ESCHBACH, Circuit Judge.
In these consolidated petitions1 we are asked to decide whether a rule recently adopted by the National Labor Relations Board governing grants of superseniority to union officers is rational and consistent with the National Labor Relations Act, and also in one case (No. 83-2900), whether the rule was properly applied to the facts. The rule in question is that of Gulton Electro-Voice, Inc., 266 N.L.R.B. 406 (1983), enforced sub nom. Local 900, IUE v. NLRB, 727 F.2d 1184 (D.C.Cir.1984), declaring lawful only superseniority provisions for officials who must be on the job in order to accomplish their duties directly related to administering the collective bargaining agreement. We enforce the orders of the Board.
I
A. Nos. 83-2900 and 83-3153 {Ex-Cell-O)
In April 1980 Nora Becky Smith was elected recording secretary of Local 1384 of the United Automobile, Aerospace and Agricultural Implement Workers of America (UAW), the collective bargaining representative for the production and maintenance employees at the Elwood, Indiana, plant of Ex-Cell-0 Corporation. Exercising a superseniority provision of the collective bargaining agreement, the union secured her transfer from the midnight shift to the day shift.2 Because of this transfer Emma Hartley, an employee with more seniority than Smith, was transferred to the afternoon shift against her wishes.3 Hartley filed an unfair labor practice charge with the Board, protesting her transfer.
On July 28, 1980, the Board’s General Counsel issued a complaint against Local 1384, alleging that the union’s maintenance and enforcement of the superseniority provision unlawfully caused the employer to discriminate against its employees on the basis of their union activity, in violation of [485]*485§ 8(b)(1)(A) and § 8(b)(2) of the National Labor Relations Act (the “Act”), 29 U.S.C.. § 158(b)(1)(A), (b)(2).
A hearing on the complaint was held before an administrative law judge (“AU”) on February 17, 1981. On a basically undisputed factual record the AU found that the duties of the recording secretary4 made it desirable that she be assigned to the day shift, in order to have ready access to the president and other collective bargaining officials who were on that shift. He found that when two officers are on different shifts, communications breakdowns can and have occurred, with results harmful to the functioning of the union. He concluded that the shift assignment provision in question bore a sufficiently direct relationship to the effective and efficient representation of the local as to render it lawful under United Electrical, Radio and Machine Workers Local 623, 230 N.L.R.B. 406 (1977) (Limpco Manufacturing, Inc.), petition for review denied sub nom. D’Amico v. NLRB, 582 F.2d 820 (3d Cir.1978). He accordingly dismissed the complaint.
The General Counsel filed exceptions, and on September 30, 1983, the Board rendered its decision. Local 1384, UAW, 267 N.L.R.B. 1303 (1983). Without disputing the factual findings of the AU, the Board pointed out that it had since overruled Limpco in Gulton Electro-Voice, Inc., 266 N.L.R.B. 406 (1983), enforced sub nom. Local 900, IUE v. NLRB, 727 F.2d 1184 (D.C.Cir.1984). Under the standard of Gui-tón a union officer may not be granted superseniority unless the officer's position requires an on-the-job presence at specific times in order to ensure the enforcement of the collective bargaining agreement and the prompt processing of grievances. The Board concluded that the recording secretary’s functions do not meet that criterion. The Board conceded that the shift assignment provision in question would make the union’s operations more efficient and effective but stated that it was not in the business of promoting such concerns at the expense of rights assured by § 7 of the Act. Accordingly, the Board, reversing the AU, held that by maintaining and enforcing the superseniority provision for the recording secretary the union had violated § 8(b)(1)(A) and § 8(b)(2) of the Act.
The union petitions us to set aside the Board’s ruling (No. 83-2900), and the Board cross-petitions for enforcement (No. 83-3153).
