The night before Pesach, we search for chametz on our property (bedikas chametz). By rabbinic decree, it is not enough to nullify our chametz but we must also search for and destroy our chametz as well. The Roomba, a robotic vacuum cleaner that autonomously cleans your floors, has been available for over 20 years. Imagine a more advanced version, an autonomous chametz detector (ACD), with arms and legs that can go through your whole house (including drawers, closets, pockets and knapsacks), find any chametz and remove it. Is a contraption like that sufficient for bedikas chametz?

I. Machine Checking

Rav Dov Lior (cont., Israel) was asked a related question. If someone invents an electronic chametz detector (ECD), for example, a machine that sniffs out gluten, can the device be used for bedikas chametz? Rav Lior responds that if the ECD is tested thoroughly to ensure it works properly, then a negative result would be sufficient for bedikas chametz. However, it is unwise to use such a machine because of the possibility of a false positive. What if the ECD is triggered by a minute amount of chametz or by chametz that is in a place we are not required to check? The positive result would force you to do extra cleaning and checking (Responsa Devar Chevron, Orach Chaim, vol. 2 no. 271).

A bedikas chametz machine like that requires human interaction. Imagine a machine that autonomously checks for chametz while you relax or take care of other things. Can you use that for bedikas chametz? Effectively, the ACD serves like an agent, a shaliach. In general, it is best for the homeowner to do at least part of the bedikas chametz himself rather than hand off the mitzvah to someone else (Magen Avraham 432:5). If that is not possible, he can appoint a shaliach to check for chametz. Indeed, it seems from the Gemara (Pesachim 4b) that in some places they hired a person to search for chametz but the homeowner did a little searching himself (Pri Megadim, Eshel Avraham 532:5). However, we are discussing a machine, not a shaliach.

II. Unrequested Assistance

Consider someone driving home for bedikas chametz who gets stuck in traffic. Ideally, he should call and appoint someone a shaliach to check for him. If he fails to do so, and a concerned friend, guest or relative checks for chametz without being appointed, does this suffice for the mitzvah? When the man finally arrives home late at night, does he need to check for chametz? Rav Shlomo Zalman Auerbach (20th c.,e Israel) writes that bedikas chametz has value even without being appointed a shaliach because it prevents the individual from violating the prohibition against owning chametz on Pesach. All Jews are responsible for each other’s religious wellbeing. However, a shaliach fulfills the mitzvah on behalf of the homeowner and recites the blessing on bedikas chametz whereas the unappointed friend does not fulfill the mitzvah nor recite the blessing (Minchas Shlomo, second edition, 58:4). Therefore, when the man finally arrives home, presumably he must fulfill the mitzvah and conduct his own search for chametz even if his friend already did it.

I believe we see a similar ruling in the laws of mourning. Someone whose close relative passes away but has not yet been buried has the status of an onen. An onen does not perform mitzvos, although he is still bound by the Torah’s prohibitions. What does an onen do about bedikas chametz? Rav Yehudah Ayash (18th c., Algeria) writes that while an onen is exempt from bedikas chametz, others can check for him on their own (me-atzmam), meaning without being appointed a shaliach. They do not fulfill the mitzvah and do not recite the blessing but they help him avoid the prohibition against owning chametz on Pesach (Responsa Beis Yehudah, no. 5). Rav Ephraim Zalman Margoliyos (19th c., Ukraine) disagrees about the appointment of a shaliach. Since this is a mitzvah with a limited time frame that can be fulfilled with no effort, an onen can appoint a shaliach to do bedikas chametz who then recites the blessing (Hilchos Onen, par. 8). According to Rav Ayash, someone who is not appointed a shaliach can do bedikas chametz for another person. Rav Margoliyos does not disagree but believes we do not need that concept for an onen. More recently, Rav Nassan Gestetner (20th c., Israel) questions Rav Margoliyos’ claim that an onen, who is exempt from the mitzvah, can appoint a shaliach. If he is exempt, then he cannot appoint someone else to do a mitzvah from which he is exempt (Le-Horos Nassan, vol. 13 no. 93).

III. Man and Machine

We see that someone or something that is not a shaliach cannot fulfill the mitzvah for a person. A machine cannot be a shaliach and therefore cannot fulfill the mitzvah of bedikas chametz for its owner. One could suggest that a machine is merely an extension of its owner. For example, someone who uses a feather and spoon during bedikas chametz to gather pieces of chametz is using the feather and spoon as an extension of his hands. No one would suggest that he does not fulfill the mitzvah because he is using utensils. However, he holds the utensils in his hands so they are literally extensions of him. In contrast, the ACD moves autonomously, independent of any person, and cannot be considered an extension of the person.

Rav Lior (loc. cit.) adds another possibility regarding the electronic chametz detector. Rav Shlomo Kluger (19th c., Ukraine) writes that a room obtains a different status if it is cleaned completely of chametz more than three days before the night of bedikas chametz. After three days without chametz, the room gains a presumption (chazakah) of lacking chametz. It is like a room where chametz is never brought that does not require bedikas chametz (Chochmas Shlomo 433:11). If you use a chametz detector three days before bedikas chametz, any room it declares free of chametz does not need to be checked (assuming no one brought new chametz there). Similarly, you can use an ACD to clean your house of chametz three days before bedikas chametz, although you should still check one room just to fulfill the mitzvah.

Rabbi Gil Student is the editor of TorahMusings.com. His latest book, Articles of Faith: Traditional Jewish Belief in the Internet Era, is available online and in bookstores near you.