As Cato’s new research fellow for Defense and Homeland Security (and someone who’s written extensively on how the terror threat to the United States is hardly an “existential” one), I was glad to see this headline on the cover of latest Rolling Stone (right behind the left ear of Radiohead lead singer Thom Yorke): “The Fake Domestic Terror Threat: How the FBI Became a Factory of Fear” — even if it’s a bit hyperbolic. (The article is not online.)

The author, Guy Lawson, does not tell readers much that they could not have gathered from the Washington Post or the New York Review of Books. But he repeats something that bears repeating: Six plus years of fevered searching for terrorists on American soil has turned up precious little of the real thing.

The hunt, led by the FBI, has found several wanna-be jihadis willing to sign up for phony terror plots often organized by FBI informants, various illegal immigrants with shady overseas connections, a number of people gathering funds for foreign terrorist organizations, and only a handful of true terrorists (and not particularly formidable ones). A report from NYU’s Center for Law and Security finds that from September 11, 2001 through September 11, 2006, only “four individuals have been convicted of federal crimes of terrorism” in the United States and “no sleeper cell with logistical or tactical links to al Qaeda has been convicted of plotting an attack to be carried out within the U.S.” That means we have found no terrorist sleeper cells in the United States since September 11, as the FBI admitted.

Time and again, federal officials held press conferences to announce the break-up of a terrorist plot and vaguely described the disaster prevented. The evening news and the headlines repeated their lurid claims. Months later, the inside pages of the papers would report that the plot was not what we were told — and TV doesn’t even bother. The plans have turned out to be unfeasible or preliminary. On other occasions, it turned out the plotters visited a terrorist camp but did little plotting. Some charges have been dismissed. Some have been completely bogus.

Experts, like an FBI agent Lawson quotes, say that just because you haven’t found something, it doesn’t mean it’s not there. That’s indisputable. But when several federal agencies, local police, alarmed citizens, and ambitious federal prosecutors search for terrorists for years and find almost none, you have good evidence that there just aren’t many to find. To that some will say that absence of evidence isn’t evidence of absence. But that expression is illogical. If you spent two hours spent searching your car for your lost wallet, it is good evidence that it’s not there, though it’s not proof.

Don’t mistake me. The domestic terror threat is not altogether false. Most of those the government has prosecuted in the name of counter-terrorism should have gone to prison or been deported, and the FBI should not quit looking. The point is simply that the threat is greatly exaggerated.

Without that exaggeration it would be harder, obviously, to justify illegal wiretapping and other brazen assertions of unconstitutional executive power. Lawson mentions another consequence of overreaction to domestic terrorism; one that is mostly ignored: fewer resources devoted to fighting good old-fashioned crime. He quotes a Northern Illinois police officer frustrated by the funds the FBI devotes to chasing terrorists when there is plenty of real federal crime going unsolved and wonders if this is the best use of our tax dollars. He could have gone further.

The FBI has shifted about 2,400 agents from crime to counter-terrorism in recent years, despite the doubling of its topline budget — now $6.4 billion. The result is likely more fraud, more racketeering, more mafia. In a 2005 report, Justice Department inspector general Glenn Fine notes that the FBI opened 45 percent fewer criminal investigations in 2004 than 2001 and referred 27 percent fewer cases to a U.S. Attorney for prosecution. Cases opened on violent crime dropped 47 percent, financial crimes 40 percent, public corruption 42 percent and American criminal enterprises — often the mafia — 50 percent.

Even readers skeptical about the merits of federal policing ought to agree that it is wiser for the feds to chase real criminals than imaginary terrorists. As Jim Harper recently said here, terrorists usually impose large costs only by inducing the unwitting help of their victims. By encouraging the FBI to ignore its traditional responsibilities, we magnify the costs of terrorism. A recalibration of priorities is in order. But American politics being what they are, that will take a few hundred more articles like Lawson’s.