In United Mine Workers v. Arkansas Oak Flooring Co., 351 U.S. 62, 76 S.Ct. 559, 100 L. Ed. 941, references to postlegislative history were referred to in the opinion of the Court.
In Thayer, the court first announced that if the activity causing dismissal was protected under § 7 of the Act then denial of reinstatement was unlawful. If the activity was unprotected under § 7, however, the legality of the denial was to be determined according to a balancing test.