BARNHART v. WALTON
BARNHART, COMMISSIONER OF SOCIAL SECURITY v. WALTON
certiorari to the united states court of appeals for the fourth circuit
The Social Security Act authorizes payment of Title II disability insurance benefits and Title XVI Supplemental Security Income to individuals who have an inability to engage in any substantial gainful activity by reason of any medically determinable … impairment … which has lasted or can be expected to last for a continuous period of not less than 12 months . 42 U. S. C. §423(d)(1)(A) (emphasis added); accord, §1382c(a)(3)(A). The Social Security Administration (Agency) denied benefits to respondent Walton, finding that his inability to engage in substantial gainful activity lasted only 11 months. The District Court affirmed, but the Fourth Circuit reversed, holding that the 12-month duration requirement modifies impairment not inability, that the statute leaves no doubt that no similar duration requirement relates to an inability, and that therefore Walton was entitled to benefits despite Agency regulations restricting them to those unable to work for 12 months. The court decided further that Walton qualified for benefits because, prior to his return to work, his inability would have been expected to last 12 months. It conceded that the Agency had made Waltons actual return to work within 12 months of his onset date and before the Agencys decision date determinative on this point, 20 CFR §§404.1520(b), 1592(d)(2), but found that the regulations conflicted with the statute. It noted that Waltons work simply counted as part of a 9-month trial work period during which persons entitled to Title II benefits may work without loss of benefits, 42 U. S. C. §422(c).
Held: The Agencys interpretations of the statute fall within its lawful interpretative authority. Pp. 413.
(a) The Agencys reading of the term inability is reasonable. The statute requires both an inability to engage in any substantial gainful activity and an impairment providing reason for the inability, adding that the impairment must last or be expected to last not less than 12 months. The Agency has determined in both its formal regulations and its interpretation of those regulations that the inability must last the same amount of time. Courts grant considerable leeway to an agencys interpretation of its own regulations, and the Agency has properly interpreted its regulation here. Thus, this Court must decide (1) whether the statute unambiguously forbids that interpretation, and if not, (2) whether the interpretation exceeds permissible bounds. Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837. First, the Act does not unambiguously forbid the regulation. That the statutes 12-month phrase modifies only impairment shows only that the provision says nothing explicitly about the inabilitys duration. Such silence normally creates, but does not resolve, ambiguity. Second, the Agencys construction is permissible. It supplies a duration requirement, which the statute demands, in a way that consistently reconciles the statutory impairment and inability language. The Agencys regulations also reflect the Agencys own longstanding interpretation, which should be accorded particular deference, North Haven Bd. of Ed. v. Bell, 456 U. S. 512, n. 12. Finally, Congress has frequently amended or reenacted the relevant provisions without change. Waltons claim that Title IIs 5-month waiting period for entitlement protects against a claimant with a chronic, but only briefly disabling, disease shows, at most, that the Agency could have chosen other reasonable time periods. Moreover, Title XVI has no such period, yet Walton offers no explanation why its identical definitional language should be interpreted differently in a closely related context. Waltons argument that the Agencys interpretation should be disregarded because its formal regulations were only recently enacted is also rejected. E.g., Smiley v. Citibank (South Dakota), N. A., 517 U. S. 735. And the Agencys longstanding interpretation is not automatically deprived of the judicial deference otherwise its due because it was previously reached through means less formal than notice and comment rulemaking. Chevron, supra, at 843. Pp. 410.
(b) Also consistent with the statute is the Agencys regulation providing that [y]ou are not entitled to a trial work period if you perform work … within 12 months of the onset of the impairment … and before the date of any … decision finding … you …disabled, 20 CFR §404.1592(d)(2) (emphasis added). The statute is ambiguous, and the regulation treats a pre-Agency-decision actual return to work as if it were determinative of the can be expected to last question. The statutes complexity, the vast number of claims it engenders, and the consequent need for agency expertise and administrative experience lead the Court to read the statute as delegating to the Agency considerable authority to fill in matters of detail related to its administration. See Schweiker v. Gray Panthers, 453 U. S. 34. The interpretation at issue is such a matter. Pp. 1012.
235 F. 3d 184, reversed.
Breyer, J., delivered the opinion of the Court, Parts I and III of which were unanimous, and Part II of which was joined by Rehnquist, C. J., and Stevens, OConnor, Kennedy, Souter, Thomas, and Ginsburg, JJ. Scalia, J., filed an opinion concurring in part and concurring in the judgment.
