OPINION OF THE COURT
BECKER, Circuit Judge.
I. Preliminary Statement
This case arises under section 10(j) of the National Labor Relations Act, 29 U.S.C. § 10® (1976), which enables the National Labor Relations Board or its designated agent to seek interim injunctive relief from a federal district court pending the Board’s own administrative adjudication of an unfair labor practice complaint.1 As the jurisprudence has evolved, interim injunctive relief may be granted under section 10® without the showing of irreparable harm and a likelihood of success on the merits, which are the ordinary requisites for a preliminary injunction. Instead, a federal district court must merely find “reasonable cause” to believe an unfair labor practice has occurred and must determine that the relief sought is “just and proper.”
In this case, Regional Director Gerald Kobell, as agent for the Board, contended before the district court that interim relief was required under section 10® to thwart a joint venture by a failing bus line and the company that took over its operations to divest themselves unlawfully of a particular union as the bargaining representative of their drivers.2 After a three-day hearing, the district court denied the section 10® injunction because it found no reasonable cause to believe that a violation of the NLRA had occurred and because it concluded that it was not just and proper to grant relief. The Director appeals, and we affirm.
The appeal is complex and requires us to address difficult and important issues concerning the propriety of section 10® relief and the scope of appellate review over district court determinations in this field. It will therefore be helpful to sketch at the outset the manner in which the opinion will be developed.
We begin in Part II with a review of the evidence adduced at a hearing before the district court to show an alleged plot by appellee Holland Industries and its “Short-way” subsidiary to refuse discriminatorily to hire unionized employees of the operation it was assuming and thereby to evade the obligation that otherwise might well have existed to bargain collectively with the union those employees had previously elected as their representative. We then proceed in Part III to analyze whether the district court committed reversible error in finding no reasonable cause to believe that the defendants had committed unfair labor practices. This analysis shall sequentially entail (A) a discussion of the meaning of “reasonable cause” under section 10®, (B) an examination of the scope of our review [1079]*1079over district court determinations with respect to “reasonable cause,” and (C) an application of that standard to the determination of the district court in this case. In this part we conclude that the district court’s decision that no reasonable cause existed was reversible error.
We then proceed in Part IV to a similar analysis of whether the district court also erred in denying relief on grounds that it was not “just and proper.” Here too our analysis begins with a discussion of the concept “just and proper,” including a discussion of the broad purposes of section 10(j). We next examine the scope of our review over district court determinations that a given form of relief is not just and proper, and end this part of the opinion by applying the selected standard of review to the determination of the district court in the ease.
We conclude that the district court did not abuse its discretion in finding that the relief requested by the Regional Director was not just and proper under the particular circumstances of this case. Accordingly, we will affirm the judgment.
II. Facts
Since 1962, under operating authority granted by the Pennsylvania Public Utility Commission (“PUC”), appellee Suburban Lines has operated a charter bus service and a commuter bus service between Washington, Pennsylvania and-Pittsburgh. Since 1969, the Amalgamated Transit Union, Local 1543 (“ATU”) has represented Suburban’s 38 drivers and mechanics and has entered into a series of collective bargaining agreements with Suburban.3 The most recent agreement, which expired December 31, 1982, provided for wages averaging $8.60 per hour.
During 1981 and 1982, Suburban Lines did not fare well financially.4 In April of 1982, J.C. Hilty, the president and general manager of Suburban (and owner of 77 of the 737 shares of its stock), answered a job advertisement in Bus Rider magazine placed by appellee Holland Industries. Holland is a New York and Toledo-based firm, which through several subsidiaries operates a number of bus lines throughout the nation. Many of these subsidiaries had collective bargaining agreements with local affiliates of the Teamster’s Union at wage rates then averaging less than five dollars per hour. The record does not disclose what response, if any, Holland gave to Hilty’s submission. It is apparent from the record, however, that prior to July 15, 1982, Holland must have communicated at least something to some responsible official of Suburban. On that date, at a meeting presided over by Hilty, the Suburban board of directors discussed an offer by Holland to [1080]*1080purchase Suburban. While the minutes of that meeting, which are a matter of record, do not disclose the board’s opinion of the Holland offer, there was at least discussion of a counteroffer being made to Holland and an estimate made of the liquidation value of Suburban’s assets.
