Appellants, neighbors in the Jardines de Arecibo housing development ("JDA") in Arecibo, Puerto Rico ("neighbors"), and the Superior Court of Puerto Rico for the District of Arecibo ("Superior Court"), appeal from an order of the United States District Court for the District of Puerto Rico permanently enjoining enforcement of a final judgment of the Superior Court mandating the immediate closure of Casa Marie, Hogar Geriatrico, Inc. ("Casa Marie"), a live-in, elder-care facility located in the JDA. The Superior Court judgment was based on a determination that Casa Marie was operating in violation of local zoning ordinances and JDA restrictive covenants. Appellees, the owners and operators of Casa Marie, and fourteen of its elderly and handicapped residents, instituted the federal action to enjoin enforcement of the Superior Court judgment. The federal district court ruled that the neighbors' resort to the Commonwealth courts to close Casa Marie violated the federally protected rights of Casa Marie residents under 42 U.S.C. § 1983 ("section 1983") and the Fair Housing Act, 42 U.S.C. § 3604 ("Title VIII" or "FHA").

* BACKGROUND

A. The Opening and Expansion of Casa Marie.

The Jardines de Arecibo housing development was established in 1967. Each property in the development is subject to restrictive covenants allowing only detached single-family residences, prohibiting uses or offensive activities constituting a "nuisance," and requiring prior approval of all construction and alterations. On April 25, 1986, Casa Marie, a live-in facility for elderly handicapped persons, was established by Maria Pla Placencio on a dead-end street in a section of JDA zoned residential (R-3). The R-3 zoning classification allows one and two-family residences, rowhouses, or apartment buildings; elder-care facilities are not allowed except as a variance.

On May 7, 1986, Casa Marie applied to the Department of Social Services ("DSS") for a license to operate an elder-care facility in two single-family residences located on adjacent Lots 19 and 20. The minimum DSS licensure requirements included endorsements from the fire, police, and health departments,1 and a valid variance permit from the Administracion de Reglamentos y Permisos ("A.R.P.E."), the agency authorized to oversee and administer local zoning laws. On May 21, 1986, A.R.P.E. granted Casa Marie a variance permit, and on February 4, 1987, Casa Marie was granted a six-month provisional DSS license to operate an elder-care facility on Lots 19 and 20, pending full compliance with all other licensing requirements. When its provisional DSS license lapsed in August 1987, Casa Marie was denied a permanent DSS license due in part to the discovery that the A.R.P.E. variance permit might be applicable to Lot 19 only. DSS nevertheless allowed Casa Marie to continue to operate under DSS supervision.

During 1987, the Casa Marie owners began to expand operations, incorporating a third single-family residence, on Lot 21, by constructing wheelchair ramps connecting the buildings on Lots 19, 20 and 21.2 The owners did not seek or secure the required A.R.P.E. construction permits for these renovations. On January 21, 1988, several Casa Marie neighbors filed an administrative complaint with A.R.P.E., pursuant to P.R. Laws Ann. tit. 23, §§ 71x, 72 (1987),3 requesting that A.R.P.E. order Casa Marie to cease all construction and that A.R.P.E. institute judicial action to compel Casa Marie to demolish the unauthorized structures.

B. The Superior Court Judgment and Appeal.

On April 18, 1988, while their administrative action was pending before A.R.P.E., the neighbors filed a complaint in the Superior Court against Casa Marie and its owners, alleging violations of the zoning ordinances and the JDA restrictive covenants. The neighbors requested injunctive relief requiring demolition of the inter-building renovations and a cessation of all operations. The A.R.P.E. and Superior Court actions were consolidated in the Superior Court.4

In May 1988, in order to remedy its zoning violations, Casa Marie submitted a proposal to A.R.P.E. whereby Lots 19, 20 and 21 would be "grouped" into one property for zoning purposes.

On July 14, 1988, however, the Superior Court entered judgment against Casa Marie, finding, inter alia, that

(1) Casa Marie violated local zoning laws by its failure to obtain a valid variance permit for Lot 21, and valid construction permits for the renovations on Lots 19, 20 and 21;

(2) Casa Marie was engaged in a "commercial-institutional" use, not a "residential use" as required by the covenants;

(3) Increased levels of traffic and noise in the neighborhood, and the neighbors' fears of "disturbing" the elderly residents, whom they considered "strangers in the neighborhood," had "creat[ed] a dislocation or disorder in the lifestyle of the residential area" which constituted a "nuisance" under the restrictive covenants;

(4) Certain businesses located in JDA's R-3 zone--for example, a medical office and a day-care nursery--also violated the restrictive covenants, but those violations were insufficient to extinguish the covenants under the equitable doctrine of "changed circumstances"; and

(5) Even if A.R.P.E. were to permit a variance for Casa Marie in the future, thereby excusing its past zoning violations, A.R.P.E. was without authority under Puerto Rico law to supersede or excuse Casa Marie's coincident violations of the restrictive covenants.

The Superior Court ordered immediate cessation of the unauthorized operations at Casa Marie, demolition of the unauthorized renovations within four months, and notification of the closure of the elder-care facility to all Casa Marie residents.

Upon notification of the Superior Court judgment, A.R.P.E. suspended action on the Casa Marie "lot grouping" proposal. Without an A.R.P.E. permit, Casa Marie was ineligible for a permanent DSS operating license.

