After a lengthy period of study, my Shabbat morning shiur has reached the end of the laws of Eruvin, the last section of which dealt with carrying on Shabbat inside hotels and hospitals in an area not bounded by an Eruv.
One may one carry within a private domain on Shabbat. The process of making what we call an Eruv is actually called ‘Eruv Chatzerot’ – merging of courtyards (or private domains). Fearful of error, the rabbis required this process to allow one to carry even between adjacent private domains. So to allow neighbours to carry between their gardens on Shabbat, they must make a Eruv: this involves each contributing a quantity of food (in effect, buying a box of matzot between them) and declaring one of the homes as a joint dining room/kitchen for all of the homes. In the eyes of halachah, this ‘merges’ the homes into a single private domain, enabling the inhabitants to carry freely through all the dwellings and gardens.
This process is duplicated (in a slightly different way and on a much larger scale) for a city Eruv, such as the one that surrounds much of our community.
Shared public areas
This situation is complicated by the fact that some buildings (such as blocks of flats) have shared public areas: e.g. lobbies and stair-wells. In these situations, the rabbis legislated as follows:
Public courtyards… if one has made an eruv, one may carry, but if one has not made an eruv, on may not. (Shabbat 6a)
Since the house is a private dwelling and the courtyard is permitted to all, one is effectively carrying from one domain to another, even though (technically) they are both private domains. To make a ‘fence’ to the law, to avoid inadvertent sin, the rabbis prohibited this so that one will not end up carrying from a private domain to a public one. (Rashi ad loc.)
To avert this, the rabbis require each inhabitant of the block to contribute to the Eruv. However, the presence of a gentile (who, of course, is not bound by the laws of Shabbat) presents a difficulty, as he/she has equal rights to the public area, but cannot participate in the Eruv. This is overcome by ‘hiring’ rights of access for a nominal sum from any gentile resident. Assuming that every gentile agrees, the Eruv becomes functional.
Hotels and hospitals
Clearly, these arrangements cannot work in places where the residents come on go on a frequent basis, the most common examples being hotels and hospitals. May one carry between rooms of a hotel or hospital or from one’s room to the public areas? This obviously has major ramifications for travellers and patients. However, the matter is quite simple:
People who live around a courtyard and all eat at one table, even if each has his own house, do not need a Eruv, because they are like members of one household. Similarly, if several people eat in one room, each at his own table, even if each has his own room. (Shulchan Aruch Orech Chaim 370)
Sharing a table is akin to an Eruv – i.e. the central dining room functions as a ready-made Eruv and one may carry within the premises (provided, of course, that it is entirely enclosed) without restriction.
This describes a modern hotel, but does not deal with a hospital. However, it seems that if the management has the right to move the residents from one location to another (definitely the case in a hospital), they do not have sufficient rights to their room for it to confer halachic significance:
If they (the owners) can remove him at any time….(no Eruv is needed) (Bi’ur Halachah 370)
This means that patients (and visitors) in a hospital may carry freely within the building on Shabbat. It seems that the original concern that led the rabbis to require an Eruv in shared buildings only applies where the each resident lives permanently in his own residence and usually eats there too.