I’ve been told you can’t mention or even joke about weapons or bombs in an airport or on a plane. Does that rule violate the First Amendment?
What you’ve heard is right — if you joke about having a weapon or a bomb at the airport or on an airplane, you can be prosecuted. Moreover, no court has ever held that such laws violate the First Amendment.
These laws don’t punish you for joking about a bomb, exactly. They punish you for threatening to do something against the law or for saying that you know somebody who is going to do something against the law, when you really don’t. Some courts, however, have ruled that “just joking” about a bomb will result in only a light penalty, while making a serious, though false, bomb threat will result in a much heavier one.
Regardless, just as you shouldn’t yell “Fire!” in a crowded theater that is not ablaze or make a false report to the police, you definitely shouldn’t even joke about bombs or weapons when you’re at the airport or aboard an airplane.