First, we must caution you that nothing that we write here is to be seen as a ruling that would exempt you from adjudication with parents who might (hopefully, not) sue you, as we have not heard their specific claims. We are simply trying to help you set a general policy of how you believe things should run in this regard.
First, we must briefly address your confiscation policy. There is halachic discussion whether (and/or for how long) a school may confiscate a student’s property as a preventive or punitive measure.[1] Our opinion is that it is permitted as part of the leeway that Halacha gives parents and teachers who need reasonable measures to enforce discipline appropriately. You can more or less put the halachic debate to rest by taking two steps, which are usually worthwhile in any case. One is to have the parents explicitly give their agreement to clearly stated school policies, including a teacher’s right to confiscate items from the students. The other is to instruct the teachers not to grab the objects, but instead to firmly inform the students that they are either to hand over the item or face strong disciplinary measures. In any case, however, the school has a right to responsibly confiscate property that students bring or use contrary to the rules of the school.
Now we will deal with the question of liability for the theft of the cell phones. Your school receives funds primarily to teach, but your responsibilities extend naturally to other services, including guarding the property that you decide to confiscate. This is similar to a craftsman, whose main job is to work on his customer’s property but who also is expected to make an effort to ensure that the property does not disappear. In fact, the mishna[2] states that a craftsman has the status of a shomer sachar (a paid watchman), who is obligated to pay for objects that are stolen or lost under his watch.[3]
What if a shomer sachar watches the object as well as he can, but it is stolen anyway? Would we say that since he is exempt from damages that happen due to oness (extenuating circumstances beyond one’s normal control),[4] he is also exempt in such a case, or would we say that he is obligated because he is responsible for thefts? There is a machloket among Rishonim[5] regarding if a shomer sachar is obligated to pay in a case of theft that took place despite his doing a proper professional job of guarding. Among the classical poskim, the Shulchan Aruch[6] rules that the shomer sachar must pay unless the loss occurred due to armed robbery,[7] whereas the Shach[8] says that he is exempt from any oness, including one that ends up in a theft.
There is another reason for exemption. The Maharshach[9] distinguishes between different kinds of shomrei sachar. A professional shomer is obligated to do an especially professional job and must pay for any type of theft. However, one who is considered a shomer sachar because of side benefits he receives (e.g., a craftsman[10]) is not obligated when he did as good a job as one can expect. Not all authorities agree with the Maharshach,[11] but his approach is another possible reason to exempt a shomer who is not guarding property as his primary task, as is the case of your school.
In short, at first glance, it is not clear cut whether a school that had children’s property stolen from its safe is responsible to pay. This is in addition to what we mentioned above that we are not allowed to give a definite ruling without the other litigants being able to present their side of the story, which can introduce surprising insights. This case, like many others, begs for some sort of agreement or compromise.
On the other hand, it is inappropriate for “your hands to be tied” educationally by a fear of liability. Therefore, we recommend that you receive the parents’ formal agreement that in the case of confiscation, the school will not be responsible for the loss of the property. Generally, it is possible for one who has someone else’s item in his possession to refuse to take responsibility as a watchman.[12] This can happen even when the owner is not happy to surrender the object. For example, if a lender requests collateral for a loan and says that he is taking it on condition that he does not accept the obligations of a shomer, by giving the collateral, the borrower shows he is agreeing to the condition.[13] In contrast, one who is a shomer over an object he found, in which case the Torah obligates him, cannot make such conditions. Similarly, if the school forcibly confiscates an object from a child, such that there is no agreement at the time the school takes possession of the object, it cannot make conditions at that time to avoid responsibility. However, if the aforementioned agreement with parents includes an exemption from payment in the event the confiscated item is lost or stolen, and the parents agree, even if reluctantly, then this arrangement is valid.