The three branches of the U.S. Government are the legislative, executive, and judicial.
Article I of the Constitution defines the legislative branch and vests power to legislate in the Congress of the United States.
The executive powers of the President are defined in Article 2.
Article 3 places judicial power in the hands of one Supreme Court and inferior courts as Congress sees necessary to establish
Congress and the President nominates individuals to serve in the Federal judiciary; the Supreme Court can declare a law enacted by Congress or an action by the President unconstitutional; and Congress can impeach the President and Federal court justices and judges.