The NSA doesn't consider itself bound by law and hasn't since its inception. During the Church Committee hearings in the 70s, the NSA's general counsel admitted

The NSA doesn't consider itself bound by law and hasn't since its inception. During the Church Committee hearings in the 70s, the NSA's general counsel admitted as much: “No existing statutes control, limit, or define the signals intelligence activities of the NSA.” -Roy Banner