How we cite our quotes: (Section.Subsection.Paragraph) or (Section.Paragraph)
Quote #1
The second ground asserted by the President's counsel in support of the claim of absolute privilege rests on the doctrine of separation of powers. Here it is argued that the independence of the Executive Branch within its own sphere, insulates a President from a judicial subpoena in an ongoing criminal prosecution, and thereby protects confidential Presidential communications. (IV.B.2)
The president claims that the he's protected by the separation of powers doctrine from the power of the judicial branch, even in a criminal case. This is pretty scary, if you think about it. Unless he's impeached, there's nothing anyone can do.
Quote #2
But this presumptive privilege must be considered in light of our historic commitment to the rule of law. (IV.C.3)
The Supremes are clear that the president's privilege isn't the only consideration in this case. There's those pesky issue of the rule of law and due process.
Quote #3
The President, both as Commander-in-Chief and as the Nation's organ for foreign affairs has available intelligence services whose reports are not and ought not to be published to the world. It would be intolerable that courts, without the relevant information, should review and perhaps nullify actions of the Executive taken on information properly held secret. (IV.C.7)
The Court cites an earlier case that stated that a court has no authority to subpoena the president's tapes without knowing for sure what is on the tapes. Unfortunately for Nixon, the special prosecutor did have a pretty good idea of what was on those tapes, based on testimony some White House staffers gave to the Watergate Committee. And it definitely wasn't about foreign affairs.