The Supreme Court has held that a ruling by the General Counsel of the National Labor Relations Board that no "employees," as defined by the National Labor Relations Act, were involved in a labor dispute precluded the possibility that picketing activities arising out of the dispute constituted a violation of section 8(b)(4)(B) of the act. In this circumstance, the Court held that the pre-emption doctrine should not be invoked when its application will tend to thwart federally established labor relations policy.
Labor Law: Implementation of Congressionally Declared National Labor Policy Precludes Invocation of Doctrine of Pre-Emption,
1966 Duke Law Journal
Available at: https://scholarship.law.duke.edu/dlj/vol15/iss4/5