Who is a Jew-Determining Jewish identity in cases of question and doubt:
According to Jewish law, a person is only determined to be a Jew [i.e. to contain a G-dly soul, be obligated in the Torah and Mitzvos, and be part of the Jewish nation in the eyes of G-d and his people] if his mother is Jewish [i.e. direct maternal lineage], or he converted to Judaism in a Halachically valid conversion, as will be explain in A. This Halacha will mainly focus on the verification of these two claims. What if someone is unsure if his/her mother was Jewish, or if he had a Kosher conversion? Furthermore, even if one claims to be sure that his mother was Jewish, or that he converted in a Kosher method, how do we determine that his claim is true? Do we simply believe the claim of Jewish identity of any person, and if he says his mother is Jewish, or that he converted, he is believed, or do we require investigation and verification of proofs?
Note: To follow is a mere synopsis of the subject. In all cases of question or doubt one is to bring the issue to a Beis Din that is familiar in these matters.
Definition of a Jew:
Jewish mother: According to Jewish law, a person [who did not convert in a Kosher method] is only considered Jewish if his/her mother is Jewish [i.e. direct maternal lineage]. [This means that all his/her direct maternal ancestors are descendants of a woman who was present at the giving of the Torah on Har Sinai, or that someone in her direct maternal lineage converted a Kosher conversion.] One who was born from a Jewish mother is a full-fledged Jew even if one’s father, or someone in the paternal lineage, is/was not Jewish. One whose mother is not Jewish, is not considered Jewish even if their father is Jewish. One who is Jewish, remains Jewish even if he or his direct maternal ancestors converted r”l to a different religion. [Accordingly, there is no such thing in Halacha as a half Jew or quarter Jew, either someone is Jewish or not. Use of such terms is inaccurate, and does not change the true definition of the person, just as calling an African person a Chinese, does not make him Chinese.]
Conversion: A gentile who converts through a Halachically valid conversion is defined as a full-fledged Jew for all purposes. If the conversion was not valid according to Halacha, the individual remains a full-fledged gentile for all purposes.
The law of a questionable Jew: If one is unsure if his mother is Jewish, then he is considered a gentile, until proof is found of his mother’s Jewish identity. [Thus, there is no such concept as a questionable Jew, if he has question as to whether his mother was Jewish, as one is considered a gentile until he determines that his mother is Jewish.] However, the concept of a questionable Jew does apply in a case that a person claims to be Jewish [either due to having a Jewish mother, or due to conversion] but his claim contains suspicion, or requires Halachic proof according to the Poskim. Below we will discuss when we believe a person’s claim of being Jewish and when we require proof of his claim.
If one says his mother is Jewish, is he to be believed?
Allowing him to marry a Jew: In general, if a person says he is Jewish [due to his mother being Jewish] then he is believed to be Jewish and is allowed to marry another Jew. Some Poskim rule that this applies even if the person came from a different country. Other Poskim however rule that if an individual came from a different country then [in order to be allowed to marry a Jew] he must prove his Jewishness, even if he acts like an observant Jew. [Practically, we no longer rely on the above Chazaka regarding Jews who come from areas where intermarriage is common, such as the USSR, and if the person desires to marry a Jew, they must proof their Jewishness, or convert. This especially applies if there is a reason to place doubt into the person’s claim of Jewishness. In Israel, the Rabbanut requires all foreigners to prove their Jewish identity and provide testimony from authorized Rabbis in the Diaspora in order to be allowed to marry or perform Aliyah.]
Other matters, such as Tefillin: The above requirement for a Jew from out of country to bring proof of his Jewishness even if he acts like an observant Jew, only applies with regards to allowing him to marry a Jew. However, regarding all other matters of Judaism [such as Tefillin, Minyan etc], any person who states that he is Jewish [i.e. his mother is Jewish], is believed even without bringing proof.
If one says he is Jewish because he converted, is he to be believed?
