The Pattern Makers' League of North America, AFL-CIO (League), a labor union, provides in its constitution that resignations are not permitted during a strike or when a strike is imminent. The League fined 10 of its members who, in violation of this provision, resigned during a strike and returned to work. The National Labor Relations Board held that these fines were imposed in violation of § 8(b)(1)(A) of the National Labor Relations Act, 29 U.S.C. § 158(b)(1)(A). We granted a petition for a writ of certiorari in order to decide whether § 8(b)(1)(A) reasonably may be construed by the Board as prohibiting a union from fining members who have tendered resignations invalid under the union constitution.

* The League is a national union composed of local associations (locals). In May 1976, its constitution was amended to provide that

"[n]o resignation or withdrawal from an Association, or from the League, shall be accepted during a strike or lockout, or at a time when a strike or lockout appears imminent."

This amendment, known as League Law 13, became effective in October 1976, after being ratified by the League's locals. On May 5, 1977, when a collective-bargaining agreement expired, two locals began an economic strike against several manufacturing companies in Rockford, Illinois, and Beloit, Wisconsin. Forty-three of the two locals' members participated. In early September 1977, after the locals formally rejected a contract offer, a striking union member submitted a letter of resignation to the Beloit Association.1 He returned to work the following day. During the next three months, 10 more union members resigned from the Rockford and Beloit locals and returned to work. On December 19, 1977, the strike ended when the parties signed a new collective-bargaining agreement. The locals notified 10 employees who had resigned that their resignations had been rejected as violative of League Law 13.2 The locals further informed the employees that, as union members, they were subject to sanctions for returning to work. Each was fined approximately the equivalent of his earnings during the strike.

The Rockford-Beloit Pattern Jobbers' Association (Association) had represented the employers throughout the collective-bargaining process. It filed charges with the Board against the League and its two locals, the petitioners. Relying on § 8(b)(1)(A), the Association claimed that levying fines against employees who had resigned was an unfair labor practice.3 Following a hearing, an Administrative Law Judge found that petitioners had violated § 8(b)(1)(A) by fining employees for returning to work after tendering resignations. Pattern Makers' League of North America, 265 N.L.R.B. 1332, 1339 (1982) (decision of G. Wacknov, ALJ). The Board agreed that § 8(b)(1)(A) prohibited the union from imposing sanctions on the 10 employees.4 Pattern Makers' League of North America, supra. In holding that League Law 13 did not justify the imposition of fines on the members who attempted to resign, the Board relied on its earlier decision in Machinists Local 1327 (Dalmo Victor II), 263 N.L.R.B. 984 (1982), enf. denied, 725 F.2d 1212 (CA9 1984).5

The United States Court of Appeals for the Seventh Circuit enforced the Board's order. 724 F.2d 57 (1983). The Court of Appeals stated that by restricting the union members' freedom to resign, League Law 13 "frustrate[d] the overriding policy of labor law that employees be free to choose whether to engage in concerted activities." Id., at 60. Noting that the "mutual reliance" theory was given little weight in NLRB v. Textile Workers, 409 U.S. 213, 93 S.Ct. 385, 34 L.Ed.2d 422 (1972), the court rejected petitioners' argument that their members, by participating in the strike vote, had "waived their Section 7 right to abandon the strike." 724 F.2d, at 60-61. Finally, the Court of Appeals reasoned that under Scofield v. NLRB, 394 U.S. 423, 89 S.Ct. 1154, 22 L.Ed.2d 385 (1969), labor organizations may impose disciplinary fines against members only if they are "free to leave the union and escape the rule[s]." 724 F.2d, at 61.

We granted a petition for a writ of certiorari, 469 U.S. 814, 105 S.Ct. 79, 83 L.Ed.2d 27 (1984), to resolve the conflict between the Courts of Appeals over the validity of restrictions on union members' right to resign.6 The Board has held that such restrictions are invalid and do not justify imposing sanctions on employees who have attempted to resign from the union. Because of the Board's "special competence" in the field of labor relations, its interpretation of the Act is accorded substantial deference. NLRB v. Weingarten, Inc., 420 U.S. 251, 266, 95 S.Ct. 959, 968, 43 L.Ed.2d 171 (1975). The question for decision today is thus narrowed to whether the Board's construction of § 8(b)(1)(A) is reasonable. See NLRB v. City Disposal Systems, Inc., 465 U.S. 822, 830, 104 S.Ct. 1505, 1510, 79 L.Ed.2d 839 (1984). We believe that § 8(b)(1)(A) properly may be construed as prohibiting the fining of employees who have tendered resignations ineffective under a restriction in the union constitution. We therefore affirm the judgment of the Court of Appeals enforcing the Board's order.

Section 7 of the Act, 29 U.S.C. § 157, grants employees the right to "refrain from any or all [concerted] . . . activities. . . ."7 This general right is implemented by § 8(b)(1)(A). The latter section provides that a union commits an unfair labor practice if it "restrain[s] or coerce[s] employees in the exercise" of their § 7 rights.8 When employee members of a union refuse to support a strike (whether or not a rule prohibits returning to work during a strike), they are refraining from "concerted activity." Therefore, imposing fines on these employees for returning to work "restrain[s]" the exercise of their § 7 rights. Indeed, if the terms "refrain" and "restrain or coerce" are interpreted literally, fining employees to enforce compliance with any union rule or policy would violate the Act.

