Please read Elizabeth Holtzman's excellent piece, The Impeachment of George W. Bush
, in The Nation
. She lays it out both simply and persuasively, for example:
On December 17 President Bush acknowledged that he repeatedly authorized wiretaps, without obtaining a warrant, of American citizens engaged in international calls. On the face of it, these warrantless wiretaps violate FISA, which requires court approval for national security wiretaps and sets up a special procedure for obtaining it. Violation of the law is a felony.