opinion: SEARS, ROEBUCK & CO. v. SAN DIEGO COUNTY DISTRICT COUNCIL OF CARPENTERS
  No. 76-750.
  Argued November 7, 1977
  Decided May 15, 1978
  SteveNS, J., delivered the opinion of the Court, in which BurgeR, C. J., and White, BlacicmuN, Powell, and Rehnquist, JJ., joined. BlacKMUN, J., post, p. 208, and Powell, J., post, p. 212, filed concurring opinions. BrennáN, J., filed a dissenting opinion, in which Stewart and Marshall, JJ., joined, post, p. 214.
  H. Warren Siegel argued the cause for petitioner. With him on the briefs were Lawrence M. Cohen and Jeffrey S. Goldman.
  Jerry J. Williams argued the cause for respondent. With him on the brief were J. Albert Woll and Laurence Gold.
  John W. Noble, Jr., filed a brief for the American Retail Federation as amicus curiae urging reversal.
  Solicitor General McCree, John S. Irving, Carl L. Taylor, Norton J. Come, and Linda Sher filed a brief for the National Labor Relations Board as amicus curiae urging affirmance.
  Mr. Justice Stevens
  delivered the opinion of the Court.
  The question in this case is whether the National Labor Relations Act, as amended, deprives a state court of the power to entertain, an action by an employer to enforce state trespass laws against picketing which is arguably — but not definitely — prohibited or protected by federal law.
  I
  On October 24, 1973, two business representatives of respondent Union visited the department store operated by petitioner (Sears) in Chula Vista, Cal., and determined that certain carpentry work was being performed by men who had not been dispatched from the Union hiring hall. Later that day, the Union agents met with the store manager and requested that Sears either arrange to have the work performed by a contractor who employed dispatched carpenters or agree in writing to abide by the terms of the Union's master labor agreement with respect to the dispatch and use of carpenters. The Sears manager stated that he would consider the request, but he never accepted or rejected it.
  Two days later the Union established picket lines on Sears' property. The store is located in the center of a large rectangular lot. The building is surrounded by walkways and a large parking area. A concrete wall at one end separates the lot from residential property; the other three sides adjoin public sidewalks which are adjacent to the public streets. The pickets patrolled either on the privately owned walkways next to the building or in the parking area a few feet away. They carried signs indicating that they were sanctioned by the “Carpenters Trade Union." The picketing was peaceful and orderly.
  Sears' security manager demanded that the Union remove the pickets from Sears’ property. The Union refused, stating that the pickets would not leave unless forced to do so by legal action. On October 29, Sears filed a verified complaint in the Superior Court of California seeking an injunction against the continuing trespass; the court entered a temporary restraining order enjoining the Union from picketing on Sears’ property. The Union promptly removed the pickets to the public sidewalks. On November 21, 1973, after hearing argument on the question whether the Union’s picketing on Sears’ property was protected by state or federal law, the court entered a preliminary injunction. The California Court of Appeal affirmed. While acknowledging the pre-emption guidelines set forth in San Diego Building Trades Council v. Garmon, 359 U. S. 236, the court held that the Union’s continuing trespass fell within the longstanding exception for conduct which touched interests so deeply rooted in local feeling and responsibility that pre-emption could not be inferred in the absence of clear evidence of congressional intent.
  The Supreme Court of California reversed. 17 Cal. 3d 893, 553 P. 2d 603. It concluded that the picketing was arguably protected by § 7 of the Act, 29 U. S. C. § 157, because it was intended to secure work for Union members and to publicize Sears’ undercutting of the prevailing area standards for the. employment of carpenters. The court reasoned that the trespassory character of the picketing did not disqualify it from arguable protection, but was merely a factor which the National Labor Relations Board would consider in determining whether or not it was in fact protected. The court also considered it “arguable” that the Union had engaged in recog-nitional picketing subject to §8 (b)(7)(C) of the Act, 29 U. S. C. § 158 (b)(7)(C), which could not continue for more than 30 days without petitioning for a representation election. Because the picketing was both arguably protected by § 7 and arguably prohibited by § 8, the court held that state jurisdiction was pre-empted under the Garmon guidelines.
  Since the Wagner Act was passed in 1935, this Court has not decided whether, or under what circumstances, a state court has power to enforce local trespass laws against a union’s peaceful picketing. The obvious importance of this problem led us to grant certiorari in this case. 430 U. S. 905.
  II
  We start from the premise that the Union’s picketing on Sears’ property after the request to leave was a continuing trespass in violation of state law. We note, however, that the scope of the controversy in the state court was limited. Sears asserted no claim that the picketing itself violated any state or federal law. It sought simply to remove the pickets from its property to the public walkways, and the injunction issued by the state court was strictly confined to the relief sought. Thus, as a matter of state law, the location of the picketing was illegal but the picketing itself was unobjectionable.
  As a matter of federal law, the legality of the picketing was unclear. Two separate theories would support an argument by Sears that the picketing was prohibited by § 8 of the NURA, and a third theory would support an argument by the Union that the picketing was protected by § 7. Under each of these theories the Union’s purpose would be of critical importance.
  If an object of the picketing was to force Sears into assigning the carpentry work aw’ay from its employees to Union members dispatched from the hiring hall, the picketing may have been prohibited by § 8 (b)(4)(D). Alternatively, if an object of the picketing was to coerce Sears into signing a prehire or members-only type agreement with the Union, the picketing was at least arguably subject to the prohibition on recognitional picketing contained in §8 (b)(7)(C). Hence, if Sears had filed an unfair labor practice charge against the Union, the Board’s concern would have been limited to the question whether the Union’s picketing had an objective proscribed by the Act; the location of the picketing would have been irrelevant.
  On the other hand, the Union contends that the sole objective of its action was to secure compliance by Sears with area standards, and therefore the picketing was protected by § 7. Longshoremen v. Ariadne Shipping Co., 397 U. S. 195. Thus, if the Union had filed an unfair labor practice charge under § 8 (a) (1) when Sears made a demand that the pickets leave its property, it is at least arguable that the Board would have found Sears guilty of an unfair labor practice.
