The Supreme Court rejected absolute executive privilege in the 1974 case United States v. this man
If 
the power is not absolute, should President Nixon be able to claim executive 
privilege ... For the United States: The President's power to claim executive 
privilege is... [DOC] [TLE] United States v. Nixon | Oyez [PAR] A case in which the Court held that the President does not have executive 
privilege in immunity from subpoenas or other civil court actions.