On September 9, 1989, in their appeal of the Superior Court judgment to the Supreme Court of Puerto Rico, the Casa Marie owners alleged, for the first time, that the neighbors had discriminated against Casa Marie's handicapped residents under the Puerto Rico Bill of Rights for Aged Persons. See P.R. Laws Ann. tit. 8, §§ 341-347, 343(b) (1987) ("All aged persons shall be entitled to ... live in a dignified environment that satisfies their basic housing ... needs"; authorizing aged persons to bring a "priority" private cause of action in Commonwealth courts). The Supreme Court of Puerto Rico affirmed the Superior Court judgment in November 1989.5

C. The Enforcement and Contempt Proceedings.

Casa Marie continued to operate. The neighbors requested a hearing to compel compliance with the Superior Court judgment. At the Superior Court hearing on August 15, 1990, the Casa Marie owners unsuccessfully attempted to interpose Title VIII claims, presumably in behalf of the residents. On October 2, 1990, Legal Services Corporation ("Legal Services") filed a motion to intervene in the Superior Court enforcement proceedings in behalf of five Casa Marie residents ("intervenors"). At the same time, Legal Services brought an independent action in behalf of the intervenors, asserting claims under section 3604 of the FHA,6 the Puerto Rico Bill of Rights for Aged Persons, and 42 U.S.C. § 1983. The intervenors' section 1983 claims alleged that the Superior Court had acted in concert with the neighbors to deprive Casa Marie residents of their civil rights under the Constitution and laws of the United States.

On October 9, 1990, the Superior Court issued a civil contempt decree in the neighbors' enforcement proceedings, ordering the arrest and imprisonment of Casa Marie's owners in the event they failed to comply with its final judgment by November 5, 1990.

On October 23, a different Superior Court judge allegedly expressed ("off the record") reluctance to address intervenors' belated initiatives to stave off the contempt proceedings against Casa Marie for refusing to comply with the Superior Court's final judgment mandating closure. Nevertheless, no order was entered disposing of the motion to intervene or the newly filed Superior Court lawsuit.

D. The Federal District Court Action.

Three days later, on October 26, a complaint was filed in the federal district court by Casa Marie, its owners, and nine other residents (hereinafter "nonintervenors"). The complaint alleged that the neighbors and the Superior Court had acted in concert to enforce the zoning ordinances and the JDA restrictive covenants in a discriminatory manner--in violation of the Equal Protection Clause of the United States Constitution, and Title VIII--in order to deprive the elderly handicapped residents of their right to live in an integrated community. The complaint requested injunctive relief, compensatory and punitive damages, and attorney fees.

The district court allowed Legal Services and the five would-be Superior Court intervenors to intervene in the federal court action. After a four-day hearing, the district court determined that the neighbors had violated section 1983 and FHA sections 3604(f) and 3617 by resorting to the courts of the Commonwealth to enforce the relevant zoning ordinances and restrictive covenants as a means of effecting a discriminatory eviction of the elderly handicapped Casa Marie residents from the neighborhood. See Casa Marie v. Superior Court of Puerto Rico for District of Arecibo, 752 F. Supp. 1152, 1167-69 (D.P.R.1990). The district court permanently enjoined the neighbors from executing their Superior Court judgment and the Superior Court contempt decree. The neighbors and the Superior Court appealed.

The neighbors advance three contentions on appeal: first, the district court improperly rejected their affirmative defenses based on res judicata, collateral estoppel and the statute of limitations; second, appellees failed to sustain their burden of proof on the section 1983 and Title VIII claims; and third, under the Anti-Injunction Act and the Younger abstention doctrine, the district court improperly enjoined the pending Superior Court enforcement and contempt proceedings. We need not confront the entire panoply of appellants' arguments, however, as we conclude that (1) appellees' section 1983 claims should have been dismissed, and (2) their Title VIII claims should not have been entertained by the district court since the pending Superior Court proceedings would afford plaintiffs an adequate forum.

A. The Section 1983 Claims.

The neighbors contend on appeal that the residents failed to establish an essential element of their section 1983 claims; namely that the neighbors acted "under color of state law" by resorting to the Commonwealth courts to enforce the restrictive covenants against Casa Marie. Relying on Shelley v. Kraemer, 334 U.S. 1, 68 S. Ct. 836, 92 L. Ed. 1161 (1948), the district court concluded that the neighbors' resort to the Commonwealth judicial system to enforce the JDA restrictive covenants in a discriminatory manner met the "state action" requirement under section 1983. Casa Marie, 752 F. Supp. at 1166.

There are two components to the "state action" requirement:

First, the deprivation must be caused by the exercise of some right or privilege created by the State or by a rule of conduct imposed by the State or by a person for whom the State is responsible.... Second, the party charged with the deprivation must be a person who may fairly be said to be a state actor. This may be because he is a state official, because he has acted together with or has obtained significant aid from state officials, or because his conduct is otherwise chargeable to the State.

Lugar v. Edmondson Oil Co., 457 U.S. 922, 937, 102 S. Ct. 2744, 2753, 73 L. Ed. 2d 482 (1982); United States v. Price, 383 U.S. 787, 794, 86 S. Ct. 1152, 1157, 16 L. Ed. 2d 267 (1966) ("Private persons, jointly engaged with state officials in the prohibited action, are acting 'under color' of law for purposes of [section 1983]. To act 'under color' of law does not require that the accused be an officer of the State. It is enough that he is a willful participant in joint activity with the State or its agents."). It is obvious, nonetheless, that something more than mere resort to a state court is required to transform the moving party into "a co-conspirator or a joint actor with the judge." Dennis v. Sparks, 449 U.S. 24, 28, 101 S. Ct. 183, 186, 66 L. Ed. 2d 185 (1980); see also Lugar, 457 U.S. at 937, 102 S.Ct. at 2753; McDougald v. Jenson, 786 F.2d 1465, 1488-89 (11th Cir.), cert. denied, 479 U.S. 860, 107 S. Ct. 207, 93 L. Ed. 2d 137 (1986). Appellees advance two grounds for finding the requisite "state action" in the present case.7

1. Corruption, Conspiracy, Usurpation, or Collusion.

An actual conspiracy between a state court and a party attempting a plainly prohibited act would constitute "state action." Cf. Adickes v. S.H. Kress & Co., 398 U.S. 144, 150-52, 90 S. Ct. 1598, 1604-06, 26 L. Ed. 2d 142 (1970). The residents contend that the Superior Court judge improperly abandoned his judicial role by permitting the neighbors to draft the final judgment against Casa Marie, contrary to the normal practice in Commonwealth courts. The neighbors counter that they merely transcribed the court's ore tenus ruling at its request. As the district court made no findings of fact on the residents' conspiracy allegation, and no uncontroverted record evidence supports it, we decline to credit their conclusory allegation as a sufficient basis for finding "state action" in these circumstances. See, e.g., Schucker v. Rockwood, 846 F.2d 1202, 1205 (9th Cir.) (conclusory allegations of conspiracy between court and litigants insufficient to establish "state action"), cert. denied, 488 U.S. 995, 109 S. Ct. 561, 102 L. Ed. 2d 587 (1988).