On August 9, 1982, several significant events occurred. First, an attorney for Suburban, acting as incorporator, filed articles of incorporation for “Short Way Suburban Lines, Inc.,” a wholly owned subsidiary of Holland Industries. Second, the Suburban stockholders held a special meeting and voted to accept a plan of liquidation approved earlier that day by the Suburban board of directors. According to Francis Olczak, a union driver for Suburban and owner of 10 shares of its 737 shares of stock, Hilty stated at the shareholders’ meeting that Shortway had agreed to hire him (Hilty) as manager but that Holland, the acquiring company, would not be hiring any of the Suburban drivers.5
There was also evidence produced at the evidentiary hearing before the district court from which it might be inferred that, while all of this was happening at the shareholder and director level of Suburban, Hilty began an effort to persuade or coerce the Suburban drivers into accepting the Teamsters as their bargaining representatives. According to testimony and an affidavit of Suburban driver Paul Phillips, Hilty told him that the new company would deal only with Teamsters.6 Moreover, according to Olczak, Hilty told him on August 13 that Holland Industries “would deal only with the Teamsters Union,” and that Holland would hire the Suburban drivers only if they would “go Teamsters.” Olczak further testified that Hilty asked him to poll the other drivers to see if they would agree to changing their bargaining representative. Olczak testified that he complied with Hilty’s request and that a week later he told Hilty that none of the other drivers would agree to switching their bargaining representative.
Evidence was also adduced that Holland Industries then decided that none of its Shortway employees would come from Suburban.7 According to the testimony of Karl Thomas Wegerbauer, president of Holland Industries and of Shortway, this decision, which was reached sometime in early September, not to hire Suburban employees was not caused by any lack of applications from Suburban drivers.
On September 8 the Suburban board of directors met again. The directors approved sale of the company to Shortway [1081]*1081for approximately one million dollars, twice the liquidation value estimated at the earlier July 15 meeting.8 On September 14 the deal was finalized. Sale of the company, which was to take place on October 30, was contingent, however, on approval by the PUC of permanent transfer of Suburban’s routes to Shortway. On September 15, the appropriate filings were made to the PUC in support of this transfer.
Between September 14 and October 30, Suburban and Shortway continued what the Regional Director regards as a clandestine and illegal venture to evade the obligations created by NLRB v. Burns International Security Services, Inc., 406 U.S. 272, 92 S.Ct. 1571, 32 L.Ed.2d 61 (1972) and Howard Johnson Co. v. Detroit Joint Executive Board, 417 U.S. 249, 94 S.Ct. 2236, 41 L.Ed.2d 46 (1974). Those cases impose a duty upon an employer who takes over a unionized operation and who conducts essentially the same business there as its predecessor to bargain collectively with the representative elected by the workers of the predecessor, provided that those workers constitute a majority of the successor’s workforce. The Regional Director argues, in essence, that by discriminatorily refusing to hire Suburban employees — a plan accomplished by lying to them about when applications were due and when jobs were available — Shortway sought to evade its obligations under Burns and Howard Johnson and to rid itself of the high-priced ATU.
In support of this theory, the Regional Director notes that Holland/Shortway began hiring admittedly less experienced drivers in Detroit to take over operation of Suburban’s Pennsylvania routes. According to uncontroverted testimony of Louis Keplar, Hilty — who arguably knew that Holland had already decided not to hire any Suburban drivers, see supra at 1080— told Keplar in late September that the new company would be getting in touch with him and that “there was no reason to hound [Hilty] every day.” Then, in early October, according to testimony from Suburban driver Phillips, Hilty told Phillips that the Suburban drivers would have jobs, though not for a month or so. According to testimony of Warren S. George, vice-president of the ATU, on October 15 Short-way attorney Sanford Pollack returned a telephone call and told George that, while Shortway was “presently training drivers in the Toledo/Detroit area for [the Pennsylvania] jobs,” it would consider the Suburban drivers for subsequent openings. Pollack also sent George a letter dated October 19 containing job applications and stating, “We anticipate to begin operation with a complete staff and, therefore, see no urgent need in the return of the enclosed.” What Pollack did not reveal was that Short-way had not yet completed its hiring for the Pennsylvania jobs; between October 15 and 25 Shortway hired five more drivers.9 In sum, the Regional Director would have liked the district court to have found an illegal attempt to lull ATU members into a false sense of security and then to lie to ATU members — or at least speak recklessly — about the availability of employment.10
[1082]*1082Meanwhile, the deal between Suburban and Shortway was running into difficulty. On October 29, following a hearing at which the ATU had lodged a protest against the proposed sale, the PUC directed Suburban not to abandon service pending the PUC’s final decision on transferring operation of the bus routes to Shortway. Temporary authority for Shortway to operate the routes, which the PUC had granted on October 15, remained in force. Thus, at least until the PUC decided differently, Shortway could operate the routes. But until the PUC approved permanent transfer of the routes to Shortway, the September 14 agreement did not permit consummation of the sale of Suburban to Short-way.
Faced with the PUC obstacle, Shortway and Suburban executed a second deal on October 29. Under the new agreement, Suburban would lease its buses and equipment to Shortway in return for a fixed rental. The lease would last as long as Shortway had temporary authority to operate the Suburban routes. Shortway began operations the next day. It also recognized the Teamsters as the bargaining representative for its employees. The Teamsters and Shortway agreed that the Shortway drivers would operate under a collective bargaining agreement in effect with another Holland subsidiary. Wages under this collective bargaining agreement averaged $4.80 per hour, considerably less than that paid by predecessor Suburban to the drivers, who were affiliated with the ATU.
