Page:Glacier Northwest v. Teamsters.pdf/17

2 determined that, “[w]hen an activity is arguably subject to §7 or §8 of the Act” (which, respectively, concern employees’ right to engage in concerted activity and unfair labor practices), “the States as well as the federal courts must defer to the exclusive competence of the National Labor Relations Board [(NLRB or Board)].” 359 U. S., at 245. The Court went on to explain that this prophylactic rule of pre-emption may apply even to state-court claims arising under state private law (rather than the NLRA or a comparable state regulatory scheme) and even to claims seeking remedies not available from the Board. Id., at 246–248. Nor, under the Court’s rule, is the State’s power to act restored if the NLRB “fail[s] to determine the status of the disputed conduct by declining to assert jurisdiction, or by refusal … to file a charge; or by adopting some other disposition which does not define the nature of the activity with unclouded legal significance.” Id., at 245–246.

Garmon acknowledged that the NLRA’s pre-emption implications “ ‘are of a Delphic nature,’ ” leaving the States’ residual power in a “ ‘penumbral area [that] can be rendered progressively clear only by the course of litigation.’ ” Id., at 240–241 (quoting Machinists v. Gonzales, 356 U. S. 617, 619 (1958); Weber v. Anheuser-Busch, Inc., 348 U. S. 468, 480–481 (1955)). It thus emphasized that “Congress has entrusted administration of the labor policy for the Nation to a centralized administrative agency,” making it “essential to the administration of the Act” that determinations about protected and prohibited conduct “be left in the first