Despite this language from the Act, the Court in NLRB v. Allis-Chalmers Mfg. Co., 388 U.S. 175, 87 S.Ct. 2001, 18 L.Ed.2d 1123 (1967), held that § 8(b)(1)(A) does not prohibit labor organizations from fining current members. In NLRB v. Textile Workers, supra, and Machinists v. NLRB, 412 U.S. 84, 93 S.Ct. 1961, 36 L.Ed.2d 764 (1973) (per curiam ), the Court found as a corollary that unions may not fine former members who have resigned lawfully. Neither Textile Workers, supra, nor Machinists, supra, however, involved a provision like League Law 13, restricting the members' right to resign. We decide today whether a union is precluded from fining employees who have attempted to resign when resignations are prohibited by the union's constitution.9

The Court's reasoning in Allis-Chalmers, supra, supports the Board's conclusion that petitioners in this case violated § 8(b)(1)(A). In Allis-Chalmers, the Court held that imposing court-enforceable fines against current union members does not "restrain or coerce" the workers in the exercise of their § 7 rights.10 In so concluding, the Court relied on the legislative history of the Taft-Hartley Act. It noted that the sponsor of § 8(b)(1)(A) never intended for that provision " 'to interfere with the internal affairs or organization of unions,' " 388 U.S., at 187, 87 S.Ct., at 2010, quoting 93 Cong.Rec. 4272 (1947) (statement of Sen. Ball), and that other proponents of the measure likewise disclaimed an intent to interfere with unions' "internal affairs." 388 U.S., at 187-190, 87 S.Ct., at 2010-2012. From the legislative history, the Court reasoned that Congress did not intend to prohibit unions from fining present members, as this was an internal matter. The Court has emphasized that the crux of Allis-Chalmers' holding was the distinction between "internal and external enforcement of union rules. . . ." Scofield v. NLRB, 394 U.S., at 428, 89 S.Ct., at 1157. See also NLRB v. Boeing Co., 412 U.S. 67, 73, 93 S.Ct. 1952, 1956, 36 L.Ed.2d 752 (1973).

The congressional purpose to preserve unions' control over their own "internal affairs" does not suggest an intent to authorize restrictions on the right to resign. Traditionally, union members were free to resign and escape union discipline.S11 In 1947, union constitutional provisions restricting the right to resign were uncommon, if not unknown.12 Therefore, allowing unions to "extend an employee's membership obligation through restrictions on resignation" would "expan[d] the definition of internal action" beyond the contours envisioned by the Taft-Hartley Congress. International Assn. of Machinists, Local 1414 (Neufeld Porsche-Audi, Inc.), 270 N.L.R.B. No. 209, p. 11 (1984).13

Language and reasoning from other opinions of this Court confirm that the Board's construction of § 8(b)(1)(A) is reasonable. In Scofield v. NLRB, supra, the Court upheld a union rule setting a ceiling on the daily wages that members working on an incentive basis could earn. The union members' freedom to resign was critical to the Court's decision that the union rule did not "restrain or coerce" the employees within the meaning of § 8(b)(1)(A). It stated that the rule was "reasonably enforced against union members who [were] free to leave the union and escape the rule." Id., at 430, 89 S.Ct., at 1158. The Court deemed it important that if members were unable to take full advantage of their contractual right to earn additional pay, it was because they had "chosen to become and remain union members." Id., at 435, 89 S.Ct., at 1160 (emphasis added).

The decision in NLRB v. Textile Workers, 409 U.S. 213, 93 S.Ct. 385, 34 L.Ed.2d 422 (1972), also supports the Board's view that § 8(b)(1)(A) prohibits unions from punishing members not free to resign. There, 31 employees resigned their union membership and resumed working during a strike. We held that fining these former members "restrained or coerced" them, within the meaning of § 8(b)(1)(A). In reaching this conclusion, we said that "the vitality of § 7 requires that the member be free to refrain in November from the actions he endorsed in May." Id., at 217-218, 93 S.Ct., at 387. Restrictions on the right to resign curtail the freedom that the Textile Workers Court deemed so important. See also Machinists v. NLRB, 412 U.S. 84, 93 S.Ct. 1961, 36 L.Ed.2d 764 (1973).

Section 8(b)(1)(A) allows unions to enforce only those rules that "impai[r] no policy Congress has imbedded in the labor laws. . . ." Scofield, supra, 394 U.S., at 430, 89 S.Ct., at 1158. The Board has found union restrictions on the right to resign to be inconsistent with the policy of voluntary unionism implicit in § 8(a)(3).14 See International Assn. of Machinists, Inc., Local 1414 (Neufeld Porsche-Audi, Inc.), supra; Machinists Local 1327 (Dalmo Victor II), 263 N.L.R.B., at 992 (Chairman Van de Water and Member Hunter, concurring). We believe that the inconsistency between union restrictions on the right to resign and the policy of voluntary unionism supports the Board's conclusion that League Law 13 is invalid.

Closed shop agreements, legalized by the Wagner Act in 1935,15 became quite common in the early 1940's. Under these agreements, employers could hire and retain in their employ only union members in good standing. R. Gorman, Labor Law, ch. 28, § 1, p. 639 (1976). Full union membership was thus compulsory in a closed shop; in order to keep their jobs, employees were required to attend union meetings, support union leaders, and otherwise adhere to union rules. Because of mounting objections to the closed shop, in 1947—after hearings and full consideration—Congress enacted the Taft-Hartley Act. Section 8(a)(3) of that Act effectively eliminated compulsory union membership by outlawing the closed shop. The union security agreements permitted by § 8(a)(3) require employees to pay dues, but an employee cannot be discharged for failing to abide by union rules or policies with which he disagrees.16

Full union membership thus no longer can be a requirement of employment. If a new employee refuses formally to join a union and subject himself to its discipline, he cannot be fired. Moreover, no employee can be discharged if he initially joins a union, and subsequently resigns. We think it noteworthy that § 8(a)(3) protects the employment rights of the dissatisfied member, as well as those of the worker who never assumed full union membership. By allowing employees to resign from a union at any time, § 8(a)(3) protects the employee whose views come to diverge from those of his union.

League Law 13 curtails this freedom to resign from full union membership. Nevertheless, petitioners contend that League Law 13 does not contravene the policy of voluntary unionism imbedded in the Act. They assert that this provision does not interfere with workers' employment rights because offending members are not discharged, but only fined. We find this argument unpersuasive, for a union has not left a "worker's employment rights inviolate when it exacts [his entire] paycheck in satisfaction of a fine imposed for working." Wellington, Union Fines and Workers' Rights, 85 Yale L.J. 1022, 1023 (1976). Congress in 1947 sought to eliminate completely any requirement that the employee maintain full union membership.17 Therefore, the Board was justified in concluding that by restricting the right of employees to resign, League Law 13 impairs the policy of voluntary unionism.