Between November 1, 1982, and January of 1983, a rather curious event occurred: Shortway fired or transferred back to Detroit 27 of the 31 drivers it had originally hired.11 It has since hired four of the former Suburban employees.
Formal legal proceedings challenging the propriety of the events described above began on November 9,1982, when the ATU filed an unfair labor practice charge with the NLRB. After an investigation, the NLRB, acting through Regional Director Kobell, filed an unfair labor practice complaint against the defendants. The complaint, dated December 30, 1982, accused them of violating sections 8(a)(1), 8(a)(2), 8(a)(3), 8(a)(4), and 8(a)(5) of the NLRA. 29 U.S.C. §§ 158(a)(l)-(5). Three months later, on March 4, 1983, the Regional Director petitioned the district court for the Western District of Pennsylvania for interim injunctive relief under section 10(j).12 [1083]*1083The Regional Director requested, among other items, that the district court order the bus companies to make reinstatement offers to the displaced Suburban drivers, that the bus companies be required to recognize the ATU as the bargaining representative of the employees driving the old Suburban routes, and that the collective bargaining agreement between Suburban and the ATU be reinstated as governing the terms and conditions of the current employees.
The district court held three days of hearings on the complaint (April 18, 19 and 20) during which it heard testimony from fifteen witnesses called by the Director. The bus companies moved at the close of the Director’s case for a directed verdict (or for the dismissal of the complaint). On April 20, 1983, the district court granted the bus companies’ motion and dismissed the Regional Director’s petition for interim injunctive relief.
Although the grounds upon which the district court dismissed the complaint will be taken up in detail below, they may be summarized as follows. First, while not specifically finding any of the testimony mentioned above to lack credibility or relevance, the district court nonetheless held that there was no reasonable cause to believe that an unfair labor practice had occurred. Although accepting arguendo (1) that the employees of the new company were less competent than the old Suburban employees; (2) “that the new owners of the bus line did not encourage the former employees to seek employment; ” and (3) that “the former employees may have been confused as to how to go about applying,” the district court nonetheless stressed that Shortway had never actually refused to hire any Suburban applicant. The district court also suggested that the old Suburban employees would not have been willing to work at the Shortway wage rates anyway and further held that there was no showing that anti-union animus solely motivated Shortway.
As a further basis for denying interim injunctive relief, the district court held that the relief sought by the NLRB was not “just and proper.” In reaching this conclusion, the district court reasoned that a backpay award by the NLRB could fully remedy any discriminatory refusals to hire and that the ATU was a “small and intimate” union that could reconstitute itself upon favorable action by the NLRB.
•III. Reasonable Cause
To have prevailed in the district court, the Regional Director needed to show that the evidence described above gave reasonable cause to believe that an unfair labor practice had occurred. We turn to an exploration of the meaning of this phrase.
A. The Meaning of “Reasonable Cause”
It is settled that the “reasonable cause” standard under section 10(j) bars the district court from behaving as if it had general jurisdiction over the nation’s labor laws. The district court may not decide whether or not to issue relief based on its own belief as to whether an unfair labor practice has been committed. See, e.g., Boire v. Inter[1084]*1084national Brotherhood of Teamsters, Chauffeurs, Warehousemen & Helpers, 479 F.2d 778, 792 (5th Cir.1973); Schauf-fler v. Local 1291, 292 F.2d 182 (3d Cir. 1961) (10(7) case). The amount of evidence required by the “reasonable cause” determination is less than that required to prove a violation. Yet, except to note that it is a “low threshold of proof,” see Eisenberg v. Wellington Hall Nursing Home, Inc., 651 F.2d 902, 905-06 (3d Cir.1981), this circuit has not yet resolved the precise meaning of “reasonable cause” in section 10(j) cases. We believe, however, that doctrine developed in cases brought under section 10(7) of the NLRA, 29 U.S.C. § 160(7), a companion provision directing the NLRB to seek interim injunctive relief when certain specified unfair labor practices are reasonably believed to have occurred, is helpful in ascertaining that meaning.13
We see no reason why courts should accord “reasonable cause” a different meaning in 10(j) cases than they do in 10(7) cases. In Wellington Hall, 651 F.2d at 905, this court noted that in an earlier case, Eisenberg v. Hartz Mountain Corp., 519 F.2d 138, 143 (3d Cir.1975), “we held that reasonable cause to believe a violation of the act has occurred, a standard for injunc-tive relief originally developed in cases arising under section 10(7) of the Act, is also applicable to section 10(j) proceedings.” While this equation of the standard in section 10(j) cases with the standard in 10(7) cases does not, of course, mandate that all features of the “reasonable cause” standard must be the same, it is worth observing that there is nothing in those cases that suggests the appropriateness of any distinction. In a leading section 10(7) case, Hirsch v. Building & Construction Trades Council, 530 F.2d 298, 302 (3d Cir. 1976), the court held that the burden of proof faced by a regional director is “relatively insubstantial.” Moreover, the court held that the district court need not be satisfied with the “validity of the legal theory upon which [the Regional Director] predicates his charges.” So long as the legal theory presented by a regional director is “substantial and not frivolous,” the district court may grant appropriate relief in a section 10(7) case.