2. Neutrality and the Use of Courts to Enforce Restrictive Covenants.

The residents argue, in the alternative, that Shelley v. Kraemer, 334 U.S. 1, 68 S. Ct. 836, 92 L. Ed. 1161 (1948), supports the district court's "state action" determination. In Shelley, the Supreme Court found "state action" where private parties resorted to the state courts to enforce a facially discriminatory restrictive covenant which provided, inter alia, that "no part of said property ... shall be, for said term of Fifty-years, occupied by any person not of the Caucasian race, it being intended hereby to restrict the use of said property ... against the occupancy as owners or tenants of any portion of said property for resident or another purpose by people of the Negro or Mongolian Race." Id. at 4, 68 S.Ct. at 838. The residents insist that Shelley likewise encompasses judicial action to enforce a facially neutral covenant in a discriminatory manner.

Two decades ago, this court propounded a clear limiting principle for applying the "state action" standard enunciated in Shelley. See Lavoie v. Bigwood, 457 F.2d 7, 11-12 (1st Cir.1972). Distinguishing Shelley from Griffin v. Maryland, 378 U.S. 130, 84 S. Ct. 1770, 12 L. Ed. 2d 754 (1964), Judge Coffin aptly noted:

In [Griffin,] a deputy sheriff had ordered certain black patrons to leave a privately-owned amusement park, had arrested them when they refused to do so, and had brought a prosecution for criminal trespass. The Court recounted Maryland's argument that itmay ... constitutionally enforce an owner's desire to exclude particular persons from his premises even if the owner's desire is in turn motivated by a discriminatory purpose. The State, it is said, is not really enforcing a policy of segregation since the owner's ultimate purpose is immaterial to the State....

The Court responded that such were not the facts of the case before it, in that "The president of the corporation which owned and managed the park testified that he had instructed [the deputy sheriff] to enforce the park's policy of racial segregation." A state, then, must be more strictly neutral than to permit any of its officers to identify the subjects of the discrimination in the first instance. Although it was not cited in Griffin, we take Shelley to be an earlier application of the same principle. To enforce the covenant and thereby disrupt a transaction between a willing seller and a willing buyer, the state court had necessarily to take evidence that the prospective buyer was black and to take notice that the clause being enforced was a racially restrictive one.

But while, on the facts of Shelley and Griffin, the Court had no occasion to announce a narrower theory indicating when a state police officer or court is "neutral" for the purposes of the Fourteenth Amendment, we think that, apart from cases involving racial discrimination, Maryland's argument suggests a workable theory. That is, a state may at the behest of private persons apply sanctions pursuant to general rules of law which have discriminatory as well as non-discriminatory application if it does not accept the responsibility of employing a discriminatory classification. Such responsibility would exist when, in resorting to a state sanction, a private party must necessarily make the state privy to his discriminatory purpose. Similarly, in such a case as this, the state would retain a neutral posture unless it was necessarily apprised of the landlord's purpose to violate rights of free speech and association. While not entirely satisfactory, this approach at least recognizes conscious state involvement without insisting upon an unattainable purity.

Lavoie, 457 F.2d at 11-12 (emphasis added) (citations omitted).

The residents have not established "state action" under the Lavoie "neutrality" principle. The zoning ordinances and the restrictive covenants are facially neutral, and presumptively valid under Puerto Rico law. Furthermore, the Casa Marie residents were not parties to the Superior Court action prior to the entry of the final judgment. Thus, it cannot be determined on any evidentiary basis that the Superior Court was either apprised of any discriminatory animus on the part of the neighbors, or asked to consider any discriminatory effect that the belatedly alleged selective enforcement of the zoning ordinances and restrictive covenants might occasion. Without indulging conjecture, therefore, it cannot be concluded that the Superior Court must necessarily have been made privy to any allegedly discriminatory design on the part of the neighbors. See id. at 12. Absent "state action," the district court should have dismissed the section 1983 claims as a basis for injunctive relief, and the Superior Court as a party-defendant.

B. The Fair Housing Act Claims.

1. Casa Marie and the Intervenors.

Unlike the nonintervenors, these federal plaintiffs attempted to litigate their federal claims in the district court, notwithstanding their continuing involvement in two pending Superior Court proceedings. In these circumstances, the district court should have abstained in deference to the proceedings pending in the Superior Court.

a. The Anti-Injunction Act.

The Anti-Injunction Act provides that "[a] court of the United States may not grant an injunction to stay proceedings in a State court except as expressly authorized by Act of Congress, or where necessary in aid of its jurisdiction, or to protect or effectuate its judgments." 28 U.S.C. § 2283 (1990) (emphasis added). Appellants challenge the district court ruling that Title VIII is an "express" exception within the meaning of the Anti-Injunction Act. See Casa Marie, 752 F. Supp. at 1169-71. Asserting that neither the language of Title VIII, nor its legislative history, expressly authorizes a federal court to enjoin a state court proceeding, appellants argue that the Anti-Injunction Act constitutes an "absolute prohibition" on federal injunctive relief. See, e.g., Atlantic Coast Line R. Co. v. Brotherhood of Locomotive Eng'rs, 398 U.S. 281, 297, 90 S. Ct. 1739, 1748, 26 L. Ed. 2d 234 (1970) ("Any doubts as to the propriety of a federal injunction ... should be resolved in favor of permitting the state courts to proceed....").8 We agree.