B. No. 84-1170 (Otis Elevator)
From February 1980 through June 1981 David Carter, a production clerk, was the financial secretary-treasurer of Local 826 of the International Union of Electrical, Radio and Machine Workers, the collective bargaining representative of the production and maintenance and plant clerical workers at the Bloomington, Indiana, facility of the Otis Elevator Company. Under a super-seniority provision of the collective bar[486]*486gaining agreement, union officers were accorded a preference for layoff and recall.5
In the late summer of 1980, Otis reduced its work force. Linda L. Fields, a production clerk with more seniority than Carter, was transferred to a lower paying job as inventory clerk. Without the superseniority provision, Carter would have been transferred instead of Fields.6
On September 10, 1980, Fields filed an unfair labor practice charge with the Board. The Board issued a complaint charging Local 826 with violations of § 8(b)(1)(A) and § 8(b)(2) of the Act. A hearing was held before an AU on July 8, 1981. The AU found that the financial secretary-treasurer, though not engaged in steward-type functions at the plant level, was nevertheless vital to the proper and efficient functioning of the union. Applying Limpco as governing law, the AU concluded that the union did not violate the Act and dismissed the complaint. The General Counsel filed exceptions, the union filed cross-exceptions, and on October 27, 1983, the Board rendered its decision. Local 826, IUE, 268 N.L.R.B. No. 12, 1983-84 NLRB Dec. (CCH) 05,973 (1983). The Board found the facts to be undisputed, affirmed the AU’s finding that the financial secretary-treasurer does not engage in steward-type functions at the plant level, and, applying Guitón, concluded that the union had indeed violated § 8(b)(1)(A) and § 8(b)(2) of the Act by according Carter superseniority as financial secretary-treasurer and causing Fields to be displaced rather than him.
The Board now applies to this court for enforcement of its order.
II
A. The Standard of Review
The unions claim that the Board’s decisions are erroneous because the rule of Guitón is an inappropriate standard for judging the lawfulness of superseniority provisions. They contend that the rule of Limpco is appropriate and should govern these cases. In addition, the union in Ex-Cell-0 contends that the Board misapplied the Guitón rule to the facts, and the union in Otis Elevator contends that it waived (and had the power to waive) the employee right that the Board seeks to vindicate.
Our review of a decision of the National Labor Relations Board is narrow. Congress has given the Board authority to develop and apply fundamental national labor policy, including the authority to formulate rules to fill the interstices of the broad provisions of the labor statutes. Beth Israel Hospital v. NLRB, 437 U.S. 483, 500-01, 98 S.Ct. 2463, 2473-74, 57 L.Ed.2d 370 (1978). Where the problem requires the balancing of legitimate conflicting interests, the function of striking that balance to effectuate national labor policy, often a difficult and delicate responsibility, has been committed by Congress primarily to the Board, subject to limited judicial review. NLRB v. Truck Drivers Local 449, International Brotherhood of Teamsters, 353 U.S. 87, 96, 77 S.Ct. 643, 647, 1 L.Ed.2d 676 (1957). The rule that the Board adopts is judicially reviewable for consistency with the Act and for rationality, but if it satisfies those criteria, the Board’s application of the rule, if supported by substantial evidence on the record as a whole, must be enforced. Beth Israel, 437 U.S. at 501, 98 S.Ct. at 2473 (citing NLRB [487]*487v. Erie Resistor Corp., 373 U.S. 221, 235-36, 83 S.Ct. 1139, 1149-50, 10 L.Ed.2d 308 (1963); Phelps Dodge Corp. v. NLRB, 313 U.S. 177, 194, 61 S.Ct. 845, 852, 85 L.Ed. 1271 (1941)).
Our analysis proceeds as follows. We first review the relevant statutes and the policies underlying them, as interpreted by the Supreme Court. We next briefly recount the history of the issue of supersen-iority for union officers before the Board. We proceed finally to the evaluation of the arguments put forward by the unions to persuade us to deny enforcement of the Board’s orders.
