with whom JUSTICE BLACKMUN joins, dissenting.
Today the Court endorses the standard for modification of consent decrees articulated by Judge Friendly in New York State Assn. for Retarded Children, Inc. v. Carey, 706 F. 2d 956 (CA2), cert. denied, 464 U. S. 915 (1988). I agree with that endorsement, but under that standard I believe the findings ofthe District Court in this action require affirmance of its order refusing to modify this consent decree.1
I
When a district court determines, after a contested trial, that a state institution is guilty of a serious and persistent violation of the Federal Constitution, it typically fashions a remedy that is more intrusive than a simple order directing the defendants to cease and desist from their illegal conduct. See Swann v. Charlotte-Mecklenburg Bd. of Ed., 402 U. 5. 1 (1971). A district court has a duty to command a remedy that is effective, and it enjoys the broad equitable authority necessary to fulfill this obligation. See id., at 15-16; Brown v. Board of Education, 349 U. S. 294, 300 (1955); see also Missouri v. Jenkins, 495 U. S. 33 (1990).
*400II
In June 1973, after finding that petitioners’ incarceration of pretrial detainees in the Charles Street Jail violated constitutional standards, the District Court appropriately entered an injunction that went “beyond a simple proscription against the precise conduct previously pursued.” National Society of Professional Engineers v. United States, 435 U. S. 679, 698 (1978). It required petitioners to discontinue (1) the practice of double celling pretrial detainees after November 30, 1973, and (2) the use of the Charles Street Jail for pretrial detention after June 30, 1976. Inmates of Suffolk County Jail v. Eisenstadt, 360 F. Supp. 676, 691 (Mass. 1973).
Petitioners did not appeal from that injunction. When they found it difficult to comply with the double-celling prohibition, however, they asked the District Court to postpone enforcement of that requirement. The court refused and ordered petitioners to transfer inmates to other institutions. The Court of Appeals affirmed. Inmates of Suffolk County Jail v. Eisenstadt, 494 F. 2d 1196 (CA1), cert. denied, 419 U. S. 977 (1974). When petitioners found that they could not comply with the second part of the 1973 injunction, the District Court postponed the closing of the Charles Street Jail, but set another firm date for compliance. While petitioners’ appeal from that order was pending, the parties entered into the negotiations that produced the 1979 consent decree. After the Court of Appeals affirmed the District Court’s order and set yet another firm date for the closing of the Charles Street Jail, Inmates of Suffolk County Jail v. Kearney, 573 F. 2d 98, 101 (CA1 1978), the parties reached agreement on a plan that was entered by the District Court as a consent decree, Inmates of Suffolk County Jail v. Kearney, Civ. Action No. 71-162-G (Mass., May 7, 1979), App. to Pet. for Cert. in No. 90-954, p. 15a.
The facility described in the 1979 decree was never constructed. Even before the plan was completed, petitioners recognized that a larger jail was required. In June 1984, *401the sheriff filed a motion in the District Court for an order permitting double celling in the Charles Street Jail. The motion was denied. The parties then negotiated an agreement providing for a larger new jail and for a modification of the 1979 decree. After they reached agreement, respondents presented a motion to modify, which the District Court granted on April 11, 1985. The court found that modifications were “necessary to meet the unanticipated increase in jail population and the delay in completing the jail as originally contemplated.” App. 110. The District Court then ordered that nothing in the 1979 decree should prevent petitioners
“from increasing the capacity of the new facility if the following conditions are satisfied:
“(a) single-cell occupancy is maintained under the design for the facility;
“(b) under the standards and specifications of the Architectural Program, as modified, the relative proportion of cell space to support services will remain the same as it was in the Architectural Program . . . .” Id., at 110-111.
There was no appeal from that modification order. Indeed, although the Boston City Council objected to the modification, it appears to have been the product of an agreement between respondents and petitioners.
In 1990,19 years after respondents filed suit, the new jail was completed in substantial compliance with the terms of the consent decree, as modified in 1985.
III
It is the terms of the 1979 consent decree, as modified and reaffirmed in 1985, that petitioners now seek to modify. The 1979 decree was negotiated against a background in which certain important propositions had already been settled. First, the litigation had established the existence of a serious *402constitutional violation. Second, for a period of almost five years after the entry of the 1973 injunction — which was unquestionably valid and which petitioners had waived any right to challenge — petitioners were still violating the Constitution as well as the injunction. See Inmates of Suffolk County Jail v. Kearney, 573 F. 2d, at 99. Third, although respondents had already prevailed, they were willing to agree to another postponement of the closing of the Charles Street Jail if petitioners submitted, and the court approved, an adequate plan for a new facility.
