PETERS, C.J.

The dispositive issue in this appeal is the scope of a trial court's authority to enjoin action taken by a civil service commission to comply with an antidiscrimination order issued by a federal court. In 1983, the civil service commission of the city of Bridgeport, after holding a promotion examination, established a list of officers to fill vacancies in the position of sergeant. The list was limited to the names of those officers who had been eligible for promotion prior to October 31, 1976, except that it contained as well the names of four minority officers who were allowed to compete for promotion by a federal court order even though they had not been eligible for promotion prior to October 31, 1976. After the commission's announcement of the composition of the list, the plaintiffs, police officers who had become eligible for promotion after October 31, 1976, brought suit in the Superior Court, claiming that the presence of the four minority officers on the list constituted reverse discrimination. The trial court agreed and ordered that the commission include on the promotion list officers who had not been eligible for promotion prior to October 31, 1976. The intervening defendants, police officers who had been eligible for promotion to sergeant prior to October 31, 1976, appeal from this judgment. We find error.

This controversy requires us to find an accommodation between state law governing civil service promotions in Bridgeport and federal court rulings arising out of protracted civil rights litigation involving the employment practices of the Bridgeport police department. There is no factual controversy about the source of this conflict between state and federal law.

Under state law, pursuant to an amendment enacted by the state legislature in a special act in 1935, the charter of the city of Bridgeport creates a civil service system providing mandatory procedures for promotions of police department officers to the position of sergeant. 22 Spec. Acts 261, No. 407; Walker v. Jankura, 162 Conn. 482, 489-90, 294 A.2d 536 (1972). Section 9 of the civil service provisions of Bridgeport's charter, obligates the civil service commission to give periodic promotion examinations for candidates for police sergeancy. To qualify to take an examination, candidates must meet eligibility requirements for the position of sergeant when the examination is held. The commission grades the examinations and creates a promotion list by ranking candidates in the order of their scores on the examination. Those who achieve scores above a designated minimum will be called, in order of rank, to fill police department vacancies in the position of sergeant as they arise; those who fall below the minimum level receive no further consideration for promotion. Under 9, the department must continue to use the promotion list for two years or until no eligible candidates remain on the list. When a promotion list expires, the commission must hold a new examination within 120 days after the next vacancy arises.

In 1972, black and hispanic Bridgeport police officers, as well as unsuccessful applicants to the department, instituted a federal court class action challenging the constitutionality of the hiring and promoting practices of the Bridgeport police department. The United States District Court, Newman, J., found that the department had been engaging in racial discrimination and ordered a number of remedial measures including the observance of temporary quotas for hiring and promoting blacks and hispanics. Bridgeport Guardians, Inc. v. Members of the Bridgeport Civil Service Commission, 354 F. Sup. 778 (D. Conn. 1973) (Guardians I). On appeal, the Court of Appeals for the Second Circuit upheld the district court's order as it applied to the hiring and recruitment of new officers. Bridgeport Guardians, Inc. v. Members of the Bridgeport Civil Service Commission, 482 F.2d 1333 (2d Cir. 1973) (Guardians II). It held, however, that the District Court erred in imposing quotas for promotion and that any court-ordered remedial alterations of promotion procedures should apply "irrespective of race or ethnic background." Id., 1341. On remand, the District Court, in an attempt to ameliorate institutional impediments to the promotion of the minority group members who had been hired under its original order, directed the department to reduce the eligibility requirements for promotion to sergeant and to deviate from 9 in determining when to hold a new promotion examination for the office of sergeant. Bridgeport Guardians, Inc. v. Members of the Bridgeport Civil Service Commission, 8 Employment Practices Decisions, par. 9508, p. 5274 (D. Conn. 1974) (Guardians III). The Court of Appeals for the Second Circuit affirmed the revised order. Bridgeport Guardians, Inc. v. Members of the Bridgeport Civil Service Commission, 497 F.2d 1113 (2d Cir. 1974) (Guardians IV), cert. denied, 421 U.S. 991, 95 S.Ct. 1997, 44 L.Ed.2d 481 (1975).

