This case concerns the Black Hills of South Dakota, the Great Sioux Reservation, and a colorful, and in many respects tragic, chapter in the history of the Nation's West. Although the litigation comes down to a claim of interest since 1877 on an award of over $17 million, it is necessary, in order to understand the controversy, to review at some length the chronology of the case and its factual setting.

* For over a century now the Sioux Nation has claimed that the United States unlawfully abrogated the Fort Laramie Treaty of April 29, 1868, 15 Stat. 635, in Art. II of which the United States pledged that the Great Sioux Reservation, including the Black Hills, would be "set apart for the absolute and undisturbed use and occupation of the Indians herein named." Id., at 636. The Fort Laramie Treaty was concluded at the culmination of the Powder River War of 1866-1867, a series of military engagements in which the Sioux tribes, led by their great chief, Red Cloud, fought to protect the integrity of earlier-recognized treaty lands from the incursion of white settlers.1

The Fort Laramie Treaty included several agreements central to the issues presented in this case. First, it established the Great Sioux Reservation, a tract of land bounded on the east by the Missouri River, on the south by the northern border of the State of Nebraska, on the north by the forty-sixth parallel of north latitude, and on the west by the one hundred and fourth meridian of west longitude,2 in addition to certain reservations already existing east of the Missouri. The United States "solemnly agree[d]" that no unauthorized persons "shall ever be permitted to pass over, settle upon, or reside in [this] territory." Ibid.

Second, the United States permitted members of the Sioux tribes to select lands within the reservation for cultivation. Id., at 637. In order to assist the Sioux in becoming civilized farmers, the Government promised to provide them with the necessary services and materials, and with subsistence rations for four years. Id., at 639.3

Third, in exchange for the benefits conferred by the treaty, the Sioux agreed to relinquish their rights under the Treaty of September 17, 1851, to occupy territories outside the reservation, while reserving their "right to hunt on any lands north of North Platte, and on the Republican Fork of the Smoky Hill river, so long as the buffalo may range thereon in such numbers as to justify the chase." Ibid. The Indians also expressly agreed to withdraw all opposition to the building of railroads that did not pass over their reservation lands, not to engage in attacks on settlers, and to withdraw their opposition to the military posts and roads that had been established south of the North Platte River. Ibid.

"No treaty for the cession of any portion or part of the reservation herein described which may be held in common shall be of any validity or force as against the said Indians, unless executed and signed by at least three fourths of all the adult male Indians, occupying or interested in the same." Ibid.4

The years following the treaty brought relative peace to the Dakotas, an era of tranquility that was disturbed, however, by renewed speculation that the Black Hills, which were included in the Great Sioux Reservation, contained vast quantities of gold and silver.5 In 1874 the Army planned and undertook an exploratory expedition into the Hills, both for the purpose of establishing a military outpost from which to control those Sioux who had not accepted the terms of the Fort Laramie Treaty, and for the purpose of investigating "the country about which dreamy stories have been told." D. Jackson, Custer's Gold 14 (1966) (quoting the 1874 annual report of Lieutenant General Philip H. Sheridan, as Commander of the Military Division of the Missouri, to the Secretary of War). Lieutenant Colonel George Armstrong Custer led the expedition of close to 1,000 soldiers and teamsters, and a substantial number of military and civilian aides. Custer's journey began at Fort Abraham Lincoln on the Missouri River on July 2, 1874. By the end of that month they had reached the Black Hills, and by mid-August had confirmed the presence of gold fields in that region. The discovery of gold was widely reported in newspapers across the country.6 Custer's florid descriptions of the mineral and timber resources of the Black Hills, and the land's suitability for grazing and cultivation, also received wide circulation, and had the effect of creating an intense popular demand for the "opening" of the Hills for settlement.7 The only obstacle to "progress" was the Fort Laramie Treaty that reserved occupancy of the Hills to the Sioux.

Having promised the Sioux that the Black Hills were reserved to them, the United States Army was placed in the position of having to threaten military force, and occasionally to use it, to prevent prospectors and settlers from trespassing on lands reserved to the Indians. For example, in September 1874, General Sheridan sent instructions to Brigadier General Alfred H. Terry, Commander of the Department of Dakota, at Saint Paul, directing him to use force to prevent companies of prospectors from trespassing on the Sioux Reservation. At the same time, Sheridan let it be known that he would "give a cordial support to the settlement of the Black Hills," should Congress decide to "open up the country for settlement, by extinguishing the treaty rights of the Indians." App. 62-63. Sheridan's instructions were published in local newspapers. See id., at 63.8

Eventually, however, the Executive Branch of the Government decided to abandon the Nation's treaty obligation to preserve the integrity of the Sioux territory. In a letter dated November 9, 1875, to Terry, Sheridan reported that he had met with President Grant, the Secretary of the Interior, and the Secretary of War, and that the President had decided that the military should make no further resistance to the occupation of the Black Hills by miners, "it being his belief that such resistance only increased their desire and complicated the troubles." Id., at 59. These orders were to be enforced "quietly," ibid., and the President's decision was to remain "confidential." Id., at 59-60 (letter from Sheridan to Sherman).

With the Army's withdrawal from its role as enforcer of the Fort Laramie Treaty, the influx of settlers into the Black Hills increased. The Government concluded that the only practical course was to secure to the citizens of the United States the right to mine the Black Hills for gold. Toward that end, the Secretary of the Interior, in the spring of 1875, appointed a commission to negotiate with the Sioux. The commission was headed by William B. Allison. The tribal leaders of the Sioux were aware of the mineral value of the Black Hills and refused to sell the land for a price less than $70 million. The commission offered the Indians an annual rental of $400,000, or payment of $6 million for absolute relinquishment of the Black Hills. The negotiations broke down.9

In the winter of 1875-1876, many of the Sioux were hunting in the unceded territory north of the North Platte River, reserved to them for that purpose in the Fort Laramie Teaty. On December 6, 1875, for reasons that are not entirely clear, the Commissioner of Indian Affairs sent instructions to the Indian agents on the reservation to notify those hunters that if they did not return to the reservation agencies by January 31, 1876, they would be treated as "hostiles." Given the severity of the winter, compliance with these instructions was impossible. On February 1, the Secretary of the Interior nonetheless relinquished jurisdiction over all hostile Sioux, including those Indians exercising their treaty-protected hunting rights, to the War Department. The Army's campaign against the "hostiles" led to Sitting Bull's notable victory over Custer's forces at the battle of the Little Big Horn on June 25. That victory, of course, was short-lived, and those Indians who surrendered to the Army were returned to the reservation, and deprived of their weapons and horses, leaving them completely dependent for survival on rations provided them by the Government.10

In the meantime, Congress was becoming increasingly dissatisfied with the failure of the Sioux living on the reservation to become self-sufficient.11 The Sioux' entitlement to subsistence rations under the terms of the Fort Laramie Treaty had expired in 1872. Nonetheless, in each of the two following years, over $1 million was appropriated for feeding the Sioux. In August 1876, Congress enacted an appropriations bill providing that "hereafter there shall be no appropriation made for the subsistence" of the Sioux, unless they first relinquished their rights to the hunting grounds outside the reservation, ceded the Black Hills to the United States, and reached some accommodation with the Government that would be calculated to enable them to become self-supporting. Act of Aug. 15, 1876, 19 Stat. 176, 192.12 Toward this end, Congress requested the President to appoint another commission to negotiate with the Sioux for the cession of the Black Hills.

This commission, headed by George Manypenny, arrived in the Sioux country in early September and commenced meetings with the head men of the various tribes. The members of the commission impressed upon the Indians that the United States no longer had any obligation to provide them with subsistence rations. The commissioners brought with them the text of a treaty that had been prepared in advance. The principal provisions of this treaty were that the Sioux would relinquish their rights to the Black Hills and other lands west of the one hundred and third meridian, and their rights to hunt in the unceded territories to the north, in exchange for subsistence rations for as long as they would be needed to ensure the Sioux' survival. In setting out to obtain the tribes' agreement to this treaty, the commission ignored the stipulation of the Fort Laramie Treaty that any cession of the lands contained within the Great Sioux Reservation would have to be joined in by three-fourths of the adult males. Instead, the treaty was presented just to Sioux chiefs and their leading men. It was signed by only 10% of the adult male Sioux population.13

Congress resolved the impasse by enacting the 1876 "agreement" into law as the Act of Feb. 28, 1877 (1877 Act), 19 Stat. 254. The Act had the effect of abrogating the earlier Fort Laramie Treaty, and of implementing the terms of the Manypenny Commission's "agreement" with the Sioux leaders.14

The passage of the 1877 Act legitimized the settlers' invasion of the Black Hills, but throughout the years it has been regarded by the Sioux as a breach of this Nation's solemn obligation to reserve the Hills in perpetuity for occupation by the Indians. One historian of the Sioux Nation commented on Indian reaction to the Act in the following words:

"The Sioux thus affected have not gotten over talking about that treaty yet, and during the last few years they have maintained an organization called the Black Hills Treaty Association, which holds meetings each year at the various agencies for the purpose of studying the treaty with the intention of presenting a claim against the government for additional reimbursements for the territory ceded under it. Some think that Uncle Sam owes them about $9,000,000 on the deal, but it will probably be a hard matter to prove it." F. Fiske, The Taming of the Sioux 132 (1917).