  Our second premise, therefore, is that the picketing was both arguably prohibited and arguably protected by federal law. The case is not, however, one in which “it is clear or may fairly be assumed” that the subject matter which the state court sought to regulate — that is, the location of the picketing — is either prohibited or protected by the Federal Act.
  Ill
  In San Diego Building Trades Council v. Garmon, 359 U. S. 236, the Court made two statements which have come to be accepted as the general guidelines for deciphering the unexpressed intent of Congress regarding the permissible scope of state regulation of activity touching upon labor-management relations. The first related to activity which is clearly protected or prohibited by the federal statute. The second articulated a more sweeping prophylactic rule:
  “When an activity is arguably subject to § 7 or § 8 of the Act, the States as well as the federal courts must defer to the exclusive competence of the National Labor Relations Board if the danger of state interference with national policy is to be averted.” Id., at 245.
  While the Garmon formulation accurately reflects the basic federal concern with potential state interference with national labor policy, the history of the labor pre-emption doctrine in this Court does not support an approach which sweeps away state-court jurisdiction over conduct traditionally subject to state regulation without careful consideration of the relative impact of such a jurisdictional bar on the various interests affected. As the Court noted last Term:
  “Our cases indicate . . . that inflexible application of the doctrine is to be avoided, especially where the State has a substantial interest in regulation of the conduct at issue and the State’s interest is one that does not threaten undue interference with the federal regulatory scheme.” Farmer v. Carpenters, 430 U. S. 290, 302.
  Thus the Court has refused to apply the Garmon guidelines in a literal, mechanical fashion. This refusal demonstrates that “the decision to pre-empt . . . state court jurisdiction over a given class of cases must depend upon the nature of the particular interests being asserted and the effect upon the administration of national labor policies” of permitting the state court to proceed. Vaca v. Sipes, 386 U. S. 171, 180.
  With this limitation in mind, we turn to the question whether pre-emption is justified in a case of this kind under either the arguably protected or the arguably prohibited branch of the Garmon doctrine. While the considerations underlying the two categories overlap, they differ in significant respects and therefore it is useful to review them separately. We therefore first consider whether the arguable illegality of the picketing as a matter of federal law should oust the state court of jurisdiction to enjoin its trespassory aspects. Thereafter, we consider whether the arguably protected character of the picketing should have that effect.
  IV
  The enactment of the NLRA in 1935 marked a fundamental change in the Nation’s labor policies. Congress expressly recognized that collective organization of segments of the labor force into bargaining units capable of exercising economic power comparable to that possessed by employers may produce benefits for the entire economy in the form of higher wages, job security, and improved working conditions. Congress decided that in the long run those benefits would outweigh the occasional costs of industrial strife associated with the organization of unions and the negotiation and enforcement of collective-bargaining agreements. The earlier notion that union activity was a species of “conspiracy” and that strikes and picketing were examples of unreasonable restraints of trade was replaced by an unequivocal national declaration of policy establishing the legitimacy of labor unionization and encouraging the practice of collective bargaining.
  The new federal statute protected the collective-bargaining activities of employees and their representatives and created a regulatory scheme to be administered by an independent agency which would develop experience and expertise in the labor relations area. The Court promptly decided that the federal agency’s power to implement the policies of the new legislation was exclusive and the States were without power to enforce overlapping rules. Accordingly, attempts to apply provisions of the “Little Wagner Acts” enacted by New York and Wisconsin were held to be pre-empted by the potential conflict with the federal regulatory scheme. Consistently with these holdings, the Court also decided that a State’s employment relations board had no power to grant relief for violation of the federal statute. The interest in uniform development of the new national labor policy required that matters which fell squarely within the regulatory jurisdiction of the federal Board be evaluated in the first instance by that agency.
  The leading case holding that when an employer grievance against a union may be presented to the National Labor Relations Board it is not subject to litigation in a state tribunal is Garner v. Teamsters, 346 U. S. 485. Garner involved peaceful organizational picketing which arguably violated § 8 (b) (2) of the federal Act. A Pennsylvania equity court held that the picketing violated the Pennsylvania Labor Relations Act and therefore should be enjoined. The State Supreme Court reversed because the union conduct fell within the jurisdiction of the National Labor Relations Board to prevent unfair labor practices.
  This Court affirmed because Congress had “taken in hand this particular type of controversy . . . [i]n language almost identical to parts of the Pennsylvania statute,” 346 U. S., at 488. Accordingly, the State, through its courts, was without power to “adjudge the same controversy and extend its own form of relief.” Id., at 489. This conclusion did not depend on any surmise as to “how the National Labor Relations Board might have decided this controversy had petitioners presented it to that body.” Ibid. The precise conduct in controversy was arguably prohibited by federal law and therefore state jurisdiction was pre-empted. The reason for pre-emption was clearly articulated:
  “Congress evidently considered that centralized administration of specially designed procedures was necessary to obtain uniform application of its substantive rules and to avoid these diversities and conflicts likely to result from a variety of local procedures and attitudes toward labor controversies. Indeed, Pennsylvania passed a statute the same year as its labor relations Act reciting abuses of the injunction in labor litigations attributable more to procedure and usage than to substantive rules. A multiplicity of tribunals and a diversity of procedures are quite as apt to produce incompatible or conflicting adjudications as are different rules of substantive law. The same reasoning which prohibits federal courts from intervening in such cases, except by way of review or on application of the federal Board, precludes state courts from doing so. Cf. Myers v. Bethlehem Shipbuilding Corp., 303 U. S. 41; Amalgamated Utility Workers v. Consolidated Edison Co., 309 U. S. 261.” Id., at 490-491 (footnote omitted). “The conflict lies in remedies .... [W]hen two separate remedies are brought to bear on the same activity, a conflict is imminent.” Id., at 498-499.
  This reasoning has its greatest force when applied to state laws regulating the relations between employees, their union, and their employer. It may also apply' to certain laws of general applicability which are occasionally invoked in connection with a labor dispute. Thus, a State’s antitrust law may not be invoked to enjoin collective activity which is also arguably prohibited by the federal Act. Capital Service, Inc. v. NLRB, 347 U. S. 501; Weber v. Anheuser-Busch, Inc., 348 U. S. 468. In each case, the pertinent inquiry is whether the two potentially conflicting statutes were “brought to bear on precisely the same conduct.” Id., at 479.