B. Statutes and Policies
Section 7 of the Act gives employees the right to participate in labor organizations and to bargain collectively, and also the right to refrain from such activity. 29 U.S.C. § 157.7 It is the policy of the Act to bar both employers and unions from restraining or coercing employees in the exercise of their § 7 rights, and the Act makes such activities unfair labor practices. § 8(a)(1) (employers), (b)(1)(A) (labor organizations), 29 U.S.C. § 158(a)(1), (b)(1)(A). In further protection of the employees’ § 7 rights, the Act makes it an unfair labor practice for an employer to encourage or discourage membership in a labor organization by discrimination in regard to hire or tenure of employment or any term or condition of employment, § 8(a)(3), 29 U.S.C. § 158(a)(3), and for a union to cause or attempt to cause an employer so to discriminate. § 8(b)(2), 29 U.S.C. § 158(b)(2).8
These § 8 provisions serve to insulate employees’ jobs from their organizational rights under § 7. Radio Officers’ Union v. NLRB, 347 U.S. 17, 40, 74 S.Ct. 323, 335, 98 L.Ed. 455 (1954). They were designed “to allow employees to freely exercise their right to join unions, be good, bad, or indifferent members, or abstain from joining any union without imperiling their livelihood.” Id. “Membership,” as used in § 8(a)(3), includes not only enrollment in the union but also participation in union activities. Id. Thus if an employer discharges a nettlesome union activist, he may be guilty of an unfair labor practice under § 8(a)(3). If at the behest of the incumbent union he provides some job-related benefit, such as longer paid vacations, to union officers, both he and the union may be guilty of an unfair labor practice under § 8(a)(3) and § 8(b)(2).
We say that such actions may, rather than would, be unfair labor practices, because improper motivation is additionally required. See Radio Officers’ Union v. NLRB, 347 U.S. 17, 42-44, 74 S.Ct. 323, 336-337, 98 L.Ed. 455 (1954). There is no unfair labor practice unless the action is taken because of the union activities of the employees directly affected, with intent to encourage or discourage union membership. Id. Improper intent need not be separately proved, however, when such en[488]*488couragement or discouragement is a natural consequence of the discriminatory action. Id. 347 U.S. at 45, 74 S.Ct. at 338. In NLRB v. Great Dane Trailers, Inc., 388 U.S. 26, 87 S.Ct. 1792, 18 L.Ed.2d 1027 (1967), the Supreme Court divided discriminatory conduct into two categories: (1) conduct so inherently destructive of employee interests that it may be deemed proscribed without need for proof of an underlying improper motive, and (2) conduct of which the harm to employee interests is comparatively slight. Id. at 33-34, 87 S.Ct. at 1797-1798. In the former case the burden is on the employer to prove that his action was actually motivated by legitimate and substantial business justifications. In the latter case the employer has the burden of coming forward with evidence of legitimate and substantial business justifications, whereupon the burden shifts to the General Counsel to prove an anti-union motivation. Id. Where union action is challenged under § 8(b)(2), we think that the same analysis would apply, except that the union, rather than the employer, would have the burden of showing legitimate and substantial business justifications. “Business justifications,” when applied to a labor union, would evidently refer to reasons relating to the advancement of the union’s “business” of acquiring and retaining recognition as bargaining representative, representing employees in the negotiation and administration of collective bargaining agreements, and conducting its own internal affairs.
