The use of this statute may have very well have prevented a variety of mass terrorist attacks, as it is a quick and effective way of getting violent prone extremists off the streets early -- before an attack takes place.  These dangerous folks often crack and lie under the gauntlet of professional interrogators aided by intensive search techniques. Civil libertarians argue, however, that this strategy often ensnares unsophisticated blowhards whose threat potential is minimal or overblown. The fact that the strategy is purposefully preventative in nature means that in many cases we’ll never be able to conclusively prove how bad the threat actually was.

It's odd that they chose not to remain silent ...