Because of what we regard as the coincidence of the reasonable cause standard under section 10(7) of the NLRA and under section 10(j) of the Act, we believe that a district court need make one of two findings before denying relief. It must find there to be no legal theory implicit or explicit in the regional director’s argument that is substantial and not frivolous. Alternatively, the district court must find insufficient evidence — at least taking the facts favorably to the Labor Board — to support any non-frivolous theory appropriate to the case at bar.
B. The Standard of Appellate Review
While the federal courts do not differ greatly on the precise meaning of “reasonable cause” in section 10(j) or section 10(7) cases, they are split on the standard of review that the courts of appeals are supposed to apply when examining the refusal of a district court to find reasonable cause. The Eighth and Ninth Circuits have held appellate review over the reasonable cause determination, at least in section 10(7) cases, to be plenary. See Wilson v. Milk Drivers & Dairy Employees Union, 491 F.2d 200, 203-04 (8th Cir.1974); Local No. 83, Construction Building Materials & Miscellaneous Drivers Union v. Jenkins, 308 F.2d 516, 517 n. 1 (9th Cir.1962) (dictum). These courts have reasoned that, because there is a “congressional policy favoring the grant of such injunctions in appropriate circumstances,” review ought not be limited to the clearly erroneous standard as it is in cases granting relief. The [1085]*1085NLRB urges us to adopt their view.14
On the other hand, the Second Circuit, in a recent opinion by Judge Friendly, and the Fifth Circuit, in an opinion by Judge Goldberg, have recognized that the district court’s finding of “reasonable cause” has both a factual and legal component. See Kaynard v. Mego Corp., 633 F.2d 1026 (2d Cir.1980) (Friendly, J.) (10(j) case); Boire v. International Brotherhood of Teamsters, Chauffeurs, Warehousemen & Helpers, 479 F.2d 778, 788 (5th Cir.1973) (10© case). Accordingly, they have applied a bifurcated standard of review under which the factual findings of the district court about what happened and what is likely to happen are reviewable under the “clearly erroneous standard” as are all factual questions, whereas the substantiality of a regional director’s legal theory tying the facts to a violation of the labor laws is deemed a legal issue, subject to plenary review. For the reasons outlined below, we reject the view of the Eighth and Ninth Circuits and adopt that of the Second and Fifth.
To begin with, the conclusion drawn by the Eighth and Ninth Circuits that appellate courts have plenary review over district court determinations that no reasonable cause exists does not necessarily follow from their assumption — which we do not, in any event, accept as necessarily true — that Congress favored injunctions in section 10© cases. Whatever Congressional policy exists in favor of injunctions would appear to be satisfied by the district court’s application of a low “reasonable cause” standard to Labor Board requests for section 10© relief. To leap from a general policy to a particular doctrine requires a mediating theory not yet presented by the Board. Moreover, we note our discomfiture at establishing an asymmetric standard of review — one which allows the district court great discretion in granting injunctive relief, but almost no discretion in denying it.15 We will want a very good reason to introduce such an abnormality into the law of appellate review.
Instead, we believe that in 10© cases, as elsewhere, the scope of appellate review should be determined by the degree of trust we possess as a general matter in the district court’s ability to make varying types of decisions correctly and the nature of the decisions made by the district court in the particular ease. As we have suggested above, the district court’s reasonable cause determination really involves two separate determinations: is there a substantial legal theory explicit or implicit in the case that would support a finding that an unfair labor practice had occurred? If a substantial legal theory exists, do the facts satisfy the theory? The first of these questions, which requires characterization of the legal theory, is itself a “legal” issue; discerning the plausible penumbras of Labor Act provisions is a task that a three-judge appellate tribunal with responsibility to secure uniformity in the law is better equipped to perform than a trial court. The second of these questions, whether the facts as found satisfy the theory, is largely a factual one; a determination of the sufficiency and credibility of the evidence is a task that a trial court is better equipped to perform than an appellate court.
