As we have seen, according to most poskim one may not violate a shvut even for the sake of a mitzva, while according to Itur one may do so. The halakha follows the majority. However, when the mitzva in question has a communal nature, one may rely on Itur in certain cases. Such cases include a situation in which the local eruv has become invalid, and if it is not fixed, many will violate the prohibition of carrying. In such a case one may ask a non-Jew to fix the eruv, even if doing so involves performing melakha that is prohibited by Torah law (MB 276:25).
Some say that even though one may, under pressing circumstances and for the public good, violate the shvut of telling a non-Jew to perform a melakha, a Jew still may not perform a rabbinically prohibited melakha for the sake of a public mitzva. Others maintain that if it is truly necessary – in a case of great need as well as a communal mitzva – then a Jew may transgress a shvut. For example, in the case above in which the eruv is down, if there is no non-Jew available to fix it and, if it is left as is, many people will carry on Shabbat, a Jew may fix the eruv, using a tie knot if possible (see 29:8 below). This is the custom in practice.
The Sages further permitted violating a shvut in order to preserve kevod ha-briyot (human dignity). For example, if one uses the bathroom but has nothing with which to wipe himself, it would be extremely embarrassing if he were to simply refrain from wiping. Because of this, the Sages allow one who finds himself in such a situation to use a muktzeh item or to tear toilet paper with a shinui, both of which are normally rabbinic prohibitions (SA 312:1; MB 12; below 13:11).
There is one special mitzva for which everyone agrees that one may violate a shvut le-khatĥila, even when there is no great need. This is the mitzva of settling the Land of Israel, and the leniency exists on account of its tremendous importance. If a Jew has the opportunity to buy a house in Israel from a non-Jew on Shabbat, he may ask the non-Jew to write up the contract on Shabbat and make sure that it is registered by the courts, as well as show the non-Jew where his money is and allow him to take the money that is coming to him. He may do so even in order to buy a small room of four square amot (one ama is 45.6 cm). Buying property from a non-Jew in Eretz Yisrael constitutes a fulfillment of the mitzva of settling the land and benefits the entire Jewish people (Ramban on Shabbat 130b; Rivash §387; SA 306:11; MB ad loc. 45-47).
. Behag, Rashba, and Rabbeinu Yehonatan agree with Itur. Rema 276:2 attempts to find some justification for the actions of those who ask a non-Jew to light a candle for them to illuminate the Friday night meal (an action that is prohibited by Torah law), by assuming that they are relying on Itur, which permits transgressing the shvut of asking a non-Jew to do melakha if it is for the sake of a mitzva. However, this is not Rema’s ruling in practice, as AHS explains in 276:13, and as we see from MB 276:24. But in the case of a communal need, according to many poskim one may rely on Itur. Thus Ĥayei Adam 62:11 cites Panim Me’irot 1:30, which states that one may ask a non-Jew to fix the eruv even if doing so entails transgressing a Torah prohibition, in order to avoid mass Shabbat desecration. This is quoted as the halakha in MB 276:25, and this is the custom in practice. Similarly, if the electricity goes off in the synagogue on Friday night in the middle of prayers, one may ask a non-Jew to turn the lights back on for the good of the community. If there are two non-Jews present, it is preferable to ask one of them to ask his friend to perform the melakha, because some maintain that such a case is considered a shvut di-shvut (see MB 307:24). If one offers the non-Jew something to eat so that when he turns on the light he himself will benefit, then this is permitted even le-khatĥila. (Also see below 25:4.)Even though we rely on Itur when it is necessary for the good of the community and permit the shvut of asking a non-Jew to do melakha for us, we do not permit a Jew to perform a rabbinic melakha directly (MB 276:21). However, in a time of great need, when there is no non-Jew available, and it is for the sake of a communal mitzva, some allow a Jew to transgress a shvut directly. This is recorded in Responsa Mahari Ashkenazi §13; Panim Me’irot 1:30; Sho’el U-meshiv 2:1:89. SSK 17:34 rules leniently in the case of a Jew fixing an eruv by using a tie knot, an act that is only rabbinically prohibited. (By fixing the eruv, one forms a meĥitza [wall] that permits carrying, and forming such a wall is rabbinically prohibited; see below 15:4; 29:8.)
If there is the possibility of an exceedingly great loss, the poskim permit telling a non-Jew to perform a Torah prohibition to prevent a Jew from desecrating Shabbat himself (MB 307:69). There are also situations in which they allow a Jew himself to transgress a rabbinic prohibition in order to avoid a great loss, such as carrying money with a shinui (Rema 301:33; SA 334:2). In contrast, when it comes to putting out a fire and everything connected to it, they are stringent, out of concern that leniency in such a case would encourage people to actually put out fire on Shabbat (see below, 16:5:1).
If masses are at risk of injury, one may extinguish a burning coal in a public thoroughfare (SA 334:27; below 16:8). One may also kill an animal whose bite causes great pain (SA 316:10; below 20:10).
. Explaining the special permission granted to desecrate Shabbat in order to buy a home in the Land of Israel (permission that is not granted for other mitzvot), Ramban writes: “It is a mitzva that benefits all Jews, that the Holy Land not be desolate” (Shabbat 130b). Rivash §387 expresses similar sentiments. The Sages state that the mitzva of settling the Land is equivalent to all the other mitzvot (Sifrei, Re’eh §53), and this permission gives expression to this idea within a halakhic framework. To be sure, according to Itur, one may transgress a shvut le-khatĥila for the sake of other mitzvot as well, but most poskim limit this leniency to settling the Land, even when there is no public good riding upon it. See Eliya Rabba 306:22, which maintains that even the act of acquisition may be undertaken on Shabbat. However, one may not carry money, since the Jew can simply show the non-Jew where the money is, and the non-Jew can then take it for himself.