Constitution of the United States of America
Article III: Judicial Branch
Article 3, Section 1:  Judicial Power and Tenure

 The judicial Power of the United States shall be vested in
one supreme Court, and in such inferior Courts as the Congress
may from time to time ordain and establish.

3.1.2  The Judges, both of the supreme and inferior Courts,
shall hold their Offices during good Behavior, and shall, at
stated Times, receive for their Services a Compensation, which
shall not be diminished during their Continuance in Office.