Opinion

JUSTICE O'CONNOR delivered the opinion of the Court. The Prison Litigation Reform Act of 1995 (PLRA) establishes standards for the entry and termination of prospective relief in civil actions challenging prison conditions. §§ 801-810, 110 Stat. 1321-66 to 1321-77. If prospective relief under an existing injunction does not satisfy these standards, a defendant or intervenor is entitled to "immediate termination" of that relief. 18 U. S. C. § 3626(b)(2) (1994 ed., Supp. IV). And under the PLRA's "automatic stay" provision, a motion to terminate prospective relief "shall operate as a stay" of that relief during the period beginning 30 days after the filing of the motion (extendable to up to 90 days for "good cause") and ending when the court rules on the motion. §§ 3626(e)(2), (3). The superintendent of Indiana's Pendleton Correctional Facility, which is currently operating under an ongoing injunction to remedy violations of the Eighth Amendment regarding conditions of confinement, filed a motion to terminate prospective relief under the PLRA. Respondent prisoners moved to enjoin the operation of the automatic stay provision of § 3626(e)(2), arguing that it is unconstitutional. The District Court enjoined the stay, and the Court of Appeals for the Seventh Circuit affirmed. We must decide whether a district court may enjoin the operation of the PLRA's automatic stay provision and, if not, whether that provision violates separation of powers principles.

I A

This litigation began in 1975, when four inmates at what is now the Pendleton Correctional Facility brought a class

System Inmates by John P. Frank; and for Erwin Chemerinsky et al. by Mr. Chemerinsky, pro se.

Sarah B. Vandenbraak, Michael D. Hess, Leonard J. Koerner, and Lorna B. Goodman filed a brief for the Association of State Correctional Administrators et al. as amici curiae. action under Rev. Stat. § 1979, 42 U. S. C. § 1983, on behalf of all persons who were, or would be, confined at the facility against the predecessors in office of petitioners (hereinafter State). 1 Record, Doc. No.1, p. 2. After a trial, the District Court found that living conditions at the prison violated both state and federal law, including the Eighth Amendment's prohibition against cruel and unusual punishment, and the court issued an injunction to correct those violations. French v. Owens, 538 F. Supp. 910 (SD Ind. 1982), aff'd in part, vacated and remanded in part, 777 F.2d 1250 (CA7 1985). While the State's appeal was pending, this Court decided Pennhurst State School and Hospital v. Halderman, 465 U. S. 89 (1984), which held that the Eleventh Amendment deprives federal courts of jurisdiction over claims for injunctive relief against state officials based on state law. Accordingly, the Court of Appeals for the Seventh Circuit remanded the action to the District Court for reconsideration. 777 F. 2d, at 1251. On remand, the District Court concluded that most of the state law violations also ran afoul of the Eighth Amendment, and it issued an amended remedial order to address those constitutional violations. The order also accounted for improvements in living conditions at the Pendleton facility that had occurred in the interim. Ibid.

The Court of Appeals affirmed the amended remedial order as to those aspects governing overcrowding and double celling, the use of mechanical restraints, staffing, and the quality of food and medical services, but it vacated those portions pertaining to exercise and recreation, protective custody, and fire and occupational safety standards. Id., at 1258. This ongoing injunctive relief has remained in effect ever since, with the last modification occurring in October 1988, when the parties resolved by joint stipulation the remaining issues related to fire and occupational safety standards. 1 Record, Doc. No. 14. B

In 1996, Congress enacted the PLRA. As relevant here, the PLRA establishes standards for the entry and termination of prospective relief in civil actions challenging conditions at prison facilities. Specifically, a court "shall not grant or approve any prospective relief unless the court finds that such relief is narrowly drawn, extends no further than necessary to correct the violation of the Federal right, and is the least intrusive means necessary to correct the violation of the Federal right." 18 U. S. C. § 3626(a)(1)(A) (1994 ed., Supp. IV). The same criteria apply to existing injunctions, and a defendant or intervenor may move to terminate prospective relief that does not meet this standard. See § 3626(b)(2). In particular, § 3626(b)(2) provides:

In any civil action with respect to prison conditions, a defendant or intervener shall be entitled to the immediate termination of any prospective relief if the relief was approved or granted in the absence of a finding by the court that the relief is narrowly drawn, extends no further than necessary to correct the violation of the Federal right, and is the least intrusive means necessary to correct the violation of the Federal right.

