Opinion
MOSK, J.For the second time in four years we consider the case of petitioner George Arakelian Farms, Inc. (hereafter Arakelian). In 1985 we affirmed an order of respondent Agricultural Labor Relations Board (hereafter Board) directing Arakelian to make its employees whole for certain violations of the Agricultural Labor Relations Act. (George Arakelian Farms, Inc. v. Agricultural Labor Relations Bd. (1985) 40 Cal.3d 654 [221 Cal.Rptr. 488, 710 P.2d 288] (Arakelian I).) Now, because of a 1987 appellate decision that assertedly affects the presumptions and burdens of persuasion in these proceedings, Arakelian has petitioned the Board for reconsideration of its order directing make-whole relief. We granted review to determine whether the Board may reopen the case and consider vacating its order without violating our decree in Arakelian I. We hold that although *1286the Board should be extremely reluctant to reopen such proceedings after this court’s order, it may nonetheless do so in a case that is not yet final when there has been an intervening change in the controlling rules of law. We conclude, however, that because there has been no relevant change in the law affecting the Board’s findings in this instance, our order affirming Arakelian’s make-whole obligation remains the law of the case.
In 1976 real party in interest United Farm Workers won a union representation election among Arakelian’s agricultural workers. The vote was 139 for the union and 12 for “no union,” with 17 ballots challenged. Arakelian filed a timely petition with the Board, objecting to the election and asking it to set aside the results. After considering and rejecting Arakelian’s election challenges, the Board certified the union as the employees’ exclusive bargaining representative.
Although the union was certified as the employee’s representative, Arakelian still asserted that the election was unfair and decided to seek judicial review of the Board’s certification decision by “technically” refusing to bargain.1 The union then brought an unfair labor practice charge, alleging that Arakelian violated Labor Code section 1153, subdivisions (a) and (e), by refusing to bargain collectively in good faith with the union.2 The Board subsequently found that Arakeliarfs refusal to bargain was a violation of section 1153, and— consistently with its former policy of awarding make-whole relief in all cases involving a technical refusal to bargain—automatically imposed make-whole relief.3 Arakelian then entered an appellate labyrinth and this litigation took on a life of its own.
Arakelian first petitioned for review on the ground that automatic imposition of make-whole relief in all technical-refusal cases was an abuse of the Board’s discretion. While that petition was pending before the Court of *1287Appeal, we agreed with Arakelian’s contention in J. R. Norton Co. v. Agricultural Labor Relations Bd., supra, 26 Cal.3d 1 (Norton). In that case we held that the Board could order make-whole relief in cases involving a technical refusal to bargain only when it appears from the totality of the employer’s conduct that the employer went through the motions of contesting the election results as a pretense to avoid bargaining. We concluded that the Board should not order make-whole relief when the employer litigated the certification issue in good faith and with a reasonable belief that the union would not have been selected as the employees’ bargaining representative had the election been conducted properly. (Id. at p. 39.)
Subsequent to our decision in Norton the Court of Appeal remanded Arakelian’s case to the Board for reconsideration. On remand the Board applied the Norton standards and concluded that Arakelian’s election challenges were not meritorious but were instead pursued with the sole intent to delay negotiations. Consequently, the Board again imposed make-whole relief. Arakelian sought judicial review of the Board’s decision for a second time. The Court of Appeal granted a writ of review and remanded the case with directions to conduct a hearing on Arakelian’s election challenges. On the union’s petition, we granted review and reversed. (Arakelian I.)
In our decision we determined that Arakelian had challenged the union’s certification in bad faith. After considering the circumstances under which Arakelian sought review, evaluating the substantive merit of its legal claims, and reviewing the margin of the union’s victory, we concluded that Arakelian could not have entertained a reasonable, good faith belief that errors in the election would have prevented the United Farm Workers from being selected as the employees’ bargaining representative. Instead, it appeared from the totality of the circumstances that Arakelian merely went through the motions of contesting the election as an elaborate pretense to avoid bargaining with the union. (Arakelian I, supra, 40 Cal.3d at p. 667.) In consequence, we affirmed the award of make-whole relief and ordered that “a decree issue enforcing the board’s order in full.” (Id. at p. 668.)
