Is a condom ever permitted according to Halakha?
First, please note than an extensive presentation of the relevant sources on both sides of the issue, can be found in my source packet on birth control (in particular, the teshuvot of Rav Moshe, sources 41-44).
To respond briefly here – It is generally understood by the larger community that condoms are always forbidden. Amongst the poskim also, the dominant, although not unanimous, voice is that barring life-threatening situations (for example, a doctor who was poked by a dirty needle and is waiting for the results from an AIDS test, or when pregnancy would be life-threatening for the woman), condoms would always be forbidden. That being said, the author of the Tzitz Eliezer, Rav Waldenberg, rules in a case where semen causes a painful, burning sensation in the woman, that the husband could use a condom because serious pain is sometimes close to the category of pikuach nefesh.
Thus, one case in which a condom can and must be used is in a case of casual sex, or any situation in which there is a risk of AIDS or venereal disease, such as when the partner’s sexual history is not fully known. While it is not permissible to engage in sex outside of marriage, that does not change the reality that if someone is already doing it, he has an obligation to himself and to his partner of pikuach nefesh, ensuring that he is not endangering lives or the health of himself or others. See the article, AIDS: A Jewish Perspective, by Rabbi Yizchak Breitowitz, for more on this topic, as well as a Joy of Text podcast where we addressed this issue.
As I mentioned, while the dominant approach is that it is forbidden, there are other positions. The key question is whether this would be considered zera levatalah. Although the man ejaculates as a result of marital sex, the semen never enters into the woman’s body. Does that make it zera levatalah or not?
The restrictive approach is based on a number of Gemarot, particularly one that has to do with women using a mokh, some type of a sponge that caused semen to spill out of the vagina after ejaculation. There is a debate how to interpret this Gemara and which position to pasken like. For a number of Rishonim the conclusion is that except for life-threatening situations, the use of such a mokh is forbidden. Most poskim follow this position and rule that a condom, like a mokh, is strictly forbidden.
However, other Rishonim rule otherwise and state that a mokh is always allowed and the debate in the Gemara was only whether it was required in some circumstances (a detailed discussion and analysis of these approaches can be found in David Feldman’s “Martial Relations, Birth Control and Abortion in Jewish Law”). Maharshal in his Yam Shel Shlomo follows these Rishonim and rules that as long as the sex is taking place in a normal way – גוף נהנה מן הגוף – one body deriving pleasure from the other body – it is permissible and not considered zera levatalah.
This becomes part of a larger discussion rooted in a sugya in the Gemara regarding anal sex, as to whether semen ejaculated in the course of martial sexual activity but not inside the woman’s body should be defined as zera levatalah or not. This could include not only anal sex, but also oral sex or ejaculation as a result of manual stimulation by the wife. A number of Rishonim say such cases do constitute zera levatalah, there are conflicting manuscripts as to what Rambam says on the matter, and the RI in Tosafot and the Tosafot HaRid say that it is not zera levatalah.
RI however states that for a man to withdraw before ejaculation and ejaculate outside his wife for the purpose of preventing pregnancy would be considered zera levatalah because then the man is purposefully being mashchit the zera, destroying the semen, and it is not just a natural consequence of sexual activity between husband and wife.
Thus, even RI who is more lenient in general might forbid the use of a condom since this could be defined as intentionally destroying the seed. It is, however, possible to distinguish between the two cases, and to say that withdrawing to ejaculate outside the vagina is in itself an act of hashchatah, destroying the seed, whereas ejaculating naturally during sex, even if a condom were put on before, is defined just as ejaculation, and not an act of destroying the seed.
Rav Moshe Feinstein (EH 1:63) develops this position at great length and demonstrates how the position of RI can serve as a strong basis to permit condom use, at least according to some Rishonim. In other teshuvot he writes that condoms “should not be permitted as a practical matter,” indicating that the concern he has in permitting it is more policy-based than halakhicaly so.
Thus, while the dominant voice is that condom use is forbidden save life-threatening situations or serious health issues, there are some poskim who follow Maharshal (and RI, understood in one way), and who are lenient in cases when other options of birth control are not working.