dissenting:
I do not agree with the majority of this court that the Career Path Policy of the United States Postal Service can be upheld in the face of the principles, spirit and letter of the Age Discrimination in Employment Act. My disagreement is based on two fundamental grounds: first, is the majority’s failure to defer to the district court’s findings of fact, all of which are supported by evidence, and none of which can be said to leave us with the “definite and firm conviction that a mistake has been committed.” Anderson v. City of Bessemer City, North Carolina, 470 U.S. 564, 105 S.Ct. 1504, 84 L.Ed.2d 518 (1985). Second, is the constricted and anomalous interpre*1001tation given the ADEA by the majority which holds that even though one component of the Postal Service’s policy violates the ADEA, that when combined with the other two components that do not, the flawed component is somehow cured.
Because I am convinced that the majority has erred in both these respects, I respectfully dissent.
I.
The Age Discrimination in Employment Act makes it unlawful for an employer to discriminate against any employee with respect to the employee’s “conditions ... of employment, because of such individual’s age; ....” 29 U.S.C. § 623(a). With regard to federal government employment, and in particular with regard to those employed in the United States Postal Service, the Act provides that “[a]ll personnel actions affecting employees ... who are at least 40 years of age ... in the United States Postal Service ... shall be made free from any discrimination based on age.” 29 U.S.C. § 633a(a). Accordingly, if without statutory justification, the Postal Service imposes an onerous condition on those of its employees in the protected age group, 40 years old or over, and that condition is harsher than the condition imposed on younger (less than 40 years of age) employees, the condition cannot be sustained without violating the Act.
In the present appeal, the United States Postal Services Career Path Policy (“CPP”) has been challenged by Level 23 postal inspectors over the age of 40, precisely because a condition of the Career Path Policy requires senior inspectors to accept undesirable, expensive and disadvantageous involuntary transfers to Major Metropolitan Areas (“MMAs”), solely because of their seniority, which the district court correlated to their age.1 The CPP, while permitting voluntary Levels 21 and 23 lateral reassignments without regard to seniority, at the same time mandates that the most senior Level 23 inspectors in the country are obliged to accept involuntary directed transfers to Major Metropolitan Areas if the needs of the Service have not been met by the voluntary transfers. These involuntary transfers are made on a “senior-first” basis and are made to locations which are regarded as extremely undesirable because of the high cost of living in those areas. Thus, because of the correlation between age and seniority, by reason of age only, the over-40 inspectors are penalized by transfers not required of their under-40 colleagues.
The district court found that this “senior-first” rule violated the Act under both disparate impact and disparate treatment theories. It found that the postal inspectors’ age and seniority were correlated; that the Postal Service knew of that correlation; and that there was no justifiable business necessity for such a policy. The district court also found that the evidence clearly demonstrated that the real business need of the Postal Service, in order to alleviate the shortage of experienced postal inspectors in major metropolitan areas, was not for senior Level 23 inspectors but rather was for “... Level 21 or higher postal inspectors of any seniority.” 667 F.Supp. 6, 19 (D.D.C.1987). Accordingly, the district court found that the Postal Service’s purported reason for the “senior-first” rule was pretextual and that the “senior-first” rule, by falling more harshly on postal inspectors over the age of 40, was discriminatory in its operation. Indeed, the district court found that the Postal Service intentionally subjected senior Level 23 inspectors to disparate treatment and did so knowingly, and therefore, willfully. Moreover, the record discloses that the findings made by the district court are supported by evidence and thus are not clearly erroneous.
Because we must defer to the district court’s findings in our role as an appellate tribunal and because the record clearly demonstrates that the senior inspectors of protected age are adversely affected and *1002adversely treated under the Postal Service Career Path Policy because of their age, I would affirm the district court’s order in all particulars.
II.
The essential flaw in the Postal Service Career Path Policy can best be illustrated by the following example which the government admitted during oral argument, accurately reflects the manner in which the Career Path Policy operates:
Let us assume hypothetically that there are 7 vacancies to be filled in MMAs through the use of the CPP. Assume further that there are 10 Level 23 postal inspectors available to fill those positions: 4 of these inspectors are over the age of 40, and 6 are under the age of 40. If 4 of the under-40 inspectors voluntarily transfer to fill 4 of the MMA vacancies under the voluntary transfer component of the CPP, there would still be 3 vacancies remaining. These 3 vacancies, under the challenged provision of the CPP, would have to be involuntarily filled by directed transfers from the remaining 4 senior inspectors who are over the age of 40. Under the present CPP, the 3 vacancies would automatically be filled by the directed involuntary transfer of 3 of the 4 remaining senior Level 23 over-40 inspectors.
