Article III, Section 1:
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. The Judges, both of the supreme and inferior Courts, shall hold their Offices during good Behaviour, and shall, at stated Times, receive for their Services, a Compensation, which shall not be diminished during their Continuance in Office.
It seems settled, though not without dissent, that state courts have no power to enjoin proceedings 1 or effectuation of judgments 2 of the federal courts, with the exception of cases in which a state court has custody of property in proceedings in rem or quasi in rem, where the state court has exclusive jurisdiction to proceed and may enjoin parties from further action in federal court. 3