body at once. Ideally, the woman should not immerse herself while standing straight up, as such a posture conceals certain areas of the body, and the rule is that the water must reach every point of the body.

Rav Moshe suggests that two women help this woman perform טבילה, and that once she is completely immersed they should grab onto her and lift her out of the water, momentarily loosening their grip so that the water can reach the area where they are holding her.

A giyoret who made one small mistake - Igrot Moshe Yoreh Deah 3:108

In 1979, Rav Moshe Feinstein was approached by a גיורת was was concerned that her conversion was invalid. As she was going to the mikveh, she excitedly told a friend of hers what she was doing. Her friend asked her how she was going to manage to tell her bosses that she would be missing work for Yom Tov. With Pesach on the horizon, the woman had thoughts to slip into work on the last days of Yom Tov so as to avoid any confrontation that might cost her her job. In fact, she did go to work those days, but only carried the necessary subway tokens, and did not do any writing while at work. Since that one time, which occurred soon after her conversion, she had been living a fully observant and dedicated lifestyle. Her fear was that since she was thinking about going into work on Yom Tov while she was in the mikveh, perhaps that counted as not accepting even one mitzva, and would thus invalidate her conversion.

Rav Moshe ruled that her conversion was completely fine, on multiple grounds:

1. She is not believed insofar as believing her would make her forbidden to her husband and cast aspersions on her children.
2. Her alleged thought counts as דברים שבלב, which cannot outweigh her explicit statement to the בית דין administering her tevila that she was accepting all of the mitzvot.
3. If a convert were to say that he was accepting all of the mitzvot but he did not think he could withstand a יהרג ואל יעבר situation, his conversion would be good anyway. Rav Moshe brings three proofs for this point (including the fact that someone who converts for marriage purposes is considered to be a valid convert, even though such a person is certainly not thinking of giving up his life for mitzvot), and concludes that the fear of losing one's job is a similar pressure that many people have a hard time withstanding, and thus it should not invalidate the conversion.
4. This woman had been living a strictly observant life for the past ten years, a fact that was known to all, and thus her initial transgression was clearly not indicative of a lack of a desire to keep any mitzva.

More on Giyoret - Igrot Moshe Yoreh Deah 3:110

The case in this teshuva is of a non-Jewish woman who was married to a Jewish man for 17 years. She lived as a Jew and their adopted children were converted and raised as Jews. She had asked to be converted in the past and had been pushed aside by the previous Rabbis of her community. Now, the new Rabbi asked Rav Moshe Feinstein if he should convert her.

Rav Moshe answered that since all evidence pointed to her sincerity to convert, she should be allowed to do so. However, since her husband was not particularly observant, she would have to be told about הלכות נדה and Shabbat and accept to keep those areas of halacha.

With regard to her having to separate from her husband for three months after conversion (the normal waiting period for a remarriage, instituted to ensure that the woman is not pregnant from the previous husband - in the case of conversion the waiting period is to separate between halachically unacceptable and halachically acceptable conversion), the issue was raised that the woman had never conceived and was now over 40 years old and thus perhaps the waiting period could be waived. Rav Moshe rejected this waiver on the grounds that since the waiting period applied when there had been no previous sin, it would not make sense to waive it for a couple that had lived in sin (intermarriage) for 17 years (לא יהא חוטא נשכר).

Giyoret - Igrot Moshe Yoreh Deah 3:109

This teshuva encompasses several short teshuvot concerning different cases of גיורות.

In the first case, Rav Moshe Feinstein was asked about a woman who converted but did not keep the mitzvot initially as her husband was not so religious. However, her husband subsequently became more observant, and she followed suit, and now she was concerned whether her conversion might be invalid due to her failure to accept the mitzvot at the time of the conversion. Adding to the complication was that the couple had already had several children. Rav Moshe ruled that the woman should undergo a second conversion (i.e. טבילה) and the children should as well (although he did not require the sons to have הטפת דם ברית).

The second case dealt with was of a non-Jewish woman who married a Jewish man and was pregnant and then decided to convert. Due to her pregnancy, she was unable to travel to a place where there was a valid בית דין and she did not feel comfortable going to the mikveh in front of men. Thus, the question was raised whether three untrained men could serve as the בית דין and if women could observe her going to the mikveh. Rav Moshe ruled that her case did not rise to the level of שעת הדחק and that if she was not ready to accept the mitzvot in full - as evidenced by her reluctance to convert properly - then she should not be accepted as a גיורת. However, Rav Moshe notes that if she does convert, then she does not need to separate from her husband from three months, as she is already pregnant.

Conservative Conversion - Igrot Moshe Yoreh De'ah 3:107

Rav Moshe Feinstein was asked in 1977 about a couple in Berkeley where the woman was a convert who had converted via a Conservative beit din and the husband was a Kohein. The couple was now becoming more religious and the woman was willing to undergo a second conversion, and they wanted to know what their status was.

Rav Moshe ruled that the husband had to divorce his wife since her initial conversion was definitely not valid. Even if the Conservative Rabbis who converted her observed mitzvot and asked her to do the same, the fact that she refused the accept the prohibition of marrying a Kohein invalidated her conversion from the get-go.

Ketubah for Shtuki and Asufi - Igrot Moshe Yoreh De'ah 3:106.3

In this final section of the teshuva, Rav Moshe discusses how we write the name of a שתוקי or an אסופי into a כתובה. These two categories, listed in the first mishna of the final chapter of קידושין, refer to individuals whose parentage is unclear and therefore their acceptability to marry a Jew is questionable. A certain city apparently had the practice to write their names followed by בן אברהם אבינו, similar to what is done for a convert. Rav Moshe ruled that such a practice should be stopped, since it would call into question the כתובות of converts if all of those categories of people would be labeled the same way.

Rav Moshe also objects to writing the mother's name, since that will potentially lead to confusion whereby one might think that the individual is from a Jewish mother and a non-Jewish father and will wind up allowing them to marry another Jew or even a Kohein.