  On the other hand, the Court has allowed a State to enforce certain laws of general applicability even though aspects of the challenged conduct were arguably prohibited by § 8 of the NLRA. Thus, for example, the Court has upheld state-court jurisdiction over conduct that touches “interests so deeply rooted in local feeling and responsibility that, in the absence of compelling congressional direction, we could not infer that Congress had deprived the States of the power to act.” San Diego Building Trades Council v. Garmon, 359 U. S., at 244. See Construction Workers v. Laburnum Constr. Corp., 347 U. S. 656 (threats of violence); Youngdahl v. Rainfair, Inc., 355 U. S. 131 (violence); Automobile Workers v. Russell, 356 U. S. 634 (violence); Linn v. Plant Guard Workers, 383 U. S. 53 (libel); Farmer v. Carpenters, 430 U. S. 290 (intentional infliction of mental distress).
  In Farmer, the Court held that a union member, who alleged that his union had engaged in a campaign of personal abuse and harassment against him, could maintain an action for damages against the union and its officers for the intentional infliction of emotional distress. One aspect of the alleged campaign was discrimination by the union in hiring hall referrals. Although such discrimination was arguably prohibited by § § 8 (b)(1)(A) and 8 (b)(2) of the NLRA and therefore an unfair labor practice charge could have been filed with the Board, the Court permitted the state action to proceed.
  The Court identified those factors which warranted a departure from the general pre-emption guidelines in the “local interest” cases. Two are relevant to the arguably prohibited branch of the Garmon doctrine. First, there existed a significant state interest in protecting the citizen from the challenged conduct. Second, although the challenged conduct occurred in the course of a labor dispute and an unfair labor practice charge could have been filed, the exercise of state jurisdiction over the tort claim entailed little risk of interference with the regulatory jurisdiction of the Labor Board. Although the arguable federal violation and the state tort arose in the same factual setting, the respective controversies presented to the state and federal forums would not have been the same.
  The critical inquiry, therefore, is not whether the State is enforcing a law relating specifically to labor relations or one of general application but whether the controversy presented to the state court is identical to (as in Garner) or different from (as in Farmer) that which could have been, but was not, presented to the Labor Board. For it is only in the former situation that a state court’s exercise of jurisdiction necessarily involves a risk of interference with the unfair labor practice jurisdiction of the Board which the arguably prohibited branch of the Garmon doctrine was designed to avoid.
  In the present case, the controversy which Sears might have presented to the Labor Board is not the same as the controversy presented to the state court. If Sears had filed a charge,, the federal issue would have been whether the picketing had a recognitional or work-reassignment objective; decision of that issue would have entailed relatively complex factual and legal determinations completely unrelated to the simple question whether a trespass had occurred. Conversely, in the state action, Sears only challenged the location of the picketing; whether the picketing had an objective proscribed by federal law was irrelevant to the state claim. Accordingly, permitting the state court to adjudicate Sears’ trespass claim would create no realistic risk of interference with the Labor Board’s primary jurisdiction to enforce the statutory prohibition against unfair labor practices.
  The reasons why pre-emption of state jurisdiction is normally appropriate when union activity is arguably prohibited by federal law plainly do not apply to this situation; they therefore are insufficient to preclude a State from exercising jurisdiction limited to the trespassory aspects of that activity.
  V
  The question whether the arguably protected character of the Union’s trespassory picketing provides a sufficient justification for pre-emption of the state court’s jurisdiction over Sears’ trespass claim involves somewhat different considerations.
  Apart from notions of “primary jurisdiction,” there would be no objection to state courts’ and the NLRB’s exercising concurrent jurisdiction over conduct prohibited by the federal Act. But there is a constitutional objection to state-court interference with conduct actually protected by the Act. Considerations of federal supremacy, therefore, are implicated to a greater extent when labor-related activity is protected than when it is prohibited. Nevertheless, several considerations persuade us that the mere fact that the Union’s trespass was arguably protected is insufficient to deprive the state court of jurisdiction in this case.
  The first is the relative unimportance in this context of the “primary jurisdiction” rationale articulated in Garmon. In theory, of course, that rationale supports pre-emption regardless of which section of the NLRA is critical to resolving a controversy which may be subject to the regulatory jurisdiction of the NLRB.. Indeed, at first blush, the primary-jurisdiction rationale provides stronger support for pre-emption in this case when the analysis is focused upon the arguably protected, rather than the arguably prohibited, character of the Union’s conduct. For to the extent that the Union’s picketing was arguably protected, there existed a potential overlap between the controversy presented to the state court and that which the Union might have brought before the NLRB. Prior to granting any relief from the Union's continuing trespass, the state court was obligated to decide that the trespass was not actually protected by federal law, a determination which might entail an accommodation of Sears’ property rights and the Union’s § 7 rights. In an unfair labor practice proceeding initiated by the Union, the Board might have been required to make the same accommodation.
  Although it was theoretically possible for the accommodation issue to be decided either by the state court or by the Labor Board, there was in fact no risk of overlapping jurisdiction in this case. The primary-jurisdiction rationale justifies pre-emption only in situations in which an aggrieved party has a reasonable opportunity either to invoke the Board’s jurisdiction himself or else to induce his adversary to do so. In this case, Sears could not directly obtain a Board ruling on the question whether the Union’s trespass was federally protected. Such a Board determination could have been obtained only if the Union had filed an unfair labor practice charge alleging that Sears had interfered with the Union’s § 7 right to engage in peaceful picketing on Sears’ property. By demanding that the Union remove its pickets from the store’s property, Sears in fact pursued a course of action which gave the Union the opportunity to file such a charge. But the Union’s response to Sears’ demand foreclosed the possibility of having the accommodation of § 7 and property rights made by the Labor Board; instead of filing a charge with the Board, the Union advised Sears that the pickets would only depart under compulsion of legal process.
  In the face of the Union’s intransigence, Sears had only three options: permit the pickets to remain on its property; forcefully evict the pickets; or seek the protection of the State’s trespass laws. Since the Union’s conduct violated state law, Sears legitimately rejected the first option. Since the second option involved a risk of violence, Sears surely had the right — perhaps even the duty — to reject it. Only by proceeding in state court, therefore, could Sears obtain an orderly resolution of the question whether the Union had a federal right to remain on its property.
