1) HALACHAH: OPENING CONTAINERS OF FOOD ON SHABBOS OR YOM TOV
The Gemara discusses opening sealed vessels on Shabbos by cutting or destroying them on Shabbos. As Rashi explains, the Gemara addresses whether the Melachah of Stirah (breaking a usable structure) is involved when one opens a container on Shabbos or Yom Tov.
The Gemara's discussion has common practical ramifications. May one open sealed bottles and other types of food containers on Shabbos or Yom Tov?
There are three possible Melachos involved with opening bottles, cans, and other containers on Shabbos and Yom Tov: Stirah (breaking a usable structure), Boneh or Makeh b'Patish (producing a finished, usable vessel), and Kore'a (tearing). An additional Isur d'Rabanan may apply: even if one does not open the container in a way which forms a usable utensil, the Rabanan prohibited opening the utensil under certain circumstances lest one open it with intention to make it into a usable utensil.
Despite these four considerations, the Beraisos here allow one to open "Chosamos sheb'Kelim," cords that fasten containers and keep them closed. Similarly, the Mishnah in Shabbos (146a, and as cited later on 33b) permits one to shatter a barrel in order to get to the food inside.
I. As an introduction to the contemporary applications of these issues, it is necessary to examine why the Beraisa and Mishnah permit one to open containers despite the four considerations mentioned above.
1. RASHI in Shabbos (146a, DH Shover) explains that one is permitted to break a barrel because the act is "Mekalkel," a destructive act. The RASHBA and RAN add that although the Rabanan prohibited one from performing a Melachah even in a destructive manner, in this case no Melachah at all is accomplished since "Ein Binyan u'Stirah b'Kelim" -- "the Melachos of Binyan and Stirah do not apply to utensils" (but only to structures and objects attached to the ground).
2. TOSFOS in Eruvin (34b, DH va'Amai) and Shabbos (146a, DH Shover) rules that if one actually produces or destroys a functional utensil on Shabbos, the prohibitions of Binyan and Stirah do apply. However, one is permitted to break open a barrel to get to its contents in one particular case: when the barrel is made of broken utensils that have been tarred together ("Mustekei"), as the Gemara mentions with regard to another matter in Beitzah (33b). The SHULCHAN ARUCH (OC 314:1) rules in accordance with the opinion of Tosfos and says that Binyan and Stirah do apply to utensils, and the only type of barrel that one may open on Shabbos is one that was broken and then glued back together. One may not break a complete, unbroken barrel in order to get the food inside of it.
3. The RITVA in Shabbos (ibid.) and TOSFOS RID there agree with Tosfos that the prohibitions of Binyan and Stirah apply to Kelim. However, they suggest that the Rabanan did not prohibit one from destroying a utensil in order to get the food inside when one wants to eat the food on Shabbos (that is, there is a "Tzorech Shabbos"). The prohibition against destroying the barrel is only mid'Rabanan since the act is not "Stirah Al Menas Livnos" (destroying with intent to build). When the object that one wants to destroy is the type that is normally not put back together, the Rabanan permitted one to destroy it for the sake of eating the food on Shabbos (because destroying such a vessel is never considered "Stirah Al Menas Livnos").
4. A fourth approach is that of the CHIDUSHEI HA'RAN in Shabbos (based on the Yerushalmi), who compares breaking open a barrel of food to cracking open a nut. The barrel is not considered a utensil at all; rather, it merely serves as a "shell" for the food inside it, and it must be broken in order to get to its contents. (According to this reasoning, the Melachah of Boneh does not apply to such a barrel; see following paragraph.)
B. BONEH and MAKEH B'PATISH
As mentioned above, the Rishonim argue whether the Melachah of Boneh applies only to objects attached to the ground or even to utensils. Even those who do not apply the Melachah of Boneh to utensils agree that another Melachah applies in the case of utensils: Makeh b'Patish, completing the formation of a vessel. The Mishnah in Shabbos (ibid.) teaches that one may not intentionally make a neat opening in a container (such as by making a clean hole in it). Such an act is considered Boneh (building an opening or a utensil) or Makeh b'Patish.
1. However, TOSFOS (Beitzah 34b, DH Ki Tanya, consistent with his opinion mentioned above in A:2) maintains that if the barrel is made of broken utensils which have been tarred together ("Mustekei"), it is not a considered a utensil even if one punctures it in a neat and usable manner. RASHI and other Rishonim do not accept this ruling.
