choshen mishpat civil law - Cell Phone Jammers in Halacha

I could not imagine cell phone jammers would be מותר, but perhaps my gut-feeling is wrong...

Either way, I would be interested in knowing how they fit into halacha, and what the reasons behind forbidding [or permitting] their use would be. I would expect an answer to both cover the angle of how it affects an innocent user of a cellphone walking by, as well as the effect on the phone companies themselves.

Also of importance: would the location of the jammer (ie. whether in public or private domain) have an effect on the halacha?

I am specifically asking with regards to Jewish law, and without considering that they are in fact illegal by secular law (at least in the US).

Answer

I wrote to Business Halacha Institute and they answered that it is prohibited to do so.

As requested, here is the conversation:

Aside from the secular law ramifications (illegal in the US):

I would be interested in knowing how cell phone jammers fit into halacha, and what the reasons behind forbidding [or permitting] their use would be.

Also of importance: would the location of the jammer (ie. whether in public or private domain) have an effect on the halacha?

They answered:

Thank you for contacting us about this interesting matter. The answer to your inquiry is that it would indeed be prohibited for one to jam the signal so that others would not be able to use their cell phones. However, it is unlikely that the damaged parties would be able to collect anything from the “jammer.”

I then wrote back:

Many thanks for your quick reply. May I know the reasons for why it would be prohibited?

Also, would it make a difference if the purpose was for a Shul (once again, disregarding US law)?

And they subsequently replied:

Jamming the signal so that one’s phone does not work is at least a grama of damage to the phone since it is rendered useless. It is not likely something for which one could demand reimbursement but it is prohibited l’chatchila.