JO ANNE B. BARNHART, COMMISSIONER OF
SOCIAL SECURITY, PETITIONER v.
CLEVELAND B. WALTON
on writ of certiorari to the united states court of appeals for the fourth circuit
Justice Breyer delivered the opinion of the Court.
The Social Security Act authorizes payment of disability insurance benefits and Supplemental Security Income to individuals with disabilities. See 49Stat. 622, as amended, 42 U. S. C. §401 et seq. (1994 ed. and V) (Title II disability insurance benefits); §1381 et seq. (Title XVI supplemental security income). For both types of benefits the Act defines the key term disability as an
[ i ] nability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months . §423(d)(1)(A) (1994 ed.) (Title II) (emphasis added); accord §1382c(a)(3)(A) (1994 ed., Supp. V) (Title XVI).
This case presents two questions about the Social Security Administrations interpretation of this definition.
First, the Social Security Administration (which we shall call the Agency) reads the term inability as including a 12 month requirement. In its view, the inability (to engage in any substantial gainful activity) must last, or must be expected to last, for at least 12 months. Second, the Agency reads the term expected to last as applicable only when the inability has not yet lasted 12 months. In the case of a later Agency determinationwhere the inability did not last 12 monthsthe Agency will automatically assume that the claimant failed to meet the duration requirement. It will not look back to decide hypothetically whether, despite the claimants actual return to work before 12 months expired, the inability nonetheless might have been expected to last that long.
The Court of Appeals for the Fourth Circuit held both these interpretations of the statute unlawful. We hold, to the contrary, that both fall within the Agencys lawful interpretive authority. See Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984) . Consequently, we reverse.
In 1996 Cleveland Walton, the respondent, applied for both Title II disability insurance benefits and Title XVI Supplemental Security Income. The Agency found that (1) by October 31, 1994, Walton had developed a serious mental illness involving both schizophrenia and associated depression; (2) the illness caused him then to lose his job as a full-time teacher; (3) by mid-1995 he began to work again part time as a cashier; and (4) by December 1995 he was working as a cashier full time.
The Agency concluded that Waltons mental illness had prevented him from engaging in any significant work, i.e. , from engag[ing] in any substantial gainful activity, for 11 monthsfrom October 31, 1994 (when he lost his teaching job) until the end of September 1995 (when he earned income sufficient to rise to the level of substantial gainful activity). See 20 CFR §§404.1574, 416.974 (2001). And because the statute demanded an inability to engage in any substantial gainful activity lasting 12, not 11, months, Walton was not entitled to benefits.
Walton sought court review. The District Court affirmed the Agencys decision, but the Court of Appeals for the Fourth Circuit reversed. Walton v. Apfel , 235 F. 3d 184, 186187 (2000). The court said that the statutes 12-month duration requirement modifies the word impairment, not the word inability. Id. , at 189. It added that the statutes language . . . leaves no doubt that there is no similar duration requirement related to an inability (to engage in substantial gainful activity). Ibid. It concluded that, because the statutes language speaks clearly and is unambiguous, Walton was entitled to receive benefits despite agency regulations restricting benefits to those unable to work for a 12-month period. Ibid.
The court went on to decide that, in any event, Walton qualified because, prior to Waltons return to work, one would have expected his inability to last 12 months. Id., at 189190. It conceded that the Agency had made Waltons actual return to work determinative on this point. See 20 CFR §§404.1520(b), 1592(d)(2) (2001). But it found unlawful the Agency regulations that gave the Agency the benefit of hindsighton the ground that they conflicted with the statutes clear command. 235 F. 3d, at 190.
For either reason, the Circuit concluded, Walton became entitled to Title II benefits no later than April 1995, five months after the onset of his illness. See 42 U. S. C. §§423(a)(1)(D)(i) (providing for a 5-month waiting period before a claimant is entitled to benefits), 423(c)(2)(A) (1994 ed.). It added that Waltons later work as a cashier was legally beside the point. That work simply counted as part of a 9-month trial work period, which the statute grants to those entitled to Title II benefits, and which it permits them to perform without loss of benefits. §422(c).
The Government sought certiorari. It pointed out that the Fourth Circuits first holding conflicts with those of other circuits, compare 235 F. 3d, at 189190, with Titus v. Sullivan , 4 F. 3d 590, 594595 (CA8 1993), and Alexander v. Richardson , 451 F. 2d 1185 (CA10 1971). It added that the Circuits views were contrary to well-settled law and would create additional Social Security costs of $80 billion over ten years. We granted the writ. We now reverse.