Fiske's words were to prove prophetic.

Prior to 1946, Congress had not enacted any mechanism of general applicability by which Indian tribes could litigate treaty claims against the United States.15 The Sioux, however, after years of lobbying, succeeded in obtaining from Congress the passage of a special jurisdictional Act which provided them a forum for adjudication of all claims against the United States "under any treaties, agreements, or laws of Congress, or for the misappropriation of any of the funds or lands of said tribe or band or bands thereof." Act of June 3, 1920, ch. 222, 41 Stat. 738. Pursuant to this statute, the Sioux, in 1923, filed a petition with the Court of Claims alleging that the Government had taken the Black Hills without just compensation, in violation of the Fifth Amendment. This claim was dismissed by that court in 1942. In a lengthy and unanimous opinion, the court concluded that it was not authorized by the Act of June 3, 1920, to question whether the compensation afforded the Sioux by Congress in 1877 was an adequate price for the Black Hills, and that the Sioux' claim in this regard was a moral claim not protected by the Just Compensation Clause. Sioux Tribe v. United States, 97 Ct.Cl. 613 (1942), cert. denied, 318 U.S. 789, 63 S.Ct. 992, 87 L.Ed. 1155 (1943).

In 1946, Congress passed the Indian Claims Commission Act, 60 Stat. 1049, 25 U.S.C. § 70 et seq., creating a new forum to hear and determine all tribal grievances that had arisen previously. In 1950, counsel for the Sioux resubmitted the Black Hills claim to the Indian Claims Commission. The Commission initially ruled that the Sioux had failed to prove their case. Sioux Tribe v. United States, 2 Ind.Cl.Comm'n 646 (1954), aff'd, 146 F.Supp. 229 (Ct.Cl.1956). The Sioux filed a motion with the Court of Claims to vacate its judgment of affirmance alleging that the Commission's decision had been based on a record that was inadequate, due to the failings of the Sioux' former counsel. This motion was granted and the Court of Claims directed the Commission to consider whether the case should be reopened for the presentation of additional evidence. On November 19, 1958, the Commission entered an order reopening the case and announcing that it would reconsider its prior judgment on the merits of the Sioux claim. App. 265-266; see Sioux Tribe v. United States, 182 Ct.Cl. 912 (1968) (summary of proceedings).

Following the Sioux' filing of an amended petition, claiming again that the 1877 Act constituted a taking of the Black Hills for which just compensation had not been paid, there ensued a lengthy period of procedural sparring between the Indians and the Government. Finally, in October 1968, the Commission set down three questions for briefing and determination: (1) What land and rights did the United States acquire from the Sioux by the 1877 Act? (2) What, if any, consideration was given for that land and those rights? And (3) if there was no consideration for the Government's acquisition of the land and rights under the 1877 Act, was there any payment for such acquisition? App. 266.

Six years later, by a 4-to-1 vote, the Commission reached a preliminary decision on these questions. Sioux Nation v. United States, 33 Ind.Cl.Comm'n 151 (1974). The Commission first held that the 1942 Court of Claims decision did not bar the Sioux' Fifth Amendment taking claim through application of the doctrine of res judicata. The Commission concluded that the Court of Claims had dismissed the earlier suit for lack of jurisdiction, and that it had not determined the merits of the Black Hills claim. The Commission then went on to find that Congress, in 1877, had made no effort to give the Sioux full value for the ceded reservation lands. The only new obligation assumed by the Government in exchange for the Black Hills was its promise to provide the Sioux with subsistence rations, an obligation that was subject to several limiting conditions. See n. 14, supra. Under these circumstances, the Commission concluded that the consideration given the Indians in the 1877 Act had no relationship to the value of the property acquired. Moreover, there was no indication in the record that Congress ever attempted to relate the value of the rations to the value of the Black Hills. Applying the principles announced by the Court of Claims in Three Tribes of Fort Berthold Reservation v. United States, 182 Ct.Cl. 543, 390 F.2d 686 (1968), the Commission concluded that Congress had acted pursuant to its power of eminent domain when it passed the 1877 Act, rather than as a trustee for the Sioux, and that the Government must pay the Indians just compensation for the taking of the Black Hills.16

The Government filed an appeal with the Court of Claims from the Commission's interlocutory order, arguing alternatively that the Sioux' Fifth Amendment claim should have been barred by principles of res judicata and collateral estoppel, or that the 1877 Act did not effect a taking of the Black Hills for which just compensation was due. Without reaching the merits, the Court of Claims held that the Black Hills claim was barred by the res judicata effect of its 1942 decision. United States v. Sioux Nation, 207 Ct.Cl. 234, 518 F.2d 1298 (1975). The court's majority recognized that the practical impact of the question presented was limited to a determination of whether or not an award of interest would be available to the Indians. This followed from the Government's failure to appeal the Commission's holding that it had acquired the Black Hills through a course of unfair and dishonorable dealing for which the Sioux were entitled to damages, without interest, under § 2 of the Indian Claims Commission Act, 60 Stat. 1050, 25 U.S.C. § 70a(5). Only if the acquisition of the Black Hills amounted to an unconstitutional taking would the Sioux be entitled to interest. 207 Ct.Cl., at 237, 518 F.2d, at 1299.17

The court affirmed the Commission's holding that a want of fair and honorable dealings in this case was evidenced, and held that the Sioux thus would be entitled to an award of at least $17.5 million for the lands surrendered and for the gold taken by trespassing prospectors prior to passage of the 1877 Act. See n. 16, supra. The court also remarked upon President Grant's duplicity in breaching the Government's treaty obligation to keep trespassers out of the Black Hills, and the pattern of duress practiced by the Government on the starving Sioux to get them to agree to the sale of the Black Hills. The court concluded: "A more ripe and rank case of dishonorable dealings will never, in all probability, be found in our history, which is not, taken as a whole, the disgrace it now pleases some persons to believe." 207 Ct.Cl., at 241, 518 F.2d, at 1302.

Nonetheless, the court held that the merits of the Sioux' taking claim had been reached in 1942, and whether resolved "rightly or wrongly", id., at 249, 518 F.2d, at 1306, the claim was now barred by res judicata. The court observed that interest could not be awarded the Sioux on judgments obtained pursuant to the Indian Claims Commission Act, and that while Congress could correct this situation, the court could not. Ibid.18 The Sioux petitioned this Court for a writ of certiorari, but that petition was denied. 423 U.S. 1016, 96 S.Ct. 449, 46 L.Ed.2d 387 (1975).

The case returned to the Indian Claims Commission, where the value of the rights-of-way obtained by the Government through the 1877 Act was determined to be $3,484, and where it was decided that the Government had made no payments to the Sioux that could be considered as offsets. App. 316. The Government then moved the Commission to enter a final award in favor of the Sioux in the amount of $17.5 million, see n. 16, supra, but the Commission deferred entry of final judgment in view of legislation then pending in Congress that dealt with the case.

On March 13, 1978, Congress passed a statute providing for Court of Claims review of the merits of the Indian Claims Commission's judgment that the 1877 Act effected a taking of the Black Hills, without regard to the defenses of res judicata and collateral estoppel. The statute authorized the Court of Claims to take new evidence in the case and to conduct its review of the merits de novo. Pub.L. 95-243, 92 Stat. 153, amending § 20(b) of the Indian Claims Commission Act. See 25 U.S.C. § 70s(b) (1976 ed., Supp. II).

