J Dubya said:
"The fact that you have to at some point present a case of proof to validate the tap means in effect it is not warrantless, just after the fact."
I'll begin by quoting the fourth amendment in its entirety:
"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."
The whole point of the 4th amendment is that the people have a right to "be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures."
The fourth explicitly says that right "shall not be violated". I don't think there's more than one way to read that. In this context, "shall not" means the government is forbidden to violate that right, period.
The laws in force at the time (English common law dating as far back as 1278) required that a warrant be issued to search and/or seize. That's the context that the fourth must be interpreted within. Building on that requirement, the fourth further declares:
"...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."
Look at the order. The law said you couldn't search or seize without a warrant. The fourth says that a warrant must be predicated upon probable cause, which itself depends upon oath or affirmation, and that the warrant must describe the place to be searched and any specific thing that is being searched for, or which they are looking to seize.
This carefully described order clearly defines "reasonable"; because the stated goal of the amendment is to protect people from unreasonable searches and seizures. Here it is:
Oath or affirmation leads to...
...probable legal cause, which leads to...
...oath or affirmation in front of a judge, which leads to...
...the judge issuing a warrant, which must...
...describe the things to be searched for or seized, which leads to...
...a fourth-amendment compliant, and therefore legal, search or seizure for only those things described.
The intent is not only stated (to keep people secure in their persons, houses, papers and effects), the whole design of the fourth is to achieve that goal.
Now, please consider: The fourth's orderly (and very reasonable) sequence has been dramatically and functionally altered in the FISA rules. There, the order is search, find probable cause, get warrant. Which violates the very specific requirements of the fourth.
Such an order ensures that citizens are no longer secure "secure in their persons, houses, papers, and effects." You can be monitored at any time, for any (or no) reason. If they find something, they get a warrant -- just a paper exercise, because they've already found it, you see? At that point, all the requirements for probable cause, oath or affirmation, and a warrant are simply window dressing, because they are guaranteed to be provided.
The whole point of the fourth is that no one should be violating your privacy unless they have good reason to assume you specifically are doing something wrong. First!
Let me demonstrate with my dress analogy:
Let us say that a lady elects to wear a skirt. Does this give us the right to look up her skirt? After all, if she didn't want us looking, she could have worn pants, is this not true?
But any reasonable person understands the privacy issue perfectly well that she is not extending anyone permission to look up her skirt just because she is wearing one. She almost certainly wishes, perfectly reasonably, to be "secure in her person", just as the fourth amendment attempts to guarantee.
But what if she is a shoplifter and is hiding merchandise up her skirt? Would this not give us the right to look up her skirt? The answer is, it would if one had knowledge that this was the case.
The constitution calls this "probable cause." The idea that a lady could hide merchandise under her skirt clearly does not translate into the right to look up all ladies' skirts - the very idea is ludicrous, is it not?
Yet the US government is telling us that the reason they are justified in looking at everyone's email and phone conversations and other activity with FISA and the like is because these activities could "enable" illicit activity.
This is precisely the same kind of reasoning we just disposed of with skirts; the only time the government should be looking at any communication is when (a) they have probable cause, (b) supported by oath or affirmation, to think that those communications are of a criminal nature, (c) they have obtained a warrant that (d) specifically describes the communications to be searched. In that order.
The argument has been made (by the government, and by some citizens) that they "need" this power in order to "save us from the terrorists."
OK. If the government really feels that they need this power, then the authors of the constitution were prescient enough to provide a legitimate means for them to attempt to get it. Nice, eh?
This is laid out in article V, "Amendment." In this case, what they'd be asking for isn't something they'd be all that likely to get, and I respectfully submit that this is likely one of the primary reasons they illegitimately took this power rather than attempting to obtain proper constitutional authority for it.
So when you say "...it is not warrantless, just after the fact", I assert this is a distinction without a difference. Wiretapping without a warrant and getting one later is still wiretapping without a warrant. Time runs in the same direction for the government as it does for the people. The protections and specifications of the fourth amendment have not themselves been amended; therefore, the government's actions under FISA are entirely unconstitutional, by definition.