What law is there agains pornography in theaters? Movie regulations?

I know about MPAA, and NATO, and those censoring associations, but those aren't law. They're voluntary. What law is there against someone opening a theater and playing home made pornographic material in it? What's to stop children from going in there? What are the laws, and where can they be found? Citations please. Thanks.

Displaying "obscene" material is illegal.

What's obscene? Ah, there's the rub ! Most laws define it in terms of "offensive to community standards of decency". That means that what's OK to screen in New York City might be obscene in Hicksville, Georgia. So you can go to a peep show store or porno theatre in Times Square and watch porn that you couldn't even rent to watch in your own home in Hicksville.

With regard to children, the laws there are tighter. Anyone who displays "indecent" material to a child is breaking the law.

Again, what's "indecent"? Well, it's whatever the jury decides it is, again, based on "Community Standards." As an example, the monthly magazine of the American Association for Nude Recreation frequently shows photos of happy families playing naked on the beach in some tropical paradise. It's distributed through the US Mail with no problems - but there are some uptight communities where public nudity is considered offensive to community standards, and it can't be delivered.

Richard