We are now on the verge of one of those grand and grave constitutional dramas that scholars and historians will study decades, maybe centuries, from now.
The president's legal position — that no law may forbid him from ordering domestic surveillance without a warrant — is not explicitly contained in the text of the Constitution, has never before been implied into it by the federal courts, and is nowhere to be found in Congress' most germane legislation on the topic. You might say, as one long ago Supreme Court justice might have put it, that the president's power to wage war in this fashion, without specific constitutional or statutory authority, stems from the discovery by government lawyers of "penumbral emanations" of such power in the Constitution itself. That doesn't mean the power does not somehow exist; it just means that no other branch of government, including the branch that has the job of interpreting the Constitution, has ever stated that it does.
There's already an interesting debate going on over at Pandagon whether or not Dems should consider pushing for impeachment, which raises the issue of the Order of Presidential Succession:
#2: Dick Cheney
#3: Denny Hastert
#4: Ted Stevens
#5: Condi Rice
As much as I would love to see Bush impeached for violating the constitution, does anyone want to live under President Cheney? Additionally, couldn't Bush just blame his lawyers for giving him bad legal advice? After all, he's neither a lawyer or constitutional scholar and could eventually try to defend himself by saying that he didn't know better. In other words, he could play the I'm-too-ignorant-to-do-my-job card as well as the I-should-have-got-a-second-opinion card.
(Aside: Arnold? What are your thoughts on Bush's predicament?)