We now consider specifically three arguments advanced by petitioners: (i) union rules restricting the right to resign are protected by the proviso to § 8(b)(1)(A); (ii) the legislative history of the Act shows that Congress did not intend to protect the right of union members to resign; and (iii) labor unions should be allowed to restrict the right to resign because other voluntary associations are permitted to do so.18

* Petitioners first argue that the proviso to § 8(b)(1)(A) expressly allows unions to place restrictions on the right to resign. The proviso states that nothing in § 8(b)(1)(A) shall "impair the right of a labor organization to prescribe its own rules with respect to the acquisition or retention of membership therein." 29 U.S.C. § 158(b)(1)(A). Petitioners contend that because League Law 13 places restrictions on the right to withdraw from the union, it is a "rul[e] with respect to the . . . retention of membership," within the meaning of the proviso.19

Neither the Board nor this Court has ever interpreted the proviso as allowing unions to make rules restricting the right to resign.20 Rather, the Court has assumed that "rules with respect to the . . . retention of membership" are those that provide for the expulsion of employees from the union.21 The legislative history of the Taft-Hartley Act is consistent with this interpretation. Senator Holland, the proviso's sponsor, stated that § 8(b)(1)(A) should not outlaw union rules "which ha[ve] to do with the admission or the expulsion of members." 93 Cong.Rec. 4271 (1947) (emphasis added). Senator Taft accepted the proviso, for he likewise believed that a union should be free to "refuse [a] man admission to the union, or expel him from the union." Id., at 4272 (emphasis added). Furthermore, the legislative history of the Labor-Management Reporting and Disclosure Act of 1959, 29 U.S.C. § 401 et seq., confirms that the proviso was intended to protect union rules involving admission and expulsion.22 Accordingly, we find no basis for refusing to defer to the Board's conclusion that League Law 13 is not a "rule with respect to the retention of membership," within the meaning of the proviso.

The petitioners next argue that the legislative history of the Taft-Hartley Act shows that Congress made a considered decision not to protect union members' right to resign. Section 8(c) of the House bill contained a detailed "bill of rights" for labor union members. H.R. 3020, § 8(c), 80th Cong., 1st Sess., 22-26 (1947). Included was a provision making it an unfair labor practice to "deny to any [union] member the right to resign from the organization at any time." H.R. 3020, supra, § 8(c)(4), at 23. The Senate bill, on the other hand, did not set forth specific employee rights, but stated more generally that it was an unfair labor practice to "restrain or coerce" employees in the exercise of their § 7 rights. H.R. 3020, 80th Cong., 1st Sess., § 8(b)(1)(A), p. 81 (1947) (as passed by Senate). The Taft-Hartley Act contains the Senate bill's general language rather than the more specific House prohibitions. See 29 U.S.C. § 158(b)(1)(A). The petitioners contend that the omission of the House provision shows that Congress expressly decided not to protect the "right to resign."

The legislative history does not support this contention. The "right to resign" apparently was included in the original House bill to protect workers unable to resign because of "closed shop" agreements. Union constitutions limiting the right to resign were uncommon in 1947, see n. 12, supra; closed shop agreements, however, often impeded union resignations. The House Report, H.R.Rep. No. 245, 80th Cong., 1st Sess. (1947), confirms that closed shop agreements provided the impetus for the inclusion of a right to resign in the House bill. The Report simply states that even under the proposed legislation, employees could be required to pay dues pursuant to union security agreements. Id., at 32. Because the closed shop was outlawed by the Taft-Hartley Act, see § 8(a)(3), 29 U.S.C. § 158(a)(3), it is not surprising that Congress thought it unnecessary explicitly to preserve the right to resign.

Even if § 8(c)(4) of the House bill, H.R. 3020, supra, was directed at restrictive union rules, its omission from the Taft-Hartley Act does not convince us that the Board's construction of § 8(b)(1)(A) is unreasonable. The House Conference Report, upon which petitioners primarily rely, does state that the specific prohibitions of § 8(c) were "omitted . . . as unfair labor practices," H.R.Conf.Rep. No. 510, 80th Cong., 1st Sess., 46 (1947), U.S.Code Cong.Serv.1947, p. 1135. But this language does not suggest that all employee rights arguably protected by the House bill were to be left unprotected. Cf. id., at 43 ("[T]he primary strike for recognition . . . was not prohibited"). Apparently, the Report was intended merely to inform House Members that the detailed prohibitions of § 8(c) were not separately included in the conference bill as "unfair labor practices." We are reluctant to reach a contrary conclusion, and thereby overturn the Board's decision, on the basis of this summary statement in the House Conference Report. Congress must have been aware that the broad language of § 8(b)(1)(A) would reach some of the same union conduct proscribed by the detailed "bill of rights."23

Petitioners concede that "absent the legislative history," the Board's construction of § 8(b)(1)(A) would be entitled to deference. Tr. of Second Oral Arg. 15 (Apr. 1985). They argue, however, that "in this instance the legislative materials are too clearly opposed to what the Board did to permit the result the Board reached." Id., at 17. We do not agree. The ambiguous legislative history upon which petitioners rely falls far short of showing that the Board's interpretation of the Act is unreasonable.24

In Textile Workers, 409 U.S., at 216, 93 S.Ct., at 387, and Machinists, 412 U.S., at 88, 93 S.Ct., at 1964 (per curiam ), the Court stated that when a union constitution does not purport to restrict the right to resign, the "law which normally is reflected in our free institutions" is applicable. Relying on this quoted language, petitioners argue that League Law 13 is valid. They assert that because the common law does not prohibit restrictions on resignation,25 such provisions are not violative of § 8(b)(1)(A) of the Act. We find no merit in this argument. Textile Workers, supra, and Machinists, supra, held only that in the absence of restrictions on the right to resign, members are free to leave the union at any time. Although the Court noted that its decisions were consistent with the common-law rule, it did not state that the validity of restrictions on the right to resign should be determined with reference to common law.