A court may not terminate prospective relief, however, if it "makes written findings based on the record that prospective relief remains necessary to correct a current and ongoing violation of the Federal right, extends no further than necessary to correct the violation of the Federal right, and that the prospective relief is narrowly drawn and the least intrusive means necessary to correct the violation." § 3626(b)(3). The PLRA also requires courts to rule "promptly" on motions to terminate prospective relief, with mandamus available to remedy a court's failure to do so. § 3626(e)(1).

Finally, the provision at issue here, § 3626(e)(2), dictates that, in certain circumstances, prospective relief shall be stayed pending resolution of a motion to terminate. Specifically, subsection (e)(2), entitled "Automatic Stay," states:

Any motion to modify or terminate prospective relief made under subsection (b) shall operate as a stay during the period

(A)(i) beginning on the 30th day after such motion is filed, in the case of a motion made under paragraph (1) or (2) of subsection (b);...

(ii)... and "(B) ending on the date the court enters a final order ruling on the motion.

As one of several 1997 amendments to the PLRA, Congress permitted courts to postpone the entry of the automatic stay for not more than 60 days for "good cause," which cannot include general congestion of the court's docket. § 123, 111 Stat. 2470, codified at 18 U. S. C. §3626(e)(3).*

C

On June 5, 1997, the State filed a motion under § 3626(b) to terminate the prospective relief governing the conditions of confinement at the Pendleton Correctional Facility. 1 Record, Doc. No. 16. In response, the prisoner class moved for a temporary restraining order or preliminary injunction to enjoin the operation of the automatic stay, arguing that § 3626(e)(2) is unconstitutional as both a violation of the Due Process Clause of the Fifth Amendment and separation of powers principles. The District Court granted the prisoners' motion, enjoining the automatic stay. See id., Doc. No. 23; see also French v. Duckworth, 178 F.3d 437, 440-441 (CA7 1999). The State appealed, and the United States intervened pursuant to 28 U. S. C. § 2403(a) to defend the constitutionality of § 3626(e)(2).

The Court of Appeals for the Seventh Circuit affirmed the District Court's order, concluding that although § 3626(e)(2) precluded courts from exercising their equitable powers to enjoin operation of the automatic stay, the statute, so construed, was unconstitutional on separation of powers grounds. See 178 F. 3d, at 447-448. The court reasoned that Congress drafted § 3626(e)(2) in unequivocal terms, clearly providing that a motion to terminate under § 3626(b)(2) "shall operate" as a stay during a specified time period. Id., at 443. While acknowledging that courts should not lightly assume that Congress meant to restrict the equitable powers of the federal courts, the Court of Appeals found "it impossible to read this language as doing anything less than that." Ibid. Turning to the constitutional question, the court characterized § 3626(e)(2) as "a self-executing legislative determination that a specific decree of a federal court... must be set aside at least for a period of time." Id., at 446. As such, it concluded that § 3626(e)(2) directly suspends a court order in violation of the separation of powers doctrine under Plaut v. Spendthrift Farm, Inc., 514 U. S. 211 (1995), and mandates a particular rule of decision, at least during the pendency of the § 3626(b)(2) termination motion, contrary to United States v. Klein, 13 Wall. 128 (1872). See 178 F. 3d, at 446. Having concluded that § 3626(e)(2) is unconstitutional on separation of powers grounds, the Court of Appeals did not reach the prisoners' due process claims. Over the dissent of three judges, the court denied rehearing en bane. See id., at 448-453 (Easterbrook, J., dissenting from denial of rehearing en bane).

We granted certiorari, 528 U. S. 1045 (1999), to resolve a conflict among the Courts of Appeals as to whether § 3626(e)(2) permits federal courts, in the exercise of their traditional equitable authority, to enjoin operation of the PLRA's automatic stay provision and, if not, to review the Court of Appeals' judgment that § 3626(e)(2), so construed, is unconstitutional. Compare Ruiz v. Johnson, 178 F.3d 385 (CA5 1999) (holding that district courts retain the equitable discretion to suspend the automatic stay and that § 3626(e)(2) is therefore constitutional); Hadix v. Johnson, 144 F. 3d 925 (CA6 1998) (same), with 178 F.3d 437 (CA7 1999) (case below).