Acting pursuant to that statute, a majority of the Court of Claims, sitting en banc, in an opinion by Chief Judge Friedman, affirmed the Commission's holding that the 1877 Act effected a taking of the Black Hills and of rights-of-way across the reservation. 220 Ct.Cl. 442, 601 F.2d 1157 (1979).19 In doing so, the court applied the test it had earlier articulated in Fort Berthold, 182 Ct.Cl., at 553, 390 F.2d, at 691, asking whether Congress had made "a good faith effort to give the Indians the full value of the land," 220 Ct.Cl., at 452, 601 F.2d, at 1162, in order to decide whether the 1877 Act had effected a taking or whether it had been a noncompensable act of congressional guardianship over tribal property. The court characterized the Act as a taking, an exercise of Congress' power of eminent domain over Indian property. It distinguished broad statements seemingly leading to a contrary result in Lone Wolf v. Hitchcock, 187 U.S. 553, 23 S.Ct. 216, 47 L.Ed. 299 (1903), as inapplicable to a case involving a claim for just compensation. 220 Ct.Cl., at 465, 601 F.2d, at 1170.20

The court thus held that the Sioux were entitled to an award of interest, at the annual rate of 5%, on the principal sum of $17.1 million, dating from 1877.21

We granted the Government's petition for a writ of certiorari, 444 U.S. 989, 100 S.Ct. 519, 62 L.Ed.2d 418 (1979), in order to review the important constitutional questions presented by this case, questions not only of long-standing concern to the Sioux, but also of significant economic import to the Government.

Having twice denied petitions for certiorari in this litigation, see 318 U.S. 789, 63 S.Ct. 992, 87 L.Ed. 1155 (1943); 423 U.S. 1016, 96 S.Ct. 449, 46 L.Ed.2d 387 (1975), we are confronted with it for a third time as a result of the amendment, above noted, to the Indian Claims Commission Act of 1946, 25 U.S.C. § 70s(b)(1976 ed., Supp. II), which directed the Court of Claims to review the merits of the Black Hills takings claim without regard to the defense of res judicata. The amendment, approved March 13, 1978, provides:

"Notwithstanding any other provision of law, upon application by the claimants within thirty days from the date of the enactment of this sentence, the Court of Claims shall review on the merits, without regard to the defense of res judicata or collateral estoppel, that portion of the determination of the Indian Claims Commission entered February 15, 1974, adjudging that the Act of February 28, 1877 (19 Stat. 254), effected a taking of the Black Hills portion of the Great Sioux Reservation in violation of the fifth amendment, and shall enter judgment accordingly. In conducting such review, the Court shall receive and consider any additional evidence, including oral testimony, that either party may wish to provide on the issue of a fifth amendment taking and shall determine that issue de novo." 92 Stat. 153.

Before turning to the merits of the Court of Claims' conclusion that the 1877 Act effected a taking of the Black Hills, we must consider the question whether Congress, in enacting this 1978 amendment, "has inadvertently passed the limit which separates the legislative from the judicial power." United States v. Klein, 13 Wall. 128, 147, 20 L.Ed. 519 (1872).

There are two objections that might be raised to the constitutionality of this amendment, each framed in terms of the doctrine of separation of powers. The first would be that Congress impermissibly has disturbed the finality of a judicial decree by rendering the Court of Claims' earlier judgments in this case mere advisory opinions. See Hayburn's Case, 2 Dall. 408, 409, 410-414, 1 L.Ed. 436 (1792) (setting forth the views of three Circuit Courts, including among their complements Mr. Chief Justice Jay, and Justices Cushing, Wilson, Blair, and Iredell, that the Act of Mar. 23, 1792, 1 Stat. 243, was unconstitutional because it subjected the decisions of the Circuit Courts concerning eligibility for pension benefits to review by the Secretary of War and the Congress). The objection would take the form that Congress, in directing the Court of Claims to reach the merits of the Black Hills claim, effectively reviewed and reversed that court's 1975 judgment that the claim was barred by res judicata, or its 1942 judgment that the claim was not cognizable under the Fifth Amendment. Such legislative review of a judicial decision would interfere with the independent functions of the Judiciary.

The second objection would be that Congress overstepped its bounds by granting the Court of Claims jurisdiction to decide the merits of the Black Hills claim, while prescribing a rule for decision that left the court no adjudicatory function to perform. See United States v. Klein, 13 Wall., at 146; Yakus v. United States, 321 U.S. 414, 467-468, 64 S.Ct. 660, 687-686, 88 L.Ed. 834 (1944) (Rutledge, J., dissenting). Of course, in the context of this amendment, that objection would have to be framed in terms of Congress' removal of a single issue from the Court of Claims' purview, the question whether res judicata or collateral estoppel barred the Sioux' claim. For in passing the amendment, Congress left no doubt that the Court of Claims was free to decide the merits of the takings claim in accordance with the evidence it found and applicable rules of law. See n. 23, infra.

These objections to the constitutionality of the amendment were not raised by the Government before the Court of Claims. At oral argument in this Court, counsel for the United States, upon explicit questioning, advanced the position that the amendment was not beyond the limits of legislative power.22 The question whether the amendment impermissibly interfered with judicial power was debated, however, in the House of Representatives, and that body concluded that the Government's waiver of a "technical legal defense" in order to permit the Court of Claims to reconsider the merits of the Black Hills claim was within Congress' power to enact.23

The question debated on the floor of the House is one the answer to which is not immediately apparent. It requires us to examine the proper role of Congress and the courts in recognizing and determining claims against the United States, in light of more general principles concerning the legislative and judicial roles in our tripartite system of government. Our examination of the amendment's effect, and of this Court's precedents, leads us to conclude that neither of the two separation-of-powers objections described above is presented by this legislation.

Our starting point is Cherokee Nation v. United States, 270 U.S. 476, 46 S.Ct. 428, 70 L.Ed. 694 (1926). That decision concerned the Special Act of Congress, dated March 3, 1919, 40 Stat. 1316, conferring jurisdiction upon the Court of Claims "to hear, consider, and determine the claim of the Cherokee Nation against the United States for interest, in addition to all other interest heretofore allowed and paid, alleged to be owing from the United States to the Cherokee Nation on the funds arising from the judgment of the Court of Claims of May eighteenth, nineteen hundred and five." In the judgment referred to by the Act, the Court of Claims had allowed 5% simple interest on four Cherokee claims, to accrue from the date of liability. Cherokee Nation v. United States, 40 Ct.Cl. 252 (1905). This Court had affirmed that judgment, including the interest award. United States v. Cherokee Nation, 202 U.S. 101, 123-126, 26 S.Ct. 588, 598-599, 50 L.Ed. 949 (1906). Thereafter, and following payment of the judgment, the Cherokee presented to Congress a new claim that they were entitled to compound interest on the lump sum of principal and interest that had accrued up to 1895. It was this claim that prompted Congress, in 1919, to reconfer jurisdiction on the Court of Claims to consider the Cherokee's entitlement to that additional interest.

Ultimately, this Court held that the Cherokee were not entitled to the payment of compound interest on the original judgment awarded by the Court of Claims. 270 U.S., at 487-496, 46 S.Ct., at 432-435. Before turning to the merits of the interest claim, however, the Court considered "the effect of the act of 1919 in referring the issue in this case to the Court of Claims." Id., at 485-486, 46 S.Ct., at 432. The Court's conclusion concerning that question bears close examination:

"The judgment of this court in the suit by the Cherokee Nation against the United States, in April, 1906 (202 U.S. 101 [, 26 S.Ct. 588, 50 L.Ed. 949]), already referred to, awarded a large amount of interest. The question of interest was considered and decided, and it is quite clear that but for the special act of 1919, above quoted, the question here mooted would have been foreclosed as res judicata. In passing the act, Congress must have been well advised of this, and the only possible construction therefore to be put upon it is that Congress has therein expressed its desire, so far as the question of interest is concerned, to waive the effect of the judgment as res judicata, and to direct the Court of Claims to re-examine it and determine whether the interest therein allowed was all that should have been allowed, or whether it should be found to be as now claimed by the Cherokee Nation. The Solicitor General, representing the government, properly concedes this to be the correct view. The power of Congress to waive such an adjudication of course is clear." Id., at 486, 46 S.Ct., at 432 (last emphasis supplied).

The holding in Cherokee Nation that Congress has the power to waive the res judicata effect of a prior judgment entered in the Government's favor on a claim against the United States is dispositive of the question considered here. Moreover, that holding is consistent with a substantial body of precedent affirming the broad constitutional power of Congress to define and "to pay the Debts . . . of the United States." U.S.Const., Art. I, § 8, cl. 1. That precedent speaks directly to the separation-of-powers objections discussed above.