  The primary-jurisdiction rationale unquestionably requires that when the same controversy may be presented to the state court or the NLRB, it must be presented to the Board. But that rationale does not extend to cases in which an employer has no acceptable method of invoking, or inducing the Union to invoke, the jurisdiction of the Board. We are therefore persuaded that the primary-jurisdiction rationale does not provide a sufficient justification for pre-empting state jurisdiction over arguably protected conduct when the party who could have presented the protection issue to the Board has not done so and the other party to the dispute has no acceptable means of doing so.
  This conclusion does not, however, necessarily foreclose the possibility that pre-emption may be appropriate. The danger of state interference with federally protected conduct is the principal concern of the second branch of the Garmon doctrine. To allow the exercise of state jurisdiction in certain contexts might create a significant risk of misinterpretation of federal law and the consequent prohibition of protected conduct. In those circumstances, it might be reasonable to infer that Congress preferred the costs inherent in a jurisdictional hiatus to the frustration of national labor policy which might accompany the exercise of state jurisdiction. Thus, the acceptability of “arguable protection” as a justification for pre-emption in a given class of cases is, at least in part, a function of the strength of the argument that § 7 does in fact protect the disputed conduct.
  The Court has held that state jurisdiction to enforce its laws prohibiting violence, defamation, the intentional infliction of emotional distress, or obstruction of access to property is not pre-empted by the NLRA. But none of those violations of state law involves protected conduct. In contrast, some violations of state trespass laws may be actually protected by § 7 of the federal Act.
  In NLRB v. Babcock & Wilcox Co., 351 U. S. 105, for example, the Court recognized that in certain circumstances non-employee union organizers may have a limited right of access to an employer’s premises for the purpose of engaging in organization solicitation. And the Court has indicated that Babcock extends to § 7 rights other than organizational activity, though the “locus” of the “accommodation of § 7 rights and private property rights . . . may fall at differing points along the spectrum depending on the nature and strength of the respective § 7 rights and private property rights asserted in any given context.” Hudgens v. NLRB, 424 U. S. 507, 522.
  For purpose of analysis we must assume that the Union could have proved that its picketing was, at least in the absence of a trespass, protected by § 7. The remaining question is whether under Babcock the trespassory nature of the picketing caused it to forfeit its protected status. Since it cannot be said with certainty that, if the Union had filed an unfair labor practice charge against Sears, the Board would have fixed the locus of the accommodation at the unprotected end of the spectrum, it is indeed “arguable” that the Union's peaceful picketing, though trespassory, was protected. Nevertheless, permitting state courts to evaluate the merits of an argument that certain trespassory activity is protected does not create an unacceptable risk of interference with conduct which the Board, and a court reviewing the Board's decision, would find protected. For while there are unquestionably examples of trespassory union activity in which the question whether it is protected is fairly debatable, experience under the Act teaches that such situations are rare and that a trespass is far more likely to be unprotected than protected.
  Experience with trespassory organizational solicitation by nonemployees is instructive in this regard. While Babcock indicates that an employer may not always bar nonemployee union organizers from his property, his right to do so remains the general rule. To gain access, the union has the burden of showing that no other reasonable means of communicating its organizational message to the employees exists or that the employer’s access rules discriminate against union solicitation. That the burden imposed on the union is a heavy one is evidenced by the fact that the balance struck by the Board and the courts under the Babcock accommodation principle has rarely been in favor of trespassory organizational activity.
  Even on the assumption that picketing to enforce area standards is entitled to the same deference in the Babcock accommodation analysis as organizational solicitation, it would be unprotected in most instances. While there does exist some risk that state courts will on occasion enjoin a trespass that the Board would have protected, the significance of this risk is minimized by the fact that in the cases in which the argument in favor of protection is the strongest, the union is likely to invoke the Board's jurisdiction and thereby avoid the state forum. Whatever risk of an erroneous state-court adjudication does exist is outweighed by the anomalous consequence of a rule which would deny the employer access to any forum in which to litigate either the trespass issue or the protection issue in those cases in which the disputed conduct is least likely to be protected by § 7.
  If there is a strong argument that the trespass is protected in a particular case, a union can be expected to respond to an employer demand to depart by filing an unfair labor practice charge; the protection question would then be decided by the agency experienced in accommodating the § 7 rights of unions and the property rights of employers in the context of a labor dispute. But if the argument for protection is so weak that it has virtually no chance of prevailing, a trespassing union would be well advised to avoid the jurisdiction of the Board and to argue that the protected character of its conduct deprives the state court of jurisdiction.
  As long as the union has a fair opportunity to present the protection issue to the Labor Board, it retains meaningful protection against the risk of error in a state tribunal. In this case the Union failed to invoke the jurisdiction of the Labor Board, and Sears had no right to invoke that jurisdiction and could not even precipitate its exercise without resort to self-help. Because the assertion of state jurisdiction in a case of this kind does not create a significant risk of prohibition of protected conduct, we are unwilling to presume that Congress intended the arguably protected character of the Union’s conduct to deprive the California courts of jurisdiction to entertain Sears’ trespass action.
  The judgment of the Supreme Court of California is therefore reversed, and the case is remanded to that court for further proceedings not inconsistent with this opinion.
  It is so ordered.
  49 Stat. 449, as amended, 29 U. S. C. §§ 151-169 (1970 ed. and Supp. V). Hereinafter, the National Labor Relations Act will be referred to as the Act or the NLRA.
  Although Sears claimed that some deliverymen and repairmen refused to cross the picket lines on the public sidewalks, the Union ultimately concluded that the picketing was then too far removed from the store to be effective. The picketing was discontinued on November 12.
  The Superior Court apparently rested its decision on two grounds: (1) that the injunction was not prohibited by state law, and (2) that the picketing was not protected by the First and Fourteenth Amendments of the Federal Constitution. Transcript of Preliminary Injunction Hearing, App. 32. Thus, the precise issue presently before the Court was not decided until the case reached the Court of Appeal.
