This action was instituted by the Equal Employment Opportunity Commission (EEOC) pursuant to § 706 of Title VII of the Civil Rights Act of 1964, 42 U.S.C. §§ 2000e-5(f), (g), alleging unfair employment practices by Safeway Stores, Inc. After the filing of initial pleadings, EEOC, Safeway and the various labor unions made up of Safeway employees joined as defendants pursuant to Fed.R.Civ.P. 19(a)(2) entered into a lengthy consent decree. Among other things, the decree provided for a change in the calculation of seniority upon transfer from one Safeway labor unit to another: “[Wjhen a vacancy occurs, an employee may transfer laterally to another job classification . . . for which he or she is qualified or qualifiable without loss of seniority. Selection of applicants for transfer shall be based upon seniority with the Company.” Record, vol. 1, at 28, ¶ VIII. C. “Seniority” is defined in the decree as “the length of continuous employment with the Company computed from the date the employee first reports for work” in any Safeway labor unit (company seniority). Record, vol. 1, at 17, ¶ I-C-6. In contrast, the various collective bargaining agreements with Safeway provided that seniority would be measured by the length of an employee’s service “within the bargaining unit” (unit seniority). Supplemental Record at 31. Therefore, the decree modified the existing seniority system to allow transfers between job classifications, and therefore between bargaining units, without the loss of seniority accrued since the original date of hire with Safeway.

Safeway initially construed the consent decree to grant company seniority to all of its employees. One of the involved unions, Delivery Drivers, Warehousemen and Helpers, Local Union No. 435, petitioned the district court to enjoin Safeway from acting on this interpretation, and Safeway requested clarification of the decree regarding the seniority provisions. In response, the district court entered an “Order Interpreting the Consent Decree and Granting Injunctive Relief.” In pertinent part, that order determined: “The Decree mandates that the seniority of all employees who have transferred from one job . . .to another since the effective date of the Decree is to be computed for all purposes . on a company-wide basis.” Record, vol. 1, at 171 (emphasis added).

Shortly after the entry of this order, 17 individual members of Local 435 were allowed to intervene in the suit. The interve*798nors had transferred from another Safeway job into Local 435 prior to the date of the consent decree and, under the court’s interpretation of the decree, they would not be credited with company seniority. Accordingly, their seniority status was adversely affected by the enhanced seniority of post-decree transferees, many of whom had no more claim to Title VII protection than intervenors.1 In a motion for modification, intervenors insisted that either all employees be accorded company seniority or that only minority members retain seniority advantages upon transfer.2

In denying the intervenors’ motion, the district court indicated that it would be willing to modify the decree only upon a strong showing:

(1) that the goals of the Decree would be substantially furthered by such a modification, or (2) that the harm to [the intervenors] outweighs (a) the benefits to minority employees from prospective application of the transfer provisions of the Decree, and (b) any harm that may result from retroactive application of these provisions.

Record, vol. 1, at 181. In addition, the court ordered the parties to meet in an attempt to agree on a modification. When the parties failed to agree or to convince the court of a compelling need for modification, intervenors’ further motion for modification was denied, forming the basis of this appeal.

While this appeal was pending, all parties stipulated to certain amendments of the original consent decree. Pursuant to this stipulation, the right to retain company seniority upon transfer terminated on July 1, 1978, approximately a year and a half after the entry of the decree. Those who transferred after the date of the decree but before this amendment became effective retained company seniority.

I.

We consider preliminarily whether the district court erred in interpreting the language of the consent decree to afford company seniority only to post-decree transferees. It is clear that the enforcing court has power to interpret a decree when its language results in confusion. See Pasadena City Board of Education v. Spangler, 427 U.S. 424, 438, 96 S.Ct. 2697, 49 L.Ed.2d 599 (1976). Ridley v. Phillips Petroleum Co., 427 F.2d 19 (10th Cir. 1970), demonstrates the breadth of a court’s discretion in constructing decrees. We held there that a court should adopt an interpretation which renders the judgment “more reasonable, effective, and conclusive.” Id. at 23 (quoting Pen-Ken Gas & Oil Corp. v. Warfield Natural Gas Co., 137 F.2d 871 (6th Cir. 1943), cert. denied, 320 U.S. 800, 64 S.Ct. 431, 88 L.Ed. 483 (1944)).

The district court’s interpretation of the seniority provisions of this consent decree was reasonable in light of the language and purpose of the decree.3 The interpretation thus becomes pari materia with the decree for purposes of this opinion.

II.