[1086]*1086In sum, because of the dual nature of the “reasonable cause” standard, an appellate court’s review must also be dichotomous. If it believes the district court erred in determining whether the legal theory implicit or explicit in the Labor Board’s case was substantial or not, it must — absent other special factors — reverse the district court. But only if it believes the district court clearly erred in finding the facts and whether the facts satisfied the theory may the appellate court reverse.16
C. Applying the Scope of Review
Having set forth the appropriate standard of review, we now apply it to the case at bar. The district court’s bench opinion can be fairly read as resting its finding of no reasonable cause on three underlying conclusions. First, it noted that, because no Suburban employee had actually applied for a job with Shortway during the relevant time period, there had been no “refusal to hire by the new employer [Shortway].” Second, it found that any anti-union animus that did exist on the part of the bus lines was not the sole reason for their failure to hire, a requirement the court grounded on footnote 8 of the Supreme Court’s opinion in Howard Johnson Co. v. Detroit Joint Executive Board, Hotel & Restaurant Employees & Bartenders International Union, 417 U.S. 249, 94 S.Ct. 2236, 41 L.Ed.2d 46 (1974). Third, it apparently concluded that, because of what it regarded as the Suburban employees’ steadfast refusal to accept employment at the Shortway wage rates, any improper behavior by Shortway was not a but-for cause of the harm alleged. We consider these predicate conclusions in turn.
1. No Actual Refusal to Hire
Implicit in the first reason set forth above as justifying a no-reasonable-cause finding is a legal theory: absent an application by a potential employee and rejection of that application by .the employer, there can be no discrimination in regard to hire constituting an unfair labor practice. We believe the district court erred in adopting this legal theory and in rejecting the opposing legal theory of appellant as insubstantial. It seems clear that there can be “discrimination in regard to hire” constituting at least a violation of section 8(a)(3) of the NLRA even when the employer never formally rejects an individual application. See Piasecki Aircraft Corp. v. NLRB, 280 F.2d 575, 583, 585, 590 (3d Cir.1960) (lack of response by unionized employees of predecessor employer to offer by successor employer to accept applications held not to cure successor’s previous discriminatory refusal to hire, at least where previous unfair labor practice created perception of futility among union employees). Posting a sign, for example, that reads “No Blacks Need Apply” or that reads “No Union Members Need Apply” and that succeeds in its objectives is just as effective (and just as offending) a method of discrimination as a pointblank refusal to hire an individual black or union-affiliated applicant.17
[1087]*1087It is equally non-frivolous, we think, to argue that, as a matter of law, an employer violates section 8(a)(3) if, by intentionally or recklessly misstating the times that applications are due or by intentionally or recklessly misrepresenting that all the jobs previously offered have been filled, the employer effectively prevents members of a certain union from applying for jobs. Finally, though perhaps not as conventional as the above-mentioned legal theories, it is also non-frivolous to argue that, by discriminating in regard to its methods of notifying potential employees of job openings— notifying potential employees in Detroit, for example, of job openings in Pennsylvania, but not even making a phone call to the head of a union representing soon-to-be unemployed, admittedly competent Suburban drivers — an employer discriminates “in regard to hire ... to discourage membership in any labor organization.”18 Cf. Kallmann v. N.L.R.B., 640 F.2d 1094 (9th Cir.1981) (fact that only nine of forty former employees applied for job with successor employer does not preclude bargaining order against successor employer where absent discriminatory practices — including unusually placed and misleading job advertisements — majority of old workforce would have been hired); Packing House & Industrial Services v. NLRB, 590 F.2d 688, 695 (8th Cir.1978) (effort spent in obtaining less experienced workers from distant city without corresponding attempts to contact predecessor’s employees held to be relevant evidence of discriminatory refusal to hire).19
Accordingly, since the NLRB’s legal theory was substantial and not frivolous, we believe the district court erred in denying section 10(j) relief to the NLRB on the basis that no Suburban employee had applied for employment with Shortway. Unless some other basis can be found for sustaining the judgment of the district court, the case must be remanded for decision under the legal theories we deem substantial.
2. The Sole Motive Theory and the Howard Johnson Case
The district court also erred in implicitly treating as frivolous the NLRB’s claim that anti-union animus did not have to be the sole motive for discriminatory behavior in order for an unfair labor practice to be found. To begin with, the authority cited against the NLRB’s proposition, footnote 8 in the Howard Johnson opinion, does not cover the ground contended for. What the Supreme Court said in this footnote was that “a new owner could not refuse to hire the employees of his predecessor solely because they were union members or to avoid having to recognize the union.” But a statement does not necessarily imply its converse; that is, the Supreme Court’s proclamation does not necessarily imply that a new owner could refuse to hire the employees of his predecessor if it did not do so solely because they were union members or to avoid having to recognize the union. Accordingly, the district court erred in holding Howard Johnson to be dispositive.
