The specifics have been determined in case law. I'm not a lawyer, so I can't give a more detailed example. I can, however, give some examples (Mass Media Law at Utah State comes bubbling back into my mind, what a fun class).
Yelling "fire" in a crowded theater, for example [0]. Another comment in this thread talks about the "clear and present danger" doctrine that came from the case. That case was followed by the Brandenburg v. Ohio [2] case in 1969, which instituted the current methodology used for determining what is "allowed" speech. That rule/methodology is called the "imminent lawless action" rule.
Yeah, I'm not a lawyer but the system seems honestly nonsensical. They found the law inconvenient, so the court just effectively added a "clear and present danger" clause to the law. If there were problems with people abusing their freedom of speech, then you'd think the natural response would be to amended the bill of rights - and not just a bunch of unelected judges dreaming up something that seems "reasonable"
I honestly can't speak to "reasonable", but this format of jurisprudence has been common for the better part of 4000 years (see Jewish law and case law that pops up in the Bible's old testament, especially the tanach).
The biggest problem with the trope is that it plants in people's heads the idea that there was EVER a Supreme Court case where the defendant was accused of yelling "fire!" in a crowded theater.
In reality, the phrase was an analogy used to justify the conviction of a man who committed the heinous crime of… making and distributing leaflets opposing the draft in World War I. So for all the high minded rhetoric in the First Amendment, it may not provide all that much protection if your speech inconveniences the government sufficiently.
One might also be tempted to draw inferences from the fact that Schenk, the man whose speech was considered not worth protecting, was a socialist pacifist, while Brandenburg, whose free speech was considered more worthy of protection, was a KKK leader promoting violence against Blacks and Jews. In the US, protecting the civil rights of Nazis has become a litmus test of civic virtue across the political spectrum. Unfortunately, that protection is extended far less vigorously and consistently to other political views.
Case law doesn’t exist in the United States of America.
You might be thinking about medieval England, or ancient Persia, where a king or judge’s word becomes law.
In the USA, people are judged individually and are equal before the law.
One exception, that is traditional, but not enumerated in law, is that the Supreme Court can strike down a law that it deems unconstitutional, but may not amend or make new laws itself. Lower courts havee Ed no such power.
First, every court of appeal can strike down a law as unconstitutional. The Supreme Court is only special in that there is no further appeal.
Second, case law absolutely determines the interpretation of each text, and each court is mildly bound by its own precendent (via stare decisis), and completely bound by the precedent of superior courts.
Third, there is no tension between these facts and people being judged individually and being equal before the law. The law must (in principle) be applied equally to everyone.
Yelling "fire" in a crowded theater, for example [0]. Another comment in this thread talks about the "clear and present danger" doctrine that came from the case. That case was followed by the Brandenburg v. Ohio [2] case in 1969, which instituted the current methodology used for determining what is "allowed" speech. That rule/methodology is called the "imminent lawless action" rule.
[0] https://supreme.justia.com/cases/federal/us/249/47/
[1] https://en.wikipedia.org/wiki/Shouting_fire_in_a_crowded_the...
[2] https://supreme.justia.com/cases/federal/us/395/444/