Our system of justice is based, partly, on the premise that it is better to let ten guilty men go free than to imprison one innocent man.

True, as far as it goes, but the equation has changed as to how much damage ten guilty men can do. Let a serial killer go by mistake, and he kills...what? Maybe five more people? Ten? Twenty?

About a dozen men took out 3,000 people and a chunk of Manhattan. If they had real weapons of mass destruction, the toll would have been much worse. The risk of making a mistake is not what it used to be, and the balance doesn't fall where it used to any more.

The FBI and CIA got endless grief for missing the bad guys. For not having enough information. For not connecting the dots. I think they can be forgiven for tightening up a bit on things.

That being said, if one knows for sure one is after an ordinary criminal, it isn't necessary to bash him with a legal weapon designed for much more dangerous people.