There are two main threads of reasoning that the administration has offered when pushed to justify its questionable actions. The first is the Authorization to Use Military Force (AUMF) which was passed by Congress in the week following September 11, 2001. It specifically pertains to actions against al Qaeda, but the administration has claimed that it provides justification for their supra-legal wiretaps.

The second justification is that President Bush's powers as Commander in Chief allow him to do whatever he deems necessary in the War on Terror (an interesting legal argument that deems anything that stands in his way, even Congressional legislation, unconstitutional).

The only court cases thus far that deal with these issues are detainee cases -- most notably, Jose Padilla. For anyone concerned about, or simply interested in, the extent of executive power, read the text of the AUMF, and the details about how and why the Padilla case has become a crucial lithmus test of presidential power…and, how the administration has been desperately trying to make these cases disappear.