II

We address the statutory question first. Both the State and the prisoner class agree, as did the majority and dissenting judges below, that § 3626(e)(2) precludes a district court from exercising its equitable powers to enjoin the automatic stay. The Government argues, however, that § 3626(e)(2) should be construed to leave intact the federal courts' traditional equitable discretion to "stay the stay," invoking two canons of statutory construction. First, the Government contends that we should not interpret a statute as displacing courts' traditional equitable authority to preserve the status quo pending resolution on the merits "[a]bsent the clearest command to the contrary." Califano v. Yamasaki, 442 U. S. 682, 705 (1979). Second, the Government asserts that reading § 3626(e)(2) to remove that equitable power would raise serious separation of powers questions, and therefore should be avoided under the canon of constitutional doubt. Like the Court of Appeals, we do not lightly assume that Congress meant to restrict the equitable powers of the federal courts, and we agree that constitutionally doubtful constructions should be avoided where "fairly possible." Communications Workers v. Beck, 487 U. S. 735, 762 (1988). But where Congress has made its intent clear, "we must give effect to that intent." Sinclair Refining Co. v. Atkinson, 370 U. S. 195, 215 (1962). The text of § 3626(e)(2) provides that "[a]ny motion to... terminate prospective relief made under subsection (b) shall operate as a stay" during a fixed period of time, i. e., from 30 (or 90) days after the motion is filed until the court enters a final order ruling on the motion. 18 U. S. C. § 3626(e)(2) (1994 ed., Supp. IV) (emphasis added). The stay is "automatic" once a state defendant has filed a § 3626(b) motion, and the statutory command that such a motion "shall operate as a stay during the [specified time] period" indicates that the stay is mandatory throughout that period of time. See Lexecon Inc. v. Milberg Weiss Bershad Hynes & Lerach, 523 U. S. 26, 35 (1998) ("[T]he mandatory 'shall'... normally creates an obligation impervious to judicial discretion").

Nonetheless, the Government contends that reading the statute to preserve courts' traditional equitable powers to enter appropriate injunctive relief is consistent with this text because, in its view, § 3626(e)(2) is simply a burdenshifting mechanism. That is, the purpose of the automatic stay provision is merely to relieve defendants of the burden of establishing the prerequisites for a stay and to eliminate courts' discretion to deny a stay, even if those prerequisites are established, based on the public interest or hardship to the plaintiffs. Thus, under this reading, nothing in § 3626(e)(2) prevents courts from subsequently suspending the automatic stay by applying the traditional standards for injunctive relief.

Such an interpretation, however, would subvert the plain meaning of the statute, making its mandatory language merely permissive. Section 3626(e)(2) states that a motion to terminate prospective relief "shall operate as a stay during" the specified time period from 30 (or 90) days after the filing of the § 3626(b) motion until the court rules on that motion. (Emphasis added.) Thus, not only does the statute employ the mandatory term "shall," but it also specifies the points at which the operation of the stay is to begin and end. In other words, contrary to JUSTICE BREYER'S suggestion that the language of § 3626(e)(2) "says nothing... about the district court's power to modify or suspend the operation of the 'stay,'" post, at 358 (dissenting opinion), § 3626(e)(2) unequivocally mandates that the stay "shall operate during" this specific interval. To allow courts to exercise their equitable discretion to prevent the stay from "operating" during this statutorily prescribed period would be to contradict § 3626(e)(2)'s plain terms. It would mean that the motion to terminate merely may operate as a stay, despite the statute's command that it "shall" have such effect. If Congress had intended to accomplish nothing more than to relieve state defendants of the burden of establishing the prerequisites for a stay, the language of § 3626(e)(2) is, at best, an awkward and indirect means to achieve that result.

Viewing the automatic stay provision in the context of § 3626 as a whole further confirms that Congress intended to prohibit federal courts from exercising their equitable authority to suspend operation of the automatic stay. The specific appeal provision contained in § 3626(e) states that "[a]ny order staying, suspending, delaying, or barring the operation of the automatic stay" of § 3626(e)(2) "shall be appealable" pursuant to 28 U. S. C. § 1292(a)(1). § 3626(e)(4). At first blush, this provision might be read as supporting the view that Congress expressly recognized the possibility that a district court could exercise its equitable discretion to enjoin the stay. The two Courts of Appeals that have construed § 3626(e)(2) as preserving the federal courts' equitable powers have reached that conclusion based on this reading of § 3626(e)(4). See Ruiz v. Johnson, 178 F. 3d, at 394; Hadix v. Johnson, 144 F. 3d, at 938. They reasoned that Congress would not have provided for expedited review of such orders had it not intended that district courts would retain the power to enter the orders in the first place. See ibid. In other words, "Congress understood that there would be some cases in which a conscientious district court acting in good faith would perceive that equity required that it suspend" the § 3626(e)(2) stay, and "Congress therefore permitted the district court to do so, subject to appellate review." Ruiz v. Johnson, supra, at 394.

