Mr. Justice Rehnquist
delivered the opinion of the Court.
Since the Depression of the 1930’s, the Government has taken increasingly upon itself the task of insulating the economy at large and the individual from the buffeting of economic fortune. The federal old-age, survivors, and disability insurance provisions of the Social Security Act (SSA) are possibly the pre-eminent examples: attempts to obviate, through a program of forced savings, the economic dislocations that may otherwise accompany old age, disability, or the death of a breadwinner. As an exercise in governmental administration, the social security system is of unprecedented dimension; in fiscal year 1977 nearly 150 million claims were filed.
Given this magnitude, the number of times these SSA claims have reached this Court warrants little surprise. Our cases evidence a sensitivity to the legislative and administrative problems posed in the design of such a program and in the adjudication of claims on this scale. The problems are generally of two types. The first is categorization. In light of the specific dislocations Congress wishes to alleviate, it is necessary to define categories of beneficiaries. The process of categorization presents the difficulties inherent in any line-drawing exercise where the draftsman confronts a universe of potential beneficiaries with different histories and distinct needs. He strives for a level of generality that is administratively practicable, with full appreciation that the included class has members whose “needs” upon a statutorily defined occurrence may not be as marked as those of isolated individuals outside the classification. “General rules are essential if a fund of this magnitude is to be administered with a modicum of efficiency, even though such rules inevitably produce seemingly arbitrary consequences in some individual cases.” Califano v. Jobst, 434 U. S. 47, 53 (1977). A process of case-by-case adjudication that would provide a “perfect fit” in theory would increase administrative expenses to a degree that benefit levels would probably be reduced, precluding a perfect fit in fact. Mathews v. Lucas, 427 U. S. 495, 509 (1976); Weinberger v. Salfi, 422 U. S. 749, 776-777 (1975).
The second type of problem that has been brought to this Court involves the Social Security Administration’s procedures for dispute resolution where benefits have been denied, decreased, or terminated because the Administration has concluded that the claimant is not entitled to what he has requested or to what he has received in the past-. Again the Court has been sensitive to the special difficulties presented by the mass administration of the social security system. After the legislative task of classification is completed, the administrative goal is accuracy and promptness in the actual allocation of benefits pursuant to those classifications. The magnitude of that task is not amenable to the full trappings of the adversary process lest again benefit levels be threatened by the costs of administration. Mathews v. Eldridge, 424 U. S. 319, 343-349 (1976); Richardson v. Perales, 402 U. S. 389, 406 (1971). Fairness can best be assured by Congress and the Social Security Administration through sound managerial techniques and quality control designed to achieve an acceptable rate of error.
This case involves a challenge to a categorization. Appellees Norman J. Boles and Margaret Gonzales represent a nationwide class of all illegitimate children and their mothers who are allegedly ineligible for insurance benefits under the SSA because in each case the mother was never married to the wage earner who fathered her child. Section 202 (g)(1) of the SSA, as amended, 42 U. S. C. §402 (g)(1), only makes “mother’s insurance benefits” available to widows and divorced wives. By virtue of this Court’s decision in Wein-berger v. Wiesenfeld, 420 U. S. 636 (1975), “mother’s insurance benefits” are available to widowers, leaving the title of these benefits a misnomer. There we held that the provision of such benefits only to women violated the Due Process Clause of the Fifth Amendment.
Norman W. Boles died in 1971. He left a widow, Nancy L. Boles, and their two children, who were each promptly awarded child’s insurance benefits. Nancy Boles receives mother’s insurance benefits. Appellee Gonzales lived with Norman W. Boles for three years before his marriage to Nancy Boles and bore a son by him, Norman J. Boles. Gonzales sought mother’s insurance benefits for herself and child’s benefits for her son. Her son was granted benefits, but her personal request was denied because she had never been married to the wage earner.
Gonzales exhausted her administrative remedies and then filed this suit in the United States District Court for the Western District of Texas. The District Court certified a class of “all illegitimate children and their mothers who are presently ineligible for Mother’s Insurance Benefits solely because 42 U. S. C. §402 (g)(1) restricts such benefits to women who were once married to the fathers of their children.” App. to Juris. Statement la-2a. The District Court found that § 202 (g)(1) of the SSA was unconstitutional. There were three steps in its logic.