Because the CPP operates in precisely this manner — a manner that patently discriminates against inspectors in the protected age group — it is clear beyond peradventure that the implementation of the CPP by the Postal Service violates the ADEA. Neither the explanations offered by the Service nor the justification proffered by the majority can alter the stark reality of the policy’s operation: if an inspector is over 40, he will suffer the disadvantage of an adverse and undesirable posting not otherwise imposed upon any younger colleague.
A.
Here Arnold has argued that the Postal Service’s CPP discriminates against senior (and thus older) Level 23 postal inspectors by requiring these older inspectors to involuntarily transfer to MMAs, rather than being randomly assigned to MMAs without regard to their seniority — ergo age. Arnold advanced two theories of discrimination. Arnold first claimed that the “senior-first” rule has a disparate impact on the class of Level 23 inspectors who are over the age of 40 and thus are protected by the ADEA. The district court agreed, finding that the “[plaintiffs’ statistics establish that the adverse effects of the senior-first rule, which involuntarily transfers the oldest postal inspectors to cities with high costs of living, or causes them to resign or volunteer for lateral transfer, falls more harshly on postal inspectors 40 years of age and older than on postal inspectors under 40 years of age.” 667 F.Supp. at 18-19.
Arnold also has contended that the senior-first rule constitutes disparate treatment of the senior Level 23 inspectors because the Postal Service knew the correlation between age and seniority but nevertheless implemented the use of the rule, thus intentionally discriminating against the older inspectors on the basis of their age by forcing them to transfer to cities to which they did not wish to transfer. The district court also found in favor of Arnold on this theory, finding that the “[djefen-dant was unable to proffer a legitimate, nondiscriminatory reason for using the senior-first rule because no such reason exists.” Id. at 19.
B.
On appeal, the Postal Service attacked the district court’s conclusions on four fronts. First, it argued that the district court erred in applying disparate impact analysis — typically applied under Title VII — to an ADEA case. Second, the Postal Service argued that, even if disparate impact analysis is appropriate in an ADEA context, the district court erred in finding that the directed involuntary transfer under the CPP had a disparate impact in the instant case. Third, the Postal Service argued that the “senior-first” rule is job-related and thus falls within the business *1003necessity exception to the ADEA. And finally, the Postal Service challenged the district court’s finding of disparate treatment on the ground that the district court applied the wrong legal standard in reaching its conclusion.
C.
Although the majority discusses the applicability of the disparate impact theory to ADEA cases, it ultimately reaches no conclusion on this issue. The majority apparently rejects the district court’s factual finding that the CPP had a disparate impact on older postal inspectors. It does so, however, without reviewing the district court’s finding under our clearly erroneous standard of review.
With respect to disparate treatment, the majority rejects as “clearly erroneous” the district court’s finding that the “senior-first” policy amounted to disparate treatment of older postal inspectors. As with disparate impact, the majority reaches this conclusion because it ignores the impact of the “senior-first” rule of mandatory transfer. Rather, the majority argues that the appropriate analysis must include the voluntary transfers permitted under the CPP.
D.
As I have indicated, my disagreement with the majority is manifold. First, unlike the majority, I believe that this case requires us to address the application of the disparate impact theory to ADEA cases. I would hold that in this respect there is no meaningful distinction between Title VII and the ADEA and that the disparate impact theory should be available to ADEA plaintiffs. Secondly, I believe that the majority has reversed the district court’s finding of disparate impact without reference to either the appropriate standard of review or to the considerable evidence in the record supporting the district court’s finding. Lastly, I believe that without analyzing the extensive record, and without deferring to the district court’s findings of fact supported by evidence, the majority has improperly substituted its personal judgment for the district court’s findings. I turn first, therefore, to a consideration of Arnold’s disparate impact theory.
III.
A.
The Postal Service has argued that disparate impact analysis is not available in cases arising under the ADEA, I can discern no compelling argument why it should not. That the ADEA’s coverage and provisions are substantially similar to the provisions of Title VII is no accident. The similarity between these two statutes flows from the fact that the ADEA was modeled after Title VII, relying on much of Title VII’s actual language for its content. See Lorillard v. Pons, 434 U.S. 575, 584, 98 S.Ct. 866, 872, 55 L.Ed.2d 40 (1978).