The critical flaw in this construction, however, is that § 3626(e)(4) only provides for an appeal from an order preventing the operation of the automatic stay. § 3626(e)(4) ("Any order staying, suspending, delaying, or barring the operation of the automatic stay" under § 3626(e)(2) "shall be appealable"). If the rationale for the provision were that in some situations equity demands that the automatic stay be suspended, then presumably the denial of a motion to enjoin the stay should also be appealable. The one-way nature of the appeal provision only makes sense if the automatic stay is required to operate during a specific time period, such that any attempt by a district court to circumvent the mandatory stay is immediately reviewable.

The Government contends that if Congress' goal were to prevent courts from circumventing the PLRA's plain commands, mandamus would have been a more appropriate remedy than appellate review. But that proposition is doubtful, as mandamus is an extraordinary remedy that is "granted only in the exercise of sound discretion." Whitehouse v. Illinois Central R. Co., 349 U. S. 366, 373 (1955). Given that curbing the equitable discretion of district courts was one of the PLRA's principal objectives, it would have been odd for Congress to have left enforcement of § 3626(e)(2) to that very same discretion. Instead, Congress sensibly chose to make available an immediate appeal to resolve situations in which courts mistakenly believe-under the novel scheme created by the PLRA-that they have the authority to enjoin the automatic stay, rather than the extraordinary remedy of mandamus, which requires a showing of a "clear and indisputable" right to the issuance of the writ. See Mallard v. United States Dist. Court for Southern Dist. of Iowa, 490 U. S. 296, 309 (1989). In any event, § 3626(e) as originally enacted did not provide for interlocutory review. It was only after some courts refused to enter the automatic stay, and after the Court of Appeals for the Fifth Circuit would not review such a refusal, that Congress amended § 3626(e) to provide for interlocutory review. See In re Scott, 163 F. 3d 282, 284 (CAS 1998); Ruiz v. Johnson, supra, at 388; see also 18 U. S. C. § 3626(e)(4) (1994 ed., Supp. IV).

Finally, the Government finds support for its view in § 3626(e)(3). That provision authorizes an extension, for "good cause," of the starting point for the automatic stay, from 30 days after the § 3626(b) motion is filed until 90 days after that motion is filed. The Government explains that, by allowing the court to prevent the entry of the stay for up to 60 days under the relatively generous "good cause" standard, Congress by negative implication has preserved courts' discretion to suspend the stay after that time under the more stringent standard for injunctive relief. To be sure, allowing a delay in entry of the stay for 60 days based on a good cause standard does not by itself necessarily imply that any other reason for preventing the operation of the stay-for example, on the basis of traditional equitable principles-is precluded. But § 3626(e)(3) cannot be read in isolation. When §§ 3626(e)(2) and (3) are read together, it is clear that the district court cannot enjoin the operation of the automatic stay. The § 3626(b) motion "shall operate as a stay during" a specific time period. Section 3626(e)(3) only adjusts the starting point for the stay, and it merely permits that starting point to be delayed. Once the 90-day period has passed, the § 3626(b) motion "shall operate as a stay" until the court rules on the § 3626(b) motion. During that time, any attempt to enjoin the stay is irreconcilable with the plain language of the statute.

