"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probablecause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized." – Fourth Amendment
Was Bush (Congress, the NSA, whomever) wrong to employ the kinds of wiretaps he did? Did he violate Constitutional law? I don’t know. Just because a certain power is not forbidden to the federal government by the Constitution, doesn’t mean it’s licit.