C. Superseniority for Union Officers: History Before the Board
Collective bargaining agreements commonly allocate certain employee benefits, such as choice of shift, priority for overtime work, or precedence in layoffs and recalls, to employees on the basis of their seniority. A “superseniority” provision is one that assigns to certain union members a seniority greater than their “natural” seniority for the purpose of making them specially eligible for certain seniority-linked benefits, or which grants them such benefits directly, regardless of their natural seniority. Superseniority provisions are suspect under the National Labor Relations Act because they are inherently discriminatory in a way that arguably tends to encourage enrollment and active participation in the union. When such encouragement is the sole purpose of the provision, there is no question that it violates the Act. See Radio Officers’ Union v. NLRB, 347 U.S. 17, 42-44, 74 S.Ct. 323, 336-337, 98 L.Ed. 455 (1954). But the Board and the courts have long recognized that superseniority provisions may sometimes serve a legitimate purpose that overrides any tendency they may have to encourage union participation. See, e.g., Dairylea Cooperative, Inc., 219 N.L.R.B. 656 (1975) (well established that steward superseniority limited to layoff and recall is proper), enforced sub nom. NLRB v. Milk Drivers Local 338, 531 F.2d 1162 (2d Cir.1976). Formulating rules that draw the line between lawful and unlawful superseniority provisions is a task that has given the Board some difficulty, especially with respect to union officers. The cases we review today arise out of the Board’s most recent attempt to draw the line in Gulton Electro-Voice, Inc., 266 N.L. R.B. 406 (1983), enforced sub nom. Local 900, IUE v. NLRB, 727 F.2d 1184 (D.C.Cir. 1984).9
[489]*489The Board first treated the lawfulness of superseniority provisions in Dairylea Cooperative, Inc., 219 N.L.R.B. 656 (1975), enforced sub nom. NLRB v. Milk Drivers Local 338, 531 F.2d 1162 (2d Cir.1976). The Dairylea collective bargaining agreement contained a provision making each union steward the senior employee in his craft for all seniority-linked contractual benefits, including preference in layoff and recall, assignment of overtime, job assignment, and choice of vacation period, shift, hours, and day off. The Board held that steward superseniority in layoff and recall is lawful because it furthers the effective administration of bargaining agreements on the plant level by encouraging the continued presence of the steward on the job. Id. at 658. This function, according to the Board, redounds to the benefit of all unit employees, and such discrimination as it may create is simply an incidental side effect of that more general benefit. Id. But the Board found no evidence that superseniority for stewards going beyond layoff and recall serves any purpose other than the impermissible one of giving union stewards special economic or other on-the-job benefits solely because of their position in the union. Id. The Board held accordingly that superseniority clauses that are not on their face limited to layoff and recall are presumptively unlawful, with the burden of rebutting the presumption (i.e., establishing justification) resting on the party asserting their lawfulness. Id.
The Board addressed the question of the lawfulness of superseniority provisions benefiting union officers in United Electrical, Radio and Machine Workers of America, Local 623, 230 N.L.R.B. 406 (1977) (Limpco Manufacturing, Inc.), petition for review denied sub nom. D’Amico v. NLRB, 582 F.2d 820 (3d Cir.1978), and found itself deeply divided. The collective bargaining agreement provided a preference for layoff and recall for the union’s recording secretary, who performed no steward-type functions. Dairylea had declared such preferences lawful for stewards, and the issue the Board faced was whether they were also lawful for union officers or whether they fell within the scope of Dairy lea’s rebuttable presumption of invalidity. An aggregate majority of the Board, with two members dissenting, held that the superseniority provision in question was lawful. According to the Board, Dairylea was not intended to circumscribe which union representatives could be recipients of superseniority but rather to articulate the appropriate objectives of superseniority provisions, in the light of the legitimate statutory purpose of facilitating the effective administration of the collective bargaining agreement on the plant level. Id. at 407. Union officers, according to the Board, could be just as involved as stewards in the administration of the collective bargaining agreement, without performing steward-type duties. Id. at 408. Once it has been demonstrated that the official responsibilities of the union officer in question bear a direct relationship to the effective and efficient representation of unit employees, the Board held, the officer is entitled to the benefit of the same presumption afforded to union stewards.10 Id. Finding that this test was met in the case of the union’s recording secretary, the Board dismissed the complaint. Id.