The statutory definition of disability has two parts. First, it requires a certain kind of inability, namely an inability to engage in any substantial gainful activity. Second it requires an impairment, namely a physical or mental impairment, which provides reason for the inability. The statute adds that the impairment must be one that has lasted or can be expected to last … not less than 12 months. But what about the inability? Must it also last (or be expected to last) for the same amount of time?
The Agency has answered this question in the affirmative. Acting pursuant to statutory rulemaking authority, 42 U. S. C. §§405(a) (Title II), 1383(d)(1) (Title XVI), it has promulgated formal regulations that state that a claimant is not disabled regardless of [his] medical condition, if he is doing substantial gainful activity. 20 CFR §404.1520(b) (2001). And the Agency has interpreted this regulation to mean that the claimant is not disabled if within 12 months after the onset of an impairment … the impairment no longer prevents substantial gainful activity. 65 Fed. Reg. 42774 (2000). Courts grant an agencys interpretation of its own regulations considerable legal leeway. Auer v. Robbins, 519 U. S. 452, 461 (1997) ; Udall v. Tallman, 380 U. S. 1, 1617 (1965) . And no one here denies that the Agency has properly interpreted its own regulation.
Consequently, the legal question before us is whether the Agencys interpretation of the statute is lawful. This Court has previously said that, if the statute speaks clearly to the Ibid. precise question at issue, we must give effect to the unambiguously expressed intent of Congress. Chevron , 467 U. S., at 842843. If, however, the statute is silent or ambiguous with respect to the specific issue, we must sustain the Agencys interpretation if it is based on a permissible construction of the Act. Id., at 843. Hence we must decide (1) whether the statute unambiguously forbids the Agencys interpretation, and, if not, (2) whether the interpretation for other reasons, exceeds the bounds of the permissible. Ibid.; see also United States v. Mead Corp., 533 U. S. 218, 227 (2001) .
First, the statute does not unambiguously forbid the regulation. The Fourth Circuit believed the contrary primarily for a linguistic reason. It pointed out that, linguistically speaking, the statutes 12-month phrase modifies only the word impairment, not the word inability. And to that extent we agree. After all, the statute, in parallel phrasing, uses the words which can be expected to result in death. And that structurally parallel phrase makes sense in reference to an impairment, but makes no sense in reference to the inability.
Nonetheless, this linguistic point is insufficient. It shows that the particular statutory provision says nothing explicitly about the inabilitys duration. But such silence, after all, normally creates ambiguity. It does not resolve it.
Moreover, a nearby provision of the statute says that an
individual shall be determined to be under a disability only if his … impairment . . . [is] of such severity that he is not only unable to do his previous work but cannot . . . engage in any other kind of substan- tial gainful work which exists in the national econ- omy. 42 U. S. C. §423(d)(2)(A) (Title II); accord §1382c(a)(3)(B) (Title XVI).
In other words, the statute, in the two provisions, specifies that the impairment, both must last 12 months and also must be severe enough to prevent the claimant from engaging in virtually any substantial gainful work. The statute, we concede, nowhere explicitly says that the impairment must be that severe ( i.e. , severe enough to prevent substantial gainful work) for 12 months . But that is a fair inference from the language. See Brief for AARP et al. as Amici Curiae 13 (conceding that an impairment must remain of disabling severity for 12 months). At the very least the statute is ambiguous in that respect. And, if so, then it is an equally fair inference that the inability must last 12 months. That is because the latter statement ( i.e., that the claimant must be unable to engage in any substantial gainful activity for a year) is the virtual equivalent of the former statement ( i.e. , that the impairment must remain severe enough to prevent the claimant from engaging in substantial gainful work for a year). It simply rephrases the same point in a slightly different way.
Second, the Agencys construction is permissible. The interpretation makes considerable sense in terms of the statutes basic objectives. The statute demands some duration requirement. No one claims that the statute would permit an individual with a chronic illnesssay high blood pressureto qualify for benefits if that illness, while itself lasting for a year, were to permit a claimant to return to work after only a week, or perhaps even a day, away from the job. The Agencys interpretation supplies a duration requirement, which the statute demands, while doing so in a way that consistently reconciles the statutory impairment and inability language.