First, it read Weinberger v. Wiesenfeld, supra, as holding that mother’s insurance benefits are chiefly for the benefit of the child. It quoted from a passage in that opinion where this Court observed:
“[Section] 402 (g), linked as it is directly to responsibility for minor children, was intended to permit women to elect not to work and to devote themselves to the care of children. . . .
“That the purpose behind § 402 (g) is to provide children deprived of one parent with the opportunity for the personal attention of the other could not be more clear in the legislative history.” 420 U. S., at 648-649.
On the basis of this language it then concluded that for purposes of equal protection analysis, the pertinent discrimination in this case is not unequal treatment of unwed mothers, but rather discrimination against illegitimate children. In its final step the District Court held that the application of § 202 (g)(1) at issue here is unconstitutional, relying on cases of this Court invalidating on constitutional grounds legislation that discriminated against illegitimates solely because of their status at birth. E. g., Weber v. Aetna Casualty & Surety Co., 406 U. S. 164 (1972); Gomez v. Perez, 409 U. S. 535 (1973); Jimenez v. Weinberger, 417 U. S. 628 (1974); Trimble v. Gordon, 430 U. S. 762 (1977).
We noted probable jurisdiction, 439 U. S. 1126 (1979), and now conclude that the District Court incorrectly analyzed the equal protection issue in this case. We accordingly reverse.
As this Court noted in Weinberger v. Wiesenfeld, supra, at 643, § 202 (g) “was added to the Social Security Act in 1939 as one of a large number of amendments designed to 'afford more adequate protection to the family as a unit.’ H. R. Rep. No. 728, 76th Cong., 1st Sess., 7 (1939).” The benefits created in 1939 “were intended to provide persons dependent on the wage earner with protection against the economic hardship occasioned by loss of the wage earner’s support.” Califano v. Jobst, 434 U. S., at 50; see Mathews v. De Castro, 429 U. S. 181, 185-186 (1976). Specifically, § 202 (g) “was intended to permit women [and now men] to elect not to work and to devote themselves to care of children.” 420 U. S., at 648. The animating concern was the economic dislocation that occurs when the wage earner dies and the surviving parent is left with the choice to stay home and care for the children or to go to work, a hardship often exacerbated by years outside the labor force. “Mother’s insurance benefits” were intended to make the choice to stay home easier. But the program was not designed to be, and we think is not now, a general system for the dispensing of child-care subsidies. Instead, Congress sought to limit the category of beneficiaries to those who actually suffer economic dislocation upon the death of a wage earner and are likely to be confronted at that juncture with the choice between employment or the assumption of full-time child-care responsibilities.
In this light there is an obvious logic in the exclusion from § 202 (g) of women or men who have never married the wage earner. “Both tradition and common experience support the conclusion that marriage is an event which normally marks an important change in economic status.” Califano v. Jobst, supra, at 53. Congress could reasonably conclude that a woman who has never been married to the wage earner is far less likely to be dependent upon the wage earner at the time of his death. He was never legally required to support her and therefore was less likely to have been an important source of income. Thus, the possibility of severe economic dislocation upon his death is more remote.
We confronted an analogous classification in Mathews v. De Castro, supra, which involved a challenge to the exclusion of divorced women from “wife’s income benefits.” In concluding that the classification did not deny equal protection, we observed:
“Divorce by its nature works a drastic change in the economic and personal relationship between a husband and wife. . . . Congress could have rationally assumed that divorced husbands and wives depend less on each other for financial and other support than do couples who stay married. The problems that a divorced wife may encounter when her former husband becomes old or disabled may well differ in kind and degree from those that a woman married to a retired or disabled husband must face. . . . She may not feel the pinch of the extra expenses accompanying her former husband’s old age or disability. ... It was not irrational for Congress to recognize this basic fact in deciding to defer monthly payments to divorced wives of retired or disabled wage earners until they reach the age of 62.” 429 U. S., at 188-189.
Likewise, Weinberger v. Salfi, 422 U. S. 749 (1975), upheld a 9-month duration-of-relationship eligibility requirement for the wife and stepchildren of a deceased wage earner. The stated purpose of the requirement was “to prevent the use of sham marriages to secure Social Security payments.” Id., at 767. We found that the only relevant constitutional argument was whether “the test [appellees could not] meet [was] not so rationally related to a legitimate legislative objective that it [could] be used to deprive them of benefits available to those who [did] satisfy that test.” Id., at 772. We recognized that the statutory requirement would deny benefits in some cases of legitimate, sincere marriage relationships.