  The court was referring to this statement in the Garmon opinion:
  “When an activity is arguably subject to § 7, or § 8 of the Act, the States as well as the federal courts must defer to the exclusive competence of the National Labor Relations Board if the danger of state interference with national policy is to be averted.” 359 U. S., at 245.
  The court also reaffirmed the conclusion of the Superior Court that the injunction was not prohibited by either state law or the Federal Constitution.
  In concluding that the state courts were “not preempted from exercising their general jurisdiction in matters of trespass related to labor disputes,” App. to Pet. for Cert. A-10, the Court of Appeal noted that the right to peaceful possession of property was regarded as basic in California and that the assumption of state jurisdiction would not directly infringe on the jurisdiction of the National Labor Relations Board, since no attempt had been made to invoke that jurisdiction. In a subsequent amended opinion, the Court of Appeal also emphasized the fact that the trial court injunction was narrowly confined to the “ ‘location' of the controversy as opposed to the purpose of the acts . . . and did not deny the Union effective communication with all persons going to Sears.” 125 Cal. Rptr. 245, 252 (1975).
  The issue was left open by the Court in Meat Cutters v. Fairlawn Meats, Inc., 353 U. S. 20, 24-25. Cf. Taggart v. Weinacker’s, Inc., 283 Ala. 171, 214 So. 2d 913 (1968), cert. dismissed, 397 U. S. 223.
  The state courts have divided on the question of state-court jurisdiction over peaceful trespassory activity. For cases in addition to this one in which pre-emption was found, see, e. g., Reece Shirley & Ron’s, Inc. v. Retail Store Employees, 222 Kan. 373, 565 P. 2d 585 (1977); Freeman v. Retail Clerks, 58 Wash. 2d 426, 363 P. 2d 803 (1961). For cases reaching a contrary conclusion, see, e. g., May Department Stores Co. v. Teamsters, 64 Ill. 2d 153, 355 N. E. 2d 7 (1976); People v. Bush, 39 N. Y. 2d 529, 349 N. E. 2d 832 (1976); Hood v. Stafford, 213 Tenn. 684, 378 S. W. 2d 766 (1964).
  The State Superior Court and the Court of Appeal concluded that the Union’s activity violated state law. Because it concluded that the state courts lacked jurisdiction to entertain the state trespass claim, the California Supreme Court did not address the merits of the lower court rulings. The Union contends that those rulings were incorrect. Though we regard the state-law issue as foreclosed in this Court, there is of course nothing in our decision on the pre-emption issue which bars consideration of the Union’s arguments by the California Supreme Court on remand.
  Section 8 (b) (4) (D) provides in part that it shall be an unfair labor practice for a labor organization or its agents—
  “to threaten, coerce, or restrain any person engaged in commerce or in an industry affecting commerce, where ... an object thereof is—
  “forcing or requiring any employer to' assign particular work to employees in a particular labor organization or in a particular trade, craft, or class rather than to employees in another labor organization or in another trade, craft, or class, unless such employer is failing to conform to an order or certification of the Board determining the bargaining representative for employees performing such work.” 29 U. S. C. § 158 (b) (4) (D).
  There are two provisos to § 8 (b) (4) which exempt certain conduct from its prohibitions, but they appear to have no application in this case.
  Section 8 (b) (7) (C) provides in part that “[i]t shall be an unfair labor practice for a labor organization or its agents—
  “to picket . . . any employer where an object thereof is forcing or requiring an employer to recognize or bargain with a labor organization as the representative of his employees . . . unless such labor organization is currently certified as the representative of such employees:
  “where such picketing has been conducted without a petition . . . [for a representation election] being filed within a reasonable period of time not to exceed thirty days from the commencement of such picketing. . . .” 29 U. S. C. §158 (b)(7)(C).
  As to conduct clearly protected or prohibited by the federal statute, the Court stated:
  “When it is clear or may fairly be assumed that the activities which a State purports to regulate are protected by § 7 of the National Labor Relations Act, or constitute an unfair labor practice under § 8, due regard for the federal enactment requires that state jurisdiction must yield. To leave the States free to regulate conduct so plainly within the central aim of federal regulation involves too great a danger of conflict between power asserted by Congress and requirements imposed by state law.” 359 U. S., at 244.
  This sensitivity to the consequences of pre-emption is undoubtedly attributable, at least in part, to the way in which the labor pre-emption doctrine has evolved. The doctrine is to a great extent the result of this Court's ongoing effort to decipher the presumed intent of Congress in the face of that body’s steadfast silence. Mr. Justice Frankfurter aptly described the difficulty of this never-completed task: “The statutory implications concerning what has been taken from the States and what has been left to them are of a Delphic nature, to be translated into concreteness by the process of litigating elucidation.” Machinists v. Gonzales, 356 U. S. 617, 619. And it is “because Congress has refrained from providing specific directions with respect to the scope of pre-empted state regulation, [that] the Court has been unwilling to 'declare pre-empted all local regulation that touches or concerns in any way the complex interrelationships between employees, employers, and unions Farmer v. Carpenters, 430 U. S. 290, 295-296 (citation omitted).
  “We have refused to apply the pre-emption doctrine to activity that otherwise would fall within the scope of Garmon if that activity 'was a merely peripheral concern of the Labor Management Relations Act . . . [or] touched interests so deeply rooted in local feeling and responsibility that, in the absence of compelling congressional direction, we could not infer that Congress had deprived the States of the power to act.' . . . We also have refused to apply the pre-emption doctrine ‘where the particular rule of law sought to be invoked before another tribunal is so structured and administered that, in virtually all instances, it is safe to presume that judicial supervision will not disserve the interests promoted by the federal labor statutes.’ ” Id., at 296-297.
  The Court’s rejection of an inflexible pre-emption approach is reflected in other situations as well. Where only a minor aspect of the controversy presented to the state court is arguably within the regulatory jurisdiction of the Labor Board, the Court has indicated that the Garmon rule should not be read to require pre-emption of state jurisdiction. Hanna Mining Co. v. Marine Engineers, 382 U. S. 181. The Court has also indicated that if the state court can ascertain the actual legal significance of particular conduct under federal law by reference to “compelling precedent applied to essentially undisputed facts,” San Diego Building Trades Council v. Garmon, 359 U. S., at 246, the court may properly do so and proceed to adjudicate the state cause of action. Permitting the state court to proceed under these circumstances deprives the litigant of the argument that the Board should reverse its position, or, perhaps, that precedent is not as compelling as one adversary contends.
