[Boogieman]

Well, you could easily be charged with reckless endangerment or the equivalent in criminal court as well.

[EnderWiggin1970]

IANAL.... Seems to me the question of whether it is a criminal act (yelling "fire" in a crowded theater) depends 99% on whether there is in fact a dangerous fire. If there is no fire (or it is so minor or controllable as to not be a hazard if dealt with), then it constitutes fraud and any harm that comes of it would be squarely the fault of the person yelling the warning. (Which might be mitigated if and to the extent to which they might show it was some sort of honest mistake.)

On the other hand if there is a serious fire, speaking truth even if it has dangerous consequences should be protected speech IMO. Should a person who sees a fire keep silent, thus delaying the warning that could save many lives? That would be insane, but would be a consequence of lawsuits punishing people for telling the truth in such situations.