In 1976, the sergeant promotion list that had been in force during Guardians III expired. The first vacancy after its expiration occurred on July 2, 1976. Thus, the 120 day provision of 9 required the commission to hold a new examination by October 31, 1976. Claiming a shortage of funds, however, the commission did not hold the examination within the 120 day period. Indeed, it scheduled no examination for more than three years. On November 21, 1979, the commission announced that it would hold a promotion examination for the position of sergeant on January 26, 1980. The announcement stated that only those officers who had been eligible for promotion prior to October 31, 1976, would be allowed to take the examination. This limitation prompted the minority officers who had been hired pursuant to the Guardians I order, but who had been otherwise ineligible for promotion prior to October 31, 1976, to move that the Guardians District Court clarify the order concerning promotions that it had issued in Guardians III The Guardians court, Newman, J., sitting by designation, granted their motion and ordered that the commission allow minority group members to take the examination and to compete for promotions even if they had not been eligible prior to October 31, 1976, provided that, on the date the commission announced the examination, the officers had served the department for at least one year and met other eligibility requirements. Judge Newman's clarification rendered each of the moving officers eligible to take the examination.

Before the commission could hold the announced examination, several officers filed suit in federal court challenging the examination's validity as a job-related selection device and obtained an injunction that forced the commission to cancel the examination. See Members of the Bridgeport Housing Authority Police v. Bridgeport, 85 F.R.D. 624 (D. Conn. 1980). In May, 1983, after the parties to Bridgeport Housing Authority Police had agreed upon an examination format, the commission announced that it would hold a sergeant promotion examination in June, 1983, and that any officer who had been eligible for promotion to the rank of sergeant on January 26, 1980, would be eligible to take the examination. A number of officers who had been eligible for promotion prior to October 31, 1976, immediately filed appeals with the commission demanding that the commission set October 31, 1976, rather than January 26, 1980, as the date of eligibility. The commission denied these appeals, held the examination, and created a new promotion list for the position of sergeant in accordance with its announcement. Upon further protest by the senior officers, however, the commission on November 28, 1983, reconsidered its position and announced that only those officers who had been eligible for promotion on October 31, 1976, and those officers covered by Judge Newman's clarification order would be allowed to compete for vacant sergeant positions. The commission disqualified all other officers from the promotion list.

The officers who had taken the examination and had been disqualified by the commission sought relief in federal court by moving to intervene in the Guardians litigation. The District Court in that case, Daly, J., denied their motion on December 13, 1983. They did not appeal the denial of their motion. Instead, on December 15, 1983, they filed the present suit in Connecticut Superior Court, seeking to enjoin the commission from deleting their names from the promotion list. The intervening defendants, candidates whose names remained on the promotion list, successfully moved to intervene in the case.

After a full hearing, the trial court ruled in favor of the plaintiffs. The court enjoined the commission from eliminating the plaintiffs from the promotion list, ordered their promotion on the same basis as all other participants, and prohibited the commission from using race as a criterion for promotion. The court held that the commission had engaged in illegal discrimination by holding the plaintiffs, but not the minority group members, to the requirement of eligibility for promotion on October 31, 1976. The court acknowledged that Judge Newman's clarification order purported to extend only to "[m]inority group members hired pursuant to [Guardians I] . . . ." It concluded nonetheless that it should interpret Judge Newman's order in light of the requirement enunciated by the Second Circuit in Guardians II "that there be no discrimination as to eligibility which would result in a promotional preference for minority policemen." Adopting this view, the trial court construed Judge Newman's clarification as an order making all police officers, regardless of their race, eligible for the examination and promotion if they had in-grade service of one year as of the date that the examination was announced. Finding the announcement date of the 1983 examination to be May 2, 1983, it ordered the commission to include the names of the plaintiffs on the promotion list.

