John writes to clarify the powers of the US Supreme Court, and gives some excellent examples:

I see that Roger has been conducting a debate with somebody named "George" who says Marbury v. Madison means that "the Supreme Court is the final arbiter of the Constitution. The president is not allowed to interpret the Constitution."

Of course, that is a grossly misleading overstatement. The Supreme Court is only final with regard to the cases, controversies and parties that are (properly) before it. What is final is a Supreme Court decision - NOT ITS OPINION.

The decision is final (binding on the parties) simply because there is no further appeal. But everyone is free to disagree with the opinions of the justices and to act accordingly. The fact that US v. Nixon forced Nixon to turn over the Watergate tapes does not prevent a later president from asserting executive privilege.

In McCullough v. Maryland (1819) the Supreme Court said it was constitutional for Congress to create a national bank. Andrew Jackson believed it was unconstitutional. In his veto message of 1832, Jackson explained why he was not bound by John Marshall's opinion on this.
http://www.yale.edu/lawweb/avalon/presiden/veto/ajveto01.htm

In Dred Scott v. Sandford (1857), the Supreme Court said it was unconstitutional for Congress to ban slavery in the Western territories the U.S. had purchased from France and Mexico. Lincoln believed it was constitutional and, indeed, his goal was to do exactly that. In these speeches, Lincoln argued that the finality of the Dred Scott decision applied only to the parties to the case. Everyone else was free to reject the "rule" or "principles" of the decision and act accordingly.
http://www.bartleby.com/251/1003.html
http://www.bartleby.com/251/1006.html
http://www.bartleby.com/124/pres31.html