Obviously any plan would have to satisfy constitutional standards. It was equally obvious that a number of features of the plan, such as the site of the new facility or its particular architectural design, would not be constitutionally mandated. In order to discharge their duty to provide an adequate facility, and also to avoid the risk of stern sanctions for years of noncompliance with an outstanding court order, it would be entirely appropriate for petitioners to propose a remedy that exceeded the bare minimum mandated by the Constitution. Indeed, terms such as “minimum” or “floor” are not particularly helpful in this context. The remedy is constrained by the requirement that it not perpetuate a constitutional violation, and in this sense the Constitution does provide a “floor.” Beyond that constraint, however, the remedy's attempt to give expression to the underlying constitutional value does not lend itself to quantitative evaluation. In view of the complexity of the institutions involved and the necessity of affording effective relief, the remedial decree will often contain many, highly detailed commands. It might well be that the failure to fulfill any one of these specific requirements would not have constituted an independent constitutional violation, nor would the absence of any one element render the decree necessarily ineffective. The duty of the District Court is not to formulate the decree with the fewest provisions, but to consider the various interests involved and, in the sound exercise of its discretion, to *403fashion the remedy that it believes to be best.2 Similarly, a consent decree reflects the parties’ understanding of the best remedy, and, subject to judicial approval, the parties to a consent decree enjoy at least as broad discretion as the District Court in formulating the remedial decree. Cf. Firefighters v. Cleveland, 478 U. S. 501, 525-526 (1986).
From respondents’ point of view, even though they had won their case, they might reasonably be prepared to surrender some of the relief to which they were unquestionably entitled — such as enforcing the deadline on closing the Charles Street Jail — in exchange for other benefits to be included in an appropriate remedy, even if each such benefit might not be constitutionally required. For example, an agreement on an exercise facility, a library, or an adequate place for worship might be approved by the court in a consent decree, even if each individual feature were not essential to the termination of the constitutional violation. In *404fact, in this action it is apparent that the two overriding purposes that informed both the District Court’s interim remedy and respondents’ negotiations were the prohibition against double celling and the closing of the old jail. The plan that was ultimately accepted, as well as the terms of the consent decree entered in 1979, were designed to serve these two purposes.
The consent decree incorporated all the details of the agreed upon architectural program. A recital in the decree refers to the program as “both constitutionally adequate and constitutionally required.”3 That recital, of course, does not indicate that either the court or the parties thought that every detail of the settlement — or, indeed, any of its specific provisions — was “constitutionally required.” An adequate remedy was constitutionally required, and the parties and the court were satisfied that this program was constitutionally adequate. But that is not a basis for assuming that the parties believed that any provision of the decree, including the prohibition against double celling, was constitutionally required.4
*405IV
The motion to modify that ultimately led to our grant of certiorari was filed on July 17, 1989. As I view these cases, the proponents of that motion had the burden of demonstrating that changed conditions between 1985 and 1989 justified a further modification of the consent decree. The changes that occurred between 1979 and 1985 were already reflected in the 1985 modification. Since petitioners acquiesced in that modification, they cannot now be heard to argue that pre-1985 developments — either in the law or in the facts— provide a basis for modifying the 1985 order. It is that order that defined petitioners’ obligation to construct and to operate an adequate facility.
Petitioners’ reliance on Bell v. Wolfish, 441 U. S. 520 (1979), as constituting a relevant change in the law is plainly misplaced. That case was pending in this Court when the consent decree was entered in 1979. It was the authority on which the sheriff relied when he sought permission to double cell in 1984, and, of course, it was well known to all parties when the decree was modified in 1985. It does not qualify as a changed circumstance.5
*406The increase in the average number of pretrial detainees is, of course, a change of fact. Because the size of that increase had not been anticipated in 1979, it was appropriate to modify the decree in 1985.6 But in 1985, the steady progression in the detainee population surely made it foreseeable that this growth would continue. The District Court’s finding that “the overcrowding problem faced by the Sheriff is neither new nor unforeseen,” Inmates of Suffolk County Jail v. Kearney, 734 F. Supp. 561, 564 (Mass. 1990), is amply supported by the record.