In addition, the Agencys regulations reflect the Agencys own longstanding interpretation. See Social Security Ruling 8252, p. 106 (cum. ed. 1982) (In considering duration, it is the inability to engage in [substantial gainful activity] that must last the required 12-month period); Disability Insurance State Manual §316 (Sept. 9, 1965), Government Lodging, Tab C, (Duration of impairment refers to that period of time during which an individual is continuously unable to engage in substantial gainful activity because of an impairment); OASI Disability Insurance Letter No. 39 (Jan. 22, 1957), id., Tab A, p. 1 (duration requirement refers to the expected duration of the medical impairment at a level of severity sufficient to preclude substantial gainful activity). And this Court will normally accord particular deference to an agency interpretation of longstanding duration. North Haven Bd. of Ed. v. Bell, 456 U. S. 512, 522, n. 12 (1982) .
Finally, Congress has frequently amended or reenacted the relevant provisions without change. E.g. , Social Security Amendments of 1965, §303(a)(1), 79Stat. 366; see also S. Rep. No. 404, 89th Cong., 1st Sess., pt. I, pp. 9899 (1965) ([T]he committees bill . . . provide[s] for the payment of disability benefits for an insured worker who has been or can be expected to be totally disabled throughout a continuous period of 12 calendar months (emphasis added)); id. , at 98 (rejecting effort to provide benefits to those with short-term, temporary disabilit[ies], defined as inability to work for six months); H. R. Rep. No. 92231, p. 56 (1971) (No benefit is payable, however, unless the disability is expected to last (or has lasted) at least 12 consecutive months (emphasis added)); S. Rep. No. 744, 90th Cong., 1st Sess., 49 (1967) (The committee also believes . . . that an individual who does substantial gainful work despite an impairment or impairments that otherwise might be considered disabling is not disabled for purposes of establishing a period of disability). These circumstances provide further evidenceif more is neededthat Congress intended the Agencys interpretation, or at least understood the interpretation as statutorily permissible. Commodity Futures Trading Commn v. Schor , 478 U. S. 833, 845846 (1986) .
Walton points in reply to Title II language stating that a claimant who is under a disability . . . shall be entitled to a … benefit … beginning with the first month after a waiting period of five consecutive calendar months … throughout which he has been under a disability. 42 U. S. C. §§423(a)(1)(D)(i). He adds that this 5-month waiting period assures a lengthy period of time during which the applicant (who must be under a disability throughout) has been unable to work. And it thereby provides ironclad protection against the claimant who suffers a chronic, but only briefly disabling disease, such as the claimant who suffers high blood pressure in our earlier example. See supra, at 7. This claim does not help Walton, however, for it shows, at most, that the Agency might have chosen other reasonable time periodsa matter not disputed. Regardless, Waltons waiting period argument could work only in respect to Title II, not Title XVI. Title XVI has no waiting period, though it uses identical definitional language. And Walton does not explain why we should interpret the same statutory words differently in closely related contexts. See Department of Revenue of Ore. v. ACF Industries, Inc., 510 U. S. 332, 342 (1994) ( [I]dentical words used in different parts of the same act are intended to have the same meaning (quoting Sorenson v. Secretary of Treasury, 475 U. S. 851, 860 (1986) (some internal quotation marks omitted)).
Walton also asks us to disregard the Agencys interpretation of its formal regulations on the ground that the Agency only recently enacted those regulations, perhaps in response to this litigation. We have previously rejected similar arguments. Smiley v. Citibank (South Dakota), N. A., 517 U. S. 735, 741 (1996) ; United States v. Morton, 467 U. S. 822, 835836, n. 21 (1984) .
Regardless, the Agencys interpretation is one of long standing. See supra, at 8. And the fact that the Agency previously reached its interpretation through means less formal than notice and comment rulemaking, see 5 U. S. C. §553, does not automatically deprive that interpretation of the judicial deference otherwise its due. Cf. Chevron , 467 U. S., at 843 (stating, without delineation of means, that the power of an administrative agency to administer a congressionally created … program necessarily requires the formulation of policy ) (quoting Morton v. Ruiz, 415 U. S. 199, 231 (1974) )). If this Courts opinion in Christensen v. Harris County, 529 U. S. 576 (2000) , suggested an absolute rule to the contrary, our later opinion in United States v. Mead Corp., 533 U. S. 218 (2001) , denied the suggestion. Id., at 230231 ([T]he want of notice and comment does not decide the case). Indeed, Mead pointed to instances in which the Court has applied Chevron deference to agency interpretations that did not emerge out of notice-and-comment rulemaking. 533 U. S., at 230231 (citing NationsBank of N. C., N. A. v. Variable Annuity Life Ins. Co., 513 U. S. 251, 256257 (1995) ). It indicated that whether a court should give such deference depends in significant part upon the interpretive method used and the nature of the question at issue. 533 U. S., 229231 . And it discussed at length why Chevron did not require deference in the circumstances there presenta discussion that would have been superfluous had the presence or absence of notice-and-comment rulemaking been dispositive. 533 U. S., at 231234.