Under Title VII, employees can prove discrimination by showing either disparate impact or disparate treatment. See Griggs v. Duke Power Co., 401 U.S. 424, 91 S.Ct. 849, 28 L.Ed.2d 158 (1971). Because of the similarity between Title VII and the ADEA, many ADEA cases within and without this Circuit have utilized the “tripartite evidentiary scheme developed in the context of Title VII litigation,” Krodel v. Young, 748 F.2d 701, 705 (D.C.Cir.1984), cert. denied, 474 U.S. 817, 106 S.Ct. 62, 88 L.Ed.2d 51 (1985), in disparate treatment cases arising in the ADEA context. See also; Loeb v. Textron, Inc., 600 F.2d 1003, 1015 (1st Cir.1979); Schwager v. Sun Oil Co., 591 F.2d 58, 60-61 (10th Cir.1979). Similarly, many Courts of Appeals now allow employees to establish a violation of the ADEA by demonstrating disparate impact alone. See e.g. Blum v. Witco Chemical Corp., 829 F.2d 367, 372 (3d Cir.1987); Holt v. Gamewell Corp., 797 F.2d 36, 37 (1st Cir.1986); EEOC v. Borden’s Inc., 724 F.2d 1390, 1394-95 (9th Cir.1984); Leftwich v. Harris-Stowe State College, 702 F.2d 686, 690 (8th Cir.1983); Geller v. Markham, 635 F.2d 1027, 1032 (2d Cir.1980), cert. denied, 451 U.S. 945, 101 S.Ct. 2028, 68 L.Ed.2d 332 (1981). Two of this court’s ADEA opinions have made reference to disparate impact analysis, although neither directly addressed the question of whether *1004that analysis should be employed in ADEA cases. See Schmid v. Frosch, 680 F.2d 248, 250-51 (D.C.Cir.1982); Krodel, 748 F.2d at 709.
As I have indicated, there is no reason why disparate impact theory should not be available for those seeking relief under the ADEA. The similarity between Title VII and the ADEA, along with the ADEA’s history, argue in favor of such importation. In Lorillard, 434 U.S. at 584, 98 S.Ct. at 872, the Supreme Court observed that “the [substantive] provisions of the ADEA were derived in haec verba from Title VII.” Moreover, in Griggs, 401 U.S. at 429, 91 S.Ct. at 852, the Court explained that Congress’s objective in enacting Title VII was “plain from the language of the statute” and, on the basis of that language, held that Title VII “proscribes not only overt discrimination but also practices that are fair in form but discriminatory in operation.” Id. at 431, 91 S.Ct. at 853. See also Watson v. Fort Worth Bank and Trust, — U.S. -, 108 S.Ct. 2777, 2785-86, 101 L.Ed.2d 827 (1988) (Facially neutral employment practices that have significant adverse effects on protected groups may violate Title VII without proof of discriminatory intent).
Given that the text of the ADEA was derived largely from that of Title VII, and given that the Supreme Court’s acceptance of disparate impact theory was based on Title VII’s express language, it would be anomalous to conclude that disparate impact analysis should not be followed in proving an ADEA violation. Indeed, no Court of Appeals that has been faced with this question has decided it differently.
Moreover, Title VII, by its terms, is designed to protect against discrimination based on an individual’s race, color, religion, sex, or national origin. 42 U.S.C. § 2000e-2. Each of these categories shares a single distinctive feature: each is a facet of human existence with which a person is born, and which is largely beyond his or her control. Thus, under Title VII, Congress has decreed that certain adverse employment decisions made by employers based on an individual’s possession of any of these characteristics, is repugnant and illegal. In enacting the ADEA, Congress has also decreed that employment decisions based on age, (an equally immutable characteristic), are similarly repugnant and illegal.
Because I am satisfied that in this context, there is no distinction between Title VII and the ADEA, I conclude that the district court did not err when it stated that “a violation of the ADEA may be proved by showing that an employment practice, such as the senior-first rule, which is involved in this case, has a disparate impact on a protected class, namely postal inspectors 40 years of age and above.” 667 F.Supp. at 19.
B.
Having concluded that the district court did not err in applying the theory of disparate impact in this case. I consider next the appropriate standard of review for the district court’s finding that the “senior-first” component of the CPP did in fact have a disparate impact on the most senior Level 23 inspectors. The record contains evidence that supports the district court’s finding of disparate impact — a finding to which we must defer unless clearly erroneous.
