BUCKLEY v. VALEO 1 Per Curiam vide that its own officers may make appointments to such office or commission. So framed, the claim that Congress may provide for this manner of appointment under the Necessary and Proper Clause of Art. I stands on no better footing than the claim that it may provide for such manner of appointment because of its substantive authority to regulate federal elections. Congress could not, merely because it concluded that such a measure was "necessary and proper" to the discharge of its substantive legislative authority, pass a bill of attainder or ex post facto law contrary to the prohibitions contained in § 9 of Art. I. No more may it vest in itself, or in its officers, the authority to appoint officers of the United States when the Appointments Clause by clear implication prohibits it from doing so. The trilogy of cases from this Court dealing with the constitutional authority of Congress to circumscribe the President's power to remove officers of the United States is entirely consistent with this conclusion. In Myers v. United States, 272 U. S. 52 (1926), the Court held that Congress could not by statute divest the President of the power to remove an officer in the Executive Branch whom he was initially authorized to appoint. In explaining its reasoning in that case, the Court said: "The vesting of the executive power in the President was essentially a grant of the power to execute the laws. But the President alone and unaided could not execute the laws. He must execute them by the assistance of subordinates. . . . As he is charged specifically to take care that they be faithfully executed, the reasonable implication, even in the absence of express words, was that as part of his executive power he should select those who were