  “In addition to the judicially developed exceptions referred to in [n. 13, supra], Congress itself has created exceptions to the Board’s exclusive jurisdiction in other classes of cases. Section 303 of the Labor Management Relations Act, 1947, 61 Stat. 158, as amended, 29 U. S. C. § 187, authorizes anyone injured in his business or property by activity viola-tive of § 8 (b) (4) of the NLRA, 61 Stat. 140, as amended, 29 U. S. C. § 158 (b) (4), to recover damages in federal district court even though the underlying unfair labor practices are remediable by the Board. See Teamsters v. Morton, 377 U. S. 252 (1964). Section 301 of the LMRA, 29 U. S. C. § 185, authorizes suits for breach of a collective-bargaining agreement even if the breach is an unfair labor practice within the Board’s jurisdiction. See Smith v. Evening News Assn., 371 U. S. 195 (1962). Section 14 (c) (2) of the NLRA, as added by Title VII, § 701 (a) of the Labor-Management Reporting and Disclosure Act of 1959, 73 Stat. 541, 29 U. S. C. § 164 (c) (2), permits state agencies an,d state courts te' assert jurisdiction over ‘labor disputes over which the Board declines, pursuant to paragraph (1) of this subsection, to assert jurisdiction.’ ” Farmer v. Carpenters, supra, at 297 n. 8.
  For a brief summary of the development of this national policy, see R. Gorman, Labor Law 1-6 (1976).
  “Comparison of the State and Federal statutes will show that both governments have laid hold of the same relationship for regulation, and it involves the same employers and the same employees. Each has delegated to an administrative authority a wide discretion in applying this plan of regulation to specific cases, and they are governed by somewhat different standards. Thus, if both laws are upheld, two administrative bodies are asserting a discretionary control over the same subject matter, conducting hearings, supervising elections and determining appropriate units for bargaining in the same plant.
  “We therefore conclude that it is beyond the power of New York State to apply its policy to these appellants as attempted herein.” Bethlehem Steel Co. v. New York Labor Relations Bd., 330 U. S. 767, 775-777.
  See n. 16, supra.
  La Crosse Telephone Corp. v. Wisconsin Employment Relations Bd., 336 U. S. 18, 24-26.
  Plankinton Packing Co. v. Wisconsin Employment Relations Bd., 338 U. S. 953.
  The apparent objective of the picketing was to pressure an employer into coercing employees into joining the union.
  This Court has summarily reversed several cases in which the state court purported to regulate labor union activities under provisions of state labor laws comparable to the prohibitions of the federal Act. See, e. g., Pocatello Building & Constr. Trades Council v. C. H. Elle Constr. Co., 352 U. S. 884, rev’g 78 Idaho 1, 297 P. 2d 519 (1956); Electrical Workers v. Farnsworth & Chambers Co., 353 U. S. 969, rev’g 201 Tenn. 329, 299 S. W. 2d 8 (1957).
  As the Court noted recently in Farmer v. Carpenters: “[I]t is well settled that the general applicability of a state cause of action is not sufficient to exempt it from pre-emption. ‘[I]t [has not] mattered whether the States have acted through laws of broad general application rather than laws specifically directed towards the governance of industrial relations.’ . . . Instead, the cases reflect a balanced inquiry into such factors as the nature of the federal and state interests in regulation and the potential for interference with federal regulation.” 430 U. S., at 300 (emphasis added).
  As Professor Cox has noted:
  “[A]n antitrust statute is not the kind of general law [which should avoid the reach of the pre-emption doctrine]. Such statutes are based upon a view of policj'' towards combinations and collective action in the market place which is the very subject addressed by Congress in the NLRA. That the state laws primarily apply to business combinations and merely sweep collective action by employees within the same rule does not sufficiently lessen the narrowness of focus.” Labor Law Preemption Revisited, 85 Harv. L. Rev. 1337, 1357 (1972).
  “Respondent argues that Missouri is not prohibiting the IAM's conduct for any reason having to do with labor relations but rather because that conduct is in contravention of a state law which deals generally with restraint of trade. It distinguishes Garner on the ground that there the State and Congress were both attempting to regulate labor relations as such.
  “We do not think this distinction is decisive. In Garner the emphasis was not on two conflicting labor statutes but rather on two similar remedies, one state and one federal, brought to bear on precisely the same conduct.” 348 U. S., at 479.
  Motor Coach Employees v. Lockridge, 403 U. S. 274, reaffirmed the notion that state regulation of activity arguably prohibited by the federal Act cannot avoid pre-emption simply because it is pursuant to a law of general application. In Lockridge, a union member who failed to pay his monthly dues was suspended from membership in the union and discharged from employment at union request. The union’s conduct in securing Loekridge’s discharge was arguably prohibited by §§ 8 (b) (1) (A) and 8 (b) (2) or protected by § 7. But rather than filing an unfair labor practice charge with the Labor Board, Lockridge brought suit in state court on a breach-of-contract theory. He alleged that the union breached a promise implicit in the union constitution that it would not secure his discharge pursuant to the union security clause in the collective-bargaining agreement for missing one month’s dues.
  The Court noted that both the state court and the Board would “inquire into the proper construction of union regulations in order to ascertain whether the union properly found [Lockridge] to have been derelict in his dues-paying responsibilities, where his discharge was procured on the asserted grounds of nonmembership in the union.” 403 U. S., at 293. The Court further noted that the “possibility that, in defining the scope of the union’s duty to [Lockridge], the state courts would directly and eonsciously implicate principles of federal law . . . was real and immediate. . . . Lockridge’s entire case turned upon the construction of the applicable union security clause, a matter as to which . . . federal concern is pervasive and its regulation complex.” Id., at 296. Pre-emption was required in the Court’s view because the state court was exercising jurisdiction over a controversy which was virtually identical to that which could have been presented to the Board. Permitting the state court to exercise jurisdiction pursuant to a law of general application in these circumstances would have entailed a “ ‘real and immediate’ potential for conflict with the federal scheme. . . .” Farmer v. Carpenters, 430 U. S., at 301 n. 10.
