Politics: Wiretap controversy - Impeachable offense?

There has been lots of thunder and lightening over President Bush authorizing electronic intelligence gathering of communication between suspected terrorists without the usual FISA court approval.

FISA is a special Federal court that was established under the Foreign Intelligence Surveillance Act.

Critics claim that Bush has violated the Fourth Amendment:

Amendment IV
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 probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Defenders of Bush are citing Article II Section II:

Section 2
The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States.

I'm not a lawyer and so I'll leave that to others to figure out. But as a typical citizen of the United States, I'm sitting here wondering, what the heck is going on?

If Mr. Suspected Terrorist with a cell phone in foreign country X calls Mr. So and So in the USA, would you want to know what they are talking about?

I don't know how long it takes for FISA approval to occur but I suspect in the fast paced world of intelligence gathering, there might be times when a tip will go dry long before a couple of lawyers can file the paper work.

Imagine some intelligence agent testifying before Congress: we had a tip that several of the people in that suspected terror cell were communicating to coordinate a bombing. We found a laptop with some cell phone numbers and were waiting for approval to tap those numbers but the bombing happened.

Imagine the outrage all around?

I'd think some would want to impeach the President if he failed to take such steps in a post-9/11 world and a terrorist attack occurred on American soil.

UPDATE: I saw this item from Kaus:

Aren't the parameters of the great eavesdropping debate becoming clearer? 1) The administration bypassed the special FISA court, not because it would somehow have been too time consuming to obtain warrants, but because warrants wouldn't have been granted under the "probable cause" standard; 2) the warrants wouldn't have been granted because the wiretaps were quasi-data-mining wiretaps, trolling phone calls of 10% likely suspects for tipoff phrases like "Brooklyn Bridge;" 3) that's probably illegal; 4) but it's also probably a good way to stop terror plots--it hardly presents a "false choice;"

I'm not clear what would constitute "probable cause."

I suppose if the targeted cell phone number was from a known terrorist that would pass as "probable cause?" I suppose a known terrorist would be someone who has been involved in a prior terrorist act? But what constitutes proof they were involved in a prior terrorist act? Is direct hands on participation the standard?

What if a known terrorist is caught and his cell phone logs are obtained, would anyone he called be considered a suspected terrorist and thus subject to electronic eavesdropping? Would that be sufficient "probable cause" to intercept phone calls?

I suppose in the context of traditional criminal law that would NOT be probable cause. It would be like saying, embezzler Mr. Smith has a cell phone and everyone on his cell phone log is an accomplice so we should wiretap all those numbers.

Kaus maybe right to assert that in the context of terrorism, one may have to LOWER the "probable cause" standard because the stakes are HIGHER should intelligence fail to pick up a threat.