delivered the opinion of the Court. †
This case requires us to decide whether a federal court may-pass on the validity of an Indian tribe’s ordinance denying membership to the children of certain female tribal members.
Petitioner Santa Clara Pueblo is an Indian tribe that has been in existence for over 600 years. Respondents, a female member of the tribe and her daughter, brought suit in federal court against the tribe and its Governor, petitioner Lucario Padilla, seeking declaratory and injunctive relief against enforcement of a tribal ordinance denying membership in the tribe to children of female members who marry outside the tribe, while extending membership to children of male members who marry outside the tribe. Respondents claimed that this rule discriminates on the basis of both sex and ancestry in violation of Title I of the Indian Civil Rights Act of 1968 (ICRA), 25 U. S. C. §§ 1301-1303, which provides in relevant part that “[n]o Indian tribe in exercising powers of self-government shall . . . deny to any person within its jurisdiction the equal protection of its laws.” § 1302 (8).1
Title I of the ICRA does not expressly authorize the bringing of civil actions for declaratory or injunctive relief to *52enforce its substantive provisions. The threshold issue in this case is thus whether the Act may be interpreted to impliedly authorize such actions, against a tribe or its officers, in the federal courts. For the reasons set forth below, we hold that the Act cannot be so read.
I
Respondent Julia Martinez is a full-blooded member of the Santa Clara Pueblo, and resides on the Santa Clara Reservation in Northern New Mexico. In 1941 she married a Navajo Indian with whom she has since had several children, including respondent Audrey Martinez. Two years before this marriage, the Pueblo passed the membership ordinance here at issue, which bars admission of the Martinez children to the tribe because their father is not a Santa Claran.2 Although the children were raised on the reservation and continue to reside there now that they are adults, as a result of their exclusion from membership they may not vote in tribal elections or hold secular office in the tribe; moreover, they have no right to remain on the reservation in the event of their *53mother’s death, or to inherit their mother’s home or her pos-sessory interests in the communal lands.
After unsuccessful efforts to persuade the tribe to change the membership rule, respondents filed this lawsuit in the United States District Court for the District of New Mexico, on behalf of themselves and others similarly situated.3 Petitioners moved to dismiss the complaint on the ground that the court lacked jurisdiction to decide intratribal controversies affecting matters of tribal self-government and sovereignty. The District Court rejected petitioners’ contention, finding that jurisdiction was conferred by 28 U. S. C. § 1343 (4) and 25 U. S. C. § 1302 (8). The court apparently concluded, first, that the substantive provisions of Title I impliedly authorized civil actions for declaratory and injunc-tive relief, and second, that the tribe was not immune from such suit.4 Accordingly, the motion to dismiss was denied. 402 F. Supp. 5 (1975).
Following a full trial, the District Court found for petitioners on the merits. While acknowledging the relatively recent origin of the disputed rule, the District Court never*54theless found it to reflect traditional values of patriarchy still significant in tribal life. The court recognized the vital importance of respondents’ interests,5 but also determined that membership rules were “no more or less than a mechanism of social . . . self-definition,” and as such were basic to the tribe’s survival as a cultural and economic entity. Id., at 15.6 In sustaining .the ordinance’s validity under the “equal protection clause” of the ICRA, 25 U. S. C. § 1302 (8), the District Court concluded that the balance to be struck between these competing interests was better left to the judgment of the Pueblo:
“[T]he equal protection guarantee of the Indian Civil Rights Act should not be construed in a manner which would require or authorize this Court to> determine which traditional values will promote cultural survival and should therefore be preserved .... Such a determination should be made by the people of Santa Clara; not only because they can best decide what values are important, but also because they must live with the decision every day. . . .
“. . . To abrogate tribal decisions, particularly in the delicate area of membership, for whatever 'good’ reasons, is to destroy cultural identity under the guise of saving it.” 402 F. Supp., at 18-19.
On respondents’ appeal, the Court of Appeals for the Tenth Circuit upheld the District Court’s determination that 28 U. S. C. § 1343 (4) provides a jurisdictional basis for actions *55under Title I of the ICRA. 540 F. 2d 1039, 1042 (1976). It found that “since [the ICRA] was designed to provide protection against tribal authority, the intention of Congress to allow suits against the tribe was an essential aspect [of the ICRA]. Otherwise, it would constitute a mere unenforceable declaration of principles.” Ibid. The Court of Appeals disagreed, however, with the District Court’s ruling on the merits. While recognizing that standards of analysis developed under the Fourteenth Amendment’s Equal Protection Clause were not necessarily controlling in the interpretation of this statute,'the Court of Appeals apparently concluded that because the classification was one based upon sex it was presumptively invidious and could be sustained only if justified by a compelling tribal interest. See id., at 1047-1048. Because of the ordinance’s recent vintage, and because in the court’s view the rule did not' rationally identify those persons who were emotionally and culturally Santa Clarans, the court held that the tribe’s interest in the ordinance was not substantial enough to justify its discriminatory effect: Ibid.