2. In addition, if the opening was already there but an object was attached to the utensil to block the opening (such as a lid which is tarred onto the barrel), one may remove that object. Such an act is not considered the formation of a utensil (Shabbos 48b, and Rashi DH Magufah).
The Poskim permit one to tear the wrapping of a package in such a way that the wrapper cannot be used again. A combination of reasons allows one to be lenient in this matter. (See SHEMIRAS SHABBOS K'HILCHASAH, ch. 9, fn. 11; IGROS MOSHE OC 1:122.)
D. GEZEIRAH SHEMA YISKAVEN LA'ASOS KLI
The Gemara in Beitzah (33b) states clearly that one is prohibited to puncture a barrel even in a way which does not produce a clean hole and which does not constitute Boneh or Makeh b'Patish mid'Oraisa. The Rabanan prohibited this act lest a person puncture the barrel in a way that does constitute Boneh or Makeh b'Patish.
However, the Gemara concludes that if the barrel is made of broken utensils which have been tarred together ("Mustekei"), there is no concern that one will puncture it with intention to create a clean hole, since a person has no desire to save such a vessel for further use (Rashi). The Poskim add that any container which is usually discarded after it is emptied of its contents falls into this category. The Rabanan did not prohibit one from forming a rough hole in such a container; a person normally does not try to puncture such a container in a neat way because he has no intention to use it in a permanent manner (Shemiras Shabbos k'Hilchasah, ch. 9, fn. 10).
II. HALACHAH: How do these considerations apply in practice today?
The SHEMIRAS SHABBOS K'HILCHASAH (ch. 9) provides a comprehensive summary of the rulings of RAV SHLOMO ZALMAN AUERBACH zt'l and other contemporary authorities with regard to opening containers on Shabbos or Yom Tov. (The following summary applies only to opening containers in such a way that no letters or illustrations are torn. If letters or illustrations are torn, the act of opening the container may be prohibited because of "Mochek," erasing.)
A. SEALED PLASTIC BAGS OR PAPER CONTAINERS
1. Containers which are made to be emptied and disposed of as soon as they are opened (such as small packets of sugar) may be opened and emptied on Shabbos (even if a neat opening is formed). Rav Moshe Feinstein zt'l (IGROS MOSHE OC 1:122) compares opening such a container to cracking the shell of a nut. Like the shell of a nut, the wrapper of the food item has no use other than to protect the food until it is eaten (see above, I:A:4).
2. Containers made to hold the food while one eats and to be disposed of after their contents are eaten (such as bags of potato chips, plastic milk bags and paper milk cartons) may be opened according to Rav Moshe Feinstein (who compares such containers to nutshells as well), provided that the person intends to dispose of them after he finishes their contents.
However, Rav Shlomo Zalman Auerbach zt'l categorizes such containers as utensils rather than shells. Nevertheless, he compares them to a wine barrel made of broken utensils which have been tarred together ("Mustekei"; see above, I:D) since such containers are not made to last (Shemiras Shabbos k'Hilchasah, ch. 9, fn. 7 and 10; Minchas Shlomo 91:12). Therefore, one should not open such containers in a manner in which a neat opening is formed (see above I:B). Moreover, a plastic bag whose sides have been pressed together to create a seal at the top and bottom may not be opened neatly by pulling it apart at the sides (ibid., ch. 9, fn. 19). One is permitted, however, to open such containers in a way that a rough, untidy opening is formed. (The CHAZON ISH OC 51:11 is more stringent and judges these containers to be the same as those in category A:3 below.)
3. Containers which are made to be saved and reused after they are emptied are not comparable to "Mustekei." Therefore, one is prohibited to make even an untidy opening in such a container lest one make a neat opening and transgress an Isur d'Oraisa (of Boneh or Soser), as mentioned above (I:D).
a. However, Rav Shlomo Zalman Auerbach permits one to open such a container if one punctures it or otherwise renders it unusable as a container either before he opens it or while he opens it (Shemiras Shabbos k'Hilchasah 9:2, 3, and 12).
b. Also, if the container is sealed with only a string or a paper cover which must be cut in order to open it, one is permitted to cut the string (in a way which renders the string unusable for future use), as the Gemara here rules with regard to "Chosamos sheb'Kelim" (ibid. 9:9 and 14).
c. Similarly, if the lid or opening is clearly distinct from the rest of the bag or container but is connected to the container by a pull-off strip, one is permitted to remove the pull-off strip since it is comparable to a lid that has been tarred onto a barrel (see above, I:B:2). (This is the ruling of Rav Shlomo Zalman Auerbach in a letter printed in MA'OR HA'SHABBOS, Peninei ha'Ma'or 6:4, in which he explicitly rejects what was written in Shemiras Shabbos k'Hilchasah 9:18).
