Millions not a couple of dozen Americans “sucked into the vacuum”

ABC’s Nightline had an NSA whistleblower alleging illegal spying (the link has the Nightline video) could have eavesdropped on millions of Americans. As the source for the NY Times article blowing the cover of the operation (thoughts and implications here), he is apparently the target of rage by the Administration on the leaking of the program.

The damage to domestic and foreign credibility may be severe,
although not to those who feel "no holds barred" is the name of the
game. "Do as we say, not as we do" is not a good motto for a role model.

Meanwhile, Opinio Juris notes a number of "prominent law scholars and attorneys" rejected the Administration’s claims to have the right to conduct this surveillance in a letter:

The letter critiques the Department of Justice’s legal justifications
for the NSA wiretapping program, in particular, the U.S. government’s
reliance on the Sept. 11 Resolution authorizing military force, to
circumvent or avoid the restrictions created by the Foreign
Intelligence Surveillance Act (FISA). Of course it is well-crafted,
reasonable, and persuasive. It takes a couple of unnecessary shots at
John Yoo, I think, but it is still very sensible in focusing on the
statutory rather than constitutional arguments. But while I am halfway
persuaded, I do wonder if the law prof letter relies too heavily on a
FISA provisions limiting wiretaps to 15 days after the declaration of

The argument against the right to do anything hinges on what the authorization for the use of military force (AUMF) comprises:

[E]ven where Congress has declared war—a more formal step than an
authorization such as the AUMF—the law limits warrantless wiretapping
to the first fifteen days of the conflict. Congress explained that if
the President needed further warrantless surveillance during wartime,
the fifteen days would be sufficient for Congress to consider and enact
further authorization. [footnote omitted] Rather than follow this
course, the President acted unilaterally and secretly in contravention
of FISA’s terms. The DOJ letter remarkably does not even mention FISA’s
fifteen-day war provision, which directly refutes the President’s
asserted "implied" authority.