Thus, although we should not construe a statute to displace courts' traditional equitable authority absent the "clearest command," Califano v. Yamasaki, 442 U. S., at 705, or an "inescapable inference" to the contrary, Porter v. Warner Holding Co., 328 U. S. 395, 398 (1946), we are con vinced that Congress' intent to remove such discretion is unmistakable in § 3626(e)(2). And while this construction raises constitutional questions, the canon of constitutional doubt permits us to avoid such questions only where the saving construction is not "plainly contrary to the intent of Congress." Edward J. DeBartolo Corp. v. Florida Gulf Coast Building & Constr. Trades Council, 485 U. S. 568, 575 (1988). "We cannot press statutory construction 'to the point of disingenuous evasion' even to avoid a constitutional question." United States v. Locke, 471 U. S. 84, 96 (1985) (quoting George Moore Ice Cream Co. v. Rose, 289 U. S. 373, 379 (1933)); see also Pennsylvania Dept. of Corrections v. Yeskey, 524 U. S. 206, 212 (1998) (constitutional doubt canon does not apply where the statute is unambiguous); Commodity Futures Trading Comm'n v. Schor, 478 U. S. 833, 841 (1986) (constitutional doubt canon "does not give a court the prerogative to ignore the legislative will"). Like the Court of Appeals, we find that § 3626(e)(2) is unambiguous, and accordingly, we cannot adopt JUSTICE BREYER'S "more flexible interpretation" of the statute. Post, at 355. Any construction that preserved courts' equitable discretion to enjoin the automatic stay would effectively convert the PLRA's mandatory stay into a discretionary one. Because this would be plainly contrary to Congress' intent in enacting the stay provision, we must confront the constitutional issue.

III

The Constitution enumerates and separates the powers of the three branches of Government in Articles I, II, and III, and it is this "very structure" of the Constitution that exemplifies the concept of separation of powers. INS v. Chadha, 462 U. S. 919, 946 (1983). While the boundaries between the three branches are not" 'hermetically' sealed," see id., at 951, the Constitution prohibits one branch from encroaching on the central prerogatives of another, see Loving v. United States, 517 U. S. 748, 757 (1996); Buckley v. Valeo, 424 U. S. 1, 121-122 (1976) (per curiam). The powers of the Judicial Branch are set forth in Article III, § 1, which states that the "judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish," and provides that these federal courts shall be staffed by judges who hold office during good behavior, and whose compensation shall not be diminished during tenure in office. As we explained in Plaut v. Spendthrift Farm, Inc., 514 U. S., at 218-219, Article III "gives the Federal Judiciary the power, not merely to rule on cases, but to decide them, subject to review only by superior courts in the Article III hierarchy."

Respondent prisoners contend that § 3626(e)(2) encroaches on the central prerogatives of the Judiciary and thereby violates the separation of powers doctrine. It does this, the prisoners assert, by legislatively suspending a final judgment of an Article III court in violation of Plaut and Hayburn's Case, 2 Dall. 409 (1792). According to the prisoners, the remedial order governing living conditions at the Pendleton Correctional Facility is a final judgment of an Article III court, and § 3626(e)(2) constitutes an impermissible usurpation of judicial power because it commands the district court to suspend prospective relief under that order, albeit temporarily. An analysis of the principles underlying Hayburn's Case and Plaut, as well as an examination of § 3626(e)(2)'s interaction with the other provisions of § 3626, makes clear that § 3626(e)(2) does not offend these separation of powers principles.

Hayburn's Case arose out of a 1792 statute that authorized pensions for veterans of the Revolutionary War. See Act of Mar. 23, 1792, ch. 11, 1 Stat. 243. The statute provided that the circuit courts were to review the applications and determine the appropriate amount of the pension, but that the Secretary of War had the discretion either to adopt or reject the courts' findings. Hayburn's Case, supra, at 408-410. Although this Court did not reach the constitutional issue in Hayburn's Case, the statements of five Justices, acting as circuit judges, were reported, and we have since recognized that the case "stands for the principle that Congress cannot vest review of the decisions of Article III courts in officials of the Executive Branch." Plaut, supra, at 218; see also Morrison v. Olson, 487 U. S. 654, 677, n. 15 (1988). As we recognized in Plaut, such an effort by a coequal branch to "annul a final judgment" is "'an assumption of Judicial power' and therefore forbidden." 514 U. S., at 224 (quoting Bates v. Kimball, 2 Chipman 77 (Vt. 1824)).

