May be found at the following link.
Although this pertains more to telemarketing, it can also apply to spammers hanging signs on public or private property.

http://antitele.home.texas.net/free_speech.html

There have been numerous amendments by the US Supreme Court, especially when it comes to commercial applications and limits to disturbing the peace after normal working hours.

GW

Thanks for the article, GW. It is clear that commercial "free speech" is quite different from and more restricted than individual free speech. And that's the way it should be.

DenverShark

Post deleted due to the link being removed from the net.

GW