Arrest Trump. He directly incited violence.

• The First Amendment protects the right to express even the most repugnant, hateful speech so long as it is not a direct incitement to violence.
• President Donald Trump crossed that line at Wednesday's "Stop the Steal" rally when he urged a mob to march to the US Capitol and "fight like hell" and then called them "great patriots" after the insurrection.
• The president directly incited deadly violence. He must be prosecuted for it.
• This is an opinion column. The thoughts expressed are those of the author.

Contrary to popular misunderstanding, shouting "Fire!" in a crowded theater is not the established legal threshold separating protected speech from criminally inciting speech.

The oft-quoted misbegotten phrase "fire in a crowded theater" was born of Supreme Court Justice Oliver Wendell Holmes' opinion in Schenck v. United States, which upheld the conviction of a socialist anti-war activist for passing out pamphlets opposing the draft in World War I.

It was one of the worst judicial infringements on free speech in American history. And, thankfully, it was effectively rendered moot by 1969's Supreme Court decision Brandenburg v. Ohio, which held that even the most vile, racist speech is protected by the First Amendment unless it "is directed to inciting or producing imminent lawless action and is likely to incite or produce such action."

As a staunch free-speech advocate, I don't say the following lightly: President Donald Trump should be arrested and prosecuted for inciting violence.

Trump's long history of advocating political violence, his willful attempts to disenfranchise millions of American voters, and his cheerleading of deadly Capitol rioters even after the crime was committed Wednesday are why his speech reaches the Brandenburg threshold of "inciting or producing imminent lawless action."

What Trump did is magnitudes worse than shouting 'fire' in a crowded theater

Let's be clear about this: Trump incited a riot that led directly to the deaths of a Capitol Police officer and one of his own supporters, an unprecedented evacuation of Congress in session, and the temporary halt to the Electoral College certification.

After a federal prosecutor left open the possibility of going after Trump over the insurrection on the Capitol, the president's legal team was able to convince him of the legal jeopardy he's in.

According to a report in The New York Times, Trump recorded his non-concession video in which he belatedly denounced the rioters (whom he professed his love for in a video the previous day) because his aides convinced him he stood the chance of being prosecuted on suspicion of "illegally inciting the attack by telling supporters to march on the Capitol and show strength."

Trump has avoided prosecution many times because his prodigious lying and often unintelligible speaking patterns make it difficult to discern whether he's serious about or even fully understands what he's saying.

But as I wrote earlier this week, the conventional wisdom of "take Trump seriously, not literally," was permanently put to rest Wednesday when Trump's supporters - whom he has been regularly goading toward political violence for five years - took him literally.

Trump relentlessly referred to the news media as "enemies of the people." Reporters were targeted and violently assaulted during the siege, some absurdly and falsely accused of being "antifa." The phrase "Murder the Media" was scrawled on one of the Capitol's doors.

The president has single-handedly destroyed millions of Americans' faith in democracy with unhinged lies about election fraud that were repeatedly laughed out of court - including a Supreme Court that is one-third Trump appointees.

And after telling an enraged mob to march on the Capitol and "fight harder," he rejected his own vice president's pleas to intervene and try to put a stop to the madness. It was said to be only when Trump found the right-wing populist rabble that he created to be behaving in a "low class" manner when he agreed to record a brief video in which he urged his supporters, described by him as "great patriots," to end the violence.

Trump's words did this.

His rank idiocy and compulsive dishonesty cannot, and must not, shield him from legal consequences.

The president has blood on his hands. For the sake of justice and the future of American democracy: Arrest him. Prosecute him. Bar him from ever again holding office.

• Read more:
• Trump's violent MAGA mob shows the Republican Party isn't worth saving. Disband it and start over.
• This was a coup. Trump's been leading the country toward this for 5 years.
• Trump must be prosecuted, or we should just admit presidents are above the law
• Trump-supporting 'Stop the Steal' mobs are a reminder that political violence is always inexcusable