WHY WE NEED JUDICIAL OVERSIGHT

We need it because the Executive Branch, especially under Cheney, can't be trusted to obey the law. You may recall that 2 years ago, Gen. Hayden, then head of the NSA, had a mediocre understanding of the 4th Amendment:

UNIDENTIFIED MALE: My understanding is that the Fourth Amendment to the Constitution specifies that you must have probable cause to be able to do a search that does not violate an American‘s right against unlawful searches and seizures. Do you use...

GEN. MICHAEL HAYDEN: Well, actually, the Fourth Amendment actually protects all of us against unreasonable search and seizure. That‘s what it says.

UNIDENTIFIED MALE: But the measure is probable cause, I believe.

HAYDEN: The amendment says unreasonable search and seizure.

UNIDENTIFIED MALE: But does it not say probable...

HAYDEN: No.

UNIDENTIFIED MALE: ... the court standard...

HAYDEN: The amendment says...

UNIDENTIFIED MALE: ... the legal standard...

HAYDEN: ... unreasonable search and seizure.

UNIDENTIFIED MALE: ... the legal standard is probable cause.

HAYDEN: Just to be very clear—and believe me, if there‘s any amendment to the Constitution that employees of the National Security Agency are familiar with, it‘s the Fourth. And it is a reasonableness standard in the Fourth Amendment.

Here's the actual 4th 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.

If we can't trust the head of the NSA, then we surely can't trust a mere NSA shift supervisor to make the right decisions.

Further, Hayden never seems to have gotten up to speed on this important legal issue, according to Barton Gellman of the WaPo:

By the end of February, Goldsmith and Philbin had reached their conclusion: Parts of the surveillance operation had no support in law. Comey was so disturbed that he drove to Langley one evening to compare notes with Scott W. Muller, the general counsel at the CIA. Muller "got it immediately," agreeing with the Goldsmith-Philbin analysis, Comey said.

"At the end of the day, I concluded something I didn't ever think I would conclude, and that is that Pat Philbin and Jack Goldsmith understood this activity much better than Michael Hayden did," he said.