The Anti-Injunction Act is "an historical mechanism (Act of March 2, 1793, 1 Stat. 334, 335) for achieving harmony in one phase of our complicated federalism by avoiding needless friction between two systems of courts having potential jurisdiction over the same subject-matter." Hale v. Bimco Trading, Inc., 306 U.S. 375, 378, 59 S. Ct. 526, 527, 83 L. Ed. 771 (1939). The three exceptions enumerated in the Act must be narrowly construed. See Mitchum v. Foster, 407 U.S. 225, 228-29, 92 S. Ct. 2151, 2154-55, 32 L. Ed. 2d 705 (1972); Atlantic Coast Line, 398 U.S. at 298, 90 S.Ct. at 1748. While it is beyond dispute that the residents' section 1983 claims come within an "express" exception to section 2283, see Mitchum, 407 U.S. at 240-41, 92 S.Ct. at 2161-62 (legislative history of section 1983 demonstrates obvious congressional distrust of state courts, which were often "in league with those who were bent upon abrogation of federally protected rights"), we are unable to discern any statutory language or legislative history which indicates that Congress expressly excepted Title VIII claims from the operation of the Anti-Injunction Act.

In Mitchum v. Foster, 407 U.S. 225, 92 S. Ct. 2151, 32 L. Ed. 2d 705 (1972), the Supreme Court prescribed a two-part analysis for determining whether a federal statute comes within the Anti-Injunction Act's "expressly authorized" exception: (1) the statute "must have created a specific and uniquely federal right or remedy, enforceable in a federal court of equity," and (2) the federal right or remedy must be such that it can be "given its intended scope only by the stay of a state court proceeding." Id. at 237-38, 92 S.Ct. at 2159-60 (emphasis added). We need only consider the second prong of the Mitchum test, but cf. infra note 16, which would seem to require some indication that Congress suspected that state courts, as a routine practice, would not vindicate Title VIII rights. See, e.g., Zajac v. Federal Land Bank, 909 F.2d 1181, 1195 (8th Cir.1990) (Agricultural Credit Act constitutes express exception, as it is aimed at eradicating "past abuses of state court foreclosure proceedings.").

Congress contemplated concurrent state-federal court jurisdiction over Title VIII claims. See 42 U.S.C. § 3613(a)(1)(A); cf. General Motors Corp. v. Buha, 623 F.2d 455, 459 (6th Cir.1980) (ERISA is an "express" exception because of its preemption and exclusive federal jurisdiction provisions); Dilworth v. Riner, 343 F.2d 226, 230-32 (5th Cir.1965) (Title II of Civil Rights Act of 1964 constitutes "express" exception, as it vests exclusive jurisdiction in federal courts); Walling v. Black Diamond Coal Mining Co., 59 F. Supp. 348, 350 (W.D.Ky.1943) (Fair Labor Standards Act constitutes "express" exception; although jurisdiction is concurrent, injunctive relief is available only in federal court ). But see Total Plan Servs., Inc. v. Texas Retailers' Ass'n, 925 F.2d 142, 145 (5th Cir.1991) (ERISA not "express" exception). Without more, the vesting of concurrent jurisdiction would seem to imply a vote of confidence in the integrity and competence of state courts to adjudicate Title VIII claims. Significantly, unlike the situation in Mitchum, appellees cite no legislative history intimating that congressional mistrust of state courts figured however slightly in the enactment of Title VIII.

Appellees instead argue that Congress implicitly demonstrated mistrust of state and local government in general by enabling private litigants to sue for federal injunctive relief against municipalities which enact or enforce zoning ordinances in a discriminatory fashion. Their argument distends the Act's restrictive language ("expressly authorized by Act of Congress") to absurd limits. If Mitchum's second prong were to be considered satisfied whenever Congress enacted a statute authorizing injunctive relief, or by the mere fact that a local government might be made a defendant in a particular case, the rule requiring narrow construction of the Act's exceptions would be rendered largely meaningless, and with it the general presumption that state courts are competent to protect federal rights. See Vendo Co. v. Lektro-Vend Corp., 433 U.S. 623, 636, 97 S. Ct. 2881, 2890, 53 L. Ed. 2d 1009 (1977) (listing twenty-six federal statutes authorizing injunctive relief, and noting that such a blanket test would "eviscerate" the Anti-Injunction Act as a meaningful restraint on federal courts). Accordingly, we conclude that the Anti-Injunction Act barred federal injunctive relief in favor of Casa Marie and the intervenors.

b. Younger Abstention.

Even assuming that Title VIII were to be considered an express exception to the Anti-Injunction Act, appellants argue that the district court should have abstained, in the interests of comity and federalism, from interfering with pending state court proceedings which implicate such vital state interests, see Younger v. Harris, 401 U.S. 37, 91 S. Ct. 746, 27 L. Ed. 2d 669 (1971): namely, the Commonwealth's important stake in protecting the integrity of the contempt power as the ultimate means of ensuring compliance with the final judgments of its courts, see Juidice v. Vail, 430 U.S. 327, 97 S. Ct. 1211, 51 L. Ed. 2d 376 (1977), and of "vindicat[ing] [the State's interest in] the regular operation of its judicial system," id. at 335, 97 S.Ct. at 1217. Again, we agree.

