Halakhah su Levitico 18:3

We are not permitted to follow the ways of the gentiles, nor adopt their styles in dress or in hair style or similar things, as it is said: "You shall not follow the ways of the gentile."³Leviticus 20:33. It is [also] said: "In their ways you shall not follow"⁴Leviticus 18:3. It is [also] said: "Guard yourself lest you be ensnared to follow them."⁵Deuteronomy 12:30. You should not wear a garment which is specifically worn by them as a symbol of ostentation, such as a garment of high-ranking officers. For example, the Talmud states:⁶Maseches Sanhedrin 74a. that it is forbidden for a Jew to be similar to them even in regard to shoelaces; if their practice was to tie one way and the practice of Jews to tie another way, or if their practice was to wear red shoelaces and Jews wear black shoelaces because the color black indicates humility, submissiveness and modesty. [In all such instances] it is forbidden for a Jew to deviate. From these examples everyone should learn how to apply these standards to his time and place. A garment designed for showiness or immodesty must not be worn by a Jew, but rather his clothing should be made in a style which suggests humility and modesty. The following is mentioned in Sifrei: You should not say that since they go out with scarlet I shall go out with scarlet, since they go out with kulsin (the word kulsin meaning weaponry) I also shall go out with kulsin, because these practices are indicative of arrogance and haughtiness which are not the heritage of Jacob. Rather, our heritage demands of us to be modest and humble, and not be influenced by the haughty. Similarly, any custom or statute of which there is a suspicion of idolatrous intent or background should be avoided by Jews. Similarly, you should not cut your hair or style your hair as they do, but rather you should be distinct, in your clothing and speech and all other endeavors just as you are distinct in your perspectives and concepts. Similarly, it is said: "I have set you apart from the nations."⁷Leviticus 20:26.

A number of arguments auguring against use of data derived from Nazi experimentation have appeared in articles published in rabbinic journals. The most sweeping criticism of utilization of this information is based upon an appeal to a well known and fundamental principle of Jewish law: "Everything may be utilized for healing, save for idolatry, some forms of sexual licentiousness and homicide" (Pesaḥim 28a). It is alleged that it is this principle that is employed by Rambam in his Commentary on the Mishnah, Pesaḥim 66a, in explaining the basis of the approbation expressed by the Sages for certain actions on the part of King Hezekiah. The Gemara reports that Hezekiah suppressed a certain medical work and that his conduct found favor in the eyes of the Sages. Rambam, together with other classical commentators on the Talmud, is troubled by the Sages' endorsement of what appears to have been a singularly irrational act. Medical works are indispensable aids in effecting cures and preserving life. One would have anticipated that the Sages would have advocated the broadest possible dissemination of medical knowledge rather than its suppression. One explanation offered by Rambam in resolution of this perplexity is that the work in question advocated modes of therapy "which the Torah does not permit to be used for healing." Rambam's reference is either to practices that are themselves idolatrous in nature, or more likely, to the "ways of the Amorites" and kindred practices prohibited because of their association with idolatry and encompassed within the ambit of the prohibition "and you shall not walk in their statutes" (Leviticus 18:3). Nevertheless, in context, Rambam's comments must be understood as restricted to a ban against performance of an illicit act for therapeutic purposes, not as banning subsequent utilization of information gleaned from the performance of such an illicit act.

Women who rub up on each other is forbidden, from it being like that of the forbidden sexual actions of the Egyptians (cf. Lev. 18:3), upon which we were warned. And it is appropriate to strike them with disciplinary flogging since they have committed a prohibited action. And there is for a man to be careful about his wife's activities in this regard and to hold back women who are known to be involved in this from coming into see his wife or for her to visit them.

The Aruch Laner (commentary to Makkot 21a s.v. Gam Im), on the other hand, states that one violates a biblical prohibition even if his intention is not for idolatry. The Aruch Laner and Rav Gestetner note that the Rambam and Shulchan Aruch seem to agree with this view, as they do not confine this prohibition only to one whose intention is for idolatry. Moreover, Rav Gestetner observes that Tosafot (Gittin 20b s.v. B’chtovet) clearly indicate that a biblical prohibition is violated even if one’s intention is not for idolatry.⁹The Maharam Schick (commentary to Sefer Hamitzvot, mitzvah 254) contends that the prohibition of kitovet ka’aka is related to the prohibition to imitate gentile practices (Vayikra 18:3) and as such is violated as long as the tattoo is made for no (substantive) reason.

He prohibited us from following in the ways of the idolaters, and from behaving according to their practices - and even with their clothing and with their gatherings in their assemblies. And that is His, may He be exalted, saying, "You shall not follow the practices of the nation(s)" (Leviticus 20:23). And in the explanation (Sifra, Acharei Mot, Section 8:8), it appears - "I only said those that were established for them from their forefathers." And the language of the [Sifra] (Sifra, Acharei Mot, Chapter 13:8) is, "'And in their statutes you shall not walk' (Leviticus 18:3) - in their customs, those things that are established for them, such as theatres and circuses." And these were types of assemblies in which they would gather for worship of the images. "Rabbi Meir says, 'These are the ways of the Amorites, which the Sages enumerated.' Rabbi Yehudah says, 'that you not round [your face], and not cultivate locks, and not wear the hair komi.'" And one who does one of these things is liable for lashes. And the prohibition of this content was repeated in another place. And that is His saying, "Take heed unto yourselves, lest you are drawn in after them" (Deuteronomy 12:30). Lest you resemble them and do their deeds and it becomes a stumbling block; that you should not say, "Since they are going out with telusin, I will also go out with telusin" - and that is a type of weapon of the Persians. And you already know the language of the prophet (Zephaniah 1:8), "and all such as are clothed in foreign garments." And this is all to distance ourselves from them and to revile all of their practices, and even their clothes. And the regulations of this commandment have been explained in the sixth [chapter] of Shabbat. (See Parashat Kedoshim; Mishneh Torah, Foreign Worship and Customs of the Nations 11.)