The dissenters took a rather different view of Dairylea. According to them, the objective of superseniority provisions legitimated by the Board in Dairylea was not the effective and efficient representation of unit employees in general, but only the effective administration of bargaining agreements on the plant level, i.e., the processing of grievances and the enforcement of the collective bargaining agreement on [490]*490the job. Id. at 409. Only thus, they said, is the discriminatory effect of superseniority balanced by benefits to all employees; the Board’s broader standard tips the balance against individual employee rights by tying job benefits to political activism in the union. Id. The dissenters would have held presumptively valid only those super-seniority provisions which enable union officials with on-the-job grievance adjustment responsibilities to remain on the job in order to carry out those responsibilities.11
In a major change of course, a unanimous Board of different composition12 decided in 1983 to overrule Limpco and its progeny and adopt the general view of the Limpco dissent. Gulton Electro-Voice, Inc., 266 N.L.R.B. 406 (1983), enforced sub nom. Local 900, IUE v. NLRB, 727 F.2d 1184 (D.C.Cir.1984). In Guitón the union’s recording secretary and financial secretary-treasurer were accorded superseniority with respect to layoff and recall. The Board found these preferences to be unlawful, on the ground that those officers had no responsibility for grievance processing and on-the-job contract administration. The Board found, as it had found in Dairy-lea, that stewards have a need to maintain an on-the-job presence in order to carry out their duties, and that job retention super-seniority is therefore justified for them, despite the fact that it discriminates on the basis of union-related activities. Id. at 408. But the Board departed from Dairylea at the next step: it declared all other grants of superseniority to be unlawful. Dairylea was more tentative; grants of superseniority not in the service of steward-like duties on the plant level were presumptively unlawful, but the presumption could be overcome by proof of justification. Under Guitón no other justification is allowed:
We will find unlawful those grants of superseniority extending beyond those employees responsible for grievance processing and on-the-job contract administration. We will find lawful only those superseniority provisions limited to employees who, as agents of the union, must be on the job to accomplish their duties directly related to administering the collective-bargaining agreement.
266 N.L.R.B. at 409.
Elaborating on the case of union officers, the Board stated that job retention super-seniority is unnecessary for them, because they can continue to perform their union duties when laid off. Id. According to the Board, even if an officer must be replaced because of a layoff, changes in union officers are not so disruptive to unit representation as to warrant a blanket grant of superseniority. Id. The Board noted that there had been no showing in any case involving superseniority for union officers that unions would be crippled in their ability to administer collective bargaining agreements without the benefit of officer superseniority. Id.
The Board has since applied the principles of Gulton in Niagara Machine & Tool Works, 267 N.L.R.B. 661 (1983), enforced, 746 F.2d 143 (2d Cir.1984), striking down a layoff preference for certain officers who were members of the union’s executive board but who had no duties requiring their presence in the plant.
D. The Unions’ Arguments
1. Arguments Against the Rule in Guitón
The union in Ex-Cell-0 argues that the sole justification for superseniority countenanced in Guitón is excessively narrow. In fact, the union contends, superseniority for a union officer is proper where it has at most a slight impact on individual employee rights and serves the substantial legitimate purpose of promoting effective and effi[491]*491cient union representation. In support of this contention the union cites many cases in which the Board and courts of appeal have approved superseniority provisions for such reasons.
If the union is asking us to substitute our judgment for the Board’s as to the proper justification for superseniority provisions, we decline to do so. The Board has determined that such provisions aré justified only when they are necessary for the effective administration of the collective bargaining agreement on the job. We cannot upset this determination unless we are satisfied that it is irrational or inconsistent with the Act. This is not shown by arguments to the effect that a different weighing and balancing of the competing interests involved would support a broader standard of justification. For similar reasons we find unpersuasive the contention of the union in Otis Elevator that the Board has failed to balance properly the individual rights protected by § 8(a)(3) and § 8(b)(2) against the collective rights the Act is designed to foster and protect. The union states that the function of layoff-and-recall preferences for union officers is to assure continuity of local union leadership, and that continuity in office enables the union to carry out its legally mandated duties of fair and effective representation and to bargain collectively. The Board expressly considered the value of continuity of office in Gulton, see 266 N.L.R.B. at 409; supra p. 15, and found it to be insufficient justification. We cannot say that its determination was irrational or contrary to the Act.
