American Constitutions, both state and federal, divides the government into three separate departments—the legislative, executive, and judicial. This separation and the consequent exclusive character of the powers conferred upon each of the three departments is basic and vital—not merely a matter of governmental mechanism. It may be stated then, as a general rule inherent in the American constitutional system, that, unless otherwise expressly provided or incidental to the powers conferred, the legislature cannot exercise either executive or judicial power; the executive cannot exercise either legislative or judicial power; the judiciary cannot exercise either executive or legislative power. Decided May 14, 1928 (argued April 10, 1928). Opinion of the Court: George Sutherland → go there Dissenting: Holmes, McReynolds. Topic: Separation of powers. Springer v. Government of the Philippine Islands, 277 U.S. 189 (1928), was a decision of the United States Supreme Court concerning the Appointments Clause. Wiki link