On appeal, the intervening defendants claim that the trial court erroneously (1) construed Judge Newman's clarifying order, (2) concluded that the commission had engaged in illegal discrimination, and (3) issued an injunction when money damages would have sufficed to remedy any harm suffered by the plaintiffs. In light of our disposition of this case, we need not specifically address the latter two issues.

Our threshold inquiry concerns the propriety of the trial court's decision to construe, and to enforce its construction of, a federal court order. By including on the promotion list certain minority group members who had not been otherwise eligible for promotion on October 31, 1976, the civil service commission was attempting to comply with a federal court order. The plaintiffs' challenge to the legality of the commission's special treatment of the minority group members constituted, in effect, a collateral attack on the federal court order. The trial court provided a receptive forum for such an attack. In rejecting a literal interpretation of Judge Newman's clarifying order and instead recasting the order to comport with its own interpretation of Guardians II, the trial court in effect modified Judge Newman's clarifying order.

Collateral attacks on judgments of courts of coordinate jurisdiction are disfavored in this state. See Department of Health Services v. CHRO, 198 Conn. 479, 487-89, 503 A.2d 1151 (1986); Cologne v. Westfarms Associates, 197 Conn. 141, 147, 496 A.2d 476 (1985). In the interests of finality and judicial economy, challenges to a court order should be brought to the court that issued the order or to an appellate court of proper jurisdiction. Because of its familiarity with the facts of the case and the reasons underlying its decision, the court from which an order emanates occupies a preferred position for clarification of the meaning of its language and for adaptation of its order to changed circumstances. See United States v. Fluor Corporation, 436 F.2d 383 (2d Cir. 1970), cert. denied, 402 U.S. 945, 91 S.Ct. 1623, 29 L.Ed.2d 114 (1971); Lapin v. Shulton, Inc., 333 F.2d 169 (9th Cir.), cert. denied, 379 U.S. 904, 85 S.Ct. 193, 13 L.Ed.2d 177 (1964); Coleman v. Patterson, 57 F.R.D. 146, 148-49 (S.D.N.Y. 1972); James Blackstone Memorial Assn. v. Gulf Mobil Ohio R. Co., 28 F.R.D. 385 (D. Conn. 1961). Principles of comity urge upon state courts the exercise of restraint before they venture into modification and reconstruction of facially valid federal court orders. Only in narrowly defined circumstances are state courts authorized to enjoin parties from pursuing federal court relief and from obeying federal court orders. See Donovan v. Dallas, 377 U.S. 408, 84 S.Ct. 1579, 12 L.Ed.2d 409 (1964); Central National Bank of Boston v. Stevens, 169 U.S. 432, 18 S.Ct. 403, 42 L.Ed. 807 (1898); see also Deposit Bank v. Frankfort, 191 U.S. 499, 512, 24 S.Ct. 154, 48 L.Ed. 276 (1903); Aristocrat Health Club of Hartford, Inc. v. Chaucer, 451 F. Sup. 210, 214, 218 (D. Conn. 1978). We therefore hold that, except in the most compelling circumstances, the courts of this state should decline to afford litigants the opportunity to launch collateral attacks on orders issued by federal courts and should refuse to grant relief that would entail interfering with the execution of such orders. See Jamaica Hospital v. Blum, 68 App. Div.2d 1, 416 N.Y.S.2d 294 (1979); Banco Do Brasil v. Madison Steamship Corporation, 61 Misc.2d 1028, 1030-32, 307 N.Y.S.2d 341 (N.Y.Sup.Ct. 1970); Wolgin v. State Mutual Investors, 265 Pa. Super. 525, 532-34, 402 A.2d 669 (1979); see also Reserve Mining Co. v. Minnesota Pollution Control Agency, 267 N.W.2d 720, 725 (Minn. 1978).