Marrying a Jew: If a person who was known to be a gentile, claims that he went through a Kosher conversion and became Jewish, he is not believed to be allowed to marry a Jew unless he supplies witnesses [or other proof of his conversion], or reconverts. This applies even if this person now acts like an observant Jew. If, however, the person was always held to be Jewish, and now says that in truth he converted, then he is believed without witnesses. Now, although some Poskim argue that even such a person must bring witnesses, nevertheless, the custom is like the former opinion. [In Israel, the Rabbanut requires all foreigners to prove their Jewish identity and provide authorized conversion papers, in order to be allowed to marry, or make Aliyah.]
Other matters, such as Tefillin: The above requirement for a gentile to bring proof of his conversion even if he is now an observant Jew, only applies with regards to allowing him to marry a Jew. However, regarding all other matters of Judaism [such as Tefillin, Minyan etc], if he acts as an observant Jew he is believed to have converted even if he does not bring proof of his conversion.
How to verify the claims of a person who says that his mother is Jewish:
As explained in B, the custom today is to require proof of Jewishness for people who come from out of the country, from areas where assimilation was common, and in any case that there is reasonable doubt. The Batei Dinim have several ways of verifying a person’s claim of Jewishness. Some Poskim suggest the following criteria:
- Checking the legal identification cards of the person or his mother, and seeing if it says that he or she is Jewish.
- Verifying the Jewish names of the person and his family.
- Knowledge of Yiddish, and acting like a Jew or knowledge of Jewish customs.
The person in question must fulfill at least two of the above three conditions to be considered a Jew, and there must not be any other reason to cast doubt on his Jewishness. In today’s times, one also heavily relies on the opinion of an investigator who is trained and experienced in verifying whether the person’s claim is true or not. [So is done today in all Batei Dinim].
 This means that either all her maternal lineage goes back to Har Sinai, or that someone in her maternal lineage converted a Kosher conversion.
 See “Who is a Jew” by Rabbi Emanuel Shochat for a full overview on this subject.
 Michaber E.H. 4:5 “A Jew who has relations with one of these woman, the offspring follows the mother’s identity.” 4:19 “A gentile who had a child with a Jewess, the child is a Jew”; 7:17; 44:9 [regarding Kiddushin]; Rama O.C. 282:3 [regarding getting Aliyah]; Y.D. 159:3 [regarding Ribis]; E.H. 16:2; 44:9; Shach Y.D. 159:7; Admur 282:8 “A slave who has not been emancipated has the same status as a woman. However, if his mother is Jewish, then he is considered a complete Jew for all matters.”; Admur Hilchos Ribis 79; Rambam Hilchos Issurei Biyah 12:7; 15:3-4, 6; Rebbe Yochanon in Yevamos 17a and 23a and 45b based on Devarim 7:3-4; Mishnah Kiddushin 66b, 68b; Ramban on Vayikra 24:10
Did we ever follow paternal lineage and not maternal lineage? According to some sources, prior to the giving of the Torah, paternal lineage was followed to determine the identity of a Jew, and not maternal lineage. [See Sifra Toras Kohanim Emor 14 and Chochmei Tzarfat brought in Ramban on Vayikra 24:10] The Ramban ibid negates this suggestion, and claims we always followed maternal lineage, even prior to Matan Torah.
 Michaber and Rama ibid; Rambam ibid; Gemara ibid
Conversion: Some Poskim rule that the daughter of a gentile father and Jewess requires conversion. [Yearos Dvash Derush 17, brought in Pischeiy Teshuvah E.H. 4/1; Avnei Nezer 16 on Tosafos Yevamos 16b] Practically we do not rule this way. [Avnei Nezer 16; Yeshuos Yaakov 4/8; Beis Yitzchak 26; Achiezer 21; Chazon Ish 6/7]
 Michaber and Rama ibid; Rambam ibid; Gemara ibid
Other opinions: The Midrash records the opinion of Rebbe Yaakov Kfar Nevorai who held we follow paternal lineage, and not maternal lineage. His teacher, Rebbe Chagaiy negated this opinion as inaccurate and told his student, Rebbe Yaakov, that he deserves lashes for making such a statement. [Bereishis Raba 7b] This Rebbe Yaakov Kfar Nevorai is considered a controversial figure in the Talmud, and some considered him a sinner and heretic.