The Court's decision in NLRB v. Marine & Shipbuilding Workers, 391 U.S. 418, 88 S.Ct. 1717, 20 L.Ed.2d 706 (1968), demonstrates that many union rules, although valid under the common law of associations, run afoul of § 8(b)(1)(A) of the Act.26 There the union expelled a member who failed to comply with a rule requiring the "exhaust[ion of] all remedies and appeals within the Union . . . before . . . resort to any court or other tribunal outside of the Union." Id., at 421, 88 S.Ct., at 1720. Under the common law, associations may require their members to exhaust all internal remedies. See, e.g., Medical Soc. of Mobile Cty. v. Walker, 245 Ala. 135, 16 So.2d 321 (1944). Nevertheless, the Marine Workers Court held that "considerations of public policy" mandated a holding that the union rule requiring exhaustion violated § 8(b)(1)(A), 29 U.S.C. § 158(b)(1)(A). 391 U.S., at 424, 88 S.Ct., at 1721; see also Scofield v. NLRB, 394 U.S., at 430, 89 S.Ct., at 1158 (union rule is invalid under § 8(b)(1)(A) if it "impairs [a] policy Congress has imbedded in the labor laws").

The Board reasonably has concluded that League Law 13 "restrains or coerces" employees, see § 8(b)(1)(A), and is inconsistent with the congressional policy of voluntary unionism. Therefore, whatever may have been the common law, the Board's interpretation of the Act merits our deference.

The Board has the primary responsibility for applying " 'the general provisions of the Act to the complexities of industrial life.' " Ford Motor Co. v. NLRB, 441 U.S. 488, 496, 99 S.Ct. 1842, 1848, 60 L.Ed.2d 420 (1979), quoting NLRB v. Erie Resistor Corp., 373 U.S. 221, 236, 83 S.Ct. 1139, 1149, 10 L.Ed.2d 308 (1963), in turn citing NLRB v. Steelworkers, 357 U.S. 357, 362-363, 78 S.Ct. 1268, 1271-1272, 2 L.Ed.2d 1383 (1958). Where the Board's construction of the Act is reasonable, it should not be rejected "merely because the courts might prefer another view of the statute." Ford Motor Co. v. NLRB, supra, 441 U.S., at 497, 99 S.Ct., at 1849. In this case, two factors suggest that we should be particularly reluctant to hold that the Board's interpretation of the Act is impermissible. First, in related cases this Court invariably has yielded to Board decisions on whether fines imposed by a union "restrain or coerce" employees.27 Second, the Board consistently has construed § 8(b)(1)(A) as prohibiting the imposition of fines on employees who have tendered resignations invalid under a union constitution.28 Therefore, we conclude that the Board's decision here is entitled to our deference.

The Board found that by fining employees who had tendered resignations, the petitioners violated § 8(b)(1)(A) of the Act, even though League Law 13 purported to render the resignations ineffective. We defer to the Board's interpretation of the Act and so affirm the judgment of the Court of Appeals enforcing the Board's order.

It is so ordered.

Justice WHITE, concurring.

I agree with the Court that the Board's construction of §§ 7 and 8(b)(1)(A) is a permissible one and should be upheld. The employee's rights under § 7 include, among others, the right to refrain from joining or assisting a labor organization and from engaging in concerted activities for mutual aid or protection. The right to join or not to join a labor union includes the right to resign, and § 8(b)(1)(A) forbids unions to interfere with that right except to the extent, if any, that such interference is permitted by the proviso to that section, which preserves the union's right to prescribe its own rules with respect to the acquisition or retention of membership. The proviso might be read as permitting restrictions on resignation during a strike, since they would seem to relate to the "retention" of membership. But it can also be sensibly read to refer only to the union's right to determine who shall be allowed to join and to remain in the union. The latter is the Board's interpretation. Under that view, restrictions on resignations are not saved by the proviso, and the rule at issue in this case may not be enforced.

For the Act to be administered with the necessary flexibility and responsiveness to "the actualities of industrial relations," NLRB v. Steelworkers, 357 U.S. 357, 362-364, 78 S.Ct. 1268, 1271-1272, 2 L.Ed.2d 1383 (1958), the primary responsibility for construing its general provisions must be with the Board, and that is where Congress has placed it. "[W]e should 'recognize without hesitation the primary function and responsibility of the Board' " to apply these provisions to particular, and often complex, situations. Ford Motor Co. v. NLRB, 441 U.S. 488, 496, 99 S.Ct. 1842, 1849, 60 L.Ed.2d 420 (1979), quoting NLRB v. Insurance Agents, 361 U.S. 477, 499, 80 S.Ct. 419, 432, 4 L.Ed.2d 454 (1960). Where the statutory language is rationally susceptible to contrary readings, and the search for congressional intent is unenlightening, deference to the Board is not only appropriate, but necessary.

This is such a case. The Board has adopted a sensible construction of the imprecise language of §§ 7 and 8 that is not negated by the legislative history of the Act. That Congress eliminated from the bill under consideration a provision that would have made certain restrictions on resignation unfair labor practices falls short of indicating an intention to foreclose the Board's reading. By the same token, however, there is nothing in the legislative history to indicate that the Board's interpretation is the only acceptable construction of the Act, and the relevant sections are also susceptible to the construction urged by the union in this case. Therefore, were the Board arguing for that interpretation of the Act, I would accord its view appropriate deference.

Because I do not understand it to be inconsistent with the foregoing views, I join the Court's opinion.

Justice BLACKMUN, with whom Justice BRENNAN and Justice MARSHALL join, dissenting.

Today the Court supinely defers to a divided-vote determination by the National Labor Relations Board that a union commits an unfair labor practice when it enforces a worker's promise to his fellow workers not to resign from his union and return to work during a strike, even though the worker freely made the decision to join the union and freely made the promise not to resign at such a time, and even though union members democratically made the decision to strike in full awareness of that promise. The Court appears to adopt the NLRB's rule that enforcement of any such promise, no matter how limited and no matter how reasonable, violates the breaching worker's right to refrain from concerted activity. The Board's rule, however, finds no support in either the language of §§ 7 and 8(b)(1)(A) of the National Labor Relations Act on which the Court purports to rely, or in the general goals of the Act, which it ignores. Accordingly, the undeserved deference accorded that rule has produced a holding that improperly restricts a union's federally protected right to make and enforce its own rules, and at the same time traduces the broader aim of federal labor policy implicated by this right: to preserve the balance of power between labor and management by guaranteeing workers an effective right to strike.