B. BOTTLE CAPS AND SCREW-OFF COVERS
1. Flat, metal bottle caps -- the type which are lifted off with a bottle opener -- may be removed (Mishnah Berurah OC 314:17, Chazon Ish 51:112, Minchas Shlomo 91:12). Their removal does not constitute an act of Stirah or Boneh on the bottle because these caps clearly are separate entities from the bottles even before they are removed (see above, I:B:2).
However, there is another problem with removing caps of bottles. Under certain circumstances, the removal of the cap from the bottle constitutes the formation of a new utensil (the cap), and thus one transgresses Boneh (or Makeh b'Patish) as far as the cap itself is concerned. When does the removal of the cap from the bottle make it fit for future use (to use as a cap for other bottles) and when is the cap already considered to be a usable cap even before it is removed from the bottle?
Rav Shlomo Zalman Auerbach establishes the following guideline. If the bottle cap can be used to cover another bottle when it is removed in its present state (such as by breaking the bottle within the cap and removing the bottle from the cap), then it is already considered a usable utensil and one may remove it. In the case of lift-off metal caps (such as the cap of a beer bottle), the cap in its present state can be used to cover other bottles to a certain extent, and therefore one who removes such a cap does not form a new utensil (Minchas Shlomo ibid.; Shemiras Shabbos k'Hilchasah ch. 9, fn. 61).
2. Screw-off metal bottle caps which do not leave behind a ring when removed, or plastic bottle caps even if they do leave behind a ring (which was originally attached to the cap at a number of distinct points) may be removed. Their removal is not considered Soser or Boneh of the bottle, nor is it considered the formation of a new, usable bottle cap, since the bottle cap was already a distinct, usable utensil which did not require further formation, as mentioned above. (This applies only to the type of removable, ring-less bottle cap which has slits on bottom which allow the cap to be screwed off. A cap which is physically warped or widened as it is unscrewed may not be removed. See letter of Rav Auerbach in Ma'or ha'Shabbos, Peninei ha'Ma'or 6:3.)
In the case of plastic caps, even though they are connected to the ring while on the bottle, they were originally distinct caps in their own right and were simply fused to the ring at the factory (by melting). Even after they are placed on the bottle, they appear as distinct entities from the rings. Removing the plastic cap from the ring is therefore like removing the lid of a barrel that was tarred onto the barrel (see above, I:B:2; Minchas Shlomo ibid.). Others point out that in many factories the plastic caps are attached to the rings before they are affixed to the bottle, and they are placed on the bottle with the application of mild to strong pressure. Accordingly, they are already considered usable utensils in their present state (on the bottle), such that if the bottle would be broken and removed from underneath them, they (cap and ring together) could be reapplied to another bottle. Therefore, one does not make a utensil when he removes a plastic cap from its ring (see Peninei ha'Ma'or 6:5).
(The difference between these plastic caps and metal caps which leave a ring on the bottle is that the metal cap never existed before as two separate parts, a top and a ring. When it was placed on the bottle, it was one large piece which was fitted to the bottle with a shrinking process. Breaking the two apart involves the creation of a new item: a re-usable bottle cap which did not exist before.)
3. A metal bottle cap which leaves a ring around the bottle neck when removed (where the ring was formerly part of the cap) may not be removed on Shabbos or Yom Tov because it cannot be used on another bottle without removing its ring first. Similarly, a cap which becomes physically widened or warped in any other way when removed may not be removed on Shabbos. In both of these cases, the removal of the bottle cap completes the formation of a usable cap (Minchas Shlomo ibid., Shemiras Shabbos k'Hilchasah 9:17, Rav Y. S. Elyashiv, Rav Binyamin Zilber; others, however, permit the removal of all bottle caps -- see TZITZ ELIEZER 14:45).
Rav Shlomo Zalman Auerbach zt'l permits one to open this type of cap, however, if he first punctures the cap (in a manner which does not destroy any letters or illustrations printed on the cap), or if one otherwise renders it unusable for covering bottles before or while he removes it (Shemiras Shabbos k'Hilchasah 9:3 and 17).