There are two channels through which a consent decree may later be modified.*7994 Rule 60(b) allows for relief from a final judgment, order or proceeding upon a showing that “the judgment is void,” that “it is no longer equitable that the judgment should have prospective application,” or for “any other reason justifying relief.” Fed. R. Civ.P. 60(b)(4), (5), (6). In addition, a court of equity has continuing jurisdiction to modify a decree upon changed circumstances, even if the decree was entered by consent. United States v. Swift & Co., 286 U.S. 106, 52 S.Ct. 460, 76 L.Ed. 999 (1932). However, a court’s power to modify is not to be lightly exercised to change the settled terms of a consent decree. An appellate court must be particularly reluctant to alter a decree because the entering court has broad discretion in the administration of such decrees. See Franks v. Bowman Transportation Co., 424 U.S. 747, 763-64, 96 S. Ct. 1251, 47 L.Ed.2d 444 (1976); EEOC v. American Telephone & Telegraph Co., 556 F.2d 167,178 (3d Cir. 1977), cert. denied, 438 U.S. 915, 98 S.Ct. 3145, 57 L.Ed.2d 1161 (1978); United States v. Allegheny-Ludlum Industries, Inc., 517 F.2d 826, 850 (5th Cir. 1975), cert. denied, 425 U.S. 944, 96 S.Ct. 1684, 48 L.Ed.2d 187 (1976); West Virginia v. Chas. Pfizer & Co., 440 F.2d 1079, 1085-86 (2d Cir.), cert. denied, 404 U.S. 871, 92 S.Ct. 81, 30 L.Ed.2d 115 (1971). A trial court’s ruling on a Rule 60(b) motion will not be disturbed by this court absent an abuse of discretion. Winfield Associates, Inc. v. Stonecipher, 429 F.2d 1087, 1090 (10th Cir. 1970).

Intervenors’ first objection to the decree is that a grant of enhanced seniority rights to all post-decree transferees rather than to all employees or to minority transferees only does not fulfill any legitimate purpose of Title VII. We agree that the purpose of Title VII is to secure relief to members of a class — those who may be subject to employment discrimination “on the basis of race, color, religion, sex, or national origin.” 5 42 U.S.C. § 2000e-2. But to argue that the terms of a consent decree may not vary from the statutory limits of Title VII6 is to misconceive the nature of consent decrees and to ignore the strong policy embodied in Title VII in favor of voluntary settlements.7 See Alexander v. Gardner-Denver Co., 415 U.S. 36, 44, 94 S.Ct. 1011, 39 L.Ed.2d 147 (1974); United States v. Allegheny-Ludlum Industries, Inc., 517 F.2d 826 (5th Cir. 1975), cert. denied, 425 U.S. 944, 96 S.Ct. 1684, 48 L.Ed.2d 187 (1976). Of course, the statute may provide the broad outlines of the objectives to be reached and the mechanisms to be used. This court would not countenance governmental coercion in directions wholly outside the purview of congressional pronouncement under the aegis of consent decree negotiations.

It is not the purpose of Rule 60(b) or the inherent powers of chancery to allow the modification of a consent decree merely because it reaches a result which could not *800have been forced on the parties through litigation. For example, in V. T. A., Inc. v. Airco, Inc., 597 F.2d 220 (10th Cir. 1979), this court upheld a consent decree against a Rule 60(b)(4) attack. The appellant claimed that the relief afforded by the consent decree was in violation of federal patent law and was therefore void. This court responded that “[e]ven if the parties’ consent decree does technically run afoul of federal patent law principles, the problem would be one Of relief from an erroneous judgment, not a void one.” Id. at 226. We held that Rule 60(b)(4) “is not available to correct mere legal error.” Id. See also Mayberry v. Maroney, 558 F.2d 1159, 1164 (3d Cir. 1977). In United States v. Swift & Co., 286 U.S. 106, 52 S.Ct. 460, 76 L.Ed. 999 (1932), the Supreme Court held that an “injunction, whether right or wrong, is not subject to impeachment in its application to the conditions that existed at its making.” Id. at 119, 52 S.Ct. at 464. The fact that a consent decree exceeds the law by prohibiting lawful conduct, Swift & Co. v. United States, 276 U.S. 311, 328-31, 48 S.Ct. 311, 72 L.Ed. 587 (1928), or by granting an unauthorized remedy, Walling v. Miller, 138 F.2d 629 (8th Cir. 1943), cert. denied, 321 U.S. 784, 64 S.Ct. 781, 88 L.Ed. 1076 (1944), does not render it void. Such efforts may be grounds for reversal on appeal of the judgment, but they are not grounds for collateral attack.