* A.

Having determined that the individual worker standing alone lacked sufficient bargaining power to achieve a fair agreement with his employer over the terms and conditions of his employment, Congress passed the NLRA in order to protect employees' rights to join together and act collectively. See 29 U.S.C. § 151. Thus, the heart of the Act is the protection of workers' § 7 rights to self-organization and to free collective bargaining, which are in turn protected by § 8 of the Act. 29 U.S.C. §§ 157 and 158.

Because the employees' power protected in the NLRA is the power to act collectively, it has long been settled that the collective has a right to promulgate rules binding on its members, so long as the employee's decision to become a member is a voluntary one and the rules are democratically adopted. When these requirements of free association are met, the union has the right to enforce such rules "through reasonable discipline," including fines. See NLRB v. Allis-Chalmers Mfg. Co., 388 U.S. 175, 181, 87 S.Ct. 2001, 2007, 18 L.Ed.2d 1123 (1967). Unless internal rules can be enforced, the union's status as bargaining representative will be eroded, and the rights of the members to act collectively will be jeopardized. Ibid. "Union activity, by its very nature, is group activity, and is grounded on the notion that strength can be garnered from unity, solidarity, and mutual commitment. This concept is of particular force during a strike, where the individual members of the union draw strength from the commitments of fellow members, and where the activities carried on by the union rest fundamentally on the mutual reliance that inheres in the 'pact.' " NLRB v. Textile Workers, 409 U.S. 213, 221, 93 S.Ct. 385, 389, 34 L.Ed.2d 422 (1972) (dissenting opinion); see Allis-Chalmers, 388 U.S., at 181, 87 S.Ct., at 2007.

It is in the proviso to § 8(b)(1)(A), 29 U.S.C. § 158(b)(1)(A), that Congress preserved for the union the right to establish "the contractual relationship between union and member." Textile Workers, 409 U.S., at 217, 93 S.Ct., at 387. Recognizing "the law which normally is reflected in our free institutions," id., at 216, 93 S.Ct., at 387, Congress in the proviso preserved a union's status as a voluntary association free to define its own membership. The proviso states that the creation of a union unfair labor practice for a violation of the workers' right to refrain from collective action does not "impair the right of a labor organization to prescribe its own rules with respect to the acquisition or retention of membership therein." 29 U.S.C. § 158(b)(1)(A). As the Court has recognized previously and now concedes, the legislative history indicates that the proviso was meant to ensure that the employees' "right to refrain" would not be understood "to interfere with the internal affairs or organization of unions." Ante, at 102, quoting Allis-Chalmers, 388 U.S., at 187, 87 S.Ct., at 2010, in turn quoting 93 Cong.Rec. 4272 (1947) (statement of Sen. Ball). The "right to refrain" simply "was not intended to give the Board power to regulate internal union affairs, including the imposition of disciplinary fines, with their consequent court enforcement, against members who violate the unions' constitutions and bylaws." NLRB v. Boeing Co., 412 U.S. 67, 71, 93 S.Ct. 1952, 1955, 36 L.Ed.2d 752 (1973). See also Scofield v. NLRB, 394 U.S. 423, 428, 89 S.Ct. 1154, 1157, 22 L.Ed.2d 385 (1969).

Sensitive to both the Act's central goal of facilitating collective action, and the Taft-Hartley Act's protection against coercion of employees, the Court previously has interpreted the proviso to distinguish between two kinds of union rules. Reasonable union rules that represent obligations voluntarily incurred by members were intended to be free from federal regulation under § 8, while union rules that seek to coerce an employee by utilizing the employer's power over his employment status, or otherwise compel him to take on duties or join in concerted activities he never consented to, were intended to be subject to regulation by the Board. Because rules that regulate the relationship between the union and his employer could be used to coerce an employee into becoming involved with the union in order to protect his job, such rules would impair the employee's free association rights. "[T]he repeated refrain throughout the debates on § 8(b)(1)(A) and other sections [was] that Congress did not propose any limitations with respect to the internal affairs of unions, aside from barring enforcement of a union's internal regulations to affect a member's employment status." Allis-Chalmers, 388 U.S., at 195, 87 S.Ct., at 2014. The proviso was designed "to make it clear that . . . [a]ll we are trying to cover [in § 8] is the coercive and restraining acts of the union in its efforts to organize unorganized employees." 93 Cong.Rec. 4433 (1947) (statement of Sen. Ball). Until today, the Court has rejected the proposition that the proviso does not protect a union rule merely because the rule has an impact beyond the confines of the labor organization, Scofield, 394 U.S., at 431-432, 89 S.Ct. at 1158-1159, or because it is not a rule about the expulsion of members. Cf. ante, at 108-110.

League Law 13 is an internal union rule, a "rule with respect to the acquisition or retention of membership" protected by the proviso to § 8(b)(1)(A). It requires that employees who freely choose to join the union promise to remain members during a strike or lockout, as well as during the time when a strike or lockout appears imminent. In other words, the rule imposes a condition upon members of the bargaining unit who would like to acquire membership rights. The rule stands for the proposition that to become a union member one must be willing to incur a certain obligation upon which others may rely; as such, it is a rule literally involving the acquisition and retention of membership. Conversely, League Law 13 does not in any way affect the relationship between the employee and the employer. An employee who violates the rule does not risk losing his job, and the union cannot seek an employer's coercive assistance in collecting any fine that is imposed. The rule neither coerces a worker to become a union member against his will, nor affects an employee's status as an employee under the Act. Thus, it clearly falls within the powers of any voluntary association to enact and enforce "the requirements and standards of membership in the union itself," so as to permit the association effectively to pursue collective goals. 93 Cong.Rec. 4433 (1947) (remarks of Sen. Ball).