Unfortunately, our decision in Arakelian I did not end the matter. Pursuant to its regular practice, the Board remanded the case to the regional director for a determination of Arakelian’s monetary obligation under the make-whole award. Before the director determined the precise amount of the employees’ relief, the Court of Appeal for the Third District decided the case of William Dal Porto & Sons, Inc. v. Agricultural Labor Relations Bd. (1987) 191 Cal.App.3d 1195 [237 Cal.Rptr. 206] (Dal Porto). Dal Porto involved an employer’s refusal to bargain with *1288union representatives in the context of “surface bargaining.”4 The Dal Porto court held that the Board may impose make-whole relief in such cases only after it determines that the parties would have reached an agreement but for the employer’s unlawful refusal to bargain. According to the Dal Porto court, when innocent and wrongful conduct combine to prevent an agreement between the parties, make-whole relief is appropriate only if the employer’s wrongful conduct was primarily responsible for the breakdown in negotiations. (Id. at p. 1207.)
Subsequent to the Dal Porto decision, the Board opted to apply the decision retroactively to pending matters involving charges of surface bargaining. However, the Board refused to apply the decision to matters involving an employer’s technical refusal to bargain, reasoning that in such cases there would be no bargaining history from which it could conclude that the parties would have reached an agreement but for the employer’s wrongful conduct.5 Despite this rational determination, Arakelian nonetheless petitioned the Board to reopen the liability phase of its case and reconsider its make-whole order in light of Dal Porto. Arakelian offered to produce evidence of the subsequent negotiations, after the make-whole period had ended, to show that the parties would not have entered into a contract even if they had negotiated in good faith.6 The Board refused to reopen the proceedings, and Arakelian once again sought judicial review.
The Court of Appeal granted review and determined that the Board erred in refusing to apply Dal Porto to pending cases involving a technical refusal to bargain, The court dismissed the union’s claim that our previous decision in Arakelian I was res judicata, because it was convinced that Arakelian had not been given an opportunity to litigate the applicability of the Dal Porto “but for” ¡test in that proceeding. The court then concluded that if the Board was authorized to impose make-whole relief even if the parties would not have consummated an agreement, the remedy would be transformed into a penalty designed to punish an employer for seeking judicial review. *1289Thus, the court directed the Board to reopen the liability phase of these proceedings. We granted the union’s petition for review and now reverse.
The United Farm Workers renews its contention that once a party has litigated its unfair labor practice claim before the Board and a reviewing court has passed on the Board’s action, the preclusive effects of res judicata prevent further litigation of the issue. According to the union, our decision in Arakelian I was a final judgment on the merits, and even an intervening change in the law does not justify reopening the matter. The contention is unpersuasive.
Arakelian I affirmed the Board’s order awarding make-whole relief, an order that was a product of the Board’s bifurcated process for adjudicating unfair labor claims. The Board divides that process into a “liability phase” and a “compliance phase”; the National Labor Relations Board (NLRB) follows the same procedure. (See N.L.R.B. v. C.C.C. Associates, Inc. (2d. Cir. 1962) 306 F.2d 534, 539.) In construing the Agricultural Labor Relations Act, of course, we are guided by applicable precedent of the NLRB. (§ 1148.)
In the liability phase, the Board issues an order adjudicating whether or not the Act has been violated, but does not determine the extent of the employer’s liability. (George Arakelian Farms, Inc. (May 10, 1982) 8 ALRB No. 32, p. 2, fn. 2.) In the compliance phase, the Board reviews the backpay recommendation issued by the regional director and fixes the damages. The employer is afforded an opportunity to litigate all issues regarding the backpay order, and to rebut findings and submit evidence to mitigate the scope and extent of the damages. (Ibid.)
Make-whole orders, like the order issued in this case, are therefore interlocutory judgments. (N.L.R.B. v. C.C.C. Associates, Inc., supra, 306 F.2d 534, 539-540.) They are “General orders . . . [that] manifestly contemplate further administrative action on [the Board’s] part .... Such general orders are analogous to interlocutory judgments of courts fixing liability but leaving for future determination questions as to amount of liability; and our decrees affirming or enforcing them are analogous to our affirmance of interlocutory judgments on appeal.” (Wallace Corporation v. National Labor Relations Bd. (4th Cir. 1947) 159 F.2d 952, 954.)
