Bittul Reshus – Eruvin 26b
תלמוד בבלי מסכת עירובין דף כו/ב
כשתימצי לומר לדברי רבי אליעזר המבטל רשות חצירו רשות ביתו ביטל לרבנן המבטל רשות חצירו רשות ביתו לא ביטל
Bittul translates literally as nullification. Of course, generally, it is preferable to enact an eruvei chatzeiros [joint participation in bread, matzo or some other collection of food] from befors Shabbos when the members of a courtyard, street or town want to carry in their common domain. When there are non-Jews in the area, sechiras reshus [rental from the non-Jewish neighbors] must be put into effect as well. Bittul is a third manner of unifying separate reshuyos ha'yachid. Where eruvei chatzeiros was not performed before Shabbos began, one or more of the other Jewish residents of the enclosed area may nullify their rights in the common domain in favor of one of the residents on Shabbos. The latter resident and members of his or her household may then carry throughout the area, but the others may not. Slightly more advantageous is the case where several of the neighbors have participated in eruvei chatzeiros, but one or more of the other Jewish residents did not participate. [This is an unlikely case, since generally eruvei chatzeiros is put into effect by zechiah.1 In making a blanket zechiah it is very unlikely that you might forget to include someone!] In this case, the participants in the eruvei chatzeiros would be allowed to carry to the exclusion of the neighbors who performed the bittul. In the final analysis, bittul is obviously not a very advantageous means of unification, and is therefore rarely used. The Halachos of bittul are to be found in Shulchan Aruch, Orach Chaim 380-381.
1. One person may take his own loaf of bread and grant the other residents ownership of it by way of the halachic device of “zechiah” [literally: bestowing ownership]. This procedure is relatively simple, and readily accessible in such common sources as the Kitzur Shulchan Aruch (94:6-7; see Shulchan Aruch, Orach Chaim 366:9).