An eruv is a legal construct that allows Jews to move objects, including prayer shawls and baby strollers, within a public area on Shabbat, an act that would otherwise be prohibited. Through the eruv, the area, which can greatly range in size, becomes legally joined through two mechanisms. Firstly, one must enclose the territory, either through physical barriers or symbolic doorposts (made of strings and poles), to designate the area’s border.

Secondly, people within the area must establish a legal relationship that symbolically unifies ownership of the territory. This is accomplished through the residents sharing possession of a designated object (frequently a box of matza) and renting the territory from the local government to authorize joint use of public area for these purposes.

These processes have generated two types of controversies.

In the Diaspora, there is occasional opposition from local residents to the government providing permits for construction and space rental. Fortunately, courts have repeatedly understood that an eruv facilitates the religious liberties of observant Jews without infringing on the rights of others.

Indeed, the widespread building of eruvin in many Jewish communities, in both Israel and abroad, has enhanced religious life by allowing families, including young children and the handicapped, to attend synagogue services and celebrate Shabbat outside of their homes. Many 20th-century rabbis desired to build eruvin because they (rightly) feared that their congregants would – accidentally or otherwise – violate Shabbat regulations that greatly inhibited their activity. This sentiment, in part, was already expressed by medieval scholars who ostracized rabbis that did not construct halachically acceptable eruvin within their locales.

The aspiration to build eruvin within modern metropolises, however, generated a second, more fundamental disagreement regarding which territories may be enclosed within an eruv, as recently evidenced in the London eruv controversy. The sages asserted that biblical norms proscribe one from carrying an object more than roughly two to three meters within a public domain (e.g. a desert) or transporting something from a public domain into an enclosed private domain. The rabbis imposed similar restrictions on a carmelit, a semi-enclosed area not intended for mass thoroughfare, such as an alleyway or a courtyard enclosed on three sides.

Because the latter prohibition was a rabbinic stringency, greater leniencies were afforded to enclose the area into a private domain, including the building of a symbolic doorpost on its fourth side.

For any area (such as a city street) to be characterized as a public domain, it must be uncovered, entirely publicly owned, have a minimum width of 7.3 meters (or 9.8 meters according to some) and allow 24-hour public access. If the thoroughfare has walls, like some public markets do, the street must run uninterrupted throughout the area. Most significantly, many medieval authorities, including Rashi, claimed that a public domain requires the presence of 600,000 people – the number of Jews included in the biblical census in the desert – although this requirement was listed neither in the Talmud nor by Maimonides.

Accordingly, most medieval scholars asserted that their towns did not constitute a public domain since they lacked the requisite street width and population, or their walled cities were locked at night and did not have unobstructed streets.

New problems emerged in the modern era, as sprawling cities sprouted up and Jews moved out of walled neighborhoods into urban environs.

Many scholars, including Rabbi Jacob Brukhim of Lithuania, contended that modern streets were wide enough to constitute public domains and that one could not rely upon the criterion requiring 600,000 people.

Depending on calculations, one might further argue that more than 600,000 people daily traverse certain areas or streets within cities like New York or Paris. As such, one cannot turn large metropolitan thoroughfares into a “private domain,” even though eruvin might remain possible in smaller, less populated areas.

Besides defending the use of the 600,000 population standard, supporters of metropolitan eruvin rely on one or more of the following arguments: (1) contemporary avenues that digress with curves or turns do not fit the criterion of uninterrupted streets; (2) The buildings that frequently surround major streets (i.e., “urban canyons”) in fact provide two halachic walls, which are joined by a third wall when the street dead ends, thereby making it a carmelit; (3) The 600,000 population count may only include pedestrians, since car passengers, who are encompassed within their own domains (i.e., the walls of the vehicles) do not get tallied; (4) The 600,000 people must be found on a particular street, as opposed to the entire encompassed area; (5) Some of the dispensations afforded to a carmelit may also be used in a public domain; and (6) More substantive material that could theoretically block a street, such as a tarpaulin wrapped around a lamppost, can be used to provide a sufficient barrier.

Taken together, these arguments have facilitated the widespread building of metropolitan eruvin and arguably comprise the most creatively lenient position in contemporary halachic discourse.

The author teaches at Yeshivat Hakotel and directs the Tikvah Israel Seminars for Post- High School Students. JPostRabbi@ yahoo.com

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