The scope of Congress' power to pay the Nation's debts seems first to have been construed by this Court in United States v. Realty Co., 163 U.S. 427, 16 S.Ct. 1120, 41 L.Ed. 215 (1896). There, the Court stated:

"The term 'debts' includes those debts or claims which rest upon a merely equitable or honorary obligation, and which would not be recoverable in a court of law if existing against an individual. The nation, speaking broadly, owes a 'debt' to an individual when his claim grows out of general principles of right and justice; when, in other words, it is based upon considerations of a moral or merely honorary nature, such as are binding on the conscience or the honor of an individual, although the debt could obtain no recognition in a court of law. The power of Congress extends at least as far as the recognition and payment of claims against the government which are thus founded." Id., at 440, 16 S.Ct., at 1125-26.

Other decisions clearly establish that Congress may recognize its obligation to pay a moral debt not only by direct appropriation, but also by waiving an otherwise valid defense to a legal claim against the United States, as Congress did in this case and in Cherokee Nation. Although the Court in Cherokee Nation did not expressly tie its conclusion that Congress had the power to waive the res judicata effect of a judgment in favor of the United States to Congress' constitutional power to pay the Nation's debts, the Cherokee Nation opinion did rely on the decision in Nock v. United States, 2 Ct.Cl. 451 (1867). See 270 U.S., at 486, 46 S.Ct., at 432.

In Nock, the Court of Claims was confronted with the precise question whether Congress invaded judicial power when it enacted a joint resolution, 14 Stat. 608, directing that court to decide a damages claim against the United States "in accordance with the principles of equity and justice," even though the merits of the claim previously had been resolved in the Government's favor. The court rejected the Government's argument that the joint resolution was unconstitutional as an exercise of "judicial powers" because it had the effect of setting aside the court's prior judgment. Rather, the court concluded:

"It is unquestionable, that the Constitution has invested Congress with no judicial powers; it cannot be doubted that a legislative direction to a court to find a judgment in a certain way would be little less than a judgment rendered directly by Congress. But here Congress do not attempt to award judgment, nor to grant a new trial judicially ; neither have they reversed a decree of this court; nor attempted in any way to interfere with the administration of justice. Congress are here to all intents and purposes the defendants, and as such they come into court through this resolution and say that they will not plead the former trial in bar, nor interpose the legal objection which defeated a recovery before." 2 Ct.Cl., at 457-458 (emphasis in original).

The Nock court thus expressly rejected the applicability of separation-of-powers objections to a congressional decision to waive the res judicata effect of a judgment in the Government's favor.24

The principles set forth in Cherokee Nation and Nock were substantially reaffirmed by this Court in Pope v. United States, 323 U.S. 1, 65 S.Ct. 16, 89 L.Ed. 3 (1944). There Congress had enacted special legislation conferring jurisdiction upon the Court of Claims, "notwithstanding any prior determination, any statute of limitations, release, or prior acceptance of partial allowance, to hear, determine, and render judgment upon" certain claims against the United States arising out of a construction contract. Special Act of Feb. 27, 1942, § 1, 56 Stat. 1122. The court was also directed to determine Pope's claims and render judgment upon them according to a particular formula for measuring the value of the work that he had performed. The Court of Claims construed the Special Act as deciding the questions of law presented by the case, and leaving it the role merely of computing the amount of the judgment for the claimant according to a mathematical formula. Pope v. United States, 100 Ct.Cl. 375, 379-380, 53 F.Supp. 570, 571-572 (1944). Based upon that reading of the Act, and this Court's decision in United States v. Klein, 13 Wall. 128, 20 L.Ed. 519 (1872) (see discussion infra, at 402-405), the Court of Claims held that the Act unconstitutionally interfered with judicial independence. 100 Ct.Cl., at 380-382, 53 F.Supp., at 572-573. It distinguished Cherokee Nation as a case in which Congress granted a claimant a new trial, without directing the courts how to decide the case. 100 Ct.Cl., at 387, and n. 5, 53 F.Supp., at 575, and n. 5.

This Court reversed the Court of Claims' judgment. In doing so, the Court differed with the Court of Claims' interpretation of the effect of the Special Act. First, the Court held that the Act did not disturb the earlier judgment denying Pope's claim for damages. "While inartistically drawn the Act's purpose and effect seem rather to have been to create a new obligation of the Government to pay petitioner's claims where no obligation existed before." 323 U.S., at 9, 65 S.Ct., at 21. Second, the Court held that Congress' recognition of Pope's claim was within its power to pay the Nation's debts, and that its use of the Court of Claims as an instrument for exercising that power did not impermissibly invade the judicial function:

"We perceive no constitutional obstacle to Congress's imposing on the Government a new obligation where there had been none before, for work performed by petitioner which was beneficial to the Government and for which Congress thought he had not been adequately compensated. The power of Congress to provide for the payment of debts, conferred by § 8 of Article I of the Constitution, is not restricted to payment of those obligations which are legally binding on the Government. It extends to the creation of such obligations in recognition of claims which are merely moral or honorary. . . . United States v. Realty Co., 163 U.S. 427, [, 16 S.Ct. 1120, 41 L.Ed. 215]. . . . Congress, by the creation of a legal, in recognition of a moral, obligation to pay petitioner's claims plainly did not encroach upon the judicial function which the Court of Claims had previously exercised in adjudicating that the obligation was not legal. [Footnote citing Nock and other cases omitted.] Nor do we think it did so by directing that court to pass upon petitioner's claims in conformity to the particular rule of liability prescribed by the Special Act and to give judgment accordingly. . . . See Cherokee Nation v. United States, 270 U.S. 476, 486 [, 46 S.Ct. 428, 432, 70 L.Ed. 694]." Id., at 9-10, 65 S.Ct., at 21.

In explaining its holding that the Special Act did not invade the judicial province of the Court of Claims by directing it to reach its judgment with reference to a specified formula, the Court stressed that Pope was required to pursue his claim in the usual manner, that the earlier factual findings made by the Court of Claims were not necessarily rendered conclusive by the Act, and that, even if Congress had stipulated to the facts, it was still a judicial function for the Court of Claims to render judgment on consent. Id., at 10-12, 65 S.Ct., at 21-22.

To be sure, the Court in Pope specifically declined to consider "just what application the principles announced in the Klein case could rightly be given to a case in which Congress sought, pendente lite, to set aside the judgment of the Court of Claims in favor of the Government and to require relitigation of the suit." Id., at 8-9, 65 S.Ct., at 21. The case before us might be viewed as presenting that question. We conclude, however, that the separation-of-powers question presented in this case has already been answered in Cherokee Nation, and that that answer is completely consistent with the principles articulated in Klein.

The decision in United States v. Klein, 13 Wall. 128, 20 L.Ed. 519 (1872), arose from the following facts: Klein was the administrator of the estate of V. F. Wilson, the deceased owner of property that had been sold by agents of the Government during the War Between the States. Klein sued the United States in the Court of Claims for the proceeds of that sale. His lawsuit was based on the Abandoned and Captured Property Act of March 3, 1863, 12 Stat. 820, which afforded such a cause of action to noncombatant property owners upon proof that they had "never given any aid or comfort to the present rebellion." Following the enactment of this legislation, President Lincoln had issued a proclamation granting "a full pardon" to certain persons engaged "in the existing rebellion" who desired to resume their allegiance to the Government, upon the condition that they take and maintain a prescribed oath. This pardon was to have the effect of restoring those persons' property rights. See 13 Stat. 737. The Court of Claims held that Wilson's taking of the amnesty oath had cured his participation in "the . . . rebellion," and that his administrator, Klein, was thus entitled to the proceeds of the sale. Wilson v. United States, 4 Ct.Cl. 559 (1869).

The Court of Claims' decision in Klein's case was consistent with this Court's later decision in a similar case, United States v. Padelford, 9 Wall. 531, 19 L.Ed. 788 (1870), holding that the Presidential pardon purged a participant "of whatever offence against the laws of the United States he had committed . . . and relieved [him] from any penalty which he might have incurred." Id., at 543. Following the Court's announcement of the judgment in Padelford, however, Congress enacted a proviso to the appropriations bill for the Court of Claims. The proviso had three effects: First, no Presidential pardon or amnesty was to be admissible in evidence on behalf of a claimant in the Court of Claims as the proof of loyalty required by the Abandoned and Captured Property Act. Second, the Supreme Court was to dismiss, for want of jurisdiction, any appeal from a judgment of the Court of Claims in favor of a claimant who had established his loyalty through a pardon. Third, the Court of Claims henceforth was to treat a claimant's receipt of a Presidential pardon, without protest, as conclusive evidence that he had given aid and comfort to the rebellion, and to dismiss any lawsuit on his behalf for want of jurisdiction. Act of July 12, 1870, ch. 251, 16 Stat. 230, 235.

