If you could ensure that the interference didn't extend pass your own property, I don't think there should be a problem. That's probably not how the FCC works though.
I don't see why it's like that at all. Am I not allowed to create a small faraday cage in my garage, and inside that test out a cell phone jamming device? Why does it matter if there's literally no measurable effect on the surrounding property?
I'm not a lawyer but I do read FCC regs for fun...
A passive faraday cage on your own property that's not open to the public probably isn't an issue. As far as size goes you would be subject to local building codes of course.
Once you get into active jamming however that requires you to transmit and to transmit you need a license from the FCC. The right to transmit anywhere in the US is under the FCC's jurisdiction and doesn't have anything to do with the landowner. It may seem strange to divorce airwave rights from property rights but it's not that different from water rights or mineral rights or airspace rights, which have a long legal history of being divorced from landowner rights.
When you open your faraday cage to the public it gets a little tricky too, because if a "licensee" has the legal right to be somewhere according to you and the legal right to transmit or receive according to the FCC then you can't really legally prevent them from doing both at the same time. This idea, which is called the "OTARD rule" in some situations, is interpreted to force landlords to allow tenants to install WiFi and satellite equipment on rented property for example.
There probably is an FCC rule that would prevent stores or movie theaters or similar public places from jamming via a Faraday cage, but since actively jamming is cheaper I am not aware of any actual instances of this type. So in that sense it's a test case, but I'm reasonably certain which way it would go.
> It may seem strange to divorce airwave rights from property rights but it's not that different from water rights or mineral rights or airspace rights
It seems very much different to me, because all of those things have very obvious externalities for your neighbors. My example, where you build a faraday cage and test a signal jammer inside that cage, has no externalities (assuming a hypothetical perfect faraday cage). There would be no measurable signal an inch outside the faraday cage, and certainly none at your neighbor's property.
I think that falls in a "it's not illegal if you don't get caught" scenario -- that is, unless you make an incomplete Faraday cage, the FCC would have no real means to catch you doing that. Also, since you wouldn't be jamming anyone else's signals, nobody would report you.
You'll find out real quick if you screwed up your Faraday cage design, though.
