National Review's Byron York has an article entitled "It's Legal" supporting the proposition that the NSA surveillance program has solid legal basis.
York discusses the FISA Court of Review's In Re: Sealed Case, decided by a three-judge appellate panel in November 2002, reversing the May 17, 2002 ruling of the FISA court.
The May 17th ruling refused to acknowledge Patriot Act changes to FISA and established what the Justice Department labelled as a "chaperone requirement."
Referring to an earlier case, known as Truong, which dealt with surveillance before FISA was passed, the Court of Review wrote: "The Truong court, as did all the other courts to have decided the issue, held that the President did have inherent authority to conduct warrantless searches to obtain foreign intelligence information. . . . We take for granted that the President does have that authority and, assuming that is so, FISA could not encroach on the President's constitutional power."