Proper respect for principles of federalism and comity requires that federal courts, "anxious though [they] may be to vindicate and protect federal rights and federal interests, always endeavor[ ] to do so in ways that will not unduly interfere with the legitimate activities of the States." Younger, 401 U.S. at 44, 91 S.Ct. at 750. Except in the most extraordinary cases,9 a federal court must presume that state courts, consistent with the imperatives of the Supremacy Clause, see U.S. Const. art. VI, are fully competent to adjudicate federal constitutional and statutory claims properly presented by the parties. See Middlesex County Ethics Comm. v. Garden State Bar Ass'n, 457 U.S. 423, 431, 102 S. Ct. 2515, 2520, 73 L. Ed. 2d 116 (1982); Bettencourt v. Board of Registration in Medicine, 904 F.2d 772, 776 (1st Cir.1990).10 To obtain federal injunctive relief impeding a pending state court proceeding, therefore, the federal plaintiff must surpass the normal showing of irreparable injury, and posit the existence of an irremediable harm both "great and immediate." Younger, 401 U.S. at 46, 91 S.Ct. at 751. Even if it were determined that plaintiffs successfully surmounted this heightened standard of proof, however, it would be to no avail; the district court failed to consider two paramount, countervailing factors: (1 ) the importance of the State interest at stake in the pending Superior Court proceedings, see, e.g., Pennzoil Co. v. Texaco, Inc., 481 U.S. 1, 5, 13, 107 S. Ct. 1519, 1523, 1527, 95 L. Ed. 2d 1 (1987) (abstention warranted where Texas' lien and bond provisions, permitting writs of execution to issue prior to exhaustion of state appeals, constitute an important process "by which the State compels compliance with the judgments of its courts"); Trainor v. Hernandez, 431 U.S. 434, 444, 97 S. Ct. 1911, 1918, 52 L. Ed. 2d 486 (1977) (abstention warranted where pending state court civil action brought by State of Illinois to attach fraudulently obtained public assistance payments implicates important state interest in "safeguarding the fiscal integrity of [its] programs"); Huffman v. Pursue, Ltd., 420 U.S. 592, 604, 95 S. Ct. 1200, 1208, 43 L. Ed. 2d 482 (1975) (abstention warranted where State's prosecution of civil nuisance suit is analogous to its interest in criminal prosecution); Juidice, 430 U.S. at 335, 97 S. Ct. at 1217 (abstention warranted, as "[t]he contempt power lies at the core of the administration of a State's judicial system"); Younger, 401 U.S. at 46, 91 S.Ct. at 751 (abstention warranted in deference to pending state criminal prosecution), and (2 ) the availability of an adequate "opportunity" to raise the federal claims in the State court. See Bettencourt, 904 F.2d at 777; Gabrilowitz v. Newman, 582 F.2d 100, 102 (1st Cir.1978).

Given Casa Marie's undisputed disregard of the Superior Court's final judgment, and the unquestioned importance of the Commonwealth's interest in enforcing the judgments of its courts through civil contempt proceedings, see Juidice, 430 U.S. at 335, 97 S. Ct. at 1217; see also Pennzoil, 481 U.S. at 13, 107 S.Ct. at 1527 (State has important interest in preventing its judgments from being "rendered nugatory"); cf. Lebbos v. Judges of Superior Court, 883 F.2d 810, 814 (9th Cir.1989), we hold that the Younger doctrine barred Casa Marie and the intervenors from litigating their Title VIII claims in federal district court. As a party to the enforcement-contempt proceedings yet pending in the Superior Court, Casa Marie not only had ample opportunity, but an obligation, to raise its federal counterclaims in the Superior Court. See P.R. Laws tit. 32, App. III, R. 11.1 (a counterclaim is considered compulsory "if it arises out of the transaction or occurrence that is the subject matter of the opposing party's claim").

The intervenors belatedly sought to participate in the same enforcement-contempt proceedings which remain pending in the Superior Court, then instituted the Superior Court lawsuit whose sole purpose is to restrain enforcement of the final Superior Court judgment and contempt decree against the Casa Marie owners. Apart from their unsubstantiated and conclusory allegation that a Superior Court judge stated "off the record " that she might be disinclined to restrain enforcement of a final judgment entered by a Superior Court colleague, the intervenors neither alleged nor presented any evidence (e.g., an order denying their motion to intervene or dismissing their complaint) that they were precluded from pursuing either pending Superior Court action. Instead, so far as the present record indicates, the intervenors simply suspended their pursuit of the Title VIII claims in the pending Superior Court proceedings in favor of a fresh start in the federal court action aimed at enjoining enforcement of the final Superior Court judgment against Casa Marie.

We conclude that extraordinary injunctive relief indirectly suspending enforcement of the Commonwealth's judicial processes in the ongoing Superior Court proceedings, with its attendant depreciation of the fundamental principles underlying federalism and comity, was unwarranted. See Moore v. Sims, 442 U.S. 415, 426, 99 S. Ct. 2371, 2379, 60 L. Ed. 2d 994 (1979) (abstention appropriate "unless state law clearly bars the interposition of [federal] claims") (emphasis added). After initiating a state court proceeding, a federal plaintiff cannot escape Younger 's reach merely by abandoning the pending state court action or foregoing available state appellate remedies, New Orleans Pub. Serv., Inc. v. Council of New Orleans, 491 U.S. 350, 369, 109 S. Ct. 2506, 2518, 105 L. Ed. 2d 298 (1989); the "opportunity" to raise federal claims in a pending state court proceeding is enough to implicate Younger abstention. Juidice, 430 U.S. at 337, 97 S.Ct. at 1218. Thus, Younger abstention precluded the district court order indirectly enjoining the pending Superior Court contempt proceedings against Casa Marie and the intervenors.

2. The Nonintervenors.

The prudential considerations underlying the Anti-Injunction Act and Younger abstention require further searching inquiry in reference to the federal claims presented by the nonintervenors. The majority of cases in which federal courts abstain from enjoining pending state court proceedings involve federal plaintiffs who are actual parties to the state court proceedings. The nonintervenors were not involved in either pending Superior Court proceeding. As we have noted, however, see supra Section II.B.1.a., the state and federal courts possess concurrent jurisdiction under Title VIII, see 42 U.S.C. § 3613(a)(1)(A), offering Title VIII plaintiffs a choice of forum. Ultimately, therefore, the essential question becomes whether the nonintervenors waived or acquiesced in a waiver of the right to present their Title VIII claims in the federal forum.

a. The Anti-Injunction Act.