The Court nonetheless finds that League Law 13 violates an employee's right to refrain from collective activity and is not protected by the proviso. It reaches this conclusion by giving the proviso a cramped reading as a provision protecting only rules concerning the expulsion of members, see ante, at 108-110, ignoring in the process both the plain meaning and the legislative history of the proviso. Further, the Court never addresses the fact that the rule is a prerequisite of union membership much like any other internal union rule. Indeed, the Court entirely fails to explain why League Law 13 is not a rule "with respect to the acquisition or retention of membership," even given its own enervating understanding of the proviso. The rule, after all, is one to which a member was obliged to agree when he acquired or decided to retain membership in the union.

Moreover, Congress explicitly has rejected the Court's interpretation of §§ 7 and 8(b)(1)(A). The "right to refrain" language upon which the Court relies was contained in § 7(a) of the House version of the Act, H.R. 3020, 80th Cong., 1st Sess. (1947) (House bill). Section 7 of the House bill was divided into subsection (a), granting "employees" the right to refrain from concerted activity, and subsection (b), granting "[m]embers of any labor organization" rights concerning the "affairs of the organization." Corresponding to these provisions were § 8(b), which made it an unfair labor practice for anyone to interfere with an employee's § 7(a) rights, and § 8(c), which made it an unfair labor practice to interfere with an employee's § 7(b) rights. In particular, § 8(c) created a bill of rights for union members in their dealings with their union, establishing 10 unfair labor practices which regulated the major facets of the member-union relationship. Among these specifically enumerated rights was § 8(c)(4), which made it an unfair labor practice "to deny to any member the right to resign from the organization at any time."

Thus, the House regarded the "right to refrain" of § 7(a) as the right not to join in union activity, making it illegal for "representatives and their partisans and adherents to harass or abuse employees into joining labor organizations." H.R.Rep. No. 245, 80th Cong., 1st Sess., 30 (1947). And the House believed that § 7(b) and § 8(c) of its bill, which included a proscription of internal rules concerning a member's right to resign, regulated the member-union relationship. There is no suggestion that the House considered the right to refrain to include the right to abandon an agreed-upon undertaking at will, nor to relate to the rights against the union protected by §§ 7(b) and 8(c) of the House bill, including the right to resign at will. Rather, these distinct rights arose from separate sections of the House bill.

It is critical to an understanding of the Taft-Hartley bill, therefore, to recognize that the Senate explicitly rejected the House bill's §§ 7(b) and 8(c). It did so not, as the Court intimates, because it considered the specific provisions of §§ 7(b) and 8(c) to encompass the "right to refrain" language adopted from § 7(a), but because it decided that "the formulation of a code of rights for individual members of trade unions . . . should receive more extended study by a special joint congressional committee." S.Rep. No. 105, 80th Cong., 1st Sess., 2 (1947). Senator Taft's summary of the bill provides a clear and nonmysterious explanation of the Senate's stance on regulation of the union-member relationship:

"In the House bill union initiation fees were among 10 provisions providing for certain rights and immunities of members of labor organizations against arbitrary action by the officers of a union to which they belonged. This was the so-called bill of rights subsection in the House bill. The Senate conferees refused to agree to the inclusion of this subsection in the conference agreement since they felt that it was unwise to authorize an agency of the Government to undertake such elaborate policing of the internal affairs of unions as this section contemplated without further study of the structure of unions." 93 Cong.Rec. 6443 (1947).

And the House Conference Report, though reflecting the understatement of the vanquished, is equally clear:

"Section 8(c) of the House bill contained detailed provisions dealing with the relations of labor organizations with their members. One of the more important provisions of this section—[involving initiation fees in union shops]—is included in the conference agreement . . . and has already been discussed. The other parts of this subsection are omitted from the conference agreement as unfair labor practices. . . ." H.R.Conf.Rep. No. 510, 80th Cong., 1st Sess., 46 (1947).

In the face of this substantial legislative history indicating that the House provisions were rejected on the merits, the Court's treatment of that history, see ante, at 111, is both inaccurate and inadequate.1

Not surprisingly, the Court reaches for an alternative explanation as to why the "right to resign" provision was omitted from the Taft-Hartley amendments. We are told that the "right to resign" provision was omitted from the bill because the House, having won a provision making the closed shop illegal, was willing to give in on the right to resign. Ante, at 110-111. If this indeed explains the House's actions, its concession merely reinforces what the rest of the legislative history makes explicit: that the Senate was willing to agree to proscribe the closed shop and union shop because it agreed that they improperly coerced an employee into becoming a union member in order to keep his job. But the Senate was not willing to impose conditions on the contractual relationship between the union and its members, including a rule giving members a right to resign at will, insofar as such regulation did not affect the employment relationship. The House may have thought that the closed shop rules and the rules regulating the internal affairs of unions were similar rules aimed at preventing a union from limiting the freedom of choice of employees in what it considered impermissible ways. Drawing a different distinction, the Senate less narrowly circumscribed union discretion: rules that coerced an employee into taking collective action against his will be threatening his employment rights were prohibited, while rules that were a prerequisite of acquisition or retention of membership were to be left unregulated for the time being. Perhaps the House believed that the proscription against the closed shop and the proscription on limitations on a member's right to resign were aimed at the same evil. But the Senate obviously did not, and it prevailed.

The Court thus faces the same situation it addressed when it rejected the Board's interpretation of the recognitional-picketing provisions of the Act in NLRB v. Drivers, 362 U.S. 274, 80 S.Ct. 706, 4 L.Ed.2d 710 (1960) (Curtis Bros.). "Plainly, the [union's] conduct in the instant case would have been prohibited if the House bill had become law. . . . But the House conferees abandoned the House bill in conference and accepted the Senate proposal." Id., at 289, 80 S.Ct. at 715. As in Curtis Bros., it is therefore appropriate to recall that

" 'the Taft-Hartley Act was, to a marked degree, the result of conflict and compromise between strong contending forces and deeply held views on the role of organized labor in the free economic life of the Nation. . . . This is relevant in that it counsels wariness in finding by construction a broad policy . . . as such when, from the words of the statute itself, it is clear that those interested in just such a condemnation were unable to secure its embodiment in enacted law.' " Id., at 289-290, 80 S.Ct., at 715, quoting Carpenters v. NLRB, 357 U.S. 93, 99-100, 78 S.Ct. 1011, 1016-1017, 2 L.Ed.2d 1186 (1958).