Moreover, there are significant indications that the converse of Howard Johnson is not a correct statement of the law. Su[1088]*1088preme Court cases from Republic Aviation Corp. v. NLRB, 324 U.S. 793, 65 S.Ct. 982, 89 L.Ed. 1372 (1945), to NLRB v. Transportation Management Corp., — U.S. -, 103 S.Ct. 2469, 2471, 76 L.Ed.2d 667 (1983), establish that anti-union animus need not be the sole motivation behind a discriminatory practice — or at least a discriminatory discharge — in order to find a violation of section 8(a)(3). Thus, without deciding on the precise standard to be applied in mixed motive cases, it is clearly non-frivolous to maintain that anti-union animus need not be the sole motive for an employment decision in order for that decision to constitute an unfair labor practice.
3. No But-for Causation
As noted above, the district court also rested its finding of no reasonable cause on the conclusion that, because of what it regarded as the Suburban employees’ steadfast refusal to accept employment at the Shortway wage rates, any improper behavior by Shortway was not a but-for cause of the alleged harm. While we acknowledge that a finding of no but-for causation might render insubstantial any legal theory advanced by a regional director, the evidence needed to support such a finding was absent here. In support of its finding, the district court cited “particularly revealing” testimony of Mr. Keplar, president of the ATU, that he would not work at the “Shortway rate.”20
The testimony relied upon by the district court is an insufficient grounding for its decision. To begin with, Mr. Keplar’s individual antipathy toward working at what turned out to be the Shortway wage should not be taken as disposing of the issue of whether other ATU employees would be willing to work at the reduced wage rate offered by Shortway. More importantly, the district court’s analysis constitutes legal error, because it does not account for the effect of the alleged unfair labor practice in setting the wage rate that the Suburban drivers found unacceptable. If Shortway had not refused to hire the Suburban drivers, under the Burns doctrine the ATU might have been installed as the bargaining representative of the Shortway employees. The ATU might well have been able to extract a higher wage rate from Shortway than was pressed for by the Teamsters. Accordingly, it constituted legal error to rely on the fact that the Suburban drivers refused to accept the wage rate imposed after Shortway initially refused to hire them as proof that there was no but-for causation between the allegedly discriminatory initial refusal to hire and the ultimate inability of the Suburban drivers to regain their old positions.
To summarize our disposition of the appeal at this point, we have found that the reasons offered by the district court for not finding reasonable cause to believe an unfair labor practice had occurred were legally insufficient. However, several factors prevent this determination from resulting in our vacatur of the district court judgment. First, even under the legal theories we deem substantial here, the district court might find the evidence before it insufficient to demonstrate the applicability of those theories. Second, and very importantly, because the district court dismissed the case at the close of the Regional Director’s evidence, the defendants have not had the opportunity to present evidence related to several affirmative defenses they [1089]*1089intended to offer.21 Third, and also importantly, even if the district court erred in finding no reasonable cause to believe an unfair labor practice had occurred, its judgment could be sustained if it correctly found that no injunctive relief was just or proper.
IV. Just and Proper
A. The Scope of Appellate Review
The parties stake out the following positions concerning the standard of appellate review over the district court’s determination that the injunctive relief sought by the Regional Director was not “just and proper.” The NLRB, which lost below, argues that our review should be plenary: we should reverse if we think the relief it requested was “just and proper.” By contrast, the bus lines argue for a very narrow scope of review: we should reverse only if we determine that the district court abused its discretion.
The positions of both the NLRB and of the bus lines have as an unstated premise the notion that the amorphous phrase “just and proper relief” is one susceptible to definition. The Board’s call for “plenary review” is, of course, a demand that we determine ourselves what relief is just and proper; the bus line’s call for an abuse-of-discretion standard requires us to find some base point of justice and propriety from which to measure the district court’s departure. Despite this implicit reliance, however, neither side has made much of an effort at attempting to define “just and proper” relief, either by reference to substantive criteria or by suggesting processes the district court might undertake in its effort to achieve such relief.
The parties are not to be faulted, however, for this logical lacuna. As we shall now show, the circuit court jurisprudence has not been terribly helpful in giving content to the phrase “just and proper” as a method of cabining the otherwise unfettered discretion of the district court to fashion labor law under section 10(j) wholly according to its own notions of fairness and efficiency.
The cases cited by the Regional Director as supporting plenary review over the just and proper determination by the district court, Brown v. Pacific Telephone & Telegraph Co., 218 F.2d 542 (9th Cir.1954) and Local 83, Construction Drivers Union v. Jenkins, 308 F.2d 516, 517 n. 1 (9th Cir.1962) are neither controlling in this circuit nor unambiguous in their holdings. It is hardly clear whether the Brown court, in reversing the district court’s determination to deny 10(j) relief, held that an appellate court had plenary review over the district court’s just and proper determination and found the district court to be in error, or whether the Ninth Circuit applied the abuse of discretion standard contended for by the employers in that case and found the denial of section 10(j) relief by the district court to be an abuse of that discretion.22 It is also possible that, in the early days of section 10(j) law, the courts simply did not focus on whether a separate stan[1090]*1090dard of appellate review should exist over the just and proper determination. Local 83 is, if anything, less helpful to the NLRB.23 While it is true that in dictum and in a footnote the Ninth Circuit said that it would not apply the “clearly erroneous” standard when reviewing denials of section 10(0 relief, it appears that the Ninth Circuit was explicitly referring to the reasonable cause determination and not to the just and proper determination. See supra note 23.
