Congress shall make no law ... abridging the freedom of speech, or of the press; [unless the peasant responsible refuses to put his real name on it]...
Fixed it for you.
http://en.wikipedia.org/wiki/First_Amendment_to_the_United_States_Constitution
We don’t want the government to be a nanny-all. We shouldn’t try to ban every bad thing.
There is of course a time to be anonymous, when exposing a powerful entity of criminal behavior. Usually that is done via leaking info to an interested press. If the "troll" wishes to accuse someone of being a pedophile then he should put his name to the charge and back it up with evidence.