Here, too, the legislative history "strongly militates against a judgment that Congress intended a result that it expressly declined to enact." Gulf Oil Corp. v. Copp Paving Co., 419 U.S. 186, 200, 95 S.Ct. 392, 400, 42 L.Ed.2d 378 (1974).2

The Court also attempts to justify its result by suggesting that League Law 13 impairs a federal labor policy mandating "voluntary unionism" implicit in § 8(a)(3) of the Act, and thus is unenforceable under § 8(a)(1) of the Act. See ante, at 104, quoting Scofield, 394 U.S., at 430, 89 S.Ct., at 1158. Thus, the Court says, for the same reason that Congress determined that the closed shop should be prohibited as a violation of an employee's right to refrain from concerted activity, a promise not to leave the union during a strike should not be enforceable. Both rules, the Court intimates, "protec[t] the employment rights of the dissatisfied member." Ante, at 106.

The Court, however, again ignores the distinction between internal and external rules fashioned in its prior cases, and so misunderstands the concept of "voluntary unionism" implicated by the Act. The purpose of the union unfair labor practice provisions added to § 8(a)(3) was to "preven[t] the union from inducing the employer to use the emoluments of the job to enforce the union's rules." Scofield, 394 U.S., at 429, 89 S.Ct., at 1157. By outlawing the closed shop and the union shop Congress ensured that a union's disciplinary rules can have no effect on the employment rights of the member, and so cannot impinge upon the policy of voluntary unionism protected by § 8(a)(3) of the Act.

The proviso serves a fundamentally different purpose—to make manifest that § 8 did not grant the Board the authority to impair the basic right of all membership associations to establish their own reasonable membership rules. League Law 13 is such a rule. It binds members to a reciprocal promise not to resign and return to work during a strike. It does not involve use of the employer's power or affect an individual's employment status, and so does not implicate § 8(a)(3). A member who violates the union rule may be fined, or even expelled from the union, but his employment status remains unaffected. Despite the Court's suggestions to the contrary, "voluntary unionism" does not require that an employee who has freely chosen to join a union and retain his membership therein, in full knowledge that by those decisions he has accepted specified obligations to other members, nevertheless has a federally protected right to disregard those obligations at will, regardless of the acts of others taken in reliance on them.3

At bottom, the Court relies on an unspoken concept of voluntary unionism that, carried to its extreme, would deny to the union member—in the name of having his participation in the union be voluntary—the right to make any meaningful promise to his co-workers. The Court understands voluntariness to mean freedom from enforceable commitment, treating the union member as a juvenile or incompetent whose promise may not be enforced against him because it is presumed not to have been made with awareness of the consequences of the promise. Not only is the Court's paternalism misplaced and offensive to the member, but it threatens the power to act collectively that is at the center of the Act.

Congress' decision not to intervene in the internal affairs of a union reflects Congress' understanding that membership in a union—if not a precondition for one's right to employment—is a freely chosen membership in a voluntary association. The Court therefore has looked to "the law which normally is reflected in our free institutions" to determine whether any given membership rule is lawful. NLRB v. Textile Workers, 409 U.S., at 216, 93 S.Ct., at 387. And the common law of associations establishes that an association may place reasonable restrictions on its members' right to resign where such restrictions are designed to further a basic purpose for which the association was formed4—here, where the restriction "reflects a legitimate union interest." Scofield, 394 U.S., at 430, 89 S.Ct., at 1158. The Pattern Makers evidently promulgated League Law 13 to protect the common interest in maintaining a united front during an economic strike. Such a rule protects individual union members' decisions to place their own and their families' welfare at risk in reliance on the reciprocal decisions of their fellow workers, and furthers the union's ability to bargain with the employer on equal terms, as envisioned by the Act. As such, the rule comports with the broader goals of federal labor policy, which guarantees workers the right to collective action and, in particular, the right to strike.

Specifically, Congress has mandated that nothing in the Act, including the "right to refrain" relied upon by the Court today, "shall be construed so as either to interfere with or impede or diminish in any way the right to strike, or to affect the limitations or qualifications on that right." 29 U.S.C. § 163. The strike or the threat to strike is the workers' most effective means of pressuring employers, and so lies at the center of the collective activity protected by the Act. "The economic strike against the employer is the ultimate weapon in labor's arsenal for achieving agreement upon its terms." Allis-Chalmers, 388 U.S., at 181, 87 S.Ct., at 2007. Consequently, the Court has recognized that " '[t]he power to fine or expel strikebreakers is essential if the union is to be an effective bargaining agent.' " Ibid., quoting Summers, Legal Limitations on Union Discipline, 64 Harv.L.Rev. 1049 (1951).

To be effective, the decision to strike, like the decision to bargain collectively, must be respected by the minority until democratically revoked. The employees' collective decision to strike is not taken lightly, and entails considerable costs. See NLRB v. Mackay Radio & Tel. Co., 304 U.S. 333, 345, 58 S.Ct. 904, 910, 82 L.Ed. 1381 (1938) (employer has right permanently to replace workers on economic strike). Before workers undertake such a course, it is reasonable that they have some assurance that collectively they will have the means to withstand the pressures the employer is able lawfully to impose on them. A voluntarily and democratically adopted rule prohibiting resignations during a strike is one such means. By ensuring solidarity during a strike, it enforces the union's "legitimate interest in presenting a united front . . . and in not seeing its strength dissipated and its stature denigrated by subgroups within the unit separately pursuing what they see as separate interests." Emporium Capwell Co. v. Western Addition Community Organization, 420 U.S. 50, 70, 95 S.Ct. 977, 988, 43 L.Ed.2d 12 (1975).

Once an employee freely has made the decision to become a member of the union, has agreed not to resign during a strike, and has had the opportunity to participate in the decision to strike, his faithfulness to his promise is simply the quid pro quo for the benefits he has received as a result of his decision to band together with his fellow workers and to join in collective bargaining. For the dissatisfied member to return to work in violation of his promise, while his fellows remain on strike forgoing their wages and risking their jobs in a now-weakened effort to pressure the employer into making concessions—is to allow the breaching individual to become a free rider, enjoying the benefits of his bargain without having to live with the risks that all who sought those benefits agreed to share.