In this case, the interstitial nature of the legal question, the related expertise of the Agency, the importance of the question to administration of the statute, the complexity of that administration, and the careful consideration the Agency has given the question over a long period of time all indicate that Chevron provides the appropriate legal lens through which to view the legality of the Agency interpretation here at issue. See United States v. Mead Corp., supra; cf. also I K. Davis & R. Pierce, Administrative Law Treatise §§1.7, 3.3 (3d ed. 1994).
For these reasons, we find the Agencys interpretation lawful.
Waltons second claim is more complex. For purposes of making that claim, Walton assumes what we have just decided, namely that the statutes 12 month duration requirements apply to both the impairment and the inability to work requirements. Walton also concedes that he returned to work after 11 months. But Walton claims that his work from month 11 to month 12 does not count against him because it is part of a trial work period that the statute grants to those entitled to Title II benefits. See 42 U. S. C. §422(c). And Walton adds, he was entitle[d] to benefits becauseeven though he returned to work after 11 monthshis impairment and his inability to work were nonetheless expected to last for at least 12 months before he returned to work.
To illustrate Waltons argument, we simplify the actual circumstances. We imagine that: (1) On January 1, Year One, Walton developed (a) a severe impairment, which (b) made him unable to work; (2) Eleven (not twelve) months later, on December 1, Year One, Walton returned to work; (3) On July 1, Year Two, the Agency adjudicated, and denied, Waltons claim for benefits. Walton argues that, even though he returned to work after 11 months, had the Agency looked at the matter, not ex post , but as if it were looking prior to his return to work, the Agency would have had to conclude that both his impairment and his inability to work can be expected to last for a continuous period of not less than 12 months. §423(d)(1)(A). He consequently satisfied the 12-month duration requirement and became entitled to benefits before he returned to work; he was in turn entitled to a trial work period; and his subsequent work as a cashier, being trial work, should not count against him.
The Agencys regulations plainly reject this view of the statute. They say, You are not entitled to a trial work period if you perform work . . . within 12 months of the onset of the impairment(s) … and before the date of any notice of determination or decision finding … you … disabled . 20 CFR §404.1592(d)(2) (2001). This regulation means that the Agency, deciding before the end of Year One, might have found that Waltons impairment (or inability to work) can be expected to last for twelve months. But the Agency, deciding after a Year One in which Walton in fact returned to work, would not ask whether his impairment (or inability to work) could have been expected to last 12 months.
The legal question is whether this Agency regulation is consistent with the statute. The Court of Appeals, accepting Waltons view, concluded that it is not. It said that the Agencys rulespermitting the use of hindsight when reviewing claimsare inconsistent with the statutes plain language, 235 F. 3d, at 191. And, here, other courts have agreed. See Salamalekis v. Commissioner of Soc. Sec. , 221 F. 3d 828 (CA6 2000); Newton v. Chater , 92 F. 3d 688 (CA8 1996); Walker v. Secretary of Health & Human Servs. , 943 F. 2d 1257 (CA10 1991); McDonald v. Bowen , 818 F. 2d 559 (CA7 1986).
Nonetheless, we believe that Agency regulation is lawful. See Chevron , supra, at 843. The statute is ambiguous. It says nothing about how the Agency, when it adjudicates a matter after Year One, is to treat an earlier return to work. Its language can be expected to last 12 months, 42 U. S. C. §423(d)(1)(A), simply does not say as of what time the law measures the expectation. Indeed, from a linguistic perspective, the phrase can be expected, foresees a decisionmaker who is looking into the future, not a decisionmaker who is in the future, looking back into the past in order to see what then was, could be, or could have been expected. And read in context, the purpose of the phrase can be expected to last might be one of permitting the Agency to award benefits before 12 months have expired, not one of denying the Agency the benefit of hindsight. See 65 Fed. Reg., at 42780; cf. also S. Rep. No. 404, at 99.