The Government's appeal from the judgment in Klein's case was decided by this Court following the enactment of the appropriations proviso. This Court held the proviso unconstitutional notwithstanding Congress' recognized power "to make 'such exceptions from the appellate jurisdiction' [of the Supreme Court] as should seem to it expedient." 13 Wall., at 145. See U.S.Const., Art. III, § 2, cl. 2. This holding followed from the Court's interpretation of the proviso's effect:

"[T]he language of the proviso shows plainly that it does not intend to withhold appellate jurisdiction except as a means to an end. Its great and controlling purpose is to deny to pardons granted by the President the effect which this court had adjudged them to have." 13 Wall., at 145.

Thus construed, the proviso was unconstitutional in two respects: First, it prescribed a rule of decision in a case pending before the courts, and did so in a manner that required the courts to decide a controversy in the Government's favor.

"The court is required to ascertain the existence of certain facts and thereupon to declare that its jurisdiction on appeal has ceased, by dismissing the bill. What is this but to prescribe a rule for the decision of a cause in a particular way? In the case before us, the Court of Claims has rendered judgment for the claimant and an appeal has been taken to this court. We are directed to dismiss the appeal, if we find that the judgment must be affirmed, because of a pardon granted to the intestate of the claimants. Can we do so without allowing one party to the controversy to decide it in its own favor? Can we do so without allowing that the legislature may prescribe rules of decision to the Judicial Department of the government in cases pending before it?

* * * * *

". . . Can [Congress] prescribe a rule in conformity with which the court must deny to itself the jurisdiction thus conferred, because and only because its decision, in accordance with settled law, must be adverse to the government and favorable to the suitor? This question seems to us to answer itself." Id., at 146-147.

Second, the rule prescribed by the proviso "is also liable to just exception as impairing the effect of a pardon, and thus infringing the constitutional power of the Executive." Id., at 147. The Court held that it would not serve as an instrument toward the legislative end of changing the effect of a Presidential pardon. Id., at 148.

It was, of course, the former constitutional objection held applicable to the legislative proviso in Klein that the Court was concerned about in Pope. But that objection is not applicable to the case before us for two reasons. First, of obvious importance to the Klein holding was the fact that Congress was attempting to decide the controversy at issue in the Government's own favor. Thus, Congress' action could not be grounded upon its broad power to recognize and pay the Nation's debts. Second, and even more important, the proviso at issue in Klein had attempted "to prescribe a rule for the decision of a cause in a particular way." 13 Wall., at 146. The amendment at issue in the present case, however, like the Special Act at issue in Cherokee Nation, waived the defense of res judicata so that a legal claim could be resolved on the merits. Congress made no effort in either instance to control the Court of Claims' ultimate decision of that claim. See n. 23, supra.25

When Congress enacted the amendment directing the Court of Claims to review the merits of the Black Hills claim, it neither brought into question the finality of that court's earlier judgments, nor interfered with that court's judicial function in deciding the merits of the claim. When the Sioux returned to the Court of Claims following passage of the amendment, they were there in pursuit of judicial enforcement of a new legal right. Congress had not "reversed" the Court of Claims' holding that the claim was barred by res judicata, nor, for that matter, had it reviewed the 1942 decision rejecting the Sioux' claim on the merits. As Congress explicitly recognized, it only was providing a forum so that a new judicial review of the Black Hills claim could take place. This review was to be based on the facts found by the Court of Claims after reviewing all the evidence, and an application of generally controlling legal principles to those facts. For these reasons, Congress was not reviewing the merits of the Court of Claims' decisions, and did not interfere with the finality of its judgments.

Moreover, Congress in no way attempted to prescribe the outcome of the Court of Claims' new review of the merits. That court was left completely free to reaffirm its 1942 judgment that the Black Hills claim was not cognizable under the Fifth Amendment, if upon its review of the facts and law, such a decision was warranted. In this respect, the amendment before us is a far cry from the legislatively enacted "consent judgment" called into question in Pope, yet found constitutional as a valid exercise of Congress' broad power to pay the Nation's debts. And, for the same reasons, this amendment clearly is distinguishable from the proviso to this Court's appellate jurisdiction held unconstitutional in Klein.

In sum, as this Court implicitly held in Cherokee Nation, Congress' mere waiver of the res judicata effect of a prior judicial decision rejecting the validity of a legal claim against the United States does not violate the doctrine of separation of powers.

In reaching its conclusion that the 1877 Act effected a taking of the Black Hills for which just compensation was due the Sioux under the Fifth Amendment, the Court of Claims relied upon the "good faith effort" test developed in its earlier decision in Three Tribes of Fort Berthold Reservation v. United States, 182 Ct.Cl. 543, 390 F.2d 686 (1968). The Fort Berthold test had been designed to reconcile two lines of cases decided by this Court that seemingly were in conflict. The first line, exemplified by Lone Wolf v. Hitchcock, 187 U.S. 553, 23 S.Ct. 216, 47 L.Ed. 299 (1903), recognizes "that Congress possesse[s] a paramount power over the property of the Indians, by reason of its exercise of guardianship over their interests, and that such authority might be implied, even though opposed to the strict letter of a treaty with the Indians." Id., at 565, 23 S.Ct., at 221. The second line, exemplified by the more recent decision in Shoshone Tribe v. United States, 299 U.S. 476, 57 S.Ct. 244, 81 L.Ed. 360 (1937), concedes Congress' paramount power over Indian property, but holds, nonetheless, that "[t]he power does not extend so far as to enable the Government 'to give the tribal lands to others, or to appropriate them to its own purposes, without rendering, or assuming an obligation to render, just compensation.' " Id., at 497, 57 S.Ct., at 252 (quoting United States v. Creek Nation, 295 U.S. 103, 110, 55 S.Ct. 681, 684, 79 L.Ed. 1331 (1935)). In Shoshone Tribe, Mr. Justice Cardozo, in speaking for the Court, expressed the distinction between the conflicting principles in a characteristically pithy phrase: "Spoliation is not management." 299 U.S., at 498, 57 S.Ct., at 253.

The Fort Berthold test distinguishes between cases in which one or the other principle is applicable:

"It is obvious that Congress cannot simultaneously (1) act as trustee for the benefit of the Indians, exercising its plenary powers over the Indians and their property, as it thinks is in their best interests, and (2) exercise its sovereign power of eminent domain, taking the Indians' property within the meaning of the Fifth Amendment to the Constitution. In any given situation in which Congress has acted with regard to Indian people, it must have acted either in one capacity or the other. Congress can own two hats, but it cannot wear them both at the same time.

"Some guideline must be established so that a court can identify in which capacity Congress is acting. The following guideline would best give recognition to the basic distinction between the two types of congressional action: Where Congress makes a good faith effort to give the Indians the full value of the land and thus merely transmutes the property from land to money, there is no taking. This is a mere substitution of assets or change of form and is a traditional function of a trustee." 182 Ct.Cl., at 553, 390 F.2d, at 691.

Applying the Fort Berthold test to the facts of this case, the Court of Claims concluded that, in passing the 1877 Act, Congress had not made a good-faith effort to give the Sioux the full value of the Black Hills. The principal issue presented by this case is whether the legal standard applied by the Court of Claims was erroneous.26

The Government contends that the Court of Claims erred insofar as its holding that the 1877 Act effected a taking of the Black Hills was based on Congress' failure to indicate affirmatively that the consideration given the Sioux was of equivalent value to the property rights ceded to the Government. It argues that "the true rule is that Congress must be assumed to be acting within its plenary power to manage tribal assets if it reasonably can be concluded that the legislation was intended to promote the welfare of the tribe." Brief for United States 52. The Government derives support for this rule principally from this Court's decision in Lone Wolf v. Hitchcock.

In Lone Wolf, representatives of the Kiowa, Comanche, and Apache Tribes brought an equitable action against the Secretary of the Interior and other governmental officials to enjoin them from enforcing the terms of an Act of Congress that called for the sale of lands held by the Indians pursuant to the Medicine Lodge Treaty of 1867, 15 Stat. 581. That treaty, like the Fort Laramie Treaty of 1868, included a provision that any future cession of reservation lands would be without validity or force "unless executed and signed by at least three fourths of all the adult male Indians occupying the same." Id., at 585. The legislation at issue, Act of June 6, 1900, 31 Stat. 672, was based on an agreement with the Indians that had not been signed by the requisite number of adult males residing on the reservation.

