28 U.S.C. § 2283 : US Code - Section 2283: Stay of State court proceedings

Search 28 U.S.C. § 2283 : US Code - Section 2283: Stay of State court proceedings

A court of the United States may not grant an injunction to stay
proceedings in a State court except as expressly authorized by Act
of Congress, or where necessary in aid of its jurisdiction, or to
protect or effectuate its judgments.