Whether a State may regulate conduct that is arguably protected by § 7 of the National Labor Relations Act or arguably prohibited as an unfair labor practice by § 8.
Holding
No. When conduct is arguably subject to § 7 or § 8, state courts and federal courts must defer to the National Labor Relations Board's primary and exclusive competence.
Reasoning
Congress created a comprehensive national labor-relations system and entrusted its primary administration to the NLRB. Federal preemption in this field protects not only uniform substantive rules, but also the Board's specialized procedures and administrative judgment. Allowing states to make their own initial determinations would invite conflicting legal standards, remedies, and enforcement systems.
The Court therefore focuses on potential conflict, not merely a demonstrated conflict in the particular case. State courts are not the primary tribunals for deciding whether disputed labor activity falls within § 7's protections or § 8's prohibitions. If conduct is arguably covered, the risk that state regulation will frustrate national labor policy is sufficient to require deference to the Board.
California's adjudication rested on the premise that the unions' conduct was an unfair labor practice. But whether the peaceful picketing and economic pressure were protected, prohibited, or outside the Act was for the NLRB to decide in the first instance. Because the activity was at least arguably within §§ 7 or 8, California lacked jurisdiction to regulate it.