This Court's principal holding in Lone Wolf was that "the legislative power might pass laws in conflict with treaties made with the Indians." 187 U.S., at 566, 23 S.Ct., at 221. The Court stated:

"The power exists to abrogate the provisions of an Indian treaty, though presumably such power will be exercised only when circumstances arise which will not only justify the government in disregarding the stipulations of the treaty, but may demand, in the interest of the country and the Indians themselves, that it should do so. When, therefore, treaties were entered into between the United States and a tribe of Indians it was never doubted that the power to abrogate existed in Congress, and that in a contingency such power might be availed of from considerations of governmental policy, particularly if consistent with perfect good faith towards the Indians." Ibid. (Emphasis in original.)27

The Court, therefore, was not required to consider the contentions of the Indians that the agreement ceding their lands had been obtained by fraud, and had not been signed by the requisite number of adult males. "[A]ll these matters, in any event, were solely within the domain of the legislative authority, and its action is conclusive upon the courts." Id., at 568, 23 S.Ct., at 222.

In the penultimate paragraph of the opinion, however, the Court in Lone Wolf went on to make some observations seemingly directed to the question whether the Act at issue might constitute a taking of Indian property without just compensation. The Court there stated:

"The act of June 6, 1900, which is complained of in the

bill, was enacted at a time when the tribal relations between the confederated tribes of Kiowas, Comanches, and Apaches still existed, and that statute and the statutes supplementary thereto dealt with the disposition of tribal property and purported to give an adequate consideration for the surplus lands not allotted among the Indians or reserved for their benefit. Indeed, the controversy which this case presents is concluded by the decision in Cherokee Nation v. Hitchcock, 187 U.S. 294, [23 S.Ct. 115, 47 L.Ed. 183,] decided at this term, where it was held that full administrative power was possessed by Congress over Indian tribal property. In effect, the action of Congress now complained of was but an exercise of such power, a mere change in the form of investment of Indian tribal property, the property of those who, as we have held, were in substantial effect the wards of the government. We must presume that Congress acted in perfect good faith in the dealings with the Indians of which complaint is made, and that the legislative branch of the government exercised its best judgment in the premises. In any event, as Congress possessed full power in the matter, the judiciary cannot question or inquire into the motives which prompted the enactment of this legislation. If injury was occasioned, which we do not wish to be understood as implying, by the use made by Congress of its power, relief must be sought by an appeal to that body for redress and not to the courts. The legislation in question was constitutional." Ibid. (Emphasis supplied.)

The Government relies on the italicized sentence in the quotation above to support its view "that Congress must be assumed to be acting within its plenary power to manage tribal assets if it reasonably can be concluded that the legislation was intended to promote the welfare of the tribe." Brief for United States 52. Several adjoining passages in the paragraph, however, lead us to doubt whether the Lone Wolf Court meant to state a general rule applicable to cases such as the one before us.

First, Lone Wolf presented a situation in which Congress "purported to give an adequate consideration" for the treaty lands taken from the Indians. In fact, the Act at issue set aside for the Indians a sum certain of $2 million for surplus reservation lands surrendered to the United States. 31 Stat. 678; see 187 U.S., at 555. In contrast, the background of the 1877 Act "reveals a situation where Congress did not 'purport' to provide 'adequate consideration,' nor was there any meaningful negotiation or arm's-length bargaining, nor did Congress consider it was paying a fair price." 220 Ct.Cl., at 475, 601 F.2d, at 1176 (concurring opinion).

Second, given the provisions of the Act at issue in Lone Wolf, the Court reasonably was able to conclude that "the action of Congress now complained of was but . . . a mere change in the form of investment of Indian tribal property." Under the Act of June 6, 1900, each head of a family was to be allotted a tract of land within the reservation of not less than 320 acres, an additional 480,000 acres of grazing land were set aside for the use of the tribes in common, and $2 million was paid to the Indians for the remaining surplus. 31 Stat. 677-678. In contrast, the historical background to the opening of the Black Hills for settlement, and the terms of the 1877 Act itself, see Part I, supra, would not lead one to conclude that the Act effected "a mere change in the form of investment of Indian tribal property."

Third, it seems significant that the views of the Court in Lone Wolf were based, in part, on a holding that "Congress possessed full power in the matter." Earlier in the opinion the Court stated: "Plenary authority over the tribal relations of the Indians has been exercised by Congress from the beginning, and the power has always been deemed a political one, not subject to be controlled by the judicial department of the government." 187 U.S., at 565, 23 S.Ct., at 221. Thus, it seems that the Court's conclusive presumption of congressional good faith was based in large measure on the idea that relations between this Nation and the Indian tribes are a political matter, not amenable to judicial review. That view, of course, has long since been discredited in taking cases, and was expressly laid to rest in Delaware Tribal Business Comm. v. Weeks, 430 U.S. 73, 84, 97 S.Ct. 911, 918, 51 L.Ed.2d 173 (1977).28

Fourth, and following up on the political question holding, the Lone Wolf opinion suggests that where the exercise of congressional power results in injury to Indian rights, "relief must be sought by an appeal to that body for redress and not to the courts." Unlike Lone Wolf, this case is one in which the Sioux have sought redress from Congress, and the Legislative Branch has responded by referring the matter to the courts for resolution. See Parts II and III, supra. Where Congress waives the Government's sovereign immunity, and expressly directs the courts to resolve a taking claim on the merits, there would appear to be far less reason to apply Lone Wolf's principles of deference. See United States v. Tillamooks, 329 U.S. 40, 46, 71 S.Ct. 552, 555, 95 L.Ed. 738 (1946) (plurality opinion).

The foregoing considerations support our conclusion that the passage from Lone Wolf here relied upon by the Government has limited relevance to this case. More significantly, Lone Wolf 's presumption of congressional good faith has little to commend it as an enduring principle for deciding questions of the kind presented here. In every case where a taking of treaty-protected property is alleged,29 a reviewing court must recognize that tribal lands are subject to Congress' power to control and manage the tribe's affairs. But the court must also be cognizant that "this power to control and manage [is] not absolute. While extending to all appropriate measures for protecting and advancing the tribe, it [is] subject to limitations inhering in . . . a guardianship and to pertinent constitutional restrictions." United States v. Creek Nation, 295 U.S., at 109-110, 55 S.Ct., at 684. Accord: Menominee Tribe v. United States, 391 U.S. 404, 413, 88 S.Ct. 1705, 1711, 20 L.Ed.2d 697 (1968); FPC v. Tuscarora Indian Nation, 362 U.S. 99, 122, 80 S.Ct. 543, 557, 4 L.Ed.2d 584 (1960); United States v. Klamath Indians, 304 U.S. 119, 123, 58 S.Ct. 799, 801, 82 L.Ed. 1219 (1938); United States v. Shoshone Tribe, 304 U.S. 111, 115-116, 58 S.Ct. 794, 797, 82 L.Ed. 1213 (1938); Shoshone Tribe v. United States, 299 U.S. 476, 497-498, 57 S.Ct. 244, 251-252, 81 L.Ed. 360 (1937).

As the Court of Claims recognized in its decision below, the question whether a particular measure was appropriate for protecting and advancing the tribe's interests, and therefore not subject to the constitutional command of the Just Compensation Clause, is factual in nature. The answer must be based on a consideration of all the evidence presented. We do not mean to imply that a reviewing court is to second-guess, from the perspective of hindsight, a legislative judgment that a particular measure would serve the best interests of the tribe. We do mean to require courts, in considering whether a particular congressional action was taken in pursuance of Congress' power to manage and control tribal lands for the Indians' welfare, to engage in a thoroughgoing and impartial examination of the historical record. A presumption of congressional good faith cannot serve to advance such an inquiry.

We turn to the question whether the Court of Claims' inquiry in this case was guided by an appropriate legal standard. We conclude that it was. In fact, we approve that court's formulation of the inquiry as setting a standard that ought to be emulated by courts faced with resolving future cases presenting the question at issue here:

"In determining whether Congress has made a good faith effort to give the Indians the full value of their lands when the government acquired [them], we therefore look to the objective facts as revealed by Acts of Congress, congressional committee reports, statements submitted to Congress by government officials, reports of special commissions appointed by Congress to treat with the Indians, and similar evidence relating to the acquisition. . . .