Even if the continuing increase in inmate population had not actually been foreseen, it was reasonably foreseeable. Mere foreseeability in the sense that it was an event that “could conceivably arise” during the life of the consent decree, see ante, at 385, should not, of course, disqualify an unanticipated development from justifying a - modification. But the parties should be charged with notice of those events that reasonably prudent litigants would contemplate when negotiating a settlement. Given the realities of today’s society, it is not surprising that the District Court found a con*407tinued growth in inmate population to be within petitioners’ contemplation.
Other important concerns counsel against modification of this consent decree. Petitioners’ history of noncompliance after the 1973 injunction provides an added reason for insisting that they honor their most recent commitments. Petitioners’ current claims of fiscal limitation are hardly new. These pleas reflect a continuation of petitioners’ previous reluctance to budget funds adequate to avoid the initial constitutional violation or to avoid prolonged noncompliance with the terms of the original decree. The continued claims of financial constraint should not provide support for petitioners’ modification requests.7
The strong public interest in protecting the finality of court decrees always counsels against modifications. Cf. Teague v. Lane, 489 U. S. 288, 308-310 (1989) (plurality opinion); Mackey v. United States, 401 U. S. 667, 682-683 (1971) (Harlan, J., concurring in judgments in part and dissenting in part). In the context of a consent decree, this interest is reinforced by the policy favoring the settlement of protracted litigation. To the extent that litigants are allowed to avoid their solemn commitments, the motivation for particular settlements will be compromised, and the reliability of the entire process will suffer.
*408It is particularly important to- apply a strict standard when considering modification requests that undermine the central purpose of a consent decree. In his opinion in New York State Assn. for Retarded Children, Inc. v. Carey, 706 F. 2d 956 (CA2 1983), Judge Friendly analyzed the requested modifications in the light of the central purpose “of transferring the population of Willowbrook, whose squalid living conditions this court has already recited, to facilities of more human dimension as quickly as possible.” Id., at 967. The changes that were approved were found to be consistent with that central purpose. In this action, the entire history of the litigation demonstrates that the prohibition against double celling was a central purpose of the relief ordered by the District Court in 1973, of the bargain negotiated in 1979 and embodied in the original consent decree, and of the order entered in 1985 that petitioners now seek to modify. Moreover, as the District Court found, during the history of the litigation, petitioners have been able to resort to various measures such as “transfers to state prisons, bail reviews by the Superior Court, and a pretrial controlled release program” to respond to the overcrowding problem. 734 F. Supp., at 565. The fact that double celling affords petitioners the easiest and least expensive method of responding to a reasonably foreseeable problem is not an adequate justification for compromising a central purpose of the decree. In this regard, the Court misses the point in its observation that “[i]f modification of one term of a consent decree defeats the purpose of the decree, obviously modification would be all but impossible.” Ante, at 387. It is certainly true that modification of a consent decree would be impossible if the modification of any one term were deemed to defeat the purpose of the decree. However, to recognize that some terms are so critical that their modification would thwart the central purpose of the decree does not render the decree immutable, but rather assures that a modification will frustrate *409neither the legitimate expectations of the parties nor the core remedial goals of the decree.
After a judicial finding of constitutional violation, petitioners were ordered in 1973 to place pretrial detainees in single cells. In return for certain benefits, petitioners committed themselves in 1979 to continued compliance with the single-celling requirement. They reaffirmed this promise in 1985. It was clearly not an abuse of discretion for the District Court to require petitioners to honor this commitment.
I would affirm the judgment of the Court of Appeals.
Indeed, in an alternative holding, the District Court concluded that a modification would not be warranted even under the "flexible" standard advanced in Carey. See Inmates of Suffolk County Jail v. Kearney, 734 F. Supp. 561, 565 (Mass. 1990).