In this case, if the plaintiffs wished to question the meaning of Judge Newman's clarifying order, the propriety of the civil service commission's compliance with the order, the applicability of the order to new circumstances, or the legality of the order itself, the appropriate forum for their pursuit of these complaints was the Federal District Court that continued to retain jurisdiction over the Guardians litigation. See Guardians I, supra, 800. That forum was not definitively foreclosed to them by the District Court's denial of their motion to intervene in that litigation, since they elected not to appeal that denial to the Court of Appeals for the Second Circuit. Where a federal court that has issued an order denies a prospective intervenor's motion to enter the case to challenge the validity or application of that order, we will not allow the unsuccessful intervenor to mount such a challenge in our courts. See Gregory v. County of LaSalle, 40 Ill.2d 417, 422, 240 N.E.2d 609 (1968).

The trial court was therefore in error in its conclusion that the plaintiffs had been denied their constitutional rights to equal protection by the commission's decision to comply with Judge Newman's order in determining the class of officers eligible to take the promotion examination. As an alternate basis for upholding the trial court's judgment, the plaintiffs urge us to hold that the commission acted arbitrarily and capriciously in its selection of an eligibility date and in its belated reversal of its ruling on eligibility standards. This argument is not premised on racial discrimination, but evidences instead a dispute between senior and junior members of the Bridgeport police department. We find nothing in the record to support the plaintiff's characterization of the commission's actions.

The commission's decision to exclude officers who had not been eligible for promotion prior to October 31, 1976, represented an attempt by the commission to satisfy Judge Newman's clarification order in light of the requirements of Bridgeport civil service law. Had the examination been held in 1976 as required by law, the eligibility date would have been October 31, 1976. Had the examination been held in 1980 as contemplated by Judge Newman's clarification order, the eligibility date would have been October 31, 1976. Thus, in setting October 31, 1976, as the date of eligibility for the 1983 examination, the commission could reasonably have been trying to recreate the circumstances that had prevailed at the times that the examination should have been held.

Similarly, the commission did not act improperly in reestablishing the 1976 eligibility date after it had already held the test and announced the results using an eligibility date of January 26, 1980. The record indicates that the commission originally chose the 1980 eligibility date because it assumed that Judge Newman's clarification order so required. After considering the matter further, the commission apparently determined that Judge Newman's order and pertinent civil service statutes required that it establish October 31, 1976, as the date of eligibility.

The plaintiffs claim that civil service commissions may not alter eligibility rules for a promotion examination after the commission knows the results of the examination. The cases cited by the plaintiff in support of this proposition deal with alterations instituted by civil service commissions that were discretionary in nature. See Local 773 v. Bristol, 39 Conn. Sup. 1, 6-8, 463 A.2d 628 (1983); People ex rel. Gaynor v. Board of Fire Commissioners, 14 Ill. App.2d 329, 144 N.E.2d 763 (1957). In this case, where the commission was attempting to amend its previous decision to comport with its interpretation of a mandatory court order, its selection of a new eligibility date after the examination had taken place was permissible. See People ex rel. Gaynor v. Board of Fire Commissioners, supra, 336 (distinguishing between the commission's attempt to correct a misinterpretation of law or fact and its attempt to implement new policy); State ex rel. Dunn v. Elliott, 6 Wash.2d 426, 432-34, 107 P.2d 915 (1940). The plaintiffs presented no evidence at trial indicating that bad faith motivated the commission's alteration of the eligibility date. They do not contend that they relied to their detriment upon the commission's establishment of the original eligibility date. In light of these circumstances, we cannot conclude that the commission acted arbitrarily and capriciously in changing the eligibility date to October 31, 1976.

Because the trial court's injunction interfered with the civil service commission's attempted compliance with Judge Newman's clarifying order, we vacate the trial court's order. The commission may proceed with its efforts to satisfy the federal decree. Any further attempts by the plaintiffs to challenge the commission's implementation of the order must be made in the proper forum.