"The 'good faith effort' and 'transmutation of property' concepts referred to in Fort Berthold are opposite sides of the same coin. They reflect the traditional rule that a trustee may change the form of trust assets as long as he fairly (or in good faith) attempts to provide his ward with property of equivalent value. If he does that, he cannot be faulted if hindsight should demonstrate a lack of precise equivalence. On the other hand, if a trustee (or the government in its dealings with the Indians) does not attempt to give the ward the fair equivalent of what he acquires from him, the trustee to that extent has taken rather than transmuted the property of the ward. In other words, an essential element of the inquiry under the Fort Berthold guideline is determining the adequacy of the consideration the government gave for the Indian lands it acquired. That inquiry cannot be avoided by the government's simple assertion that it acted in good faith in its dealings with the Indians." 220 Ct.Cl., at 451, 601 F.2d, at 1162.30

We next examine the factual findings made by the Court of Claims, which led it to the conclusion that the 1877 Act effected a taking. First, the Court found that "[t]he only item of 'consideration' that possibly could be viewed as showing an attempt by Congress to give the Sioux the 'full value' of the land the government took from them was the requirement to furnish them with rations until they became self-sufficient." 220 Ct.Cl., at 458, 601 F.2d, at 1166. This finding is fully supported by the record, and the Government does not seriously contend otherwise.31

Second, the court found, after engaging in an exhaustive review of the historical record, that neither the Manypenny Commission, nor the congressional Committees that approved the 1877 Act, nor the individual legislators who spoke on its behalf on the floor of Congress, ever indicated a belief that the Government's obligation to provide the Sioux with rations constituted a fair equivalent for the value of the Black Hills and the additional property rights the Indians were forced to surrender. See id., at 458-462, 601 F.2d, at 1166-1168. This finding is unchallenged by the Government.

A third finding lending some weight to the Court's legal conclusion was that the conditions placed by the Government on the Sioux' entitlement to rations, see n. 14, supra, "further show that the government's undertaking to furnish rations to the Indians until they could support themselves did not reflect a congressional decision that the value of the rations was the equivalent of the land the Indians were giving up, but instead was an attempt to coerce the Sioux into capitulating to congressional demands." 220 Ct.Cl., at 461, 601 F.2d, at 1168. We might add only that this finding is fully consistent with similar observations made by this Court nearly a century ago in an analogous case.

In Choctaw Nation v. United States, 119 U.S. 1, 35, 7 S.Ct. 75, 94, 30 L.Ed. 306 (1886), the Court held, over objections by the Government, that an earlier award made by the Senate on an Indian tribe's treaty claim "was fair, just, and equitable." The treaty at issue had called for the removal of the Choctaw Nation from treaty-protected lands in exchange for payments for the tribe's subsistence for one year, payments for cattle and improvements on the new reservation, an annuity of $20,000 for 20 years commencing upon removal, and the provision of educational and agricultural services. Id., at 38, 7 S.Ct., at 96. Some years thereafter the Senate had awarded the Indians a substantial recovery based on the latter treaty's failure to compensate the Choctaw for the lands they had ceded. Congress later enacted a jurisdictional statute which permitted the United States to contest the fairness of the Senate's award as a settlement of the Indian's treaty claim. In rejecting the Government's arguments, and accepting the Senate's award as "furnish[ing] the nearest approximation to the justice and right of the case," id., at 35, 7 S.Ct., at 95, this Court observed:

"It is notorious as a historical fact, as it abundantly appears from the record in this case, that great pressure had to be brought to bear upon the Indians to effect their removal, and the whole treaty was evidently and purposely executed, not so much to secure to the Indians the rights for which they had stipulated, as to effectuate the policy of the United States in regard to their removal. The most noticeable thing, upon a careful consideration of the terms of this treaty, is that no money consideration is promised or paid for a cession of lands, the beneficial ownership of which is assumed to reside in the Choctaw Nation, and computed to amount to over ten millions of acres." Id., at 37-38, 7 S.Ct., at 96.

As for the payments that had been made to the Indians in order to induce them to remove themselves from their treaty lands, the Court, in words we find applicable to the 1877 Act, concluded:

"It is nowhere expressed in the treaty that these payments are to be made as the price of the lands ceded; and they are all only such expenditures as the government of the United States could well afford to incur for the mere purpose of executing its policy in reference to the removal of the Indians to their new homes. As a consideration for the value of the lands ceded by the treaty, they must be regarded as a meager pittance." Id., at 38, 7 S.Ct., at 96 (emphasis supplied).

These conclusions, in light of the historical background to the opening of the Black Hills for settlement, see Part I, supra, seem fully applicable to Congress' decision to remove the Sioux from the valuable tract of land, and to extinguish their off-reservation hunting rights.

Finally, the Court of Claims rejected the Government's contention that the fact that it subsequently had spent at least $43 million on rations for the Sioux (over the course of three-quarters of a century) established that the 1877 Act was an act of guardianship taken in the Sioux' best interest. The court concluded: "The critical inquiry is what Congress did—and how it viewed the obligation it was assuming—at the time it acquired the land, and not how much it ultimately cost the United States to fulfill the obligation." 220 Ct.Cl., at 462, 601 F.2d, at 1168. It found no basis for believing that Congress, in 1877, anticipated that it would take the Sioux such a lengthy period of time to become self-sufficient, or that the fulfillment of the Government's obligation to feed the Sioux would entail the large expenditures ultimately made on their behalf. Ibid. We find no basis on which to question the legal standard applied by the Court of Claims, or the findings it reached, concerning Congress' decision to provide the Sioux with rations.

The aforementioned findings fully support the Court of Claims' conclusion that the 1877 Act appropriated the Black Hills "in circumstances which involved an implied undertaking by [the United States] to make just compensation to the tribe."32 United States v. Creek Nation, 295 U.S., at 111, 55 S.Ct., at 684. We make only two additional observations about this case. First, dating at least from the decision in Cherokee Nation v. Southern Kansas R. Co., 135 U.S. 641, 657, 10 S.Ct. 965, 971, 34 L.Ed. 295 (1890), this Court has recognized that Indian lands, to which a tribe holds recognized title, "are held subject to the authority of the general government to take them for such objects as are germane to the execution of the powers granted to it; provided only, that they are not taken without just compensation being made to the owner." In the same decision the Court emphasized that the owner of such lands "is entitled to reasonable, certain and adequate provision for obtaining compensation before his occupancy is disturbed." Id., at 659, 10 S.Ct., at 971. The Court of Claims gave effect to this principle when it held that the Government's uncertain and indefinite obligation to provide the Sioux with rations until they became self-sufficient did not constitute adequate consideration for the Black Hills.

Second, it seems readily apparent to us that the obligation to provide rations to the Sioux was undertaken in order to ensure them a means of surviving their transition from the nomadic life of the hunt to the agrarian lifestyle Congress had chosen for them. Those who have studied the Government's reservation policy during this period of our Nation's history agree. See n. 11, supra. It is important to recognize that the 1877 Act, in addition to removing the Black Hills from the Great Sioux Reservation, also ceded the Sioux' hunting rights in a vast tract of land extending beyond the boundaries of that reservation. See n. 14, supra. Under such circumstances, it is reasonable to conclude that Congress' undertaking of an obligation to provide rations for the Sioux was a quid pro quo for depriving them of their chosen way of life, and was not intended to compensate them for the taking of the Black Hills.33

In sum, we conclude that the legal analysis and factual findings of the Court of Claims fully support its conclusion that the terms of the 1877 Act did not effect "a mere change in the form of investment of Indian tribal property." Lone Wolf v. Hitchcock, 187 U.S., at 568, 23 S.Ct., at 222. Rather, the 1877 Act effected a taking of tribal property, property which had been set aside for the exclusive occupation of the Sioux by the Fort Laramie Treaty of 1868. That taking implied an obligation on the part of the Government to make just compensation to the Sioux Nation, and that obligation, including an award of interest, must now, at last, be paid.

The judgment of the Court of Claims is affirmed.

It is so ordered.

Mr. Justice WHITE, concurring in part and concurring in the judgment.

I agree that there is no constitutional infirmity in the direction by Congress that the Court of Claims consider this case without regard to the defense of res judicata. I also agree that the Court of Claims correctly decided this case. Accordingly, I concur in Parts III and V of the Court's opinion and in the judgment.

Mr. Justice REHNQUIST, dissenting.