Unlike the situation in Hayburn's Case, § 3626(e)(2) does not involve the direct review of a judicial decision by officials of the Legislative or Executive Branches. Nonetheless, the prisoners suggest that § 3626(e)(2) falls within Hayburn's prohibition against an indirect legislative "suspension" or reopening of a final judgment, such as that addressed in Plaut. See Plaut, supra, at 226 (quoting Hayburn's Case, supra, at 413 (letter of Iredell, J., and Sitgreaves, D. J.) (" '[N]o decision of any court of the United States can, under any circumstances,... be liable to a revision, or even suspension, by the [l]egislature itself, in whom no judicial power of any kind appears to be vested' ")). In Plaut, we held that a federal statute that required federal courts to reopen final judgments that had been entered before the statute's enactment was unconstitutional on separation of powers grounds. 514 U. S., at 211. The plaintiffs had brought a civil securities fraud action seeking money damages. Id., at 213. While that action was pending, we ruled in Lampf, Pleva, Lipkind, Prupis & Petigrow v. Gilbertson, 501 U. S. 350 (1991), that such suits must be commenced within one year after the discovery of the facts constituting the violation and within three years after such violation. In light of this intervening decision, the Plaut plaintiffs' suit was untimely, and the District Court accordingly dismissed the action as time barred. Plaut, supra, at 214. After the judgment dismissing the case had become final, Congress enacted a statute providing for the reinstatement of those actions, including the Plaut plaintiffs', that had been dismissed under Lamp! but that would have been timely under the previously applicable statute of limitations. 514 U. S., at 215.

We concluded that this retroactive command that federal courts reopen final judgments exceeded Congress' authority. Id., at 218-219. The decision of an inferior court within the Article III hierarchy is not the final word of the department (unless the time for appeal has expired), and "[i]t is the obligation of the last court in the hierarchy that rules on the case to give effect to Congress's latest enactment, even when that has the effect of overturning the judgment of an inferior court, since each court, at every level, must 'decide according to existing laws.'" Id., at 227 (quoting United States v. Schooner Peggy, 1 Cranch 103, 109 (1801)). But once a judicial decision achieves finality, it "becomes the last word of the judicial department." 514 U. S., at 227. And because Article III "gives the Federal Judiciary the power, not merely to rule on cases, but to decide them, subject to review only by superior courts in the Article III hierarchy," id., at 218-219, the "judicial Power is one to render dispositive judgments," and Congress cannot retroactively command Article III courts to reopen final judgments, id., at 219 (quoting Easterbrook, Presidential Review, 40 Case W. Res. L. Rev. 905, 926 (1990) (internal quotation marks omitted)).

Plaut, however, was careful to distinguish the situation before the Court in that case-legislation that attempted to reopen the dismissal of a suit seeking money damages-from legislation that "altered the prospective effect of injunctions entered by Article III courts." 514 U. S., at 232. We emphasized that "nothing in our holding today calls... into question" Congress' authority to alter the prospective effect of previously entered injunctions. Ibid. Prospective relief under a continuing, executory decree remains subject to alteration due to changes in the underlying law. Cf. Land graf v. USI Film Products, 511 U. S. 244, 273 (1994) ("When the intervening statute authorizes or affects the propriety of prospective relief, application of the new provision is not retroactive"). This conclusion follows from our decisions in Pennsylvania v. Wheeling & Belmont Bridge Co., 13 How. 518 (1852) (Wheeling Bridge 1), and Pennsylvania v. Wheeling & Belmont Bridge Co., 18 How. 421 (1856) (Wheeling Bridge II).

In Wheeling Bridge I, we held that a bridge across the Ohio River, because it was too low, unlawfully "obstruct[edJ the navigation of the Ohio," and ordered that the bridge be raised or permanently removed. 13 How., at 578. Shortly thereafter, Congress enacted legislation declaring the bridge to be a "lawful structur[eJ," establishing the bridge as a "'post-roa[dJ for the passage of the mails of the United States,'" and declaring that the Wheeling and Belmont Bridge Company was authorized to maintain the bridge at its then-current site and elevation. Wheeling Bridge II, supra, at 429. After the bridge was destroyed in a storm, Pennsylvania sued to enjoin the bridge's reconstruction, arguing that the statute legalizing the bridge was unconstitutional because it effectively annulled the Court's decision in Wheeling Bridge 1. We rejected that argument, concluding that the decree in Wheeling Bridge I provided for ongoing relief by "directing the abatement of the obstruction" which enjoined the defendants' from any continuance or reconstruction of the obstruction. Because the intervening statute altered the underlying law such that the bridge was no longer an unlawful obstruction, we held that it was "quite plain the decree of the court cannot be enforced." Wheeling Bridge II, supra, at 431-432. The Court explained that had Wheeling Bridge I awarded money damages in an action at law, then that judgment would be final, and Congress' later action could not have affected plaintiff's right to those damages. See 18 How., at 431. But because the decree entered in Wheeling Bridge I provided for pro spec tive relief-a continuing injunction against the continuation or reconstruction of the bridge-the ongoing validity of the injunctive relief depended on "whether or not [the bridge] interferes with the right of navigation." 18 How., at 431. When Congress altered the underlying law such that the bridge was no longer an unlawful obstruction, the injunction against the maintenance of the bridge was not enforceable. See id., at 432.