  An identical result would undoubtedly obtain were an employer subjected to recognitional or secondary picketing to seek injunctive relief in state court on the theory that the union was tortiously interfering with his freedom to contract. Cf. Retail Clerks v. J. J. Newberry Co., 352 U. S. 987, summarily rev’g 78 Idaho 85, 298 P. 2d 375 (1956).
  One of the factors identified by the Court was that the conduct giving rise to the state cause of action (e. g., violence, libel, or intentional infliction of emotional distress), if proved, would not be protected by § 7 of the NLRA, and therefore there existed no' risk that state regulation of the conduct alleged in the complaint would result in prohibition of conduct protected by the federal Act. To this extent, the instant case is not controlled by the decision in Farmer. Sears’ state cause of action was for trespass, and some trespassory union activity may be protected under the federal Act. See Part V, infra. However, two points must be made regarding the apparent distinction between Farmer and the case at bar. First, Farmer itself involved some risk that protected conduct would be regulated; for, while the complaint alleged outrageous conduct, there remained a possibility that the plaintiff would only have been able to prove a robust intra-union dispute and that the state tribunal would have found that sufficient to support recovery. Second, the distinction between this case and Farmer, to the extent that it exists, has significance only with respect to the arguably protected branch of the Garmon doctrine, which we discuss in Part V; it does not detract from the support Farmer provides for our conclusion with respect to pre-emption under the arguably prohibited branch of the doctrine.
  As the Court explained:
  “If the charges in Hill’s complaint were filed with the Board, the focus of any unfair labor practice proceeding would be on whether the statements or conduct on the part of union officials discriminated or threatened discrimination against him in employment referrals for reasons other than failure to pay union dues. . . . Whether the statements or conduct of the respondents also caused Hill severe emotional distress and physical injury would play no role in the Board’s disposition of the case, and the Board could not award Hill damages for pain, suffering, or medical expenses. Conversely, the state-court tort action can be adjudicated without resolution of the ‘merits’ of the underlying labor dispute. Recovery for the tort of emotional distress under California law requires proof that the defendant intentionally engaged in outrageous conduct causing the plaintiff to sustain mental distress. . . . The state court need not consider, much less resolve, whether a union discriminated or threatened to discriminate against an employee in terms of employment opportunities. To the contrary, the tort action can be resolved without reference to any accommodation of the special interests of unions and members in the hiring hall context.
  “On balance, we cannot conclude that Congress intended to oust state-court jurisdiction over actions for tortious activity such as that alleged in this case. At the same time, we reiterate that concurrent state-court jurisdiction cannot be permitted where there is a realistic threat of interference with the federal regulatory scheme.” 430 U. S., at 304-305.
  While the distinction between a law of general applicability and a law expressly governing labor relations is, as we have noted, not disposi-tive for pre-emption purposes, it is of course apparent that the latter is more likely to involve the accommodation which Congress reserved to the Board. It is also evident that enforcement of a law of general applicability is less likely to generate rules or remedies which conflict with federal labor policy than the invocation of a special remedy under a state labor relations law.
  Moreover, decision of that issue would not necessarily have determined whether the picketing could continue. For the Board could conclude that the picketing was not prohibited by either § 8 (b) (4) (D) or § 8 (b) (7) (C) without reaching the question whether it was protected by § 7. If the Board had concluded that the picketing was not prohibited, Sears would still have been confronted with picketing which violated state law and was arguably protected by federal law. Thus, the filing of an unfair labor practice charge could initiate complex litigation which would not necessarily lead to a resolution of the problem which led to this litigation.
  In this opinion, the term "primary jurisdiction” is used to refer to the various considerations articulated in Garmon and its progeny that militate in favor of pre-empting state-court jurisdiction over activity which is subject to the unfair labor practice jurisdiction of the federal Board. This use of the term should not be confused with the doctrine of primary jurisdiction, which has been described by Professor Davis as follows:
  “The precise function of the doctrine of primary jurisdiction is to guide a court in determining whether the court should refrain from exercising its jurisdiction until after an administrative agency has determined some question or some aspect of some question arising in the proceeding before the court.
  "The doctrine of primary jurisdiction does not necessarily allocate power between courts and agencies, for it governs only the question whether court or agency will initially decide a particular issue, not the question whether court or agency will finally decide the issue.” 3 K. Davis, Administrative Law Treatise § 19.01, p. 3 (1958) (emphasis in original).
  While the considerations underlying Garmon are similar to those underlying the primary-jurisdiction doctrine, the consequences of the two doctrines are therefore different. Where applicable, the Garmon doctrine completely pre-empts state-court jurisdiction unless the Board determines that the disputed conduct is neither protected nor prohibited by the federal Act.
  Although it is clear that a state court may not exercise jurisdiction over protected conduct, it is important to note that the word "protected” may refer to two quite different concepts: union conduct which the State may not prohibit and against which the employer may not retaliate because it is covered by § 7 or conduct which a State may not prohibit even though it is not covered by § 7 of the Act. The Court considered protected conduct in the latter sense in Machinists v. Wisconsin Employment Relations Comm’n, 427 U. S. 132. There, the Court relied on a line of pre-emption analysis “focusing upon the crucial inquiry whether Congress intended that the conduct inyolved be unregulated because left 'to be controlled by the free play of economic forces.’ NLRB v. Nash-Finch Co., 404 U. S. 138, 144 (1971).” Id., at 140.
  The Union does not claim that trespassory picketing is protected from state interference under this doctrine. We merely identify this line of preemption analysis in order to make it perfectly clear that it is unaffected by our consideration of the significance of the status of the picketing as arguably protected under § 7 of the Act. We also note, however, that in the cases in which pre-emption exists even though neither § 7 nor § 8 of the Act is even arguably applicable, there is, by hypothesis, no opportunity for the National Labor Relations Board to make the initial evaluation of the controversy. In these cases, the pre-emption issue is necessarily addressed in the first instance by a state tribunal, and that tribunal must decide whether or not the conduct is actually privileged from governmental regulation.
