29 U.S.C. § 101: Issuance of restraining orders and injunctions; limitation; public policy

No court of the United States, as defined in this chapter, shall have jurisdiction to issue any restraining order or temporary or permanent injunction in a case involving or growing out of a labor dispute, except in a strict conformity with the provisions of this chapter; nor shall any such restraining order or temporary or permanent injunction be issued contrary to the public policy declared in this chapter.