Touching a niddah other than one's wife

Question

I am very confused. I had thought that the idea that a Jewish man may not touch a niddah, any niddah, except for perhaps his first-degree relatives, was basic information. Now, someone very knowledgeable has told me that this prohibition is not so; that the rules against touching not-one's-wife are only -- ok, "only" -- from the idea that one thing could lead to another.

This distinction seems like it could make a huge practical difference, for example, with handshaking in a case of significant need, or with jostling people on a bus, and other touch that is clearly (CYLOR) non-affectionate.

So what is the real reason for the prohibition for a Jewish man to touch a woman other than his wife: a pure prohibition on touching any niddah, or as a fence against relations (or against "affectionate touch" of a niddah, which it seems is also prohibited)?

Evidence that it's niddah:

• The stringencies on chuppat niddah. Although I guess there's a question of at what point the woman is considered married, to me this is good evidence, because the chances that they'd transgress under the chuppah are pretty close to zero. (But maybe, on the other hand, it could be evidence that we obey rabbinical prohibitions even if their motive no longer exists. [But then couldn't the rabbis relax their prohibition for the occasion, especially in view of the embarrassment to the bride?])

• Much of the layman's Internet, including this article, which states:

The second of these verses [...] [“Do not come near a woman during her period of uncleanness to uncover her nakedness” (Leviticus 18:19)], applies not just to one’s wife but to any other women as well, married or not (Responsa Rivash 425, Lev. 18:19). The rabbis extend this prohibition to include not just sex, but all touching. And since unmarried women do not go to the mikveh, they are considered to be always in a state of niddah –and therefore always off-limits for sex, or physical contact with men.

But from the same article:

Evidence that it's not niddah:

• Maimonides and Nahmanides, in a well-known rabbinic debate, consider how serious an infraction it is to touch a woman who is a niddah. According to Maimonides in Sefer Hamitzvot, “whoever touches a woman in niddah with affection or desire, even if the act falls short of intercourse, violates a negative Torah commandment” (Lev. 18:6,30). Yet Nahmanides’ (1194-1270) commentary states that acts such as hugging and kissing do not violate a negative commandment of the Torah, but only a rabbinic prohibition.

  The Siftei Kohen (17th century) further explains Maimonides by stating that he was only referring to hugging and kissing associated with intercourse. There are several places in the Talmud that the Amoraim (talmudic rabbis) hug and kiss their daughters (Kiddushin 81b) and sisters (Shabbat 13a), and their behavior is considered permissible.

• This answer: https://judaism.stackexchange.com/a/71543/1516

• The idea that harchakos are still stricter with one's wife

• The idea that many distinguished poskim permit strictly non-affectionate touch such as the handshake and jostling mentioned.

CYLOR

Answer 1

General: There are a number of activities which are rabbinically forbidden with one's wife when she is a nidda distinct from general prohibitions that apply to an ervah (someone carrying a karet prohibition). Incidentally, there are also some restricted activities with an ervah that are permitted with one's wife as a nidda. Most notably, the prohibitions of seclusion (Sanhedrin 37a) and gazing (Hilkhot Issurei Biah 21:4). In general, those activities rabbinically forbidden with one's wife as a nidda, are unrelated to general prohibitions with arayot and the two should not be confused.

Regarding touching a nidda: One is forbidden to touch his wife's body when she is a nidda. (Hilkhot Issurei Biah 11:19). This unique prohibition should not be confused with the general prohibition relating to arayot which likely includes nidda (see Hilhkot Issurei Biah 21:4, but cf. here).

Regarding touching arayot in general, according to Rambam (Sefer Hamitsvot Lo Taaseh 353, Hilkhot Issurei Biah 21:1) there exists a discrete prohibition of "lo tikr'vu l'galot ervah". This includes sexual contact such as hugging and kissing in a sexually pleasing manner. This isn't a prohibition of touching per se, but on intimate contact. Rambam does not indicate that there exists some other rabbinic prohibition other than this. Accordingly, non sexual contact with any erva such as a nidda (other than one's wife) would be permissible.

The one major dissenter in the ranks of the Rishonim, who extends this to contact that is not in and of itself overtly sensual, is Rabbenu Yonah (cited in Orehot Hayyim Vol II Hilkhot Biot Assurot: 13) who writes that any physical contact with a married woman (and I assume other arayot as well) is included in this Biblical prohibition:

איש אל כל שאר בשרו לא תקרבו וכן הלכה ברורה שהקריבה הזאת היא הנגיעה בידיה או בפניה או בכל אבר מאיבריה כדי ליהנות מן המגע

A man may not approach any flesh of his flesh (Leviticus 18:6), and it is clearly the law that this 'approaching' is [even] touching of her hands, face, or any of her limbs, in order to enjoy the contact.

In summary: Contact with arayot (other than one's wife) such as a nidda who is not one's wife, may be Biblically included in the prohibition of lo tikr'vu. The Torah prohibited not just sexual acts, but other forms of contact that could lead to them. Such contact would not include mere touching according to Rambam, but would include touching according to Rabbenu Yonah if it is done for pleasure.

While other touching would be strictly permissible, obviously everyone needs to employ common sense about what contact is prudent, and what risks leading to sin.

[According to Ramban (hassagot to Sefer Hamitsvot Lo Ta'aseh 353) the prohibition on intimate contact is rabbinic. Accordingly, it would be the rabbis, not the Torah that enacted this fence].