370 Opinion of BRENNAN, J. not be permitted to appeal the District Court's interlocutory order. First, restrictions on participation may also be placed on an intervenor of right and on an original party.2 If we were to accept CNA's theory of constructive denial, then it would follow that an intervenor of right also could appeal restrictions placed on its participation as a constructive denial of the right to intervene. And if an intervenor of right is to be afforded such an appeal, there is no reason to deny an appeal to an original party. For example, an original party could seek to appeal an order denying crucial discovery as an order which constructively entered summary judgment. To allow such appeals would seriously disrupt appellate procedure, and due respect for the finality doctrine counsels that the Court avoid taking steps toward that end. Second, the alternative means of relief available to CNA, and available to an original party or intervenor of right facing similar restrictions, include the ability to petition the Court of Appeals for a writ of mandamus under the All Writs Act, 28 U. S. C. § 1651. Mandamus is an appropriate avenue for relief from orders unsuited to appellate review under the collateral-order doctrine; such orders are not representative of a class of orders for which interlocutory review is generally needed, but sometimes involve extraordinary circumstances giving rise to a compelling demand for pretrial relief. See 9 J. Moore, B. Ward, & J. Lucas, Moore's Federal Practice ¶110.10, p. 136 (2d ed. 1986); 16 C. Wright, A. Miller, E. 2“An intervention of right under the amended rule [24(a)] may be subject to appropriate conditions or restrictions responsive among other things to the requirements of efficient conduct of proceedings." Advisory Committee Notes on Fed. Rule Civ. Proc. 24, 28 U. S. C. App., p. 567. And as the Court observes, a district court will not infrequently issue pretrial orders dismissing claims or restricting the scope of discovery that may compromise the ability of original parties to protect their interests, and that may not be effectively reviewable on appeal. Ante, at 377; see, e. g., Kerr V. United States District Court, 426 U. S. 394 (1976) (discovery order limiting ability of plaintiffs to pursue claims). Opinion of BRENNAN, J. 480 U. S. Cooper, & E. Gressman, Federal Practice and Procedure § 3934 (1977 and Supp. 1986); cf. Douglas Oil Co. v. Petrol Stops Northwest, 441 U. S. 211, 232 (1979) (REHNQUIST, J., concurring) (“[O]ur cases and those of the Courts of Appeals hold that review of the granting or denial of discovery is not immediately reviewable, except perhaps by way of mandamus for gross abuse of discretion on the part of the trial court"); Community Broadcasting of Boston, Inc. v. FCC, 546 F. 2d 1022, 1028 (CA9 1976) (petition for writ of mandamus appropriate for orders which, as a class, do not qualify as collateral orders, but which in individual circumstances might work irreparable harm). It is true, of course, that mandamus is to be granted "only in extraordinary situations," Kerr v. United States District Court, 426 U. S. 394, 402 (1976), and that "the All Writs Act [should not be construed to] confe[r] an independent appellate power in the Courts of Appeals to review interlocutory orders." La Buy v. Howes Leather Co., 352 U. S. 249, 263 (1957) (BRENNAN, J., dissenting). The writ may properly issue, however, when "the action of the District Court tends to frustrate or impede the ultimate exercise by the Court of Appeals of its appellate jurisdiction granted in some other provision of the law." Id., at 264. Lower courts have therefore found the writ appropriate when "effective review by later appeal seems difficult." 16 Wright, Miller, Cooper, & Gressman, supra, §3934, p. 238. See, e. g., In re EEOC, 709 F. 2d 392 (CA5 1983) (issuing writ to vacate discovery order that was effectively unreviewable on appeal); Hamilton v. Morial, 644 F. 2d 351 (CA5 1981) (issuing writ to consolidate all pending suits alleging unconstitutional overcrowding in state prisons and jails). Thus, although CNA's argument that the order here is effectively unreviewable on appeal does not constitute persuasive grounds for affording CNA an interlocutory appeal, the argument could properly be made in support of a petition for mandamus. Through that petition, CNA could seek review of both the denial of 370 Opinion of BRENNAN, J. intervention of right and of the imposition of conditions, because, as explained above, the resolution of the former determines the scope of the District Court's discretion in issuing the latter. I conclude that CNA cannot appeal the interlocutory orders limiting its participation in this lawsuit as a constructive denial of its motion to intervene. CNA has available to it the "alternative means" available to any original party or intervenor of right seeking relief from extraordinarily prejudicial interlocutory orders, including the right to appeal from a final judgment and the right to petition for a writ of mandamus. I therefore concur in the judgment and join all but Part II-B of the opinion of the Court. Syllabus 480 U. S. TOWN OF NEWTON ET AL. v. RUMERY CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FIRST CIRCUIT No. 85-1449. Argued December 8, 1986-Decided