“While it is possible to debate the wisdom of excluding legitimate claimants in order to discourage sham relationships, and of relying on a rule which may not exclude some obviously sham arrangements, we think it clear that Congress could rationally choose to adopt such a course. Large numbers of people are eligible for these programs and are potentially subject to inquiry as to the validity of their relationships to wage earners. ... Not only does the prophylactic approach thus obviate the necessity for large numbers of individualized determinations, but it also protects large numbers of claimants who satisfy the rule from the uncertainties and delays of administrative inquiry into the circumstances of their marriages.” Id., at 781-782.
It is with this background that we must analyze what the District Court in this case perceived to be the flaw in relying on dependence as a rationale for the statutory distinction between married and unmarried persons. The District Court pointed out that in 1972 Congress lifted the requirement that divorced women seeking mother’s insurance benefits show that they were in some measure dependent on the wage earner immediately before his death. It seized this fact as refutation of any characterization of these benefits as an attempt to ease the dislocation of those who had been dependent on the deceased. We think the District Court is demanding a precision not warranted by our cases.
Certainly Congress did not envision such precision. The legislative history surrounding the devolution of support requirements suggests that its effect on mother’s insurance benefits was an incidental and relatively minor byproduct of Congress’ core concern: older women who were married to wage earners for over 20 years — women who often only knew work as housewives — and who were not eligible for surviving divorced wife’s insurance benefits because state divorce laws did not permit alimony or because they had accepted a property settlement in lieu of alimony. The Social Security laws have maintained uniform support requirements for divorced wife's, divorced widow’s, and surviving divorced mother’s benefits. Obviously administration is thereby simplified. Undoubtedly, some younger divorced wives with children of deceased wage earners in their care who could not meet the old support requirements incidentally benefit from Congress’ concern that many older women were being victimized once by state divorce laws and again by the Social Security laws. However, when Congress seeks to alleviate hardship and inequity under the Social Security laws, it may quite rightly conceive its task to be analogous to painting a fence, rather than touching up an etching. We have repeatedly stated that there is no constitutional requirement that “a statutory provision . . . filte[r] out those, and only those, who are in the factual position which generated the congressional concern reflected in the statute.” Weinberger v. Salfi, 422 U. S., at 777; Mathews v. De Castro, 429 U. S., at 189. In sum, we conclude that the denial of mother’s insurance benefits to a woman who never married the wage earner bears a rational relation to the Government’s desire to ease economic privation brought on by the wage earner’s death.
But the appellees argue that to characterize the problem in this fashion is to miss the point because at root this case involves discrimination against illegitimate children. Quite naturally, those who seek benefits denied them by statute will frame the constitutional issue in a manner most favorable to their claim. The proper classification for purposes of equal protection analysis is not an exact science, but scouting must begin with the statutory classification itself. Only when it is shown that the legislation has a substantial disparate impact on classes defined in a different fashion may analysis continue on the basis of the impact on those classes.
We conclude that the legislation in this case does not have the impact on illegitimates necessary to warrant further inquiry whether § 202 (g) is the product of discriminatory purposes. See Personnel Administrator of Mass. v. Feeney, 442 U. S. 256 (1979). “Mother’s insurance benefits” are distinct from “child’s insurance benefits.” The latter are benefits paid to the minor children of the’ deceased wage earner and, as noted, Gonzales’ son did receive child’s insurance benefits. The benefit to a child as a result of the parent or guardian’s receipt of mother’s insurance benefits is incidental: mother’s insurance benefit payments do not vary with the number of children within the recipient’s care, they are not available in the foster care context, and they are lost on remarriage or if the surviving parent earns a substantial income — all despite the needs of the child. Thus, the focus of these benefits is on the economic dilemma of the surviving spouse or former spouse; the child’s needs as such are addressed through the separate child’s insurance benefits. Nor is it invariably true that whatever derivative benefits are enjoyed by the child whose parent or guardian receives mother’s insurance benefits will not be enjoyed by illegitimate children. If the illegitimate child is cared for by the deceased wage earner’s wife, she will receive mother’s insurance benefits even though she has no natural children of her own and never adopted the child. And many legitimate children live in households that are not headed by individuals eligible for mother’s benefits.
