Noting that section 8(b) was intended to preserve "the right of labor organizations to bring pressure to bear on offending employers in primary labor disputes"
Stating that section 8(b) prohibits labor unions from engaging in "secondary boycotting" by "exert[ing] pressure on an employer not involved in the relevant labor dispute ('the secondary employer') in order to obtain a favorable result in the ongoing labor dispute with another employer ('the primary employer')"
In National Labor Relations Bd. v. Business Mach. etc., CIO (228 F.2d 553) the Circuit Court of Appeals for this circuit declared (p. 559) that "The only thing proscribed by ยง 8(b)(4) is inducement or encouragement of the employees of the customers".