We granted certiorari, 431 U. S. 913 (1977), and we now reverse.
II
Indian tribes are “distinct, independent political communities, retaining their original natural rights” in matters of local self-government. Worcester v. Georgia, 6 Pet. 515, 559 (1832); see United States v. Mazurie, 419 U. S. 544, 557 (1975); F. Cohen, Handbook of Federal Indian Law 122-123 (1945). Although no longer “possessed of the full attributes of sovereignty,” they remain a “separate people, with the power of regulating their internal and social relations.” United States v. Kagama, 118 U. S. 375, 381-382 (1886). See United States v. Wheeler, 435 U. S. 313 (1978). They have power to make their own substantive law in internal matters, see Roff v. Burney, 168 U. S. 218 (1897) (mem*56bership); Jones v. Meehan, 175 U. S. 1, 29 (1899) (inheritance rules); United States v. Quiver, 241 U. S. 602 (1916) (domestic relations), and to enforce that law in their own forums, see, e. g., Williams v. Lee, 358 U. S. 217 (1959).
As separate sovereigns pre-existing the Constitution, tribes have historically been regarded as unconstrained by those constitutional provisions framed specifically as limitations on federal or state authority. Thus, in Talton v. Mayes, 163 U. S. 376 (1896), this Court held that the Fifth Amendment did not “operat[e] upon” “the powers of local self-government enjoyed” by the tribes. Id., at 384. In ensuing years the lower federal courts have extended the holding of Taitón to other provisions of the Bill of Rights, as well as to the Fourteenth Amendment.7
As the Court in Taitón recognized, however, Congress has plenary authority to limit, modify or eliminate the powers of local self-government which the tribes otherwise possess. Ibid. See, e. g., United States v. Kagama, supra, *57at 379-381, 383-384; Cherokee Nation v. Hitchcock, 187 U. S. 294, 305-307 (1902). Title I of the ICRA, 25 U. S. C. §§ 1301-1303, represents an exercise of that authority. In 25 U. S. C. § 1302, Congress acted to modify the effect of Taitón and its progeny by imposing certain restrictions upon tribal governments similar, but not identical, to those contained in the Bill of Rights and the Fourteenth Amendment.8 *58In 25 U. S. C. § 1303, the only remedial provision expressly supplied by Congress, the “privilege of the writ of habeas corpus” is made “available to any person, in a court of the United States, to test the legality of his detention by order of an Indian tribe.”
Petitioners concede that § 1302 modifies the substantive law applicable to the tribe; they urge, however, that Congress did not intend to authorize federal courts to review violations of its provisions except as they might arise on habeas corpus. They argue, further, that Congress did not waive the- tribe’s sovereign immunity from suit. Respondents, on the other hand, contend that § 1302 not only modifies the substantive law applicable to the exercise of sovereign tribal powers, but also authorizes civil suits for equitable relief against the tribe and its officers in federal courts. We consider these contentions first with respect to the tribe.
Ill
Indian tribes have long been recognized as possessing the common-law immunity from suit traditionally enjoyed by sovereign powers. Turner v. United States, 248 U. S. 354, 358 (1919); United States v. United States Fidelity & Guaranty, Co., 309 U. S. 506, 512-513 (1940); Puyallup Tribe v. Washington Dept. of Game, 433 U. S. 165, 172-173 (1977). This aspect of tribal sovereignty, like all others, is subject to the superior and plenary control of Congress. But “without congressional authorization,” the “Indian Nations are exempt from suit.” United States v. United States Fidelity & Guaranty Co., supra, at 512.
It is settled that a waiver of sovereign immunity “ 'cannot be implied but must be unequivocally expressed.’ ” United States v. Testan, 424 U. S. 392, 399 (1976), quoting, United *59States v. King, 395 U. S. 1, 4 (1969). Nothing on the face of Title I of the ICRA purports to subject tribes to the jurisdiction of the federal courts in civil actions for injunctive or declaratory relief. Moreover, since the respondent in a habeas corpus action is the individual custodian of the prisoner, see, e. g., 28 U. S. C. § 2243, the provisions of § 1303 can hardly be read as a general waiver of the tribe’s sovereign immunity. In the absence here of any unequivocal expression of contrary legislative intent, we conclude that suits against the tribe under the ICRA are barred by its sovereign immunity from suit.