Although a consent decree will not be vacated merely because it is legally erroneous, it may be altered upon a showing of changed circumstances which have produced “hardship so extreme and unexpected” as to make the decree oppressive. United States v. Swift & Co., 286 U.S. 106, 119, 52 S.Ct. 460, 76 L.Ed. 999 (1932); S. E. C. v. Jan-Dal Oil & Gas, Inc., 433 F.2d 304, 305 (10th Cir. 1970); Ridley v. Phillips Petroleum Co., 427 F.2d 19, 22 (10th Cir. 1970). We find no abuse of discretion in the district court’s determination that this decree was not rendered inequitable by changed circumstances. There is no evidence indicating that the facts — e. g., the nature and makeup of Safeway employees and operations — against which the decree and the interpreting order were framed have substantially changed.

III.

Intervenors assert an additional ground for impeaching the consent decree. They argue that International Brotherhood of Teamsters v. United States, 431 U.S. 324, 97 S.Ct. 1843, 52 L.Ed.2d 396 (1977), decided after the decree and interpretive order were entered, compels modification. In interpreting § 703(h) of Title VII, the Supreme Court in Teamsters held that “an otherwise neutral, legitimate seniority system does not become unlawful under Title VII simply because it may perpetuate preAct discrimination.” Id. at 353-54, 97 S.Ct. at 1864. We are not obliged to decide for this appeal what impact Teamsters would have on a consent decree reached after Teamsters was decided or on the outcome of subsequent litigation between these parties. We decide only that Teamsters does not require retroactive alteration of the consent decree in this case.

A similar situation was presented in Collins v. City of Wichita, 254 F.2d 837 (10th Cir. 1958). After the original judgment in Collins became final, the Supreme Court reviewed, in another case, the statute upon which the judgment was based and found it unconstitutional. In denying a Rule 60(b) motion based on the subsequent Supreme Court decision, this court held, “A change in the law or in the judicial view of an established rule of law” is not an extraordinary circumstance justifying relief. Id. at 839. The Third' Circuit- confronted a similar change in the case law on a Rule 60(b) motion in Mayberry v. Maroney, 558 F.2d 1159 (3d Cir. 1977). It concluded that the power to alter decrees “does not contemplate relief based merely on precedential evolution.” Id. at 1164. See also Chicot County Drainage District v. Baxter State Bank, 308 U.S. 371, 60 S.Ct. 317, 84 L.Ed. 329 (1940).

There are some situations where a change in the law warrants modification of an injunctive decree. For instance, in System *801Federation No. 91 v. Wright, 364 U.S. 642, 81 S.Ct. 368, 5 L.Ed.2d 349 (1961), the Supreme Court balanced the policies of finality and flexibility and determined that an amendment of the statute underlying an earlier decree made prospective enforcement of the decree inequitable. However, it was the prospective injunctive effect of the decree at issue in System Federation. The Court did not purport to erase retroactively the effect of the decree.

Other cases have held that a significant judicial clarification of the law will justify altering the future application of a decree in compelling circumstances. See Pasadena City Board of Education v. Spangler, 427 U.S. 424, 96 S.Ct. 2697, 49 L.Ed.2d 599 (1976); City & County of Denver v. Denver Tramway Corp., 187 F.2d 410, 417 (10th Cir. 1951); Coca-Cola Co. v. Standard Bottling Co., 138 F.2d 788 (10th Cir. 1943). No attempt was made in these cases to undo the effects of past enforcement.8 In contrast, intervenors seek only the unraveling of seniority already assigned to employees who transferred in reliance on the decree. Because the decree has now been amended to delete the transfer provisions, future application of the decree is no longer in issue.

There is one additional reason why Teamsters does not compel our alteration of the seniority provisions of this decree. Teamsters prohibits abrogation of a seniority system only if that system is bona fide.9. Because this case was never litigated, there has been no determination that Safeway’s seniority system is bona fide. Intervenors would have us assume at this point the system was bona fide, or at the least, remand the case for a hearing and determination. This we decline to do. The policy of voluntary settlement so important to the enforcement of Title VII would be seriously undermined if the approving court were required to establish the facts underlying the parties’ positions before approving a consent decree. The power to compromise exists partially because of the uncertainties and expense typical of adversary hearing and judicial determinations of fact. West Virginia v. Chas. Pfizer & Co., 440 F.2d 1079, 1085-86 (2d Cir.), cert. denied, 404 U.S. 871, 92 S.Ct. 81, 30 L.Ed.2d 115 (1971). We concur with the district court, “A Consent Decree would be worthless if it could be attacked on the ground that had the Court made a particular determination, such relief would then not be statutorily available.” Record, vol. 2, at 213.

We are unconvinced that the intervenors should obtain the extraordinary relief they request. The district court did not abuse its discretion in administering the decree.

AFFIRMED.