In November, Cass Sunstein wrote that the threat of terrorism warrants a reconsideration of the “clear and present danger” test. In short, the Islamic State’s proficient use of social media should make us revisit whether we are willing to protect other “extreme and hateful forms of speech.”

True, there may be value in even the most extreme and hateful forms of speech: At the very least, people can learn what other people believe. But it’s fair to ask whether that benefit might be dwarfed by the cost, if those forms of speech create a genuine risk of large numbers of deaths. …

In free societies, it’s almost always a bad idea to punish speech. But at the very least, the argument for the clear and present danger test is not quite as clear as it once was — and it might not be so well-suited to the present.

Sunstein acknowledges that Holme’s “clear and present danger” test was rejected by the Supreme Court decades ago–but that wasn’t his point of writing the article.

Two weeks ago in Slate, Eric Posner made the point far more forcefully. Not only should we reconsider these old doctrines, but we should enact a law to criminalize supporting ISIS on the internet.

Consider a law that makes it a crime to access websites that glorify, express support for, or provide encouragement for ISIS or support recruitment by ISIS; to distribute links to those websites or videos, images, or text taken from those websites; or to encourage people to access such websites by supplying them with links or instructions.

Posner knows that his proposed law would be facially unconstitutional under modern doctrine.

The obvious problem with this law is that the courts could strike it down under the First Amendment. Under current doctrine, such an anti-propaganda law is unconstitutional because it would interfere with the right of people to receive or read political information—as would proposed laws that would require Internet companies such as Facebook and Twitter to remove ISIS-related propaganda from their websites.

But like Sunstein, making an argument under current law wasn’t his point in writing the article. Rather, he seeks to shift the debate. The Court’s current doctrine only goes back to the Warren Court. In a different time, with different Justices, the government had power more to Posner’s liking:

However, these rules go back only to the 1960s. Before then, in the United States, people could be punished for engaging in dangerous speech. The U.S. government prosecuted Nazi sympathizers during World War II, draft protesters during World War I, and Southern sympathizers in the Union during the Civil War. It’s common sense that when a country is embroiled in a war, it should counter propaganda that could populate a fifth column with recruits.* The pattern in American history—and, in the other democracies as well, even today—is that during times of national emergency, certain limits on speech will be tolerated.

We do not currently face a national emergency comparable to a world war, but anti-propaganda laws may nonetheless be warranted because of the unique challenge posed by ISIS’s sophisticated exploitation of modern technology.

To borrow from Jack Balkin’s taxonomy, both Sunstein and Posner are trying to shift arguments about censoring speech from “off the wall” to “on the wall.” The idea of criminalizing blog posts that support ISIS would be unthinkable under prevailing constitutional thought. But when scholars of the caliber of Posner and Sunstein put their names on it, it lends an air of legitimacy to the idea, and gets people thinking.

Invariably, scholars that disagree with the off-the-wall ideas respond–but in responding they add more heft to the proposal. An idiotic proposal isn’t even worth reply too. Geoff Stone replied to Sunstein and Posner at the Huffington Post.

Although I certainly understand the concerns driving these suggestions, it is essential that we resist the temptation to restrict our most fundamental freedoms in moment of panic. This is not to say that our nation’s security is not important or that preventing terrorist attacks is not a critical goal. But it is to say that this is not an appropriate way to protect ourselves. …. The long and short of it is this: In the free speech arena, we have struggled for more than two hundred years to get to the right place. We should not throw that wisdom away in a panic. If we do, we will once again deeply — and rightly — regret our actions.

But no matter how cogent Stone’s reply was–I think he gets it exactly right–it only draws more attention to the question.(During the early debates over the individual mandate, many scholars deliberately didn’t even address the arguments because they did not want to even acknowledge it was feasible). Additionally, Stone’s comments will allow Posner and Sunstein to further refine their arguments.

As top scholars begin to debate, the media takes notice. Yesterday, the New York Times published an article titled ISIS Influence on Web Prompts Second Thoughts on First Amendment.

It is one of the most hallowed precepts in modern constitutional law: Freedom of speech may not be curbed unless it poses a “clear and present danger” — an actual, imminent threat, not the mere advocacy of harmful acts or ideas.

But in response to the Islamic State’s success in grooming jihadists over the Internet, some legal scholars are asking whether it is time to reconsider that constitutional line. …

Recently, though, a few legal scholars, too, have engaged in what others call First Amendment heresy. What does clear and present danger mean when terrorists are provoking violence over the Internet? Should not the government have a way, they ask, to block messages that facilitate terrorist acts tomorrow, if not today?

How many is a “few”? I count two: only Sunstein and Posner have made this argument. But it only takes two distinguished thinkers to move an argument on the wall. The article goes on to quote dissenting views from David Post and Geoff Stone who discuss why the law should not revert to what it once was. But the author notes how these precedents were developed during another dangerous time–World War II. From the article in the Times, others will consider the Posner/Sunstein arguments reasonable, and think maybe Holmes had it right, and the Warren Court’s standards are for too risky.

Plus, limiting free speech also serves other agendas, such as criminalizing hate speech on the internet. The Times quotes Jeremy Waldron:

Jeremy Waldron, a professor of legal philosophy at New York University, has raised questions about the protection of hate speech under the First Amendment, with arguments paralleling those applied to terrorist websites by Mr. Sunstein and Mr. Posner.

“I argued, in the adjacent area of hate speech, that the clear and present danger test is inadequate,” Mr. Waldron said in an interview. “You can poison the atmosphere without an immediate danger, but sometimes, waiting for an imminent danger is waiting too long.”

“In the hallowed grounds of free speech, we have been a bit naïve about how threats spread,” he said.

So even advocates who may not agree with Sunstein and Posner on terrorism will ride the bandwagon to criminalize hate speech or revenge porn or other forms of unpopular speech. I mean, we are only censoring blog posts. It’s not like we are rounding up people based on their race or religion. (I could write a book about how Trump has been a master at putting insane ideas onto the wall).

The Supreme Court’s precedents on free speech, or any other doctrine are not fixed. Geoff Stone makes the point eloquently:

All these legal experts, including Mr. Posner, agree that if today’s Supreme Court considered his proposed law, it would be struck down — probably by a vote of nine to zero.

But if more Americans who were indoctrinated by jihadist videos engage in terrorist attacks, they also agree, the nation’s mood and the court’s thinking could change.

“Five years from now, who knows?” Mr. Stone said. “You can imagine a scenario in which things get so terrible that you start watering down the protections.”

“I don’t think we’re anywhere near that point now,” he said.

Justice Breyer’s optimism that Korematsu could not repeat itself is admirable, but not realistic. I do not take anything for granted, and recognize that when crisis hits, our legal system will take a vacation. Perversely, of the current Justices on the Court, the person most likely to uphold criminalization of speech is Breyer. So much for our “stronger tradition of civil liberties.”