[FirstPrinciple]

Each branch of the Constitution is co-equal. The Founders never would have made the Supreme Court more powerful than any other branch. Each branch has the authority to interpret the Constitution. Congress is supposed to consider whether their action is Constitutional and the Executive also gets to determine whether a law just passed is Constitutional or not. Grover Cleveland routinely would veto bills that he thought didn't meet the Constitutional muster. To claim only the Supreme Court gets to interpret the Constitution is blatantly false.

[justshutupandtakeit]

Each branch must consider the constitutionality of its actions but only the Court has the ultimate word on it. Nixon had no choice but to surrender the tapes when the Court ruled he must. Even the Executive must obey the Court or make a mockery of the concept of law. Only a Clinton would believe himself to be above the law. Are you claiming that the Executive has the right to defy the USSC's rulings if it believes them unconstitutional?

It is true presidents can veto bills but that can occur for many reasons. He can veto would-be laws which are perfectly constitutional as well as would-be laws for any reason whatsoever. It is true that if he vetos a would-be law and says it was because it was unconstitutional the Court has nothing to say about it. But it only rules on actual laws not semi-laws. Bills which are prevented from becoming law are not Laws.

However there is another aspect here which gives Congress ultimate control over the whole situation. Congress has the right to restrict the Court as to its jurisdiction under the Exceptions Clause. It never has used that power but that does not remove the clause from the Constitution. All the branches are equal but the Founders intended that Congress be slightly more equal than the rest.