 Michaber and Rama E.H. 44:9 regarding Kiddushin “A Yisrael Mumar who did Kiddushin, it is valid. And even if the Mumar had a child later from a Jewish woman, his Kiddushin is valid” [They do not differentiate between if converted out of duress or willingly]; Rama Y.D. 159:3 [regarding Ribis]; Beis Yosef E.H. 157:6 “The children and all descendants of a Jewish mother who became a Mumar [remains Jewish and their Kiddushin is valid] even after many generations. This matter is an obvious Jewish law and those students who wrote differently, should have been persecuted by the Sages and excommunicated , as certainly these matters have no root and branch to rely on, and woe top one who is lenient in this” Maharik Shoresh 85; Maggid Mishneh Ishus 4, brought in Beis Yosef 44; Teshuvas Reim 47 and 49 [Rav Eliyahu Mizrachi] that this applies for all the future descendants, see there in length; Noda Beyehuda Tinyana 162, brought in Pischeiy Teshuvah 44:9 that a Mumar remains Jewish; Teshuvas Hageonim Shaareiy Tzedek 3 1:50 [regarding Mumar]; Meiri in Beis Habechira Avoda Zara 26 [regarding Mumar, however, regarding descendants-see below]; Rashbash 89; 368 [all generations]; Yachin Boaz 2:31 [all generations]; Igros Moshe E.H. 4:83 “It is not possible for a Jew to become a non-Jew. The Mumrim and their children are complete Jews and one cannot join the opposing opinions even as a Safek. The Mahrashdam made a grave error by writing otherwise”; See in great length [50 chapters] Divrei Yatziv Even Haezer 62; Radbaz 3:415; 4:12
Other opinions: Some Poskim rule that a Mumar is considered a gentile and his Kiddushin is invalid. [Opinion in Tur E.H. 44; Ittur Os Kuf 78a “One who desecrates Shabbos in public is like a gentile and his Kiddushin is invalid”; Rav Yehudaiy brought in Beis Yosef 157; Halachos Ketanos 2:240; See Teshuvas Riem ibid for a lengthy discussion on this subject; See Aruch Hashulchan E.H. 44:11; See Divrei Yatziv Even Haezer 62 who defends this approach] The Poskim ibid severely negate this approach and it cannot be used in Halacha for any leniency. [Beis Yosef ibid; Igros Moshe ibid]
The descendants of Mumarim: Some Poskim rule that although a Mumar and his/her descendants are Jewish, this only applies if the Mumar converted out of force. If, however, he/she converted out of his/her free will, then all the children born after the conversion are complete gentiles [even if both parents are Jewish]. [Teshuvas Reim ibid in name of Mahariy Chaviv; Rashdam E.H. 10; Kneses Hagedola 44 that from the grandchildren and onwards, this applies even according to Teshuvas Hareim; Beir Heiytiv E.H. 44:8; See Maharibal 2:45; Radab 6; Meiri in Beis Habechira Avoda Zara 26 rules that all the descendants of the Muamr are not Jewish] However, other Poskim vehemently negate this position, saying that a Jew remains a Jew even if his direct maternal ancestor willingly converted many generations ago. [Implication of Michaber ibid; Beis Yosef ibid severely negates the above position; Rashbash ibid; Aruch Hashulchan E.H. 44:11 “There is no root for the above words of the Poskim ibid who negate the Judaism of the descendants, as how exactly does their Jewish identity disappear? So is explained in the Rambam and all Poskim, and so is Setimas Hamichaber in 44:9. The fact that the Rashdam ibid learnt his position from the Talmudic opinion revoking Jewish identity from the ten tribes has no basis, as there it is learned from a verse” Igros Moshe E.H. 4:83 negates the above opinions from Halacha, saying they cannot be joined to any calculation of leniency]
