In AFL v. Swing, 312 U.S. 321, 61 S.Ct. 568, 85 L.Ed. 855 (1941), the Illinois Supreme Court had enjoined picketing by a labor union on the ground that there was no dispute between the employer and his immediate employees.
In United Steelworkers, the Court warned that the NLRA "does not command that labor organizations as a matter of abstract law, under all circumstances, be protected in the use of every possible means of reaching the minds of individual workers, nor that they are entitled to use a medium of communication simply because the employer is using it."