I'm thinking movie theaters or coffee shops that have huge signs "Your cell phone will not work in there. If you don't agree, don't come in", etc.
That's not to say that a movie theater or coffee shop couldn't passively attenuate cell phone signals with metallic paint or other equivalents to a giant Faraday cage. But ensuring that you're not being an ass with your radio transmissions is the FCC's specific task.
You'll find out real quick if you screwed up your Faraday cage design, though.
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 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.
If you do it in a movie theater though, it presents a safety issue, and that's a negative externality.
If you have the right piece of paper you can push 100,000 watts. (Note, if you're pushing 100,000 watts, then you do need a clear big sign outlining the dangers of standing near a 100,000 watt microwave)
Passive (blocking signals using faraday cages) is fine.
Active (blocking signals by sending other signals) is very much not fine and will attract legal attention.
England is currently changing (or at least thinking of changing) the law to allow prisons to use cell-phone jammers. They can't do it at present.
The big issue (as described in the article) as that the chance of interfering with a legitimate emergency communications system is fairly high.
But if you want to know if I think it's wrong for us to have inequality in the form of non-universal applications of morality or "law", then I'll answer with Yes.