In order to make out a disparate impact warranting further scrutiny under the Due Process Clause of the Fifth Amendment, it is necessary to show that the class which is purportedly discriminated against consequently suffers significant deprivation of a benefit or imposition of a substantial burden. If the class of beneficiaries were expanded in the fashion pressed by appellees, the beneficiaries, in terms of those who would exercise dominion over the benefits and whose freedom of choice would be enhanced thereby, would be unwed mothers, not illegitimate children. Certainly every governmental benefit has a ripple effect through familial relationships and the economy generally, its propagation determined by the proximity and sensibilities of others. Possibly the largest class of incidental beneficiaries are those who are gratified in a nonmaterial way to see a friend or relative receive benefits. Some limits must be imposed for purposes of constitutional analysis, and we conclude that in this case the incidental and, to a large degree, speculative impact on illegitimates as a class is not sufficient to treat the denial of mother’s insurance benefits to unwed mothers as discrimination against illegitimate children.
The SSA and its amendments are the product of hard choices and countervailing pressures. The desire to alleviate hardship wherever it is found is tempered by the concern that the social security system in this country remain a contributory insurance plan and not become a general welfare program. General welfare objectives are addressed through public assistance legislation. In light of the limited resources of the insurance fund, any expansion of the class of beneficiaries invariably poses the prospect of reduced benefits to individual claimants. We need look no further than the facts of this case for an illustration. The benefits available to Norman W. Boles’ beneficiaries under the Act are limited by his earnings record. The effect of extending benefits to Gonzales will be to reduce benefits to Nancy Boles and her children by 20%. Thus, the end result of extending benefits to Gonzales may be to deprive Nancy Boles of a meaningful choice between full-time employment and staying home with her children,, thereby undermining the express legislative purpose of mother’s insurance benefits. We think Congress could rationally choose to concentrate limited funds where the need is likely to be greatest.
Because of our disposition of the Fifth Amendment issue, we need not and do not reach the appellant’s other arguments: that the District Court improperly certified a nationwide class that included individuals who were not shown to have met the jurisdictional requirements of § 205 (g) of the SSA, 42 TT. S. C. § 405 (g), and that sovereign immunity barred that court’s award of retroactive monetary relief.
The judgment of the District Court is accordingly
Reversed.
Social Security Administration’s Office of Management and Administration, The Year in Review: The Administration of Social Security Programs 1977, p. ii (July 1978).
Califano v. Yamasaki, 442 U. S. 682 (1979); Califano v. Jobst, 434 U. S. 47 (1977); Califano v. Webster, 430 U. S. 313 (1977); Califano v. Goldfarb, 430 U. S. 199 (1977); Mathews v. De Castro, 429 U. S. 181 (1976); Norton v. Mathews, 427 U. S. 524 (1976); Mathews v. Lucas, 427 U. S. 495 (1976); Mathews v. Eldridge, 424 U. S. 319 (1976); Weinberger v. Salfi, 422 U. S. 749 (1975); Weinberger v. Wiesenfeld, 420 U. S. 636 (1975); Jimenez v. Weinberger, 417 U. S. 628 (1974); Richardson v. Wright, 405 U. S. 208 (1972); Richardson v. Belcher, 404 U. S. 78 (1971); Richardson v. Perales, 402 U. S. 389 (1971); Flemming v. Nestor, 363 U. S. 603 (1960). Many other cases have been disposed of by summary action. This Court has also had numerous cases involving claims arising under federal-state cooperative welfare programs authorized by the SSA. See, e. g., Graham v. Richardson, 403 U. S. 365 (1971) (Assistance to Persons Permanently and Totally Disabled); California Human Resources Dept. v. Java, 402 U. S. 121 (1971) (unemployment insurance); Dandridge v. Williams, 397 U. S. 471 (1970) (Aid to Families With Dependent Children).
