Opinion of the Court
preempts state law even when the two only arguably conflict. San Diego Building Trades Council v. Garmon, 359 U. S. 236, 245 (1959) (“When an activity is arguably subject to §7 or §8 of the [NLRA], the States as well as the federal courts must defer to the exclusive competence of the National Labor Relations Board”). This doctrine—named Garmon preemption after the case that originated it—thus goes beyond the usual preemption rule. Under Garmon, States cannot regulate conduct “that the NLRA protects, prohibits, or arguably protects or prohibits.” Wisconsin Dept. of Industry v. Gould Inc., 475 U. S. 282, 286 (1986).
Though broad, this standard has teeth. Longshoremen v. Davis, 476 U. S. 380, 394 (1986) (“The precondition for preemption, that the conduct be ‘arguably’ protected or prohibited, is not without substance”). It requires more than “a conclusory assertion” that the NLRA arguably protects or prohibits conduct. Ibid. “[A] party asserting pre-emption must advance an interpretation of the [NLRA] that is not plainly contrary to its language and that has not been ‘authoritatively rejected’ by the courts or the Board.” Id., at 395. The party must then “put forth enough evidence to enable the court to find that the Board reasonably could uphold a claim based on such an interpretation.” Ibid.
If the court determines that the party has met its burden to show that “there is an arguable case for pre-emption,” it generally must grant the party’s preemption defense and await the Board’s resolution of the legal status of the relevant conduct. Id., at 397.[1] After that, “only if the Board
- ↑ We have recognized exceptions to this rule. One allows a court to resolve a claim if the party raising it lacks a “reasonable opportunity” to secure a Board decision on the legal status of the conduct at issue. Sears, Roebuck & Co. v. Carpenters, 436 U. S. 180, 201 (1978); see also Davis, 476 U. S., at 393, n. 10. Another applies if the conduct in question is “a merely peripheral concern” of the NLRA. San Diego Building Trades Council v. Garmon, 359 U. S. 236, 243 (1959). A third covers situations