The union in Ex-Cell-0 argues that the Guitón rules constitute a radical departure from previously established principles and precedents. Construing this as an argument that the Guitón rules are irrational or contrary to the Act, we find it insufficient. The union lists four supposedly well-established principles that the Board allegedly ignored: (1) the employee’s § 7 rights must be balanced against his correlative right to engage in effective collective bargaining through union representatives of his choice; (2) preferential seniority is not so inherently discriminatory that it cannot be justified by evidence of a legitimate purpose; (3) preferential seniority which promotes the effectiveness and efficiency of the local union in discharging its duty to employees is justified; and (4) preferential seniority which serves a legitimate purpose assists rather than impedes employees’ exercise of their rights under the Act.
We are puzzled by (1); the employee’s right to engage in collective bargaining through union representatives of his choice is a § 7 right. Perhaps instead of all § 7 rights the union means only that the employee’s § 7 right not to have job benefits tied to union activism must be balanced against his right to engage in collective bargaining. If so, we think the Board, in deciding Guitón, was mindful of (1). The Board simply disagrees with the union as to which right preponderates.
Principle (2) is a distortion of the law. The lawfulness of a superseniority provision under § 8(b)(2) does not depend on the magnitude of its tendency to discriminate but on the magnitude of the encouragement it gives to employees to become union activists, given that it discriminates.13 A second flaw in principle (2) is its failure to note that not any legitimate purpose constitutes adequate justification. The purpose must be sufficiently substantial to override the tendency of the preference to encourage union activism. The present Board, of course, would. admit that preferential seniority can sometimes be justified — but only for employees who must be on the job to carry out their duties in administering the collective bargaining agreement.
It is unfair to say that the Board has ignored principle (3). That principle is simply a variant of the rule of Limpco, which [492]*492the Board considered and expressly overruled in Guitón. As for (4), we think it is merely argumentative; our study of the history of superseniority before the Board leaves us convinced that no such principle has ever been endorsed or presupposed in any case on the subject.
It is also clear that the Board’s previous decisions do not bind it in later proceedings with anything like the force of the doctrine of stare decisis in the courts. The Board is free to change its mind on matters of law that are within its competence to determine; provided it gives a reasoned analysis in support of the change. See, e.g., Motor Vehicle Manufacturers Association v. State Farm Mutual Automobile Insurance Co., 463 U.S. 29, 103 S.Ct. 2856, 2866, 77 L.Ed.2d 443 (1983); Continental Web Press, Inc. v. NLRB, 742 F.2d 1087, 1093 (7th Cir.1984). We find that this requirement is met in Guitón and its progeny. Even if the Board adopts a rule in a decision that is subsequently enforced by a court of appeals, it may later change the rule. Enforcement reflects only a determination by the court of appeals that the rule is rational and consistent with the Act, not that it is the uniquely correct rule.
In addition, the history of officer super-seniority before the Board provides scant support for the idea that the rule of Limp-co represents a stable determination of what the law ought to be. That rule never commanded the support of more than two members.14 The reasoning of those members, as set forth in Limpco, contained an unexplained transition from a narrower to a broader rule. See supra note 10 and accompanying text. While the court of appeals denied the union’s petition for review in Limpco, D’Amico v. NLRB, 582 F.2d 820 (3d Cir.1978), the court interpreted the Board’s rule as requiring the union to prove that the beneficiary of superseniority had duties that help to implement the collective bargaining agreement,15 a restriction at variance with the broad interpretation of Limpco advanced by the unions in the cases before us. According to the court, “[a]ny less rigid interpretation of the Board’s ruling would leave substantial room to dilute the statutory neutrality principle without the requisite collective bargaining justification.” Id. at 825 (emphasis added). This may be read as an implied disapproval of the broader interpretation of the Limpco rule advocated by the unions here. Furthermore, the authoritativeness of Limpco was put in question by the Board itself in American Can Co., when with no change of composition it overruled the earlier panel decision. American Can Co., 244 N.L.R.B. 736 (1979), enforced, 658 F.2d 746 (10th Cir.1981); see supra note 11. We think that that case gives a better picture than Limpco of the state of the Board’s view on the issue of superseniority for officers during the period from Dairy-lea until the Board’s membership changed. We note also that the position of the Board in Guitón as to the sorts of reasons that can and cannot justify superseniority for officers was no new invention, distilled out of thin air. It was basically the position of the Limpco dissent, supported by two members of the Board and vigorously argued in Limpco and American Can Co.
