Read other letters about this article
Note first the FBI letter refers to "the unauthorized disclosure of classified information regarding the Presidentially-authorized NSA program". This isn't described as the Constitutionally-allowed or the legal program; it is merely Presidentially-authorized.
Next, we have the esteemed Speaker Pelosi. From her letter to Hayden in Glenn's link:
Therefore, I am concerned whether, and to what extent, the National Security Agency has received specific presidential authorization for the operations you are conducting. Until I understand better the legal analysis regarding the sufficiency of the authority which underlies your decision on the appropriate way to proceed on this matter, I will continue to be concerned.
The Speaker is "concerned" about the practice, that is, unless it has received "specific presidential authorization". That would appear to be the only requirement for what Pelosi deems to be the "legal analysis regarding the sufficiency of the authority which underlies" the actions. The Constitution, Federal statutes and the US Code of Federal Regulations are just so quaint.
Just wow.