Under the "strangers to the state court proceedings" exclusion,11 the Anti-Injunction Act is inoperative if the party requesting injunctive relief in the federal court was neither a party, nor in privity with a party, to the state court proceeding sought to be enjoined. See County of Imperial v. Munoz, 449 U.S. 54, 59-60, 101 S. Ct. 289, 292-93, 66 L. Ed. 2d 258 (1980); Hale v. Bimco Trading, Inc., 306 U.S. 375, 378, 59 S. Ct. 526, 527, 83 L. Ed. 771 (1939); Chase Nat'l Bank v. City of Norwalk, 291 U.S. 431, 440, 54 S. Ct. 475, 479, 78 L. Ed. 894 (1934); Garcia v. Bauza-Salas, 862 F.2d 905, 909 (1st Cir.1988). The "strangers" exclusion presumably embraces federal plaintiffs who deliberately bypass an available opportunity to intercede in pending state court proceedings, since "[t]he law does not impose upon any person absolutely entitled to a hearing the burden of voluntary intervention in a suit to which he is a stranger." Chase Nat'l Bank, 291 U.S. at 441, 54 S.Ct. at 479.12 Neither Casa Marie nor the intervenors fit within the "strangers" exclusion, of course, but neither would their mere joinder with nonintervenors as federal plaintiffs necessarily deprive the nonintervenors of the exclusion. See generally Charles A. Wright, Arthur Miller, & Edward H. Cooper, Federal Practice & Procedure: Jurisdiction § 4449, at 416 (1981) [hereinafter Federal Practice ] ("The bare fact that one plaintiff is joined with others who were parties and who can properly be bound by a prior proceeding does not justify preclusion of the nonparty plaintiff as well.") (citing Duncan v. Town of Blacksburg, 364 F. Supp. 643, 645 (W.D.Va.1973)). The nonintervenors' status as "strangers" to these proceedings accordingly depends on whether they are bound, under the principles of res judicata or collateral estoppel, by the decisions in either pending Superior Court proceeding. See, e.g., United States Steel Corp. Plan for Employee Ins. Benefits v. Musisko, 885 F.2d 1170, 1179 (3d Cir.1989), cert. denied, 493 U.S. 1074, 110 S. Ct. 1121, 107 L. Ed. 2d 1028 (1990); Pelfresne v. Village of Williams Bay, 865 F.2d 877, 881 (7th Cir.1989).

Although it is highly questionable whether either intervenors or nonintervenors would be "bound" under res judicata principles by any judgment or contempt decree against the Casa Marie owners,13 the common interests asserted by the intervenors and nonintervenors are virtually identical in all material respects. While we need not rest our decision solely on this ground, see infra Section II.B.2.b., we are convinced that the Commonwealth courts would treat the intervenors, by reason of their initiation of the independent Superior Court action to restrain enforcement of the contempt decree, as the "virtual representatives" of the nonintervenors' interests for res judicata purposes. See, e.g., In re Medomak Canning, 922 F.2d 895, 901 (1st Cir.1990); see also 28 U.S.C. § 1738 (federal court must accord state court judgment the same preclusive effect it would be given by the courts of that State); Migra v. Warren City Sch. Dist. Bd. of Educ., 465 U.S. 75, 81, 104 S. Ct. 892, 896, 79 L. Ed. 2d 56 (1984) (same); Rojas-Hernandez v. Puerto Rico Elec. Power Auth., 925 F.2d 492, 495 (1st Cir.1991) (same).14

We recognize, of course, that "it is not enough that [the federal plaintiffs'] concerns ... mirrored those which likely impelled [the earlier plaintiffs] to start suit in superior court," Montalvo-Huertas v. Rivera-Cruz, 885 F.2d 971, 975-76 (1st Cir.1989) (citing A & P Gen. Contractors, Inc. v. Asociacion Cana, Inc., 110 P.R. Dec. 753 (1981)), and that "virtual representation does not exist between two plaintiffs merely because they raise similar [factually-related] claims," Terrell v. De Conna, 877 F.2d 1267, 1271 (5th Cir.1989); see also Diaz v. Naiveras, 118 P.R.Dec. 297 (1987) (privity not established by familial relationship). Yet nonintervenors' federal complaint is distinctive in two significant respects--one substantive and one procedural. The nonintervenors' complaint hinges entirely on their proving that the neighbors harbored the alleged discriminatory intent to exclude the residents as a group from the JDA housing development; in no sense does it focus on any particular resident as an individual target of the alleged discrimination. Thus, whatever circumstantial differences may exist among individual Casa Marie residents are entirely irrelevant to the merits of their Title VIII claims. Cf. Wilder v. Thomas, 854 F.2d 605, 620 (2d Cir.1988) (holding that two nonparties were bound where all federal plaintiffs alleged imminent injury from lack of environmental impact study on construction project, and the issues raised in the state and federal proceedings "do not vary according to individual plaintiffs"), cert. denied, 489 U.S. 1053, 109 S. Ct. 1314, 103 L. Ed. 2d 583 (1989). Each Casa Marie resident, intervenor and nonintervenor alike, at all times had, and still has, ample incentive to litigate vigorously against the threatened injury to the federally protected interests common to all residents, namely the closure of Casa Marie.

No less importantly, the "virtual representation" inquiry in the present case arises in the context of a post-judgment proceeding.15 Given the vital "finality" interests engendered by their valid judgments, we doubt very seriously that the Commonwealth courts would sanction successive attempts by individual Casa Marie residents to restrain the enforcement of the final Superior Court judgment--an unavoidable result, nonetheless, should individual residents be allowed successively to assert lack of privity in these circumstances. See, e.g., Petit v. City of Chicago, 766 F. Supp. 607, 611-12 (N.D.Ill.1991) (res judicata rules of "representation" should discourage tactical maneuvering by parties); see generally Restatement (Second) of Judgments § 62 (1981) (nonparty may be barred from relitigation of claim if, by his conduct, he induced justifiable expectation that he would "govern his conduct by the judgment in the original action").