IV
As an officer of the Pueblo, petitioner Lucario Padilla is not protected by the tribe’s immunity from suit. See Puyallup Tribe v. Washington Dept. of Game, supra, at 171-172; cf. Ex parte Young, 209 U. S. 123 (1908). We must therefore determine whether the cause of action for declaratory and injunctive relief asserted here by respondents, though not expressly authorized by the statute, is nonetheless implicit in its terms.
In addressing this inquiry, we must bear in mind that providing a federal forum for issues arising under § 1302 constitutes an interference with tribal autonomy and self-government beyond that created by the change in substantive law itself. Even in matters involving commercial and domestic relations, we have recognized that “subjecting] a dispute arising on the reservation among reservation Indians to a forum other than the one they have established for themselves,” Fisher v. District Court, 424 U. S. 382, 387-388 (1976), may “undermine the authority of the tribal cour[t] . . . and hence . . . infringe on the right of the Indians to govern themselves.” Williams v. Lee, 358 U. S., at 223.9 *60A fortiori, resolution in a foreign forum of intratribal disputes of a more “public” character, such as the one in this case, cannot help but unsettle a tribal government’s ability to maintain authority. Although Congress clearly has power to authorize civil actions against tribal officers, and has done so with respect to habeas corpus relief in § 1303, a proper respect both for tribal sovereignty itself and for the plenary authority of Congress in this area cautions that we tread lightly in the absence of clear indications of legislative intent. Cf. Antoine v. Washington, 420 U. S. 194, 199-200 (1975); Choate v. Trapp, 224 U. S. 665, 675 (1912).
With these considerations of “Indian sovereignty ... [as] a backdrop against which the applicable . . . federal statut[e] must be read,” McClanahan v. Arizona State Tax Comm’n, 411 U. S. 164, 172 (1973), we turn now to those factors of more general relevance in determining whether a cause of action is implicit in a statute not expressly providing one. See Cort v. Ash, 422 U. S. 66 (1975).10 We note at the outset that *61a central purpose of the ICRA and in particular of Title I was to “secur[e] for the American Indian the broad constitutional rights afforded to other Americans,” and thereby to “protect individual Indians from arbitrary and unjust actions of tribal governments.” S. Rep. No. 841, 90th Cong., 1st Sess., 5-6 (1967). There is thus no doubt that respondents, American Indians living on the Santa Clara Reservation, are among the class for whose especial benefit this legislation was enacted. Texas & Pacific R. Co. v. Rigsby, 241 U. S. 33, 39 (1916); see Cort v. Ash, supra, at 78. Moreover, we have frequently recognized the propriety of inferring a federal cause of action for the enforcement of civil rights, even when Congress has spoken in purely declarative terms. See, e. g., Jones v. Alfred H. Mayer Co., 392 U. S. 409, 414 n. 13 (1968); Sullivan v. Little Hunting Park, Inc., 396 U. S. 229, 238-240 (1969). See also Bivens v. Six Unknown Fed. Narcotics Agents, 403 U. S. 388 (1971). These precedents, however, are simply not dispositive here. Not only are we unpersuaded that a judicially sanctioned intrusion into tribal sovereignty is required to fulfill the purposes of the ICRA, but to the contrary, the structure of the statutory scheme and the legislative history of Title I suggest that Congress’ failure to provide remedies other than habeas corpus was a deliberate one. See National Railroad Passenger Corp. v. Na*62tional Assn. of Railroad Passengers, 414 U. S. 453 (1974); Cort v. Ash, supra.
