The DOJ, without a warrant or court order, have been utilizing a system known as "hotwatches" to track individuals of interest. The only time, upon administrative approval of this domestic spying, that a court is involved is not to safeguard the privacy interests of American citizens, but to issue a gag order to the Banks and Credit Card issuers for non-disclosure.
Really, I shouldn't be surprised at this point.
Check out the DOJ presentation obtained through FOIA requests by privacy advocate Christopher Soghoian
DOJ powerpoint presentation on Hotwatch surveillance orders of credit card transactions
Lest anyone think the damages wrought by the Bush Administration (and sadly, still continued by the Obama administration) simply don't affect anyone but foreigners and terrorists, let this be a warning to you. Our civil liberties have been eroded so terribly over the past decade, that we may never fully get them back. And, don't count on courts to help you either; the federal courts have turned into one huge rubber-stamp for the creeping surveillance society that is a very real threat to us all. Police state? Not yet. Getting there? Bet your ass, we are.
Remember when the boys in blue were your neighbors and "protected and served", and were not militarized thugs who treated every citizen as a potential enemy.