Applied here, the principles of Wheeling Bridge II demonstrate that the automatic stay of § 3626(e)(2) does not unconstitutionally "suspend" or reopen a judgment of an Article III court. Section 3626(e)(2) does not by itself "tell judges when, how, or what to do." 178 F. 3d, at 449 (Easterbrook, J., dissenting from denial of rehearing en banc). Instead, § 3626(e)(2) merely reflects the change implemented by § 3626(b), which does the "heavy lifting" in the statutory scheme by establishing new standards for prospective relief. See Berwanger v. Cottey, 178 F.3d 834, 839 (CA7 1999). Section 3626 prohibits the continuation of prospective relief that was "approved or granted in the absence of a finding by the court that the relief is narrowly drawn, extends no further than necessary to correct the violation of the Federal right, and is the least intrusive means to correct the violation," § 3626(b)(2), or in the absence of "findings based on the record that prospective relief remains necessary to correct a current and ongoing violation of a Federal right, extends no further than necessary to correct the violation of the Federal right, and that the prospective relief is narrowly drawn and the least intrusive means to correct the violation," § 3626(b)(3). Accordingly, if prospective relief under an existing decree had been granted or approved absent such findings, then that prospective relief must cease, see § 3626(b)(2), unless and until the court makes findings on the record that such relief remains necessary to correct an ongoing violation and is narrowly tailored, see § 3626(b)(3). The PLRA's automatic stay provision assists in the enforce ment of §§ 3626(b)(2) and (3) by requiring the court to stay any prospective relief that, due to the change in the underlying standard, is no longer enforceable, i. e., prospective relief that is not supported by the findings specified in §§ 3626(b)(2) and (3).

By establishing new standards for the enforcement of prospective relief in § 3626(b), Congress has altered the relevant underlying law. The PLRA has restricted courts' authority to issue and enforce prospective relief concerning prison conditions, requiring that such relief be supported by findings and precisely tailored to what is needed to remedy the violation of a federal right. See Benjamin v. Jacobson, 172 F.3d 144, 163 (CA2 1999) (en bane); Imprisoned Citizens Union v. Ridge, 169 F.3d 178, 184-185 (CA3 1999); Tyler v. Murphy, 135 F.3d 594, 597 (CA8 1998); Inmates of Suffolk County Jail v. Rouse, 129 F.3d 649, 657 (CA1 1997). We note that the constitutionality of § 3626(b) is not challenged here; we assume, without deciding, that the new standards it pronounces are effective. As Plaut and Wheeling Bridge II instruct, when Congress changes the law underlying a judgment awarding prospective relief, that relief is no longer enforceable to the extent it is inconsistent with the new law. Although the remedial injunction here is a "final judgment" for purposes of appeal, it is not the "last word of the judicial department." Plaut, 514 U. S., at 227. The provision of prospective relief is subject to the continuing supervisory jurisdiction of the court, and therefore may be altered according to subsequent changes in the law. See Rufo v. Inmates of Suffolk County Jail, 502 U. S. 367, 388 (1992). Prospective relief must be "modified if, as it later turns out, one or more of the obligations placed upon the parties has become impermissible under federal law." Ibid.; see also Railway Employees v. Wright, 364 U. S. 642, 646-647 (1961) (a court has the authority to alter the prospective effect of an injunction to reflect a change in circumstances, whether of law or fact, that has occurred since the injunction was entered); Lauf v. E. G. Skinner & Co., 303 U. S. 323, 329 (1938) (applying the Norris-LaGuardia Act's prohibition on a district court's entry of injunctive relief in the absence of findings).

The entry of the automatic stay under § 3626(e)(2) helps to implement the change in the law caused by §§ 3626(b)(2) and (3). If the prospective relief under the existing decree is not supported by the findings required under § 3626(b)(2), and the court has not made the findings required by § 3626(b)(3), then prospective relief is no longer enforceable and must be stayed. The entry of the stay does not reopen or "suspend" the previous judgment, nor does it divest the court of authority to decide the merits of the termination motion. Rather, the stay merely reflects the changed legal circumstances-that prospective relief under the existing decree is no longer enforceable, and remains unenforceable unless and until the court makes the findings required by § 3626(b)(3).