The union in Ex-Cell-0 also argues that the Board reached its decision without actually balancing the interests implicated by the specific facts of the instant case. We think the Board has been engaged in balancing the relevant factors ever since Dairylea, and that the rule in Gulton incorpo[493]*493rates the present Board’s considered judgment as to how the balance should be struck. Our study of the history of super-seniority before the Board persuades us that different points of view have been thoroughly ventilated, including that advocated by the unions here, and we are impressed by the fact that in Guitón the Board for the first time achieved unanimity. In balancing, the Board is permitted to form generalizations about classes of cases based on its experience and to apply these generalizations to future cases. It is not required to conduct on the record a detailed analysis of each case in the light of first principles, as if the issue had never before arisen.
Of course, generalizations made on the basis of past cases may be put into question by future cases presenting an unforeseeable yet compelling constellation of facts. We are persuaded that the cases before us today are not of that kind. In Ex-Cell-0 the sole reason given by the union for assigning the recording secretary to the day shift is that the assignment makes it easier for her to communicate with the president. We see no evidence in the briefs or the record that the union tried to solve the communication problem in some other way. We do not see why the president and the recording secretary cannot confer daily by telephone at mutually convenient times, nor why they cannot pass documents back and forth by means of some such device as a lock box mounted at a convenient place in the plant. The gain in convenience from face-to-face talks over the next best method of communicating strikes us as simply inadequate to justify tying a seniority-linked employment benefit such as shift preference to a union office and denying another employee her choice of shift when her seniority would otherwise entitle her to it.
In Otis Elevator the union argues at length that the value of having its financial secretary-treasurer continuously employed justified a layoff-and-recall preference for him. But under the facts of the case, that line of argument is immaterial. The financial secretary-treasurer would not have been laid off, even if he had not had the preference; he would only have been transferred to a lower paying job. See supra note 6 and accompanying text. We are at a loss to see how protection of officers from reduction in grade as a result of a layoff is of any benefit to anyone but the officers. Continuity of employment obviously has nothing to do with it.
2. Arguments That the Board Improperly Applied the Guitón Rule to the Facts
The union in Ex-Cell-0 argues that the Board improperly applied the Guitón rule to the facts of the instant case. It contends first that the recording secretary had contract administration duties making her assignment to the day shift lawful under Guitón. She maintained the membership list used for the check-off of dues, she handled all health insurance claim disputes with the insurance carrier, she prepared a list of unresolved grievances, and she processed internal union appeals that could cause settled grievances to be reinstated. This argument is fatally flawed by the union’s failure to show that these are on-the-job duties that require her presence on the day shift. The rule of Guitón is not that any person with contract administration duties, however broadly construed, may lawfully have any kind of superseniority; it is rather that persons with on-the-job contract administration duties may lawfully have such superseniority as enables the person to stay on the job to carry out those duties. It seems clear that the duties recited by the union are not of that sort.
The union also argues that if the facts are analyzed by the tests of NLRB v. Great Dane Trailers, Inc., 388 U.S. 26, 87 S.Ct. 1792, 18 L.Ed.2d 1027 (1967) (discussed supra p. 488), the shift preference provision in question would have to be sustained as lawful. In particular, the union contends that under Great Dane the provision could not be struck down without proof that it was unlawfully motivated. This argument does not purport to show that the Board misapplied the Guitón rule; it is simply another attack on the rule [494]*494itself. Treating it as such, we disagree. The Guitón rule is entirely compatible with Great Dane. If superseniority preferences are inherently destructive of the § 7 rights of employees, then under Great Dane it is not necessary for the General Counsel to prove improper motivation separately. See supra p. 488. We do not, of course, decide that superseniority preferences are inherently destructive of the § 7 rights of employees; we say only that such a determination, if made by the Board, would not necessarily be irrational or contrary to the Act. Similarly, it would not necessarily be irrational or contrary to the Act for the Board to find that the only legitimate business purpose that is sufficiently substantial to justify a superseniority preference is tha't the preference is necessary to enable the employee to be on the job to carry out contract administration duties that require his presence on the job. The rule in Gui-tón could thus be reached by reasoning from the principles of Great Dane. Great Dane, therefore, does not require a contrary result.
