Except you do have the right to shout "Fire" at a crowded theater, at least in the US. The original Supreme Court case (about criticism of the draft) was, IMO, a miscarriage of justice. Fortunately it was overturned a few decades later.

To stretch the metaphor (which was a throwaway comment in a brief, not a formal supreme court opinion about fire safety), you can shout "Fire!" in a crowded theater. What you can't do is lead a mob to a theater and tell them to set it on fire.