The bulk of our cases fall under this heading. Califano v. Jobst, supra (termination of dependent child’s benefits upon his marriage); Califano v. Webster, supra (gender-based differences in benefit computation) ; Califano v. Goldfarb, supra (gender-based differences in defining dependent of deceased wage earner); Mathews v. De Castro, supra (denial of “wife’s insurance benefits” to divorced women under 62 years of age) ; Norton v. Mathews, supra (illegitimate children denied presumption of dependency enjoyed by legitimates); Mathews v. Lucas, supra (same as Norton); Weinberger v. Salfi, supra (duration-of-relationship requirements for receipt of mother’s or child’s insurance benefits); Weinberger v. Wiesenfeld, supra (gender-based denial of survivor’s benefits to widowers) ; Jimenez v. Weinberger, supra (denial of disability insurance benefits to illegitimate children born after onset of wage earner’s disability); Richardson v. Belcher, supra (reduction in social security benefits to reflect state workmen’s compensation benefits); Flemming v. Nestor, supra (termination of insurance benefits to aliens upon their deportation).
Califano v. Yamasaki, supra (lack of prerecoupment oral hearing in overpayment cases); Mathews v. Eldridge, supra (question whether evi-dentiary hearing necessary before termination of disability insurance benefits) ; Richardson v. Wright, supra (challenge to procedures employed in suspension or termination of disability benefits); Richardson v. Perales, supra (written reports by physicians who have examined disability insurance claimants are “substantial evidence” supporting denial of benefits).
Section 202 (g) (1), as set forth in 42 U. S. C. § 402 (g) (1), provides: “(1) The widow and every surviving divorced mother (as defined in section 416 (d) of this title) of an individual who died a fully or currently insured individual, if such widow or surviving divorced mother— “(A) is not married,
“(B) is not entitled to a widow’s insurance benefit,
“(C) is not entitled to old-age insurance benefits, or is entitled to old-age insurance benefits each of which is less than three-fourths of the primary insurance amount of such individual,
“(D) has filed application for mother’s insurance benefits, or was entitled to wife’s insurance benefits on the basis of the wages and self-employment income of such individual for the month preceding the month in which he died,
“ (E) at the time of filing such application has in her care a child or such individual entitled to a child’s insurance benefit, and “ (F) in the case of a surviving divorced mother—
“(i) the child referred to in subparagraph (E) is her son, daughter, or legally adopted child, and
“(ii) the benefits referred to in such subparagraph are payable on the basis of such individual’s wages and self-employment income,
“shall (subject to subsection (s) of this section) be entitled to a mother’s insurance benefit for each month, beginning with the first month after August 1950 in which she becomes so entitled to such insurance benefits and ending with the month preceding the first month in which any of the following occurs: no child of such deceased individual is entitled to a child’s insurance benefit, such widow or surviving divorced mother becomes entitled to an old-age insurance benefit equal to or exceeding three-fourths of the primary insurance amount of such deceased individual, she becomes entitled to a widow’s insurance benefit, she remarries, or she dies. Entitlement to such benefits shall also end, in the case of a surviving divorced mother, with the month immediately preceding the first month in which no son, daughter, or legally adopted child of such surviving divorced mother is entitled to a child’s insurance benefit on the basis of the wages and self-employment income of such deceased individual.”
Section 216 (d)(3), 42 U. S. C. §416 (d)(3), states:
“(3) The term 'surviving divorced mother’ means a woman divorced from an individual who has died, but only if (A) she is the mother of his son or daughter, (B) she legally adopted his son or daughter while she was married to him and while such son or daughter was under the age of 18, (C) he legally adopted her son or daughter while she was married to him and while such son or daughter was under the age of 18, or (D) she was married to him at the time both of them legally adopted a child under the age of 18.”
Norman W. Boles had acknowledged his paternity of Norman J. Boles.
Califano v. Jobst, 434 U. S., at 52:
“The statute is designed to provide the wage earner and the dependent members of his family with protection against the hardship occasioned by his loss of earnings; it is not simply a welfare program generally benefiting needy persons.”
See also Mathews v. De Castro, 429 U. S., at 185-186.
Originally, nothing similar to mother’s insurance benefits for divorced women was provided by the SSA. Then in 1950 these benefits, subject to limitations not relevant here, were made available to a surviving divorced wife, if she had not remarried, had a child in her care entitled to child’s insurance benefits, and at the time of the wage earner’s death had been receiving at least one-half of her support from him. Act of Aug. 28, 1950, § 101 (a), 64 Stat. 485.
