[182]*182Mr. Justice Stevens
delivered the opinion of the Court.
The question in this case is whether the National Labor Relations Act, as amended,1 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 [183]*183the 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.2 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.3 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. 236,4 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.5
[184]*184The 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.6 The obvious importance of this problem led us to grant certiorari in this case. 430 U. S. 905.7
[185]*185II
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.8 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 [186]*186dispatched from the hiring hall, the picketing may have been prohibited by § 8 (b)(4)(D).9 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).10 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 [187]*187area 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
Free access — add to your briefcase to read the full text and ask questions with AI
[182]*182Mr. Justice Stevens
delivered the opinion of the Court.
The question in this case is whether the National Labor Relations Act, as amended,1 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 [183]*183the 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.2 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.3 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. 236,4 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.5
[184]*184The 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.6 The obvious importance of this problem led us to grant certiorari in this case. 430 U. S. 905.7
[185]*185II
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.8 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 [186]*186dispatched from the hiring hall, the picketing may have been prohibited by § 8 (b)(4)(D).9 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).10 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 [187]*187area 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.11 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 [188]*188Board 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.12 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.13 This refusal demonstrates that [189]*189“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, 180.14
[190]*190With 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.15
[191]*191The 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.16 Accordingly, attempts to apply provisions of the “Little Wagner Acts” enacted by New York17 and Wisconsin 18 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.19 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 Rela[192]*192tions 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.20 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 [193]*193reasoning 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.21 It may also apply' to certain laws of general applicability which are occasionally invoked in connection with a labor dispute.22 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. 468.23 In each case, the pertinent inquiry is whether [194]*194the two potentially conflicting statutes were “brought to bear on precisely the same conduct.” Id., at 479.24
On the other hand, the Court has allowed a State to enforce [195]*195certain 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 refer[196]*196rals. 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.25 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 [197]*197presented to the state and federal forums would not have been the same.26
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.27
[198]*198In 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.28 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.
[199]*199V
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,” 29 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.30 [200]*200Considerations 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 [201]*201and that which the Union might have brought before the NLRB.31 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.32
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 [202]*202the 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.33 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 [203]*203could 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.34
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.
[204]*204The Court has held that state jurisdiction to enforce its laws prohibiting violence,35 defamation,36 the intentional infliction of emotional distress,37 or obstruction of access to property38 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.39 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 [205]*205picketing 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.40 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.41
[206]*206Even on the assumption that picketing to enforce area standards is entitled to the same deference in the Babcock accommodation analysis as organizational solicitation,42 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 [207]*207protection 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,43 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.44
[208]*208The 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.