Without fail, whenever a free speech controversy hits, someone will cite this phrase as proof of limits on the First Amendment. And whatever that controversy may be, “the law”–as some have curiously called it–can be interpreted to suggest that we should err on the side of censorship. Holmes’ quote has become a crutch for every censor in America, yet the quote is wildly misunderstood.

Source: It’s Time to Stop Using the ‘Fire in a Crowded Theater’ Quote – The Atlantic