Here's a good summary: [1]

Basically, the analogy of shouting "fire" in a theater was meant to illustrate the "clear and present danger" doctrine - if an act of speech could lead to clear and present danger which there were laws against, then the speech was not protected. What's false about this analogy is that the "clear and present danger" standard isn't the standard that speech is measured against today. Instead, speech is restricted according to the "imminent lawless action" doctrine, by which speech that could lead directly to people breaking the law is not protected. This was decided in Brandenburg v. Ohio[2], and the central tenet of the ruling is:

"Advocacy of force or criminal activity does not receive First Amendment protections if (1) the advocacy is directed to inciting or producing imminent lawless action, and (2) is likely to incite or produce such action."

Thus, standing on a street corner and praising the merits of rioting and damaging property might be protected speech if it was very unlikely for anyone to take those actions, but if you did it during a restless protest march the protections of free speech may not apply.

[1]: https://en.wikipedia.org/wiki/Shouting_fire_in_a_crowded_the... [2]: https://supreme.justia.com/cases/federal/us/395/444/

It's worth noting that the phrase "shouting fire in a crowded theater" comes from a Supreme Court case in which the government imprisoned socialists for handing out flyers urging people not to submit to the draft during WWI.[1]

It's one of the most infamous decisions in the history of the Supreme Court, at one of the darkest hours in the history of the First Amendment. I think most people would be surprised to learn how far the Wilson administration went to suppress free speech during WWI. I had no idea until I read "The Great Influenza" (about the 1918 pandemic) recently.

As an aside: the Espionage Act comes from that time, and is the law that was used to jail opponents of the draft back then. It's also the law being used to charge Assange today.

1. Schenck v. United States: https://en.wikipedia.org/wiki/Schenck_v._United_States

https://www.theatlantic.com/national/archive/2012/11/its-tim... and https://www.popehat.com/2012/09/19/three-generations-of-a-ha... are illuminating.

The short version:

- It was a non-binding side comment (dicta) not particularly grounded in existing law on the decision it was presented.

- It was presented in a decision that has since been overturned in effect which is notorious as one allowing government prosecution of core political speech “because socialism”.