Murano’s: The descendants of Murano Jews are considered to have converted out of duress [even though not all were threatened with their lives] and are considered Jewish according to all, so long as they did not intermarry with gentile women. [Teshvas Ream ibid; Rashbash 89; 368; Yachin Boaz 2:31]
 Shulchan Aruch Y.D. 268; Rambam Hilchos Issurei Biyah 12:17; 13;14; Bechoros 30b; Kerisus 9a; Yevamos 46a-b
 See Admur 329:2; Michaber Even Haezer 4:34
The reason: A person is assumed to be a gentile unless proven otherwise, as Kol Haporeish Merubo Poreish. [ibid]
 Michaber Even Haezer 2:2; Rashal Kesubos 2:40; Rabbeinu Tam in Yevamos 46b; Rashba; Ramban; Pischeiy Teshuvah 2:2; Aruch Hashulchan 2:12; ; Yabia Omer 7 E.H. 1
The reason: As people contain a Chezkas Kashrus, and majority of people who say they are Jewish are Jewish. [ibid] Vetzaruch Iyun regarding if the person is not observant, how this Chezkas Kashrus is maintained. See Meiri Yevamos 46a; Shut Maharit 1:149; Merkeves Hamishneh Issurei Biyah 13:10; Rav Akiva Eiger 1:121; Kiryat Chana David 2:3; Tiferes Yisrael Kesubois 2:46; Heichal Yitzchak 1:17; Chut Hameshulash 5; Chazon Ish Y.D. 158:8; Yibum 117:7; See the following Poskim who rule he does not need to be observant today: Kovetz Teshuvos E.H. 1:33; Igros Moshe E.H. 6
Other opinions: Some Poskim rule one is not believed to say he is Jewish unless he brings proof. [Rameh; Rashi, brought in Tur 2; Beis Shmuel 2:2 suspects for this opinion]
 Shach 268:21; Bach Yoreh Deah 268; Halef Lecha Shlomo Even Haezer 15; Yabia Omer 7 E.H. 1; See also Aruch Hashulchan 269:14 “Do we require proof from people who we don’t know, and they claim to be Jewish”; See however Aruch Hashulchan in next footnote
 Beir Heiytiv Even Haezer 2:4 in name of Maharit 1:149 and Beis Hillel, and so rules Michaber Y.D. 268:10 regarding a gentile who says he converted; See however Aruch Hashulchan E.H. 2:13 that this only applies to an individual, while a family does not have to prove their Jewishness if they act like a Jew, as a family maintains a Chazaka. So is also implied from Beir Heiytiv ibid;
 See Michaber 268:10 that we are only stringent to require proof in order to marry the person
 So ruled many Dayanim and Gedolei Yisrael of today’s generation, including Rav Moshe Feinstein, Rav Elyashiv; See Psak Din of Beit Din Rabbani Haifa case number 588549/1; Techumin 6:424; 12; Koveitz Darkei Horah 12; Yabia Omer 7 E.H. 1
 See Michaber 268:10 regarding a frum person who was known to be a gentile that we are only stringent to require proof of conversion in order to marry the person; See Aruch Hashulchan 269:14 “Do we require proof from people who we don’t know and they claim to be Jewish”;
 If he is not observant: Vetzaruch Iyun regarding if the person does not act as a Jew, and how to define this. See Meiri Yevamos 46a; Shut Maharit 1:149; Merkeves Hamishneh Issurei Biyah 13:10; Rav Akiva Eiger 1:121; Kiryat Chana David 2:3; Tiferes Yisrael Kesubois 2:46; Heichal Yitzchak 1:17; Chut Hameshulash 5; Chazon Ish Y.D. 158:8; Yibum 117:7; See the following Poskim who rule he does not need to be observant today: Kovetz Teshuvos E.H. 1:33; Igros Moshe E.H. 6
 Michaber Y.D. 268:10; Yevamos 46b
 Michaber ibid
 Rambam in Michaber ibid
 Shach 268:21 in name of Bach
 See Michaber 268:10 that we are only stringent to require proof in order to marry the person
 The reason: As an observant Jew maintains a Chezkas Kashrus.
 See Psak Din of Beit Din Rabbani Haifa case number 588549/1
 Opinion of Rav Moshe Feinstein, brought in Psak Din of Beit Din Rabbani Haifa case number 588549/1
 Opinion of Rav Moshe Feinstein