On the other hand, there are appellate cases that might be construed as creating an “abuse of discretion” standard over the just and proper determination, and yet these cases are careful not to equate the range of permissible discretion in section 10(j) cases, in which the district court is acting in some sense as a reviewing court, with that normally available to the district court.24 See, e.g., Eisenberg v. Wellington Nursing Home, 651 F.2d 902 (3d Cir.1981). As one member of this panel has sagely recognized, “[kjnowing simply that one is invested with discretion does not tell much. The crucial inquiry, necessarily, is the extent of the discretionary power conferred.” R. Aldisert, The Judicial Process 742 (1976). In Wellington Hall Nursing Home, Judge Gibbons, writing for this Court stated that it was “an abuse of the discretion that section 10(j) affords" for the district court to deny a reinstatement remedy. 651 F.2d at 907. Presumably because the district court’s error was sufficiently egregious to make resolution of the issue unnecessary, that panel did not decide just how much discretion section 10(j) afforded the district court.
We do not believe we could pretend to legitimacy, or, concomitantly, that there would be much to be gained were we to attempt to give concrete character to the phrase “just and proper” by a process of reasoned elaboration relying on dictionary definition or other tools of literalism. Rather, as in Hecht v. Bowles, 321 U.S. 321, 64 S.Ct. 587, 88 L.Ed. 754 (1944), this is an instance where courts do better not so much to focus upon the particular words of the governing statute, but upon the general communication the law-making bodies were attempting to send to the courts and the public in passing the relevant act. The process to be undertaken, be it on the district or appellate levels, is much like determining the meaning of an unknown (and even unknowable) phrase from context and on the basis of shared understandings. See generally R. Dickerson, The Interpretation and Application of Statutes 103-36 (1975). This process is not determinate enough to allow an appellate tribunal to reverse a district court merely because, as a matter of first impression, it would have found differently. It does allow the appellate court, however, at least to ensure that the district court is speaking the same language as those passing the statute. The appellate court can and should ensure that, in the words of Hecht v. Bowles, the district court has focused upon “the large objectives of the Act.”
We now sketch out the primary understanding that should animate the district court in the exercise of its discretion over [1091]*1091just and proper relief in section 10(j) cases. The district court should cognize that section 10(j) was designed to enable the Labor Board to vindicate its ultimate remedial power by affording limited interim relief in instances where the passage of time reasonably necessary to adjudicate the case on its merits convinced both the Board and the federal courts that the failure to grant such relief might dissipate the effective exercise of such power.25 By the same token, the relief to be granted is only that reasonably necessary to preserve the ultimate remedial power of the Board and is not to be a substitute for the exercise of that power.26
In order to ensure meaningful appellate review over exercises of discretion guided by the above principles, the district court in making its judgment regarding the justice and propriety of 10(j) interim relief should substantially relate its understanding of this broad principle of section 10(j) law to the result it reaches in the particular ease. The discussion need not be- elaborate nor should appellate tribunals insist on formalistic incantation of the principles we sketch out today. Rather, in reaching its conclusion, the district court should discuss and determine whether the failure to grant interim injunctive relief would be likely to prevent the Board, acting with reasonable expedition,27 from effectively exercising its [1092]*1092ultímate remedial powers. The reviewing court, in applying the “abuse of discretion” standard set out in Wellington Nursing Home, should not disturb factual findings made for this purpose unless clearly erroneous. And it should not reverse the decision of the district court reached thereby (i.e., whether interim injunctive relief appears warranted) unless the undisturbed factual findings do not substantially relate to the conclusion reached.
B. Applying the Scope of Review
Although not as precise on the subject it would have been if it had had the benefit of our opinion, the district court in this case has essentially satisfied our concerns. It obviously understood the importance of preserving the ultimate remedial powers of the NLRB as well as the importance of not allowing section 10(j) to become the normal method for resolving labor disputes.28 The only close question is whether there is a substantial relationship between the facts found and the conclusion reached. For the reasons that follow, we are satisfied on this point as well.
1. Reinstatement
At two points in its bench opinion, the district court offered justifications for its decision not to compel respondents to make offers of reinstatement to the former Suburban employees. At one point, the district court found that, because a final NLRB adjudication (enforced by the court of appeals) would permit reinstatement and appropriate back pay awards to the injured Suburban employees, see Phelps Dodge Corp. v. NLRB, 313 U.S. 177, 61 S.Ct. 845, 85 L.Ed. 1271 (1941), its own failure to grant interim reinstatement relief could not produce irreparable injury. The court further expressed worry that erroneously granted interim relief would irreparably injure those originally hired by Shortway, and Shortway itself.