  As noted in Part IV, supra, the primary-jurisdiction rationale of Garmon did not require pre-emption of state jurisdiction over the Union's picketing insofar as it may have been prohibited by § 8, since the controversy presented to the state court was not the same controversy which Sears could have presented to the Board. In deciding the state-law issue, the Court had no occasion to interpret or enforce the prohibitions in § 8 of the federal Act; in deciding the unfair labor practice question, the Board's sole concern would have been the objective, not the location, of the challenged picketing.
  That accommodation would have been required only if the Board first found that the object of the picketing was to maintain area standards. Of course, if Sears had initiated the proceeding before the Board, the location of the picketing would have been entirely irrelevant and no question of accommodation would have arisen. See n. 31, supra.
  Even if Sears had elected the self-help option, it could not have been assured that the Union would have invoked the jurisdiction of the Board. The Union may well have decided that the likelihood of success was remote and outweighed by the cost of the effort and the probability that Sears in turn would have charged the Union with violating § 8 (b) (4) (D) or § 8 (b) (7) (C) of the Act. Moreover, if Sears had elected this option, and the pickets were evicted with more force than reasonably necessary, it might have exposed itself to tort liability under state law. We are unwilling to presume that Congress intended to require employers to pursue such a risky course in order to ensure that issues involving the scope of § 7 rights be decided only by the Labor Board.
  “If the National Labor Relations Act provided an effective mechanism whereby an employer could obtain a determination from the National Labor Relations Board as to whether picketing is protected or unprotected, I would agree that the fact that picketing is ‘arguably’ protected should require state courts to refrain from interfering in deference to the expertise and national uniformity of treatment offered by the NLRB. But an employer faced with 'arguably protected’ picketing is given by the present federal law no adequate means of obtaining an evaluation of the picketing by the NLRB. The employer may not himself seek a determination from the Board and is left with the unsatisfactory remedy of using ‘self-help’ against the pickets to try to provoke the union to charge the employer with an unfair labor practice.
  “So long as employers are effectively denied determinations by the NLRB as to whether ‘arguably protected’ picketing is actually protected except when an employer is willing to threaten or use force to deal with picketing, I would hold that only labor activity determined to be actuaEy, rather than arguably, protected under federal law should be immune from state judicial control. To this extent San Diego Building Trades Council v. Garmon, 359 U. S. 236 (1959), should be reconsidered.” Longshoremen v. Ariadne Shining Co., 397 U. S. 195, 201-202 (White, J., concurring).
  Youngdahl v. Rainfair, Inc., 355 U. S. 131; Construction Workers v. Laburnum, 347 U. S. 656.
  Linn v. Plant Guard Workers, 383 U. S. 53.
  Farmer v. Carpenters, 430 U. S. 290.
  Automobile Workers v. Russell, 356 U. S. 634.
  As the Court stated:
  “The employer may not affirmatively interfere with organization; the union may not always insist that the employer aid organization. But when the inaccessibility of employees makes ineffective the reasonable attempts by nonemployees to communicate with them through the usual channels, the right to exclude from property has been required to yield to the extent needed to permit communication of information on the right to organize.” 351 U. S., at 112.
  See also Central Hardware Co. v. NLRB, 407 U. S. 539.
  As the Court noted in Babcock & Wilcox:
  “It is our judgment . . . that an emptier may validly post his property against nonemployee distribution of union literature if reasonable efforts by the union through other available channels of communication will enable it to reach the employees with its message and if the employer’s notice or order does not discriminate against the union by allowing other distribution.” 351 U. S., at 112.
  In the absence of discrimination, the union’s asserted right of access for organizational activity has generally been denied except in cases involving unique obstacles to nontrespassory methods of communication with the employees. See, e. g., NLRB v. S & H Grossinger’s, Inc., 372 F. 2d 26 (CA2 1967); NLRB v. Lake Superior Lumber Corp., 167 F. 2d 147 (CA6 1948).
  This assumption, however, is subject to serious question. Indeed, several factors make the argument for protection of trespassory area-standards, picketing as a category of conduct less compelling than that for trespassory organizational solicitation. First, the right to- organize is at the very core of the purpose for which the NLRA was enacted. Area-standards picketing, in contrast, has only recently been recognized as a §7 right. Hod Carriers Local 41 (Calumet Contractors Assn.), 133 N. L. R. B. 512 (1961). Second, Babcock makes clear that the interests being protected by according limited-access rights to nonemployee, union organizers are not those of the organizers but of the employees located on the employer’s property. The Court indicated that “no . . . obligation is owed nonemployee organizers”; any right they may have to solicit on an employer’s property is a derivative of the right of that employer’s employees to exercise their organization rights effectively. Area-standards picketing, on the other hand, has no such vital link to the employees located on the employer’s property. While such picketing may have a beneficial effect on the compensation of those employees, the rationale for protecting area-standards picketing is that a union has a legitimate interest in protecting the wage standards of its members who are employed by competitors of the picketed employer.
  Not only could the Union have filed an unfair labor practice charge pursuant to § 8 (a) (1) of the Act at the time Sears demanded that the pickets leave its property, but the Board’s jurisdiction could have been invoked and the protection of its remedial powers obtained even after the litigation in the state court had commenced or the state injunction issued. See Capital Service, Inc. v. NLRB, 347 U. S. 501; NLRB v. Nash-Finch Co., 404 U. S. 138.
  The fact that Sears demanded that the Union discontinue the trespass before it initiated the trespass action is critical to our holding. While it appears that such a demand was a precondition to commencing a trespass action under California law, see 122 Cal. Rptr. 449 (1975), in order to avoid a valid claim of pre-emption it would have been required as a matter of federal law in any event.
  The Board has taken the position that “a resort to court action . . . does not violate §8 (a)(1).” NLRB v. Nosh-Finch Co., supra, at 142. If the employer were not required to demand discontinuation of the trespass before proceeding in state court and the Board did not alter its position in cases of this kind, the union would be deprived of an opportunity to present the protection issue to the agency created by Congress to decide such questions. While the union’s failure to invoke the Board's jurisdiction should not be a sufficient basis for pre-empting state jurisdiction, the employer should not be permitted to deprive the union of an opportunity to do so.
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