For example, threats are not protected because they provide no social value. The idea behind the First Amendment, wrote the founders, was that the citizens be free to criticize their government. And over the next several centuries, our courts have developed a great body of law refining and expanding that concept. In the area of national security and politics, there are no wrong ideas, and free speech is indispensable to the disclosure of truth.

The most recent and most expansive Supreme Court decision on protected speech in the context of national security was the Brandenburg case in 1969, which struck down an Ohio law that criminalized advocacy of crime, violence or terrorism as a means of accomplishing political reform. The statute was unconstitutional, the court said, because political speech is protected unless it is “directed to inciting or producing imminent lawless action and is likely to incite or produce such action.” Because this Ohio statute did not adequately distinguish between abstract advocacy versus true incitement to imminent action, the conviction of Clarence Brandenburg, a Ku Klux Klan leader, was reversed.

In looking at the question of what speech is protected and what is not, courts have always looked to context. For example, every Supreme Court decision on this subject recognizes war as an exception to the First Amendment, even though the Constitution says no such thing. The classic example cited by the older cases is recognition of the government’s unfettered right, in time of war, to ban the publication of information revealing the sailing dates of troop transports. Ten years after Brandenburg, a district judge in the United States v. Progressive case enjoined the publication of classified nuclear bomb formulas. The court found that times had changed, war was no longer limited to foot soldiers who travel to battle sites on troop transports, and even though it was not clear that a reader would imminently “build a hydrogen bomb in the basement,” the scope of the danger overwhelmed the imminence factor.

The balancing act was succinctly explained by Robert W. Warren, the district court chief judge who, when referring to Patrick Henry’s famous liberty-or-death choice, wrote, “in the short run, one cannot enjoy freedom of speech, freedom to worship, freedom of the press unless one first enjoys the freedom to live.”

The balancing test must look at what is real. The measurement of imminence changes when we are talking about detonating a nuclear bomb in New York City as opposed to an unlicensed rally blocking the Brooklyn Bridge.

The federal government should move decisively to block Inspire on the web. It is criminal incitement that has produced lawless action, and no sentient judge would today say otherwise.

It is one thing for Attorney General Eric H. Holder Jr. to excuse the journalist James Risen from revealing a book source, and quite another to permit virulent enemies to recruit, train and support those who would destroy our country. If we sanction this kind of so-called freedom, we risk horrible consequences. The Paris killings are small stuff compared with what would happen if our civilian airline system were crippled. I fear that in response to more terrorism, we would see repression on a terrifying scale.