A
Two distinct and competing purposes are manifest in the provisions of the ICRA: In addition to its objective of strengthening the position of individual tribal members vis-á-vis the tribe, Congress also intended to promote the well-established federal “policy of furthering Indian self-government.” Morton v. Mancari, 417 U. S. 535, 551 (1974); see Fisher v. District Court, 424 U. S., at 391.11 This commitment to the goal of tribal self-determination is demonstrated by the provisions of Title I itself. Section 1302, rather than providing in wholesale fashion for the extension of constitutional requirements to tribal governments, as had been initially proposed,12 selectively incorporated and in some instances modified the safeguards of the Bill of Rights to fit the unique political, cultural, and economic needs of tribal gov*63ernments.13 See n. 8, supra. Thus, for example, the statute does not prohibit the establishment of religion, nor does it require jury trials in civil cases, or appointment of counsel for indigents in criminal cases, cf. Argersinger v. Hamlin, 407 U. S. 25 (1972).14
The other Titles of the ICRA also manifest a congressional purpose to protect tribal sovereignty from undue interference. For instance, Title III, 25 U. S. C. §§ 1321-1326, hailed by some of the ICRA’s supporters as the most important part of the Act,15 provides that States may not assume civil or criminal jurisdiction over “Indian country” without *64the prior consent of the tribe, thereby abrogating prior law to the contrary.16 Other Titles of the ICRA provide for strengthening certain tribal courts through training of Indian judges,17 and for minimizing interference by the Federal Bureau of Indian Affairs in tribal litigation.18
Where Congress seeks to promote dual objectives in a single statute, courts must be more than usually hesitant to infer from its silence a cause of action that, while serving one legislative purpose, will disserve the other. Creation of a federal cause of action for the enforcement of rights created in Title I, however useful it might be in securing compliance with § 1302, plainly would be at odds with the congressional goal of protecting tribal self-government. Not only would it undermine the authority of tribal forums, see supra, at 69-60, but it would also impose serious financial burdens on already “financially disadvantaged” tribes. Subcommittee on Constitutional Rights, Senate Judiciary Committee, Constitutional *65Rights of the American Indian: Summary Report of Hearings and Investigations Pursuant to S. Res. 194, 89th Cong., 2d Sess., 12 (Comm. Print 1966) (hereinafter cited as Summary Report).19
Moreover, contrary to the reasoning of the court below, implication of a federal remedy in addition to habeas corpus is not plainly required to give effect to Congress’ objective of extending constitutional norms to tribal self-government. Tribal forums are available to vindicate rights created by the ICRA, and § 1302 has the substantial and intended effect of changing the law which these forums are obliged to apply.20 Tribal courts have repeatedly been recognized as appropriate forums for the exclusive adjudication of disputes affecting important personal and property interests of both Indians and non-Indians.21 See, e. g., Fisher v. District Court, 424 U. S. *66382 (1976); Williams v. Lee, 358 U. S. 217 (1959). See also Ex parte Crow Dog, 109 U. S. 556 (1883). Nonjudicial tribal institutions have also been recognized as competent law-applying bodies. See United States v. Mazurie, 419 U. S. 544 (1975).22 Under these circumstances, we are reluctant to disturb the balance between the dual statutory objectives which Congress apparently struck in providing only for habeas corpus relief.
B
Our reluctance is strongly reinforced by the specific legislative history underlying 25 U. S. C. § 1303. This history; extending over more than three years,23 indicates that Congress’ provision for habeas corpus relief, and nothing more, reflected a considered accommodation of the competing goals of “preventing injustices perpetrated by tribal governments, *67on the one hand, and, on the other, avoiding undue or precipitous interference in the affairs of the Indian people.” Summary Report 11.
In settling on habeas corpus as the exclusive means for federal-court review of tribal criminal proceedings, Congress opted for a less intrusive review mechanism than had been initially proposed. Originally, the legislation would have authorized de novo review in federal court of all convictions obtained in tribal courts.24 At hearings held on the proposed legislation in 1965, however, it became clear that even those in agreement with the general thrust of the review provision— to provide some form of judicial review of criminal proceedings in tribal courts — believed that de novo review would impose unmanageable financial burdens on tribal governments and needlessly displace tribal courts. See id., at 12; 1965 Hearings 22-23, 157, 162, 341-342. Moreover, tribal representatives argued that de novo review would “deprive the tribal court of all jurisdiction in the event of an appeal, thus having a harmful effect upon law enforcement within the reservation,” and urged instead that “decisions of tribal courts ... be reviewed in the U. S. district courts upon petition for a writ of habeas corpus.” Id., at 79. After considering numerous alternatives for review of tribal convictions, Congress apparently decided that review by way of habeas corpus would adequately protect the individual interests at stake while avoiding unnecessary intrusions on tribal governments.