More perniciously, a dissenting individual's decision to return to work predictably could have a snowballing effect, as apparently it did in this case, causing the strike to lose its effectiveness even though the majority of workers, having commenced collective action in reliance on a now-breached promise of solidarity, would wish to continue that action. It is hardly inconsistent with federal labor policy to enact a rule to ensure that the collective decision to remain out on strike be revocable only by procedures agreed upon collectively, not by the decision of a few dissenting individuals who believe it is in their individual interests to return to work, breaking the promise they made to abide by the majority's will. In a strike setting, therefore, "[t]he mutual reliance of his fellow members who abide by the strike for which they have all voted outweighs . . . the admitted interests of the individual who resigns to return to work." NLRB v. Textile Workers, 409 U.S., at 223, 93 S.Ct., at 390 (dissenting opinion).

Enforcement of a promise not to resign during a strike, then, is not a limitation of a § 7 right, but is a vindication of that right to act collectively and engage in collective bargaining, so long as the promise is voluntarily made. It is a way to effectuate " '[t]he majority-rule concept [that] is today unquestionably at the center of our federal labor policy.' " Allis-Chalmers, 388 U.S., at 180, 87 S.Ct., 2006, quoting Wellington, Union Democracy and Fair Representation: Federal Responsibility in a Federal System, 67 Yale L.J. 1327, 1333 (1958). As such, League Law 13 is a condition on union membership that a union might reasonably impose to advance its legitimate ends, and so is an internal union rule protected by the proviso preserving a union's right to enact reasonable rules defining the conditions of union membership.

In sum, the Court defers to the Board although the Board's position cannot fairly be said to rest on any principled application of the policies of our national labor laws. Because a majority of the Board has interpreted the terms of the NLRA in a manner inconsistent with the congressional purpose clearly expressed in the legislative scheme and amply documented in the legislative history, the Court's deference is misplaced. "The deference owed to an expert tribunal cannot be allowed to slip into a judicial inertia which results in the unauthorized assumption by an agency of major policy decisions properly made by Congress." American Ship Building Co. v. NLRB, 380 U.S. 300, 318, 85 S.Ct. 955, 967, 13 L.Ed.2d 855 (1965). We are not here "to stand aside and rubber-stamp . . . administrative decisions that [are] inconsistent with a statutory mandate or that frustrate the congressional policy underlying a statute." NLRB v. Brown, 380 U.S. 278, 291-292, 85 S.Ct. 980, 988-989, 13 L.Ed.2d 839 (1965). See also Chemical Workers v. Pittsburgh Plate Glass Co., 404 U.S. 157, 166, 92 S.Ct. 383, 390, 30 L.Ed.2d 341 (1971); 5 U.S.C. §§ 706(2)(A) and (C).

The Court previously has recognized that it violates precepts of voluntary unionism to bind a member to promises he did not knowingly make. See Machinists v. NLRB, 412 U.S. 84, 89, 93 S.Ct. 1961, 1964, 36 L.Ed.2d 764 (1973). The Board therefore properly could prevent enforcement of a rule like League Law 13 if there were evidence that the members were not aware of the provision until they had lost the ability to escape its force. Id., at 91, 93 S.Ct., at 1965 (opinion concurring in judgment). Though the § 7 right not to participate may be waived, as it was here, see Metropolitan Edison Co. v. NLRB, 460 U.S. 693, 705, 103 S.Ct. 1467, 1475, 75 L.Ed.2d 387 (1983); Allis-Chalmers, 388 U.S., at 180, 87 S.Ct., at 2006; Mastro Plastics Corp. v. NLRB, 350 U.S. 270, 280, 76 S.Ct. 349, 356, 100 L.Ed. 309 (1956), a waiver "must be clear and unmistakable." Metropolitan Edison Co. v. NLRB, supra, 460 U.S., at 708, 103 S.Ct., at 1477. The Court for that reason has agreed with the Board that it is an unfair labor practice for a union to attempt to collect a fine against a member who resigned from the union during a strike when it was not made explicit to the member that as a condition of membership he had to agree not to resign during the strike. See Machinists v. NLRB, supra.5

There is no similar suggestion in the record before us that the union members here were unaware of the promises they had made to their fellow members. If the dissenting members disagreed either with the decision to enact League Law 13, or with the decision to strike, they were free to try to influence their colleagues to their view. If they did not agree with the enactment of League Law 13, they were free as well to resign from the union when the rule was promulgated over their objection. Once the strike had begun, if they believed that the union officers were no longer acting in their best interest, they were free to try to convince their colleagues to end the strike, to replace their leaders, or even to decertify their union. See Allis-Chalmers, 388 U.S., at 191, 87 S.Ct., at 2012. Having failed to persuade the majority to their view, they should not be free to break their promise to their fellow workers.

"[T]he principle of fidelity to one's word is an ancient one." C. Fried, Contract As Promise 2 (1981). The assumption that one's freedom has been limited by being held to one's freely made bargain is as misguided in the context of the labor law as when stated as a general principle. By focusing exclusively on the right to refrain from collective action, by assuming an arid and artificial conception of the proviso circumscribing that right, and by ignoring Congress' intentions in promulgating the NLRA in the first instance, the Board and the Court abandon their proper role as mediators between any conflicting interests protected by the labor laws. In the name of protecting individual workers' rights to violate their contractual agreements, the Court debilitates the right of all workers to take effective collective action. The conclusion that freedom under the NLRA means freedom to break a freely made promise to one's fellow workers after they have relied on that promise to their detriment is not only a notion at odds with the structure and purpose of our labor law, but is an affront to the autonomy of the American worker. I dissent.

Justice STEVENS, dissenting.

The legislative history of the Labor-Management Relations Act, 1947, discussed in Part I-B of Justice BLACKMUN's dissenting opinion, coupled with the plain language in the proviso to § 8(b)(1)(A), persuades me that the "right to refrain" protected by § 7 of the Act does not encompass the "right to resign." Accordingly, I respectfully dissent.