If there is a better place to be on a spring day than the middle of campus in Chapel Hill I've yet to find it. Friday's normal noon-time bustle even added a giddy buzz of anticipation for Carolina's weekend hoops clash with Duke. Then a rented silver Jeep Cherokee Laredo rounded a building, accelerated, and plowed into a throng of students. Mass murder was averted only via sheer luck and the ability of strong, young bodies to bounce off a fender or windshield and crash into brick without sustaining a mortal wound.

Mohammed Reza Taheri-azar, 22 and a native of Iran, stands charged with nine counts of attempted murder. After he surrendered to local police Taheri-azar "allegedly made statements that he acted to avenge the American treatment of Muslims," according to an FBI official. Authorities now seem to be downplaying this statement as the investigation continues.

But there is no downplaying the disconnect between actual acts of terror and America's anti-terror policy. The soon-to-be permanent PATRIOT Act, which we are told non-stop is the vital key to stopping attacks, fights terror as prosecutors and politicians would like it to be—as a top-down, centrally-managed form of organized crime. Yet terror exists, and will continue to exist, as an opportunistic, ad hoc phenomenon, no matter how many national security letters are issued.

For Taheri-azar, the sifting of motives and indicators has begun, but results are thin. Classmates and professors profess shock. After fearful police blew the door off of Taheri-azar's apartment they found no al Qaeda secret decoder ring, unless a book by Cornell West now counts. No link to Kinko's has emerged. A seemingly comfortable home in a South Charlotte suburb where Mo-Mo went to high school affords no obvious data to mine. Yet the vital lesson hides in plain sight.

Box cutters, airliners, rental cars. This is how you make war on a free society from within. A Ryder truck, fertilizer, plastic barrels. These are the building blocks of terror. A quick mind and dark heart are the only two really indispensable (and, fortunately, fairly rare) components for making mayhem. The folly of PATRIOT is that it pretends to give the good guys access to those hearts and minds, in real time and on tape. But it is the mother of all knowledge problems. This approach supposes that if enough info can be sucked up, evil intent will become clear, and authorities can swoop in and stop it. Accordingly, some official, somewhere, is no doubt contemplating requiring FBI background checks for car rentals.

Such diffusion of attention masks the real threats. The one undisputed terror weapon to be deployed against America was anthrax. The government's best guess—facts have been hard to come by in the now stone-cold case—is that the anthrax came from U.S. government sources. An unofficial source that was twisted to some sick purpose, to be sure, but a very narrow target for improved oversight and security. This does not require a PATRIOT-sized revamping of the state's investigative powers over every citizen of the republic in order to correct. Worse, official Homeland Security doctrine, along with billions in flat-out pork, has pushed ever more lethal weapons in ever more hands around the country. This is exactly the opposite of security. Every deputy sheriff in America with access to a full-on military arsenal creates another target of opportunity for those quick minds. Alert the NSA: They will not be phoning Pakistan for instructions.

Nor will they be moving large amounts of cash around their banking accounts, or suddenly paying off credit card balances, or buying airline tickets in a hurry, or any of the millions of mundane things our PATRIOT-addled government now tracks.

They will, however, round the corner on some beautiful, innocent day, and something horrible will happen.