It seems like the Patriot Act ended up being much like the Patriot Defense System:
It was originally aimed at one set of targets (foreign terrorists), but then was "upgraded" for a different set of targets (American Citizens).
Its a common evolution in military history.
The German 88mm AA gun became a mainstay of their antitank arsenal. The French 75mm 1897 field gun ended up being developed into the main armament of the Sherman tank (they could share ammunition). The Thunderbolt and Corsair were developed as air superiority fighters but ended up primarily used as fighter-bombers.
On and on its a long list.