Clothing is intended to protect the body from cold, heat, and rain, and to provide adornment, dignity, and modesty. One who wears a sha’atnez garment for any of these purposes violates the prohibition, as the Torah states: “You shall not wear sha’atnez” (Devarim 22:11). The prohibition applies to shirts, pants, dresses, skirts, undergarments, socks, hats, cloth shoes, gloves, ties, decorative ribbons, and all other garments ordinarily worn. Even if only the garment’s hanging loop or attached label is sha’atnez, the garment may not be worn (SA YD 301:15).
The prohibition also applies when sha’atnez fabric is draped over the body for warmth, protection from heat, or modesty, even though it is not worn in the usual manner of a garment. The Torah states: “A garment of mixed kinds, sha’atnez, shall not come upon you” (Vayikra 19:19). Thus, any use of sha’atnez that provides a benefit ordinarily associated with clothing is prohibited. One may not cover oneself with a sha’atnez blanket or dry oneself with a sha’atnez towel, since both provide warmth. The Sages also prohibited using sha’atnez as a tablecloth, out of concern that someone might occasionally pull it over their legs for warmth (SA YD 301:9). For the same reason, they prohibited hanging a sha’atnez curtain, since adults or children might use it for warmth. It may, however, be hung above head height or made of stiff fabric, since it cannot then be used for warmth (ibid. 11). Nor may one use sha’atnez fabric to handle a hot pot or frozen object, since it protects the hand from heat or cold and thus provides a benefit ordinarily associated with clothing (ibid. 12).
One may, however, benefit from sha’atnez fabric in ways unrelated to clothing. Thus, it may be used for a tent or umbrella.
Moreover, according to many authorities, one may wear a sha’atnez garment when doing so serves a purpose entirely unrelated to clothing. Thus, if customs duty is imposed only on garments packed in luggage, a Jew transporting sha’atnez garments belonging to non-Jews may wear them over his clothes while crossing the border, provided he does not intend to benefit from them as clothing. Likewise, a clothing seller may put on a garment solely to display it to customers, provided he does not intend to derive any benefit from wearing it (Rosh; Ramban; Ran; Rema YD 301:6; Yam Shel Shlomo). Other authorities are stringent and prohibit wearing sha’atnez even for these purposes, whether to avoid customs duty or to display a garment to customers (Rambam, as understood by Beit Yosef; SA YD 301:5–6).[1]
Some have suggested that the authorities disagree as to whether adornment and modesty are independently considered benefits of clothing (see Ha-sha’atnez Le-halakha 4:2–4). In fact, there is no substantive disagreement, since a garment worn for adornment or modesty is generally also capable of providing warmth. The more precise definition of a garment, then, is an item capable of warming the body, even if it is worn primarily, or even exclusively, for adornment or modesty. A tie, for example, is worn for appearance but can still provide some warmth. Similarly, a woman may wear a base-layer shirt solely for modesty, but it is nevertheless considered a garment because it can provide warmth. By contrast, a sha’atnez pendant designed solely as an ornament is not considered a garment and may be worn on a chain.
The Mishna states: “One may not wear kilayim, even over ten garments, even to ‘evade’ customs duty” – that is, to qualify legally for an exemption from the tax, as explained above (Mishna, Kilayim 9:2). Later, the Mishna states: “Clothing merchants may sell in their ordinary manner,” meaning that they may model the garments on their bodies, “provided they do not intend to protect themselves from the sun in hot weather or from the rain in wet weather; the scrupulous carry the garments on a pole” (Mishna, Kilayim 9:5). Rosh and the authorities who follow his view understand these two rulings to disagree, and they rule in accordance with the latter: one may wear a garment in the ordinary manner when the sole purpose is to display it, provided one does not intend to benefit from wearing it. The same reasoning permits wearing a garment to avoid customs duty, although the scrupulous refrain from doing so. This is also the view of Yere’im, Or Zaru’a, Ramban, Ran, R. Yeruḥam, and Semag. This is not considered a case of pesik reisha, in which the prohibited benefit is inevitable, because the wearer may derive no benefit from the garment at all, as when he is already sufficiently warm. Ran further maintains that when the prohibition itself is against deriving benefit, intent to benefit is a necessary condition. The act therefore remains permitted even if some benefit is inevitable.
Rambam, by contrast, rules in accordance with both passages, indicating that he does not understand them to disagree. In his view, clothing merchants were permitted to drape garments over themselves only in a manner unlike ordinary dress, such as without putting their arms through the sleeves. Since the garment is not worn normally, the absence of intent to benefit makes the act permissible. Wearing it in the ordinary manner, however, is always prohibited (R. Avraham b. Rambam; Mahari Kurkus; Beit Yosef; among others). Other authorities understand Rambam differently. In their view, a merchant may put on a suit in the ordinary manner in order to model it, since his sole interest is in displaying the garment and he derives no benefit from wearing it. A person seeking to avoid customs duty, however, specifically needs to wear the garment in order to obtain the exemption. Although his ultimate purpose is to avoid the tax, that purpose is achieved through wearing the garment itself (Taz; Shakh).
Some maintain that one may try on a sha’atnez garment to determine whether it fits, intending to buy it and then have the sha’atnez removed, since trying it on is not intended to provide the benefits of clothing (Riaz, cited in Shiltei Giborim, following Rosh and most Rishonim). Others prohibit this because the person intends to wear the garment as part of trying it on (Ḥokhmat Adam 106:20). When a garment merely might contain sha’atnez, one may try it on and then send it for testing (Yabi’a Omer 6:27; Ḥeshev ha-Efod 1:137; see also Ha-sha’atnez Le-halakha 4:26).