[1093]*1093If this first justification offered by the district court for its refusal to grant interim reinstatement relief stood completely alone, we would be obliged to reverse under any standard of review. However compelling may be the arguments of the district court for denying reinstatement relief, and however often courts in other jurisdictions may have accepted them, see, e.g., Mack v. Air Express International, 471 F.Supp. 1119, 1125 (N.D.Ga.1979);29 Crain v. Fabsteel Co., 427 F.Supp. 316, 318 (W.D. La.1977),30 after the Wellington Nursing Home decision, they are contrary to the settled law of this circuit. As a panel of this Court explained in Wellington, an exclusive or even predominant focus on the relief to be granted to individual employees is incorrect because it ignores the harm to the bargaining process that may accompany delayed relief. 651 F.2d at 906-07. The basic theory is that denial of interim reinstatement effectively denies employees the fruits of the collective bargaining process that otherwise would have been available to them prior to ultimate reinstatement.
Later in its opinion, however, the district court offers a second justification for denying interim reinstatement. This justification appears to take account of the potential for harm to the collective bargaining process that might otherwise accompany delayed reinstatement of union-supporting employees. The district court wrote, “Given the size and intimacy of A.T.U. Local 1543, we have no reason to think that it could not swiftly and effectively reconstruct itself should the Board uphold its charge.” In effect, the district court carved out a “small and intimate” exception to the Wellington Nursing Home doctrine. Since no one can seriously contend that the district court clearly erred in its finding that the union local was small and intimate, the only question left for us is whether it was within the permissible discretion of the district court to carve out such an exception from the Wellington Nursing Home rule, that is, whether this finding substantially related to the conclusion that interim relief was not needed in the case to vindicate the ultimate remedial power of the Board.
The Regional Director argues forcefully that we should not acquiesce in the district court’s theory concerning interim reinstatement relief. It notes that given high unemployment, particularly in Western Pennsylvania, “many of the idled Suburban employees, faced with the need to secure employment, will decide to ‘vote with their feet’ and find jobs in other areas, which jobs they may be reluctant to given up in order to return to work for Suburban or Shortway.” (Pet.Br. at 39-40). “As a result,” the argument continues, “when the Board finally orders reinstatement and bargaining with the Union ‘the base of Union support would be scattered to the four winds’ and any bargaining would be on a radically different footing than that [which would be conducted were interim reinstatement ordered].” (Pet.Br. at 40, quoting Wilson v. Liberty Homes, Inc., 108 LRRM at 2708).31
[1094]*1094The problem with the Regional Director’s argument is that it lacks support in the record. There was no expert testimony or documentary evidence put forth — or at least none cited to us — showing the proclivity of employees to scatter to the four winds.32
While we would be more comfortable with the district court’s conclusion if it had more empirical evidence to support its thesis that a small and intimate union would be.better able than the average union to reform itself after the NLRB ultimately awarded reinstatement, in the absence of contrary evidence and given the seeming reasonableness of the conclusion and the district court’s superior vantage point, we cannot say that the district court’s predictive factual finding was clearly erroneous or that it was not a substantial basis for its conclusion. Nor can we say that the district court abused its discretion in finding these factors sufficient to rebut the presumption created by Wellington Nursing Home that ultimate reinstatement is unlikely adequately to vindicate the remedial powers of the Board. Accordingly, the district court did not abuse its discretion in denying section 10(j) relief.33
2. Other Relief
Our holding that the district court was within its discretion in denying interim reinstatement to the employees of Suburban disposes of several other contentions raised by the Board. Where the district court legitimately refuses to order the successor company to hire the employees of its predecessor, it makes absolutely no sense to order the successor to bargain with the representative of the unhired employees of the predecessor.34 It makes even less sense under such circumstances to impose the terms of the contract between Suburban and the ATU on the current employer (Shortway) and the bargaining representative of its employees, the Teamsters. Finally, given that the district court did not abuse its discretion in denying interim relief against the successor company, Short-way, we have no occasion here to decide whether, if Shortway was liable, Suburban would be liable on grounds that it engaged in a “joint venture” with Shortway. Cf. Alkire v. NLRB, 716 F.2d 1014 (4th Cir. 1983) (analyzing similar issue on an alter ego theory).
V. Conclusion
This case is a difficult and close one. Restricting our attention solely to the record before us and not supplementing our views with the record that has subsequently been developed in administrative proceedings, we believe the district court erred in failing to find reasonable cause to believe that an unfair labor practice had been committed. However, we cannot say [1095]*1095the district court impermissibly erred, in the absence of any contrary factual showing, in holding that, because this small and intimate union could easily reconstitute itself upon a grant of relief by the NLRB, interim reinstatement relief under section 10® of the NLRA was not just and proper. Accordingly, the judgment of the district court will be affirmed.