We are particularly reluctant to extend the protection of the "strangers" exclusion in the present action, as it has been utilized so seldom by the Supreme Court that its continued vitality has even been questioned. See, e.g., County of Imperial, 449 U.S. at 60-61, 101 S.Ct. at 293-94 (Powell, J., concurring) ("I record my willingness to reconsider Hale. It has rarely been cited and--as the Court reads it today--it creates an exception to the coverage of the Anti-Injunction Act that I think is contrary to the policy of that Act."). Moreover, withholding the "strangers" exclusion under the Anti-Injunction Act has less drastic repercussions for the federal plaintiffs than would a formal res judicata determination. Federal court abstention would not divest the federal plaintiffs of their right to litigate their Title VIII claims, but merely restrict them to the available Commonwealth forum. More importantly, of course, where the case for "virtual representation" is so compelling, and the effects of the "strangers" exclusion so obtrusive, the exercise of a federal court's narrowly confined power to enjoin a pending state court proceeding must be considered at its most suspect extension.16

b. Younger Abstention.

Even assuming the nonintervenors were somehow to escape the strictures of the Anti-Injunction Act, we believe Younger abstention would prevent federal relief enjoining enforcement of the Superior Court contempt decree. In an apparent corollary to the "strangers" exclusion, the Supreme Court has intimated that Younger abstention might not apply in some instances to a federal plaintiff who was not a party, or not "closely related" to a party, in the pending state court proceeding. See Doran v. Salem Inn, Inc., 422 U.S. 922, 928-29, 95 S. Ct. 2561, 2566-67, 45 L. Ed. 2d 648 (1975). "While there plainly may be some circumstances in which legally distinct parties are so closely related that they should all be subject to the Younger considerations which govern any one of them, this is not such a case." Id. (emphasis added); see also Trainor, 431 U.S. at 440, 97 S.Ct. at 1916 (doctrine invoked only "when litigation between the same parties and raising the same issues is ... pending in a state court") (emphasis added); Steffel v. Thompson, 415 U.S. 452, 461-62, 94 S. Ct. 1209, 1216-17, 39 L. Ed. 2d 505 (1974); Roe v. Wade, 410 U.S. 113, 125-27, 93 S. Ct. 705, 712-14, 35 L. Ed. 2d 147 (1973); Sullivan v. City of Pittsburgh, 811 F.2d 171, 177-78 (3d Cir.) (federal plaintiffs not parties to ongoing zoning proceeding, and not sufficiently "related" to parties therein), cert. denied, 484 U.S. 849, 108 S. Ct. 148, 98 L. Ed. 2d 104 (1987); Family Div. Trial Lawyers v. Moultrie, 725 F.2d 695, 702-03 (D.C.Cir.1984) (lawyers' federal "equal protection" and "takings" claims cognizable in federal court where lawyers not parties to state "neglect" proceedings); Robinson v. Stovall, 646 F.2d 1087, 1090-93 (5th Cir.1981) (federal plaintiff with section 1983 claim never arrested or tried for violation of challenged statute). The distinction Doran draws between the terms "legally distinct" and "closely related" strongly suggests that Younger's "close relationship" exclusion is far more narrow than the "strangers" exclusion under the Anti-Injunction Act, and may require federal plaintiffs who are not in strict privity to return to state court to litigate their federal claims where it is evident that their interests are sufficiently "intertwined" with the interests of parties to the state court proceedings. Hicks v. Miranda, 422 U.S. 332, 348-49, 95 S. Ct. 2281, 2291-92, 45 L. Ed. 2d 223 (1975) (interests of theatre and its employees in challenging obscenity statute held to be closely related).17

We do not think the narrow exclusion described in Doran precludes Younger abstention in relation to these nonintervenors' Title VIII claims. First, Doran and much of its progeny involve state criminal or administrative proceedings which provide no procedural mechanism which would enable nonparties to intervene to protect their interests. See, e.g., New Jersey-Philadelphia Presbytery of Bible Presbyterian Church v. New Jersey State Bd. of Higher Educ., 654 F.2d 868, 882 (3d Cir.1981) (where party is absolutely barred from intervention in state court proceedings, Younger abstention is never warranted).18 Thus, such state criminal and administrative proceedings would not satisfy an essential element of the Middlesex test, which requires that the nonparties have a meaningful opportunity to raise their federal claims in the pending state court proceeding. Middlesex, 457 U.S. at 432, 102 S.Ct. at 2521. In the present case, we have no reason to doubt that nonintervenors, and intervenors alike, would be entitled under the Puerto Rico Rules of Civil Procedure to intervene as of right in the enforcement-contempt proceeding, and the nonintervenors to join in the intervenors' independent action. See P.R. Laws tit. 32, App. III, R. 21.1 (intervention allowed "when the applicant claims a right or interest relating to the property or transaction which is the subject of the action which may as a practical matter be impaired by the final disposition of the action"); Chase Manhattan Bank v. Nesglo, Inc., 111 P.R. Dec. 767, 769 (1981) (noting liberality with which Rule 21 motions should be granted; unlike federal rule, applicants need not prove that their interests are not "adequately represented" by existing parties, and failed intervention lacks res judicata effect).