The question here is whether our decision in Arakelian I affirming the interlocutory make-whole order precludes litigation of the Dal Porto issue. Under the collateral estoppel or “issue preclusion” effect of res judicata, a party is barred from raising an issue of fact or law if the issue *1290was actually litigated and determined by a valid and final judgment in a previous proceeding, and the determination was essential to the judgment; the determination, in that instance, is conclusive in a subsequent action between the parties. (Rest.2d, Judgments, § 27.)7
While the issue of the Dal Porto test would have been more appropriately rdised before the Board in the liability phase, or immediately thereafter on appellate review (as in Dal Porto itself), Arakelian is not precluded from raising it at this stage of the proceeding: the make-whole order was interlocutory, our decision in Arakelian I merely affirmed the interlocutory order, and Arakelian has not had an opportunity to litigate the issue. The policy unáerlying the doctrine of res judicata—avoiding repetitious litigation—is not implicated by reopening the proceedings in this case.
Moreover, while res judicata rules are generally applicable to administrative orders (Pacific Coast Medical Enterprises v. Department of Benefit Payments (1983) 140 Cal.App.3d 197, 214 [189 Cal.Rptr. 558]; Bowen v. United States (7th Cir. 1978) 570 F.2d 1311, 1322), their enforcement is more flexible in this context (Bank of America v. City of Long Beach (1975) 50 Cal.App.3d 882, 890 [124 Cal.Rptr. 256]). “ ‘The key to a sound solution of problems of res judicata in administrative law is recognition that the traditional principle of res judicata as developed in the judicial system should be fully applicable to some administrative action, that the principle should not be applicable to other administrative action, and that much administrative action should be subject to a qualified or relaxed set of rules concerning res judicata.’ ” (Hollywood Circle, Inc. v. Dept, of Alchoholic Beverage Control (1961) 55 Cal.2d 728, 732 [13 Cal.Rptr. 104, 361 P.2d 712], quoting 2 Davis, Administrative Law Treatise (1st ed. 1958) p. 568.) The bifurcated administrative process of the Board and the consequent interlocutory nature of the make-whole order affirmed in Arakelian I justify flexible application of res judicata in this case.
Lastly, the fact that the interlocutory order was sufficiently final to permit appellate review pursuant to section 1160.8 is not determinative of the res judicata issue; finality for purposes of appellate review is not the same as finality for purposes of res judicata. (Rest.2d Judgments, § 13, com. b.) Such finality is lacking, and thus the rules of res judicata do not apply, if *1291an issue of law or fact essential to the adjudication of the claim has been reserved for future determination, or if the administrative agency has decided that one party should have relief but the amount of the damages, or the form or scope of other relief, remains to be determined. (Ibid.)
Accordingly, we hold that the doctrine of res judicata does not preclude the Board from reopening the proceedings to allow the parties to litigate an intervening change in the controlling rule of law.
This is not to say, however, that a party may repetitively relitigate its claims until the decision of the Board becomes final in all respects. It is inherent in our system of judicial review of agency adjudication that once a court has passed on a question of law in its review of agency action, the agency cannot act inconsistently with the court’s orders. (American Farm Lines v. Black Ball (1970) 397 U.S. 532, 541 [25 L.Ed.2d 547, 554, 90 S.Ct. 1288]; Olive Proration etc. Com. v. Agri. etc. Com. (1941) 17 Cal.2d 204, 209 [109 P.2d 918].) Instead, absent unusual circumstances, the decision of the reviewing court establishes the law of the case and binds the agency in all further proceedings. (United Dredging Co. v. Industrial Acc. Com. (1930) 208 Cal. 705, 713 [284 P. 922].) Like res judicata, the doctrine of the law of the case serves to promote finality of litigation by preventing a party from relitigating questions previously decided by a reviewing court. (People v. Shuey (1975) 13 Cal.3d 835, 841 [120 Cal.Rptr. 83, 533 P.2d 211].)
