But of course shouting fire in a crowded theater is often constitutionally protected. For instance, if there is a fire, shouting fire may be good. (It may sometimes not be good, if more people die in the panic than would have died from the fire if one had spoken more calmly — but even then, I’m pretty sure that it would be constitutionally protected.)
And in fact the line from Justice Holmes in
Schenck v. United States is “The most stringent protection of free speech would not protect a man in falsely shouting fire in a theatre and causing a panic.” That “falsely” is what’s doing the work, both in Justice Holmes’s hypothetical, and in how such a false shout would be treated by First Amendment law today. Knowingly false statements of fact are often constitutionally unprotected — consider, for instance, libel, fraud, perjury, and false light invasion of privacy. That would presumably apply to knowing falsehoods that cause a panic. (Even given bit complicated by
the Stolen Valor Act case, such knowing falsehoods that are likely to cause tangible and immediate harm are likely to be punishable, as the concurrence suggests.)
If the statement is not knowingly false, though, the analogy breaks down.