Never said legal, but local or state police have no jurisdiction in the US regarding FCC regulations, however the FCC certainly could come after you but their not being there to see you do the deed not at all likely they could do much, if they knew who and where you are, at worst they would take away your jamming toy for not being licensed or type accepted but they would have to find you, know who you are and an isolated incident is simply not worth their time, more than that, one guy RF jamming drones flying around their home isn't worth their time either, even if done many times.
If you jammed a drone, the best thing for you to do would be to keep quiet, don't tell a soul, that is where the issue gets outside of the FCC's arm. They have few employees working in field regulation, I mean tiny, most states don't have a FCC field office so they aren't there to catch you. If you are not causing damage to the drone when jammed, just causing it to land, illegal by FCC rules or not, no other agency will be brought into it. Of course law officers overreach their legal ability to regulate all the time, thats when lawyers get involved and when $$$ comes out of your pocket, but as I said, do it, stay quiet and 99.999 percent chance no one will have a clue. Go to a drone flying event and start causing trouble, that raises the odds quite a bit and you could simply be charged with disturbing the peace and it would stick, but I still think anyone could do that and likely get away with some, start repeating it and the odds drop, cause a drone to drop on someones head and now you have a very bad situation.
Disclaimer: This post was for entertainment as a what if, what is likely, not a suggestion anyone should break the law. I cannot morally, ethically or legally suggest breaking any law. Regarding the FCC, I am a former FCC field officer