We find substantial evidence in the record to support the Board’s determination that the recording secretary in Ex-Cell-0 and the financial secretary-treasurer in Otis Elevator did not have on-the-job duties of contract administration. When the Guitón rule is applied to these findings, it follows straightforwardly that the superseniority provisions in issue were unlawful. There was thus no error in the Board’s application of the rule.
3. Waiver
The union in Otis Elevator contends that it has waived the employee rights the Board seeks to vindicate. As authority the union cites Metropolitan Edison Co. v. NLRB, 460 U.S. 693, 103 S.Ct. 1467, 75 L.Ed.2d 1467 (1983), which states:
This Court long has recognized that a union may waive a member’s statutorily protected rights, including “his right to strike during the contract term, and his right to refuse to cross a lawful picket line.” [Citation omitted.] Such waivers are valid because they “rest on ‘the premise of fair representation’ and presuppose that the selection of the bargaining representative ‘remains free.’ ” [Citations omitted.] Waiver should not undermine these premises. Thus a union may bargain away its members’ economic rights, but it may not surrender rights that impair the employees’ choice of their bargaining representative. [Citation omitted.]
Id. at 705-06, 103 S.Ct. at 1476. The right that the union contends it has waived is the right of employees to be free of the limitations on their seniority rights that super-seniority for officers imposes. This, it claims, is an economic right subject to waiver under Metropolitan Edison. This argument fails because it misidentifies the right that the Board seeks to vindicate. The Board has declared superseniority for officers not involved in on-the-job administration of the collective bargaining agreement to be unlawful not because it impairs the natural seniority rights of employees but because it impairs their right to be free of discrimination that encourages union activism. This is not an economic right, because it is not a right to engage in some form of concerted activity, such as a strike, for the purpose of achieving economic advantage. See NLRB v. Niagara Machine & Tool Works, 746 F.2d 143, 150 (2d Cir. 1984); NLRB v. Midstates Metal Products, Inc., 403 F.2d 702, 705 (5th Cir.1968). We think that the right of employees to be free of discrimination that encourages union activism is one that the union may not surrender through collective bargaining, because the purpose of the right, as reflected in § 8(b)(2) of the Act, is to protect employees from certain forms of union conduct that benefit the union at the expense of the employees’ § 7 rights. This purpose would be frustrated if the union had authority to waive the right. We also think that the waiver of the right would impair the employees’ choice of their bargaining representative by enabling an incumbent union to encourage the active support of employees through the lure of employment bene[495]*495fits tied to positions in the union. Under the rule of Metropolitan Edison, therefore, the right may not be waived. See NLRB v. Magnavox Co., 415 U.S. 322, 325, 94 S.Ct. 1099, 1102, 39 L.Ed.2d 358 (1974); Local 900, IUE v. NLRB, 727 F.2d 1184, 1190 (D.C.Cir.1984).
Ill
We have given careful consideration to all the points and arguments made by the unions in both cases, whether expressly discussed in this opinion or not. Our analysis of the provenience of the Guitón rule and of the unions’ arguments against it persuades us that the rule is both rational and consistent with the Act. Therefore, we join with the two other circuits that have reviewed the rule and have declined to overturn it. See NLRB v. Niagara Machine & Tool Works, 746 F.2d 143 (2d Cir.1984) (enforcing an application of Gulton ); Local 900, IUE v. NLRB, 727 F.2d 1184 (D.C.Cir.1984) (enforcing Guitón). There is no question that the Board correctly applied the rule to the facts of the cases before us and that its rulings are supported by substantial evidence on the record as a whole. Accordingly, in No. 83-2900 the petition to set aside the Board's order is denied, and in No. 83-3153 and No. 84-1170 the orders of the Board are enforced.
SO ORDERED.