Probable Cause

It was good to see that the FBI could catch a group like the Florida bombers. By coincidence about that time, the director of the FBI in New York, Mark Mershon, visited our offices. Mr. Mershon made it clear that the FBI will not monitor or surveil anyone, including Muslim extremists, without a "criminal predicate." Generally, probable cause is the gold standard for watching. Mr. Mershon said that if someone keeps his head down and nose clean in the U.S., he can function with a great deal of freedom. That's a rough but workable description of our system.

This traditional, all-American tradeoff between liberty and risk works OK in a country populated with standard criminal types; most eventually work their way up to a police database. But what about the world of Islamic fanaticism whose recruits, notably suicide bombers (or pilots) are nearly all first-timers? Does "our system" mandate that we allow an Islamic fifth column to fly beneath the radar of probable cause and into buildings? Do we have to settle for catching bottom-feeders like the Florida plotters while the smart boys, planning a smallpox attack in Detroit, stay below what they've read is the threshold for FBI curiosity or a FISA warrant?

Daniel Henninger on the challenge of rights versus security in an unusual war.