Nevertheless we have recognized that as a procedural rule the law of the case may operate harshly, and we have fashioned a number of exceptions to the doctrine when (1) there has been an intervening change in the law, or (2) the disputed issue was not presented or considered in the proceedings below, or (3) application of the doctrine would result in a manifest injustice. (DiGenova v. State Board of Education (1962) 57 Cal.2d 167, 179-180 [18 Cal.Rptr. 369, 367 P.2d 865].) In this case Arakelian claims that all three of these exceptions apply and permit the Board to reconsider its liability decision despite our determination in Arakelian I. However, we caution that the Board should not lightly presume the existence of these exceptions; before the Board is free to disregard a lawful order of this court, judicial economy demands that Arakelian demonstrate that failure to apply Dal Porto would be a manifest misapplication of existing legal principles and would result in substantial injustice. (See People v. Shuey, supra, 13 Cal.3d at p. 846.)8
*1292 To resolve Arakelian’s contention that the Board should reopen these proceedings despite our previous decision in Arakelian I, it is necessary. to determine whether the intervening change in the law announced by the Court of Appeal in Dal Porto, supra, 191 Cal.App.3d 1195, applies to cases involving a technical refusal to bargain.9 If Dal Porto is applicable, then a change in the law has provided Arakelian a new defense that was previously unavailable when we considered its bad faith refusal to ¡bargain. If, on the other hand, Dal Porto cannot be applied to technical-refusal cases, then reconsideration of Arakelian’s substantive obligation! could involve the Board in evading an order of this court in violation of the law of the case.
We are persuaded that the Board was correct when it declined to apply Dal Porto to cases involving a technical refusal to bargain. In issuing its interim order declining to apply Dal Porto to technical-refusal cases, the Board ¡relied on its expertise and, because of its specialized knowledge, its decision is vested with a presumption of validity. (Agricultural Labor Relations Bd. v. Superior Court (1976) 16 Cal.3d 392, 411 [128 Cal.Rptr. 183, 546 P.2d 687].)
A close reading of Dal Porto reveals that it is inappropriate to apply the decision both to surface-bargaining cases and to cases involving a technical refusal to bargain. The two unfair labor practices are factually distinguishable and require different standards for evaluating the employer’s wrongful conduct. For example, to be relieved of a make-whole obligation in surface-bargaining cases, Dal Porto requires proof of legitimate disagreements on crucial subjects to show that the parties would not have entered into a collective bargaining agreement despite the unfair labor practice. (Dal Porto, supra, 191 Cal.App.3d at p. 1206.) However, in cases involving a technical refusal to bargain, an employer may avoid the make-whole remedy only if it challenged the union certification in a good faith belief that errors in th,e election affected the integrity of the selection process. (Norton, supra, 26 Cal.3d at p. 39.) If the reviewing court determines that the *1293employer’s election challenge was in fact a dilatory tactic designed to avoid bargaining, there is no opportunity to conclude, as the court did in Dal Porto, that innocent and wrongful conduct combined to produce legitimate disagreements on crucial issues, because the employer’s unfair refusal to bargain has prevented any negotiations whatsoever.
The most significant distinction between surface-bargaining cases and those involving a technical refusal to bargain lies in the quantum of evidence available to show that both innocent and wrongful factors combined to preclude agreement. In surface-bargaining cases, the employer can produce evidence of the actual negotiations between the parties to prove that they would not have entered into a collective bargaining agreement despite the employer’s wrongful conduct. In technical-refusal cases, on the other hand, the evidence that the parties would not have entered into an agreement even if they had negotiated in good faith is necessarily speculative because there is no bargaining history between the parties.10
The Board has the authority to establish evidentiary standards in unfair labor practice proceedings and may appropriately bar at the threshold proffered evidence that fails to meet these standards. (See Norton, supra, 26 Cal. 3d 1, 17.) Because the Board’s findings of fact must be supported on review by substantial evidence (§ 1160.8), the Board could properly conclude that before imposing make-whole relief in technical-refusal cases, to comply with Dal Porto it would be forced to construct a fictional collective bargaining process by accepting speculative evidence that would not satisfy the substantial evidence requirement. (Reese v. Smith (1937) 9 Cal.2d 324, 328 [70 P.2d 933]; Amyx Industries, Inc. v. N.L.R.B. (8th Cir. 1972) 457 F.2d 904, 907 [“the Board’s findings may not rest on ‘suspicion, surmise, implications or plainly incredible evidence’ .... ‘Substantial evidence is more than a scintilla and must do more than create a suspicion of the existence of the fact’ ” (italics deleted)].) The Dal Porto court acknowledged that the Board would be faced with such an evidentiary dilemma in cases involving a technical refusal to bargain and declared, “Plainly the Board need not waste its time indulging speculative evidentiary wheel-spinning. Wholly speculative evidence is not relevant and is properly excluded.” (Dal Porto, supra, 191 Cal.App.3d at p. 1211.) Consequently we conclude that the Board acted properly when it refused to accept any such *1294speculative evidence, limited Dal Porto to cases involving surface bargaining, and denied Arakelian’s motion for reconsideration at the threshold.11
The Court of Appeal was persuaded that if make-whole relief was imposed without giving an employer the opportunity to demonstrate that the parties wbuld not have entered into an agreement despite its wrongful conduct, the make-whole remedy would be transformed from a compensatory device into a penalty designed to punish the employer. Yet we have previously balanced the employees’ need for remedial compensation against the employer’s right to pursue meritorious litigation without punishment in those cases in which the employer has refused to bargain with its employees’ union representatives. In Norton, supra, 26 Cal. 3d at page 9, we adopted a test that accommodates the interests of both parties, by providing for make-whole relief only if it serves an important compensatory objective in those cases in which the employer’s election challenges are merely a stalling tactic designed tp thwart union organization. Once the Board or a reviewing court determines that such bad faith challenges motivated the employer’s conduct, make-whole relief does not punish the employer so much as compensate the employees for the actual loss of the opportunity to negotiate an agreement. (Id. at p. 31.)