Similarly, and of more direct import to the issue in this case, Congress considered and rejected proposals for federal review of alleged violations of the Act arising in a civil context. As initially introduced, the Act would have required the Attorney General to “receive and investigate” complaints *68relating to- deprivations of an Indian’s statutory or constitutional rights, and to bring “such criminal or other action as he deems appropriate to vindicate and secure such right to such Indian.”25 Notwithstanding the screening effect this proposal would have had on frivolous or vexatious lawsuits, it was bitterly opposed by several tribes. The Crow Tribe representative stated:
“This [bill] would in effect subject the tribal sovereignty of self-government to- the Federal government. . . . [B]y its broad terms [it] would allow the Attorney General to bring any kind of action as he deems appropriate. By this bill, any time a member of the tribe would not be satisfied with an action by the [tribal] council, it would allow them [sic] to file a complaint with the Attorney General and subject the tribe to a multitude of investigations and threat of court action.” 1965 Hearings 235 (statement of Mr. Real Bird).
In a similar vein, the Mescalero Apache Tribal Council argued that “[i]f the perpetually dissatisfied individual Indian were to be armed with legislation such as proposed in [this bill] he could disrupt the whole of a tribal government.” Id., at 343. In response, this provision for suit by the Attorney General was completely eliminated' from the ICRA. At the same time, Congress rejected a substitute proposed by the Interior Department that would have authorized the Department to adjudicate civil complaints concerning tribal actions, with review in the district courts- available from final decisions of the agency.26
*69Given, this history, it is highly unlikely that Congress would have intended a private cause of action for injunctive and declaratory relief to be available in the federal courts to secure enforcement of § 1302. Although the only Committee Report on the ICRA in its final form, S. Rep. No. 841, 90th Cong., 1st Sess. (1967), sheds little additional light on this question, it would hardly support a contrary conclusion.27 Indeed, its description of the purpose of Title I,28 as well as the floor *70debates on the bill,29 indicates that the ICRA was generally understood to authorize federal judicial review of tribal actions only through the habeas corpus provisions of § 1303.30 These factors, together with Congress’ rejection of proposals that clearly would have authorized causes of action other than habeas corpus, persuade us that Congress, aware of the intrusive effect of federal judicial review upon tribal self-government, intended to create only a limited mechanism for such review, namely, that provided for expressly in § 1303.
*71V
As the bill’s chief sponsor, Senator Ervin,31 commented in urging its passage, the ICRA “should not be considered as the final solution to the many serious constitutional problems confronting the American. Indian.” 113 Cong. Rec. 13473 (1967). Although Congress explored the extent to which tribes were adhering to constitutional norms in both civil and criminal contexts, its legislative investigation revealed that the most serious abuses of tribal power had occurred in the administration of criminal justice. See ibid., quoting Summary Report 24. In light of this finding, and given Congress’ desire not to intrude needlessly on tribal self-government, it is not surprising that Congress chose at this stage to provide for federal review only in habeas corpus proceedings.
By not exposing tribal officials to the full array of federal remedies available to redress actions of federal and state officials, Congress may also have considered that resolution of statutory issues under § 1302, and particularly those issues likely to arise in a civil context, will frequently depend on questions of tribal tradition and custom which tribal forums may be in a better position to evaluate than federal courts. Our relations with the Indian tribes have “always been . . . anomalous . . . and of a complex character.” United States v. Kagama, 118 U. S., at 381. Although we early rejected the notion that Indian tribes are “foreign states” for jurisdictional purposes under Art. III, Cherokee Nation v. Georgia, 5 Pet. 1 (1831), we have also recognized that the tribes remain quasi-sovereign nations which, by government structure, culture, and source of sovereignty are in many ways foreign to the constitutional institutions of the Federal and State Governments. See Elk v. Wilkins, 112 U. S. 94 (1884). As is suggested by the District Court’s opinion in this case, see supra, at 54, *72efforts by the federal judiciary to apply the statutory prohibitions of § 1302 in a civil context may substantially interfere with a tribe’s ability to maintain itself as a culturally and politically distinct entity.32
As we have repeatedly emphasized, Congress’ authority over Indian matters is extraordinarily broad, and the role of courts in adjusting relations between and among tribes and their members correspondingly restrained. See Lone Wolf v. Hitchcock, 187 U. S. 553, 565 (1903). Congress retains authority expressly to authorize civil actions for injunctive or other relief to redress violations of § 1302, in the event that the tribes themselves prove deficient in applying and enforcing its substantive provisions. But unless and until Congress makes clear its intention to permit the additional intrusion on tribal sovereignty that adjudication of such actions in a federal forum would represent, we are constrained to find that § 1302 does not impliedly authorize actions for declaratory or injunctive relief against either the tribe or its officers.
The judgment of the Court of Appeals is, accordingly,
Reversed.
Mr. Justice Blackmun took no part in the consideration or decision of this case.