It is the difficulty in determining prospectively which remedy is best that justifies a flexible standard of modification. This relationship between the characteristics of a remedial decree in structural reform litigation and the flexible standard of modification is explained in the passage that Judge Friendly found to be the best statement of the applicable legal standard:
“ ‘The judge must search for the “best” remedy, but since his judgment must incorporate such open-ended considerations as effectiveness and fairness, and since the threat and constitutional value that occasions the intervention can never be defined with great precision, the intervention can never be defended with any certitude. It must always be open to revision, even without the strong showing traditionally required for modification of a decree, namely, that the first choice is causing grievous hardship. A revision is justified if the remedy is not working effectively or is unnecessarily burdensome.’” New York State Assn. for Retarded Children, Inc. v. Carey, 706 F. 2d 956, 970 (CA2 1983) (quoting Fiss, The Supreme Court — 1978 Term — Foreword: The Forms of Justice, 93 Harv. L. Rev. 1, 49 (1979)).
The justification for modifying a consent decree is not that the decree did “too much,” but that in light of later circumstances, a modified remedy would better achieve the decree’s original goals.
The relevant passage reads in full:
“And whereas all parties agree that for the purposes of this litigation the Suffolk County Detention Center, Charles Street Facility, Architectural Program which is attached and, as modified in paragraph 3 below, incorporated in this decree, sets forth a program which is both constitutionally adequate and constitutionally required." App. to Pet. for Cert, in No. 90-954, p. 16a.
Consider, for example, the following provisions of the decree:
“(d) The paragraph headed ‘A.l.a. Lobby/reception’ on page 8 is changed by increasing the number of visitor lockers to one-hundred (100) and the tenth sentence in that paragraph is changed to read:
‘Lobby should include public telephones, drinking fountain, vending machines and bulletin boards.’
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“(j) The following paragraph shall be added to page 37:
‘Inmate laundry rooms shall be located to permit convenient access and staff supervision. Room placement and the number of laundry rooms required shall be resolved during the design phase. Each inmate laundry *405room shall contain high quality washing and clothes drying equipment, sink, sorting table, storage and ironing board.’” Id., at 17a, 18a.
As the Court agrees that Bell v. Wolfish did not constitute a change in law requiring modification of the decree, see ante, at 388, the Court does not define further the kind of changes in law that may merit modification. In particular, the Court has no occasion to draw a distinction between the type of change in law recognized in Railway Employes v. Wright, 364 U. S. 642 (1961), and the change in law that petitioners assert was effected by Bell. The distinction is nevertheless significant and deserves mention. In Railway Employes, the plaintiffs originally brought suit, alleging that a railroad and its unions discriminated against nonunion employees, a practice prohibited by the Railway Labor Act, 45 U. S. C. § 151 et seq. The defendants entered into a consent decree, promising to refrain from such discrimination. When Congress subsequently amended the Act to permit union shops, the Court concluded that a modification allowing union shops should be granted so as to further the statutory purpose. In contrast to the situation presented in Railway Employes, it cannot be con*406tended that Bell expressed a policy preference in favor of double celling. This distinction is well described by the United States, appearing as ami-cus curiae:
“Bell v. Wolfish..., which rejected a challenge to the constitutionality of double-celling, did not represent a policy decision endorsing such housing. In contrast, in amending the Railway Labor Act, Congress weighed the merits of various labor policies and specifically endorsed union shops. The amendment thus conflicted-with the consent decree’s prohibition of such clauses. Bell, in contrast, cast no doubt on the propriety of the single-cell requirement to which the parties here had agreed.” Brief for United States as Amicus Curiae 20, n. 9.
It should be noted that the figures cited by the Court, ante, at 386, n. 9, are drawn from a projection prepared before 1979. (The projection is published in a report dated January 1, 1979. See App. 61, 69.) By 1982, respondents believed that the 1979 projections underestimated the future inmate population. See Record, 2 App. 642-648. In 1985, petitioners knew that the average number of male prisoners detained in 1984 had been 320 instead of the projected number of 236. Id., at 642-650.
The Court refers to the need to “keep the public interest in mind” when deciding whether to modify a decree. Ante, at 392. It is certainly true that when exercising their equitable powers, courts should properly consider the interests of the “public.” See Brown v. Board of Education, 349 U. S. 294, 300 (1955). It must be noted, however, that a remedial decree may well contain provisions that are unpopular; a requirement of additional expenditures to improve jail conditions might be an example of such an unpopular order. Mere unpopularity does not constitute a sufficient reason for modification. As the Court explained in Brown: “Courts of equity may properly take into account the public interest.... But it should go without saying that the vitality of these constitutional principles cannot be allowed to yield simply because of disagreement with them.” Ibid.