Second, unlike the Doran-type setting in which unrelated, legally distinct parties happen to mount separate but simultaneous legal challenges to the constitutionality of a state statute, the present case involves nonintervenor "co-lessees" with a common landlord, who took no action until after the Superior Court judgment was entered, even though they had actual knowledge that a Superior Court judgment threatened the very injury they now decry as patently collusive and "discriminatory."19 Understandably, of course, the nonintervenors may have hoped that Casa Marie would prevail, obviating the need to litigate their Title VIII defenses. Even so, once again they delayed, while the neighbors obtained a contempt decree against Casa Marie. By delaying until so late in the litigation, intervenors and nonintervenors withheld defenses the presentation of which may well have aided the Superior Court in its evaluation of the neighbors' state-law claims and its determination of a measured remedy for Casa Marie's zoning law violations. More importantly, the nonintervenors' delay until after entry of the contempt decree necessarily meant that the district court, were it to grant the nonintervenors injunctive relief, effectively would be placed in the apparent position of actively condoning Casa Marie's contumacious disregard of the Superior Court judgment.

These grave concerns nonetheless do not, in our view, warrant depriving nonintervenors of the opportunity to assert their Title VIII claims in the Commonwealth courts. Rather, as a deterrent to future engenderment of needless federal-state court tensions, we conclude that nonintervenors should be held to have waived their belated claims for discretionary federal equitable relief enjoining the enforcement of the final Superior Court judgment.

Finally, we think it cannot reasonably be contended that nonintervenors' interests are no longer sufficiently "intertwined" with those of Casa Marie as to implicate Younger abstention. Cf. Collins v. County of Kendall, 807 F.2d 95, 101-02 (7th Cir.1986) (plaintiff cannot simultaneously bring a claim which asserts that his interests are interconnected with other parties, then deny their close relationship for Younger purposes), cert. denied, 483 U.S. 1005, 107 S. Ct. 3228, 97 L. Ed. 2d 734 (1987). "[A] person who is not bound by a judgment under the rules of res judicata may obtain a determination that the judgment is ineffective as to him through an action to restrain enforcement of the judgment ... when ... [t]he existence of the judgment jeopardizes a protectible interest of his; and ... [t]he character of his interest warrants his being given relief forthwith rather than on a future occasion." Restatement (Second) of Judgments § 76 (1982). But though a nonjoined third party may rest assured that a final judgment by which he is not bound will not affect his substantive legal rights, he may not escape entirely the coincident implications attendant on the entry of the valid state court judgment, or the interests of the State in "vindicat[ing] the regular operation of its judicial system," see Juidice, 430 U.S. at 335, 97 S. Ct. at 1217.

It is one thing for a stranger to attack a judgment when it is set up against him, another for him to be allowed to enjoin its enforcement or otherwise to initiate proceedings to have it declared invalid.... If the judgment really does threaten him, the question remains whether there are competing interests to be considered, particularly the interests of the parties who are concededly bound by the judgment. Giving the applicable legal relief from the effects of the judgment on him will not dissolve its legal effects on the parties to the judgment.

Restatement (Second) of Judgments § 76 cmt. c (1982) (emphasis added).

Once a valid judgment becomes final, so as to define the status quo, its enforcement is not precluded merely because the interests of those who seek to restrain its enforcement might be affected. Furthermore, absent unambiguous evidence that the state court rendered its final judgment in a discriminatory or otherwise impermissible manner, see supra Section II.A., prudential considerations normally will warrant federal court deference to the state court's assessment of any competing interests belatedly presented to the federal court which might warrant relief from the enforcement of the state court judgment.

We mention a relevant example. Title VIII does not require a showing that discriminatory intent was the sole factor, but rather a substantial factor motivating defendants' conduct. See, e.g., United States v. Birmingham, 727 F.2d 560, 562 (6th Cir.), cert. denied, 469 U.S. 821, 105 S. Ct. 95, 83 L. Ed. 2d 41 (1984); Smith v. Town of Clarkton, 682 F.2d 1055, 1065 (4th Cir.1982).20 On the other hand, no liability arises under Title VIII absent a sufficient causal link between the defendants' discriminatory actions and the threatened injury to the plaintiffs. See, e.g., Gomez v. Chody, 867 F.2d 395, 401 (7th Cir.1989) (where apartments would have been closed anyway because unfit for habitation, alleged discriminatory purpose of landlord in evicting was too attenuated); see also Edwards v. Johnson County Health Dep't., 885 F.2d 1215, 1221 n. 14 (4th Cir.1989). In the present case, nonintervenors allege that the neighbors' actions, motivated by a discriminatory animus against "persons of a handicap," were the cause of Casa Marie's closure, even though they must also concede that, at the time of the Superior Court judgment, Casa Marie's noncompliance with the zoning laws was an additional, antecedent, and efficient cause for the entry of the adverse judgment against Casa Marie.21 To enforce a zoning ordinance under P.R. Laws Ann. tit. 23, § 71x, 72 (1987), a private citizen apparently need only show that the defendant has violated the zoning laws. See supra note 3. In contrast, the district court's consideration of the federal plaintiffs' request for injunctive relief immersed the court in speculation as to whether the Superior Court, in assessing the threat posed by Casa Marie's continued operation,22 would compel closure irrespective of any discriminatory intent on the part of the neighbors.23

We do not lightly conclude that there was an implied waiver of nonintervenors' statutory right to assert their Title VIII claims in a federal forum. Nevertheless, their delay in resorting to the federal forum until the Superior Court contempt decree had been entered cannot be countenanced without encouraging the very sort of egregious intrusion upon state judicial power which Younger abstention was designed to avert. See supra Section II.B.1.b.

We vacate the permanent injunction restraining the neighbors' enforcement of the Superior Court judgment and their enforcement of the outstanding contempt decree against Casa Marie. As our abstention ruling rests on the assumption that the residents will be accorded an adequate "opportunity" to participate in the Commonwealth proceedings, however, we anticipate that the Superior Court, as it has to date--out of respect for the principles of comity and federalism--will defer further enforcement of its judgment and contempt decree, for such reasonable time as it may allow, to permit the filing and consideration of the residents' motions to intervene in the enforcement proceeding, or in the alternative, to permit intervenors to prosecute their independent action.

The district court judgment is vacated. Judgment shall enter for appellants on appellees' section 1983 claims. Double costs are awarded against Casa Marie and its owners.