In 1942, the Sioux Tribe filed a petition for certiorari requesting this Court to review the Court of Claims' ruling that Congress had not unconstitutionally taken the Black Hills in 1877, but had merely exchanged the Black Hills for rations and grazing lands—an exchange Congress believed to be in the best interests of the Sioux and the Nation. This Court declined to review that judgment. Sioux Tribe v. United States, 97 Ct.Cl. 613 (1942), cert. denied, 318 U.S. 789, 63 S.Ct. 992, 87 L.Ed. 1155 (1943). Yet today the Court permits Congress to reopen that judgment which this Court rendered final upon denying certiorari in 1943, and proceeds to reject the 1942 Court of Claims' factual interpretation of the events in 1877. I am convinced that Congress may not constitutionally require the Court of Claims to reopen this proceeding, that there is no judicial principle justifying the decision to afford the respondents an additional opportunity to litigate the same claim, and that the Court of Claims' first interpretation of the events in 1877 was by all accounts the more realistic one. I therefore dissent.

* In 1920, Congress enacted a special jurisdictional Act, ch. 222, 41 Stat. 738, authorizing the Sioux Tribe to submit any legal or equitable claim against the United States to the Court of Claims. The Sioux filed suit claiming that the 1877 Act removing the Black Hills from the Sioux territory was an unconstitutional taking. In Sioux Tribe v. United States, supra, the Court of Claims considered the question fully and found that the United States had not taken the Black Hills from the Sioux within the meaning of the Fifth Amendment. It is important to highlight what that court found. It did not decide, as the Court today suggests, that it merely lacked jurisdiction over the claim presented by the Sioux. See ante, at 384. It found that under the circumstances presented in 1877, Congress attempted to improve the situation of the Sioux and the Nation by exchanging the Black Hills for 900,000 acres of grazing lands and rations for as long as they should be needed. The court found that although the Government attempted to keep white settlers and gold prospectors out of the Black Hills territory, these efforts were unsuccessful. The court concluded that this situation was such that the Government "believed serious conflicts would develop between the settlers and the Government, and between the settlers and the Indians." 97 Ct.Cl., at 659. It was also apparent to Congress that the Indians were still "incapable of supporting themselves." Ibid.

The court found that the Government therefore embarked upon a course designed to obtain the Indians' agreement to sell the Black Hills and "endeavored in every way possible during 1875 and 1876 to arrive at a mutual agreement with the Indians for the sale. . . . " Id., at 681. Negotiation having failed, Congress then turned to design terms for the acquisition of the Black Hills which it found to be in the best interest of both the United States and the Sioux. The court found that pursuant to the 1877 agreement, Congress provided the Indians with more than $43 million in rations as well as providing them with 900,000 acres of needed grazing lands. Thus the court concluded that "the record shows that the action taken was pursuant to a policy which the Congress deemed to be for the interest of the Indians and just to both parties." Id., at 668. The court emphasized:

"[T]he Congress, in an act enacted because of the situation encountered and pursuant to a policy which in its wisdom it deemed to be in the interest and for the benefit and welfare of the . . . Sioux Tribe, as well as for the necessities of the Government, required the Indians to sell or surrender to the Government a portion of their land and hunting rights on other land in return for that which the Congress, in its judgment, deemed to be adequate consideration for what the Indians were required to give up, which consideration the Government was not otherwise under any legal obligation to pay." Id., at 667.

This Court denied certiorari. 318 U.S. 789, 63 S.Ct. 992, 87 L.Ed. 1155 (1943).

During the course of further litigation commencing in 1950, the Sioux again resubmitted their claim that the Black Hills were taken unconstitutionally. The Government pleaded res judicata as a defense. The Court of Claims held that res judicata barred relitigation of the question since the original Court of Claims decision had clearly held that the appropriation of the Black Hills was not a taking because Congress in "exercising its plenary power over Indian tribes, took their land without their consent and substituted for it something conceived by Congress to be an equivalent." United States v. Sioux Nation, 207 Ct.Cl. 234, 243, 518 F.2d 1298, 1303 (1975). The court found no basis for relieving the Sioux from the bar of res judicata finding that the disability "is not lifted if a later court disagrees with a prior one." Id., at 244, 518 F.2d, at 1303. The court thus considered the equities entailed by the application of res judicata in this case and held that relitigation was unwarranted. Again, this Court denied certiorari. 423 U.S. 1016, 96 S.Ct. 449, 46 L.Ed.2d 387 (1975).

Congress then passed another statute authorizing the Sioux to relitigate their taking claim in the Court of Claims. 92 Stat. 153. The statute provided that the Court of Claims "shall review on the merits" the Sioux claim that there was a taking and that the Court "shall determine that issue de novo." (Emphasis added.) Neither party submitted additional evidence and the Court of Claims decided the case on the basis of the record generated in the 1942 case and before the Commission. On the basis of that same record, the Court of Claims has now determined that the facts establish that Congress did not act in the best interest of the Sioux, as the 1942 court found, but arbitrarily appropriated the Black Hills without affording just compensation. This Court now embraces this second, latter-day interpretation of the facts in 1877.

Although the Court refrains from so boldly characterizing its action, it is obvious from these facts that Congress has reviewed the decisions of the Court of Claims, set aside the judgment that no taking of the Black Hills occurred, set aside the judgment that there is no cognizable reason for relitigating this claim, and ordered a new trial. I am convinced that this is nothing other than an exercise of judicial power reserved to Art. III courts that may not be performed by the Legislative Branch under its Art. I authority.

Article III vests "the judicial Power . . . of the United States" in federal courts. Congress is vested by Art. I with legislative powers, and may not itself exercise an appellate-type review of judicial judgments in order to alter their terms, or to order new trials of cases already decided. The judges in Hayburn's Case, 2 Dall. 408, 409, 413, n. 4, 1 L.Ed. 436 (1792), stated that, "no decision of any court of the United States can, under any circumstances, in our opinion, agreeable to the Constitution, be liable to a reversion, or even suspension, by the Legislature itself, in whom no judicial power of any kind appears to be vested." We have interpreted the decision in United States v. Klein, 13 Wall. 128, 20 L.Ed. 519 (1872), as having "rested upon the ground that . . . Congress was without constitutional authority to CONTROL THE EXERCISE OF . . . JUDICIAL POWER . . . By requiring this court to set aside the judgment of the Court of Claims" and as holding that Congress may not "require a new trial of the issues . . . which the Court had resolved against [a party]." Pope v. United States, 323 U.S. 1, 8, 9, 65 S.Ct. 16, 20, 21, 89 L.Ed. 3 (1944).

This principle was again applied in United States v. O'Grady, 22 Wall. 641, 647, 22 L.Ed. 772 (1875), where the Court refused to legitimize a congressional attempt to revise a final judgment rendered by the Court of Claims finding that such judgments "are beyond all doubt the final determination of the matter in controversy; and it is equally certain that the judgments of the Court of Claims, where no appeal is taken to this court, are, under existing laws, absolutely conclusive of the rights of the parties, unless a new trial is granted by that court. . . . " (Emphasis added.) The Court further found that there is only one Supreme Court and "[i]t is quite clear that Congress cannot subject the judgments of the Supreme Court to the re-examination and revision of any other tribunal or any other department of the government." Id., at 648. See also Chicago & Southern Air Lines, Inc. v. Waterman S.S. Corp., 333 U.S. 103, 68 S.Ct. 431, 92 L.Ed. 568 (1948). Congress has exceeded the legislative boundaries drawn by these cases and the Constitution and exercised judicial power in a case already decided by effectively ordering a new trial.

The determination of whether this action is an exercise of legislative or judicial power is of course one of characterization. The fact that the judicial process is affected by an Act of Congress is not dispositive since many actions which this Court has clearly held to be legitimate exercises of legislative authority do have an effect on the judiciary and its processes. Congress may legitimately exercise legislative powers in the regulation of judicial jurisdiction; and it may, like other litigants, change the import of a final judgment by establishing new legal rights after the date of judgment, and have an effect on the grounds available for a court's decision by waiving available defenses. But as the Court apparently concedes, Congress may not in the name of those legitimate actions, review and set aside a final judgment of an Art. III court, and order the courts to rehear an issue previously decided in a particular case.

The Court relies heavily on the fact that Congress was acting pursuant to its power to pay the Nation's debts. No doubt, Congress has broad power to do just that, but it may do so only through the exercise of legislative, not judicial powers. Thus the question must be, not whether Congress was attempting to pay its debts through this Act, but whether it attempted to do so by means of judicial power. The Court suggests that the congressional action in issue is justified as either a permissible regulation of jurisdiction, the creation of a new obligation, or the mere waiver of a litigant's right. These alternative nonjudicial characterizations of the congressional action, however, are simply unpe