At the same time, the Agencys regulation seems a reasonable, hence permissible, interpretation of the statute. In effect it treats a pre-Agency-decision actual return to work, e.g. , Waltons return in December Year One, as if it were determinative of the expectation question. With Year Twos hindsight, Waltons inability to work can not be expected to last 12 months. And use of that hindsight avoids the need for the Year Two decisionmaker in effect to answer a highly unwieldy question in what grammarians might call the pluperfect future tense.
Of course, administrators and judges are capable of answering hypothetical questions of this kind. But here the question concerns what must be a contrary-to-fact speculation about the future. It is a speculation that, however often raised, would rarely prove easy to resolve. And the statutes purpose does not demand its resolution. Indeed, one might ask why, other things being equal, a claimant who returns to work too early ordinarily to qualify for benefits nonetheless should qualify if, but only if, that return was a kind of medical surprise . Of course, as Walton says, such a rule would help encourage (or at least not discourage) a claimants early return to work. See generally S. Rep. No. 1856, 86th Cong., 2d Sess., 1516 (1960). But the statute does not demand that the Agency make of this desirable end an overriding interpretive principle. And the Agency has recognized and addressed the problem of work disincentives in other ways. See, e.g. , 20 CFR §§404.1574(c), 404.1575(d) (2001).
The statutes complexity, the vast number of claims that it engenders, and the consequent need for agency expertise and administrative experience lead us to read the statute as delegating to the Agency considerable authority to fill in, through interpretation, matters of detail related to its administration. See Schweiker v. Gray Panthers, 453 U. S. 34, 4344 (1981) . The interpretation at issue here is such a matter. The statutes language is ambiguous. And the Agencys interpretation is reasonable.
We conclude that the Agencys regulation is lawful.
* * *
The judgment of the Fourth Circuit is
JO ANNE B. BARNHART, COMMISSIONER OF
SOCIAL SECURITY, PETITIONER v.
CLEVELAND B. WALTON
on writ of certiorari to the united states court of appeals for the fourth circuit
Justice Scalia , concurring in part and concurring in the judgment.
I join all but Part II of the Courts opinion.
I agree that deference is owed to regulations of the Social Security Administration (SSA) interpreting the definition of disability, 42 U. S. C. §§423(d)(1)(A) (1994 ed. and Supp. V). See 65 Fed. Reg. 42774 (2000). As the Court acknowledges, the recency of these regulations is irrelevant, see ante , at 89 (citing Smiley v. Citibank (South Dakota), N. A., 517 U. S. 735, 741 (1996) ; United States v. Morton, 467 U. S. 822, n. 21 (1984)). I would therefore not go on, as the Court does, ante , at 79, to address the SSAs prior interpretation of the definition of disability in a 1982 Social Security Ruling, a 1965 Disability Insurance State Manual, and a 1957 OASI Disability Insurance Letter.
I do not believe, to begin with, that particular deference is owed to an agency interpretation of longstanding duration, ante , at 7. That notion is an anachronisma relic of the pre- Chevron days, when there was thought to be only one correct interpretation of a statutory text. A longstanding agency interpretation, particularly one that dated back to the very origins of the statute, was more likely to reflect the single correct meaning. See, e.g. , Watt v. Alaska, 451 U. S. 259, 272273 (1981) . But once it is accepted, as it was in Chevron , that there is a range of permissible interpretations, and that the agency is free to move from one to another, so long as the most recent interpretation is reasonable its antiquity should make no difference. Cf. Rust v. Sullivan, 500 U. S. 173, 186187 (1991) ; Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837, 863864 (1984) .
If, however, the Court does wish to credit the SSAs earlier interpretationsboth for the purpose of giving the agencys position particular deference and for the purpose of relying upon congressional reenactment with presumed knowledge of the agency position, see ante , at 78then I think the Court should state why those interpretations were authoritative enough (or whatever-else-enough Mead requires) to qualify for deference. See United States v. Mead Corp., 533 U. S. 218 (2001) . I of course agree that more than notice-and-comment rulemaking qualifies, see ante , at 9, but that concession alone does not validate the Social Security Ruling, the Disability Insurance State Manual, and the OASI Disability Insurance Letter. (Only the latter two, I might point out, antedate the congressional reenactments upon which the Court relies.)
The SSAs recently enacted regulations emerged from notice-and-comment rulemaking and merit deference. No more need be said.