In 1965, the remarriage bar to mother’s insurance benefits was relaxed. A woman’s rights as a surviving divorced mother would be restored if her second marriage ended in divorce. Moreover, a showing that she was receiving or entitled to receive “substantial contributions” from the wage earner at the time of his death would suffice in lieu of a showing that she received at least one-half of her support from the wage earner. Old-Age, Survivors, and Disability Amendments of 1965, § 308, 79 Stat. 377-379.
Finally, in 1972 Congress made the changes discussed by the District Court. Social Security Amendments of 1972, § 114 (c), 86 Stat. 1348.
Interestingly, younger women receiving mother’s benefits are not even mentioned in the Committee Reports on the 1972 amendment.
“Benefits, under present law, are payable to a divorced wife age 62 or older and a divorced widow age 60 or older if her marriage lasted at least 20 years before the divorce, and to> a surviving divorced mother. In order to qualify for any of these benefits a divorced woman is required to show that: (1) she was receiving at least one-half of her support from her former husband; (2) she was receiving substantial contributions from her former husband pursuant to a written agreement; or (3) there was a court order in effect providing for substantial contributions to her support by her former husband.
“In some States the courts are prohibited from providing for alimony, and in these States a divorced woman is precluded from meeting the third support requirement. Even in States which allow alimony, the court may have decided at the time of the divorce that the wife was not in need of financial support. Moreover, a divorced woman’s eligibility for social security benefits may depend on the advice she received at the time of her divorce. If a woman accepted a property settlement in lieu of alimony, she could, in effect, have disqualified herself for divorced wife’s, divorced widow’s, or surviving divorced mother’s benefits.
“The intent of providing benefits to divorced women is to protect women whose marriages are dissolved when they are far along in years — particularly housewives who have not been able to work and earn social security protection of their own. The committee believes that the support requirements of the law have operated to deprive some divorced women of the protection they should have received and, therefore, recommends that these requirements be eliminated. The requirement that the marriage of a divorced wife or widow must have lasted for at least 20 years before the divorce would not be changed.” S. Rep. No. 92-1230, p. 142 (1972).
See H. R. Rep. No. 92-231, pp. 54r-55 (1971). When the 1966 changes were made there was only passing mention of younger women receiving mother’s insurance benefits. S. Rep. No. 404, 89th Cong., 1st Sess., 108 (1965).
There are no precise figures as to the extra cost to the insurance fund posed by this expansion of mother’s insurance benefits. It can be inferred from the attention this expansion received in the legislative history that its cost was a relatively small part of the $23 million annual increase in benefits estimated for eliminating support requirements across the board. See S. Rep. No. 92-1230, supra, at 142. The Department of Health, Education, and Welfare has estimated that compliance with the District Court’s decision in this case will cost $60 million annually.
In Jimenez v. Weinberger, 417 U. S. 628 (1974), this Court struck down an absolute bar to child’s insurance benefits for illegitimate children whose paternity had never been acknowledged or affirmed by evidence of domicile with, or support by, the wage earner before the onset of the disability.
There is obviously a significant difference between this interpretation of the statutory purpose and that subscribed to by the author of this opinion in his separate concurrence in Weinberger v. Wiesenfeld, 420 U. S., at 655. To the extent that these interpretations conflict, the author feels he can do no better than quote Mr. Justice Jackson, concurring in McGrath v. Kristensen, 340 U. S. 162, 177-178 (1950):
“Precedent, however, is not lacking for ways by which a judge may recede from a prior opinion that has proven untenable and perhaps misled others. See Chief Justice Taney, License Cases, 5 How. 504, recanting views he had pressed upon the Court as Attorney General of Maryland in Brown v. Maryland, 12 Wheat. 419. Baron Bramwell extricated himself from a somewhat similar embarrassment by saying, ‘The matter does not appear to me now as it appears to have appeared to me then.’ Andrews v. Styrap, 26 L. T. R. (N. S.) 704, 706. And Mr. Justice Story, accounting for his contradiction of his own former opinion, quite properly put the matter: ‘My own error, however, can furnish no ground for its being adopted by this Court . . . .' United States v. Gooding, 12 Wheat. 460, 478. ... If there are other ways of gracefully and good-naturedly surrendering former views to a better considered position, I invoke them all.”
Compare 42 U. S. C. § 402 (g) (1) (E) with § 402 (g) (1) (F) (i).
Brief for Appellant 29 n. 22.
See Califano v. Yamasaki, 442 U. S. 682 (1979).