The argument against immunity is that the telecom companies were also represented by high priced counsel and they could determine for themselves whether the program was legal. If they believed it to be legally dicey, they should have hesitated without legislative or judicial authorization. If Presidents can go to any private company and encourage them to violate the law and then get retroactive immunity for the violation, this will undermine the separation of powers. Presidents will be encouraged to violate all sorts of laws-- even laws like FISA that are carefully crafted to constrain executive action-- secure in the knowledge that they can always get Congress to clean up their mess later on. The Detainee Treatment Act and the Military Commissions Act are not precedents for even more immunities; they are bad precedents that show that Congress is all too willing to immunize even the worst offenses-- including war crimes-- as soon as the President says the magic words "terrorism" and "national security."
I'm th' Preznit. I wanna git free pizza.
Gimme a damn pizza. In fact, gimme one fer everyone on mah staff.
An' if it's illegal, eff you. I'll fix it fer ya. Jest buy one of mah "indulgences," and I'll git a staffer t' write'cha a lawyer's note saying yer cool.
Also, if you've got a bank, I think you should send me a million bucks. Fer national security an' stuff.
Rockefeller'll fix it up.