[As] far as the duty to appear is concerned, this Court holds that Executive branch officials are not absolutely immune from compulsory congressional process—no matter how many times the Executive branch has asserted as much over the years—even if the President expressly directs such officials’ non-compliance. Today, this Court adds that this conclusion is inescapable precisely because compulsory appearance by dint of a subpoena is a legal construct, not a political one, and per the Constitution, no one is above the law. That is to say, however busy or essential a presidential aide might be, and whatever their proximity to sensitive domestic and national-security projects, the President does not have the power to excuse him or her from taking an action that the law requires. Fifty years of say so within the Executive branch does not change that fundamental truth.

Nor is the power of the Executive unfairly or improperly diminished when the Judiciary mandates adherence to the law and thus refuses to recognize a veto-like discretionary power of the President to cancel his subordinates’ legal obligations. To the contrary, when a duly authorized committee of Congress issues a valid subpoena to a current or former Executive branch official, and thereafter, a federal court determines that the subpoenaed official does, as a matter of law, have a duty to respond notwithstanding any contrary order of the President, the venerated constitutional principles that animate the structure of our government and undergird our most vital democratic institutions are preserved.