By rules put in place by the Bush Adminitration. Has a nice, safe anti-terror sound to it and you can bet your life no GOP and probably not many Dem members of Congress would vote to rescind it.
3020 is right on this one. It's profiling, and probably enough life ruining "false positives " to make it not so great a deal. Like the roundi up that filled up Gitmo, or the death penalty. Same set of motions.