For the same reasons, § 3626(e)(2) does not violate the separation of powers principle articulated in United States v. Klein, 13 Wall. 128 (1872). In that case, Klein, the executor of the estate of a Confederate sympathizer, sought to recover the value of property seized by the United States during the Civil War, which by statute was recoverable if Klein could demonstrate that the decedent had not given aid or comfort to the rebellion. See id., at 131. In United States v. Padelford, 9 Wall. 531, 542-543 (1870), we held that a Presidential pardon satisfied the burden of proving that no such aid or comfort had been given. While Klein's case was pending, Congress enacted a statute providing that a pardon would instead be taken as proof that the pardoned individual had in fact aided the enemy, and if the claimant offered proof of a pardon the court must dismiss the case for lack of jurisdiction. Klein, 13 Wall., at 133-134. We concluded that the statute was unconstitutional because it purported to "pre scribe rules of decision to the Judicial Department of the government in cases pending before it." Id., at 146.

Here, the prisoners argue that Congress has similarly prescribed a rule of decision because, for the period of time until the district court makes a final decision on the merits of the motion to terminate prospective relief, § 3626(e)(2) mandates a particular outcome: the termination of prospective relief. As we noted in Plaut, however, "[w]hatever the precise scope of Klein,... later decisions have made clear that its prohibition does not take hold when Congress 'amendes] applicable law.''' 514 U. S., at 218 (quoting Robertson v. Seattle Audubon Soc., 503 U. S. 429, 441 (1992)). The prisoners concede this point but contend that, because § 3626(e)(2) does not itself amend the legal standard, Klein is still applicable. As we have explained, however, § 3626(e)(2) must be read not in isolation, but in the context of § 3626 as a whole. Section 3626(e)(2) operates in conjunction with the new standards for the continuation of prospective relief; if the new standards of § 3626(b)(2) are not met, then the stay "shall operate" unless and until the court makes the findings required by § 3626(b)(3). Rather than prescribing a rule of decision, § 3626(e)(2) simply imposes the consequences of the court's application of the new legal standard.

Finally, the prisoners assert that, even if § 3626(e)(2) does not fall within the recognized prohibitions of Hayburn's Case, Plaut, or Klein, it still offends the principles of separation of powers because it places a deadline on judicial decisionmaking, thereby interfering with core judicial functions. Congress' imposition of a time limit in § 3626(e)(2), however, does not in itself offend the structural concerns underlying the Constitution's separation of powers. For example, if the PLRA granted courts 10 years to determine whether they could make the required findings, then certainly the PLRA would raise no apprehensions that Congress had encroached on the core function of the Judiciary to decide "cases and controversies properly before them." United Opinion of SOUTER, J.

States v. Raines, 362 U. S. 17, 20 (1960). Respondents' concern with the time limit, then, must be its relative brevity. But whether the time is so short that it deprives litigants of a meaningful opportunity to be heard is a due process question, an issue that is not before us. We leave open, therefore, the question whether this time limit, particularly in a complex case, may implicate due process concerns.

In contrast to due process, which principally serves to protect the personal rights of litigants to a full and fair hearing, separation of powers principles are primarily addressed to the structural concerns of protecting the role of the independent Judiciary within the constitutional design. In this action, we have no occasion to decide whether there could be a time constraint on judicial action that was so severe that it implicated these structural separation of powers concerns. The PLRA does not deprive courts of their adjudicatory role, but merely provides a new legal standard for relief and encourages courts to apply that standard promptly.

Through the PLRA, Congress clearly intended to make operation of the automatic stay mandatory, precluding courts from exercising their equitable powers to enjoin the stay. And we conclude that this provision does not violate separation of powers principles. Accordingly, the judgment of the Court of Appeals for the Seventh Circuit is reversed, and the action is remanded for further proceedings consistent with this opinion.

It is so ordered.

Notes

* As originally enacted, § 3626(e)(2) provided that "[a]ny prospective relief subject to a pending motion [for termination] shall be automatically stayed during the period... beginning on the 30th day after such motion is filed... and ending on the date the court enters a final order ruling on the motion." §802, 110 Stat. 1321-68 to 1321-69. The 1997 amendments to the PLRA revised the automatic stay provision to its current form, and Congress specified that the 1997 amendments "shall apply to pending cases." 18 U. S. C. § 3626 note (1994 ed., Supp. IV).