March 9, 1987 After learning that a friend, David Champy, had been indicted by a New Hampshire county grand jury for aggravated felonious sexual assault, respondent sought more information from a mutual acquaintance, who coincidently was the victim of the assault and was expected to be the principal witness against Champy. The victim called the town of Newton's Chief of Police and told him that respondent was trying to force her to drop the charges against Champy. Ultimately, respondent was arrested and accused of the state-law felony of tampering with a witness. Respondent's attorney and the prosecutor negotiated an agreement whereby the prosecutor would dismiss the charges against him if he would agree to release any claims he might have against the town, its officials, or the victim for any harm caused by his arrest. Three days later, he signed the "release-dismissal agreement," and the criminal charges against him were dropped. Ten months later, he filed this action under 42 U. S. C. § 1983 in Federal District Court, alleging that the town and its officers had violated his constitutional rights by arresting him, defaming him, and imprisoning him falsely. The suit was dismissed on the basis of the assertion by the defendants (petitioners here) of the release-dismissal agreement as an affirmative defense. The court rejected respondent's argument that the agreement was unenforceable because it violated public policy, and concluded that a release of claims under § 1983 was valid if, as here, it resulted from a decision that was voluntary, deliberate, and informed. The Court of Appeals reversed, adopting a per se rule invalidating release-dismissal agreements. Held: The judgment is reversed, and the case is remanded. 778 F.2d 66, reversed and remanded. JUSTICE POWELL delivered the opinion of the Court with respect to Parts I, II, III-A, IV, and V, concluding that: 1. The question whether the policies underlying § 1983 may in some circumstances render a waiver of the right to sue thereunder unenforceable is one of federal law, to be resolved by reference to traditional common-law principles. The relevant principle is that a promise is unenforceable if the interest in its enforcement is outweighed in the circumstances by a public policy harmed by enforcement of the agreement. P. 392. 2. Although in some cases release-dismissal agreements may infringe important interests of the criminal defendant and of society as a whole, the mere possibility of harm to such interests does not call for a per se rule invalidating all such agreements. The risk, publicity, and expense of a criminal trial may intimidate a defendant, even if he believes his defense is meritorious. But this possibility does not justify invalidating all release-dismissal agreements. In many cases a defendant's choice to enter into a release-dismissal agreement will reflect a highly rational judgment that the certain benefits of escaping criminal prosecution exceed the speculative benefits of prevailing in a civil action. Respondent's voluntary decision to enter into the agreement here exemplifies such a judgment. Respondent, a sophisticated businessman, was not in jail and was represented by an experienced criminal lawyer, who drafted the agreement. Respondent considered the agreement for three days before signing it. Because respondent voluntarily waived his right to sue under § 1983, the public interest opposing involuntary waiver of constitutional rights is no reason to hold the agreement here invalid. Pp. 392-394. 3. The District Court's decision to enforce the agreement was correct. Not only did respondent voluntarily enter into the agreement, but also the prosecutor had a legitimate reason to make this agreement that was directly related to his prosecutorial responsibilities and was independent of his discretion as to bringing criminal charges. A significant consideration in the prosecutor's decision was the fact that it spared the victim of the alleged sexual offense from the public scrutiny and embarrassment she would have endured if she had been required to testify in either the civil trial or the criminal trial concerning respondent. Pp. 397-398. JUSTICE POWELL, joined by THE CHIEF JUSTICE, JUSTICE WHITE, and JUSTICE SCALIA, concluded in Part III-B that in some cases there may be a substantial basis for the Court of Appeals' concern that releasedismissal agreements offend public policy because they may tempt prosecutors to trump up charges in reaction to a defendant's civil rights claim, suppress evidence of police misconduct, and leave deprivations of constitutional rights unremedied. However, respondent had no public. duty to institute a § 1983 action merely to further the public's interest in revealing police misconduct. Congress confined the decision to bring such actions to the injured individual, not to the public at large. Release-dismissal agreements may tempt prosecutors to bring frivolous charges or to dismiss meritorious charges in order to protect the interests of other officials. But a per se rule of invalidity fails to credit other relevant public interests and improperly assumes prosecutorial misconduct. Many § 1983 suits are marginal and some are frivolous, but the burden of defending such suits is substantial, requiring officials' time and |