Arakelian further contends that even if Arakelian I remains the law of the case despite Dal Porto, the Board should nonetheless be permitted to reopen the case because imposition of make-whole relief at this late date would havb a serious financial effect on the company. However, elementary concepts of justice require that after one has been administratively and judicially determined to be a wrongdoer he must bear the perils and consequences his own wrong has created. (Bigelow v. RKO Radio Pictures (1946) 327 U.S. 251, 265 [90 L.Ed. 652, 660-661, 66 S.Ct. 574].) Were we at this late date to determine that imposition of the make-whole remedy would be inappropriate and thereby permit the Board to reconsider its order, it is likely that Arakelian’s employees would continue to suffer because of Arakelian’s repetitive litigation tactics. Such a result would be inconsistent with the purposes of the Agricultural Labor Relations Act: unless litigation of the employer’s position furthers the policies and purposes of the act, the employer, not the affected employees, should ultimately face the consequences of its choice to litigate the representation issues rather than bargain *1295with the employees in good faith. (F & P Growers Assn. v. Agricultural Labor Relations Bd. (1985) 168 Cal.App.3d 667, 682 [214 Cal.Rptr. 355].)
Finally, we perceive no injustice in upholding the Board’s refusal to reopen this case, in light of the fact that any potentially relevant evidence Arakelian could introduce to show that no agreement would have been reached between the parties may yet be offered in the compliance phase of these proceedings. In cases involving a technical refusal to bargain any relevant evidence tending to show that no contract would have been consummated between the parties is more appropriately introduced in the compliance proceeding, because the question of what the parties might have agreed to concerns the amount of damages rather than the fact of damages. (See Great Chinese Am. Sewing Co. v. N.L.R.B. (9th Cir. 1978) 578 F.2d 251, 256.) Indeed, both the Board and the United Farm Workers concede as much, admitting that Arakelian is free to present evidence during the compliance stage that tends to mitigate any amount claimed to be owing as a result of the make-whole order we affirmed in Arakelian I.
One of the Legislature’s purposes in enacting the Agricultural Labor Relations Act was to effect a speedy resolution of agricultural labor disputes. The shortened period of time for seeking judicial review of the Board’s orders as well as the abbreviated enforcement procedures in the superior court manifest a legislative intent to avoid undue litigious delay. (Tex-Cal Land Management, Inc. v. Agricultural Labor Relations Bd. (1979) 24 Cal.3d 335, 346 [156 Cal.Rptr. 1, 595 P.2d 579].) A procedural system that encourages successive reviews by appellate courts of questions that were previously decided affects this legislative purpose and burdens the statutory rights and interests of agricultural workers, the class for whose benefit the law was adopted. (United Dredging Co. v. Industrial Acc. Com., supra, 208 Cal. 705, 714.) We recognize there are occasional instances in which, to prevent injustice, the Board may reopen a case after a decision by an appellate court because of a change in the controlling rule of law; but we again caution that such cases will arise infrequently and observe that this is not such a case.
The judgment of the Court of Appeal is reversed with directions to deny the petition of George Arakelian Farms, Inc., to review the order of respondent Agricultural Labor Relations Board, dated October 9, 1987, denying its motion to reopen the record in 6 ALRB No. 28.
Lucas, C. J., Panelli, J., and Eagleson, J., concurred.
Under the Agricultural Labor Relations Act an employer may not obtain immediate judicial review of the Board’s decision certifying a union as the employees’ exclusive bargaining representative. Instead, an employer that doubts the validity of the union certification can seek judicial review only by refusing to bargain with the union. If the employer is subsequently charged with and found guilty of an unfair labor practice under Labor Code section 1153, it may challenge the Board’s findings in court, arguing that but for violations in the conduct of the election the union would not have been selected as the employees’ bargaining representative. (Arakelian I, supra, 40 Cal.3d at p. 664.)
Unless otherwise indicated, all statutory references hereafter are to the Labor Code.
Make-whole relief is a compensatory remedy that reimburses employees for the losses they incur as a result of delays in the collective bargaining process. (J. R. Norton Co. v. Agricultural Labor Relations Bd. (1979) 26 Cal.3d 1, 36 [160 Cal.Rptr. 710, 603 P.2d 1306]. The remedy is designed to give agricultural employees the type of economic benefits they would have received if the parties had reached a timely agreement.
A party id guilty of surface bargaining when it merely goes through the motions of negotiating a collective bargaining agreement without any real intent to enter into a binding agreement. (See Bertuccio v. Agricultural Labor Relations Bd. (1988) 202 Cal.App.3d 1369, 1378 [249 Cal.Rptr. 473].)
The Court of Appeal in Dal Porto recognized in dictum that its holding might not apply to technical-refusal-to-bargain cases: “At the time of a representation election negotiations have not even begun; the issues about which the parties will bargain are unknown. It would therefore doubtless be impossible to tell whether the parties would have reached agreement had they bargained.” (Dal Porto, supra, 191 Cal.App.3d at p. 1209.)
Make-whole relief compensates employees for losses incurred in the period between the time the employer first refuses to bargain until negotiations actually begin. (Norton, supra, 26 Cal.3d at p. 3¡1.)
“Perhaps because it rests so much on logic, res judicata is especially appropriate for a Restatement, and the American Law Institute’s Restatement of Judgments (1942) has been an unusually powerful force, but it is now succeeded by a second and improved Restatement of Judgments (1982) which focuses mainly on the two subjects of ‘claim preclusion’ and ‘issue preclusion.’ The first Restatement ignored administrative res judicata, but the second Restatement usefully treats that subject in § 83 and already has significantly influenced law development.” (4 Davis, Administrative Law Treatise (2d ed. 1983) pp. 78-79.)
We emphasize that our decision should not be construed to imply that an administrative agency may overrule or nullify decisions of appellate courts. Instead, we affirm the obvious rule that administrative agencies may not void the judgment of an appellate court (Laisne v. *1292Cal. St. Bd. of Optometry (1942) 19 Cal.2d 831, 834-835 [123 P.2d 457]), and decide only that when an appellate court has announced a change in the controlling rules of law, an administrative agency may appropriately apply that decision to all pending cases.
Not all changes in the law justify disregarding the established law of the case. Instead, there must be a change in the controlling rules of law. (See, e.g., Clemente v. State of California (1985) 40 Pal.3d 202, 213 [219 Cal.Rptr. 445, 707 P.2d 818]; Davies v. Krasna (1975) 14 Cal.3d 502, 507, fn. 5 [121 Cal.Rptr. 705, 535 P.2d 1161, 79 A.L.R.3d 807]; see also Model State Administrative Procedure Act, § 5-114 (1981) which provides for reconsideration of agency action if a reviewing court determines that a relevant provision of the law was changed after the challenged action, and the changed provision may control the outcome of the proceeding.)
Arakelian conceded in its brief before the Court of Appeal that “it is not possible to determine whether the parties would have reached a contract at the time the employer refuses to bargain in a technical case.” Indeed, Arakelian relied only on the union’s subsequent wage demands to indicate that no agreement would have been consummated. The union made these demands in the parties’ negotiations after the make-whole period had ended; thus the demands were irrelevant and inadmissible.
Our conclusion that Dal Porto is inapplicable to cases involving a technical refusal to bargain makes it unnecessary to consider Arakelian’s additional contention that the law of the case was inapplicable to its petition for reconsideration, because the issue of the Dal Porto “but for” test was not before this court in Arakelian I. Arakelian did not raise the Dal Porto issue because in this technical-refusal-to-bargain case he manifestly could not do so.