In discussing this question, the majority fails to articulate any standard of review. Yet, the case law makes clear that findings of disparate impact and disparate treatment are reviewed under a clearly erroneous standard. Anderson v. City of Bessemer City, 470 U.S. 564, 573-76, 105 S.Ct. 1504, 1511-13, 84 L.Ed.2d 518 (1985) (disparate treatment); Palmer v. Shultz, 815 F.2d 84, 101 (D.C.Cir.1987) (disparate treatment); Kilgo v. Bowman Trans., Inc., 789 F.2d 859, 872-73 (11th Cir.1986) (disparate impact); Griffin v. City of Omaha, 785 F.2d 620, 625 n. 6 (8th Cir.1986) (disparate treatment); Andrews v. Bechtel Power Corp., 780 F.2d 124, 141, 142-43 (1st Cir.1985) (disparate impact), cert. denied, 476 U.S. 1172, 106 S.Ct. 2896, 90 L.Ed.2d 983 (1986); Lewis v. Bloomsburg Mills, Inc., 773 F.2d 561, 569 n. 14 (4th Cir.1985) (disparate impact); Smith v. Western Electric *1005Co., Inc., 770 F.2d 520, 524 (5th Cir.1985) (disparate impact and disparate treatment).
In Anderson the Supreme Court defined “clearly erroneous” as follows:
Although the meaning of the phrase “clearly erroneous” is not immediately apparent, certain general principles governing the exercise of the appellate court’s power to overturn findings of a district court may be derived from our cases. The foremost of these principles, ... is that “[a] finding is ‘clearly erroneous’ when although there is evidence to support it, the reviewing court on the entire evidence is left with the definite and firm conviction that a mistake has been committed.” United States v. United States Gypsum Co., 333 U.S. 364, 395, 68 S.Ct. 525, 542, 92 L.Ed. 746 (1948). This standard plainly does not entitle a reviewing court to reverse the finding of the trier of fact simply because it is convinced that it would have decided the case differently. The reviewing court oversteps the bounds of its duty under Rule 52(a) if it undertakes to duplicate the role of the lower court. “In applying the clearly erroneous standard to the findings of a district court sitting without a jury, appellate courts must constantly have in mind that their function is not to decide factual issues de novo.” Zenith Radio Corp. v. Hazeltine Research, Inc., 395 U.S. 100, 123, 89 S.Ct. 1562, 1576, 23 L.Ed.2d 129 (1969). If the district court’s account of the evidence is plausible in light of the record viewed in its entirety, the court of appeals may not reverse it even though convinced that had it been sitting as the trier of the fact, it would have weighed the evidence differently. Where there are two permissible views of the evidence, the factfinder’s choice between them cannot be clearly erroneous. United States v. Yellow Cab Co., 338 U.S. 338, 342, 70 S.Ct. 177, 179, 94 L.Ed. 150 (1949); see also Inwood Laboratories Inc. v. Ives Laboratories, Inc., 456 U.S. 844, 102 S.Ct. 2182, 72 L.Ed.2d 606 (1982).
Anderson, 470 U.S. at 573-74, 105 S.Ct. at 1511-12.
The district court s account of the evidence” in this case, was at the very least “plausible”. The majority, by ignoring the prescribed standard of review has performed precisely the type of de novo review forbidden by the Supreme Court in Anderson.
C.
In order to establish a prima facie case of age discrimination on the basis of a facially neutral employment policy’s disparate impact, a plaintiff is not required to demonstrate that the policy is the result of an employer’s discriminatory intent, but need only establish that the policy impacts disproportionately on persons protected by the ADEA. Leftwich v. Harris-Stowe State College, 702 F.2d at 690; Getter v. Markham, 635 F.2d at 1032. See also Griggs v. Duke Power Co., 401 U.S. at 431-32, 91 S.Ct. at 853-54.
Here, the district court found that the CPP had a disproportionate impact on the most senior Level 23 inspectors because its “senior-first” rule was in essence an “older-first” rule, and subjected the older postal inspectors to directed transfers first.” 667 F.Supp. at 23. The district court reached this conclusion on the basis of the statistical evidence offered into evidence by Arnold. This evidence, which constituted an appropriate way of proving disparate impact, see e.g. Hazelwood School Dist. v. United States, 433 U.S. 299, 306-309, 97 S.Ct. 2736, 2740-2742, 53 L.Ed.2d 768 (1977); International Brotherhood of Teamsters v. United States, 431 U.S. 324, 337-340, 97 S.Ct. 1843, 1855-56, 52 L.Ed.2d 396 (1977); Blum v. Witco Chemical Corp., 829 F.2d 367, 372 (3d Cir.1987); Palmer v. Schultz, 815 F.2d 84, 91 n. 6 (D.C.Cir.1987); Leftwich v. Harris-Stowe State College, 702 F.2d at 690, overwhelmingly demonstrated that a disproportionately large number of the Level 23 inspectors over the age of forty were forced, against their wills, to move to the more expensive MMAs. On the basis of this statistical evidence, the district court found that “the senior-first rule fell more harshly on plain*1006tiffs [over the age of 40] than on postal inspectors under the age of 40 ...” The district court then concluded that this factual finding supported the conclusion that the “senior-first” rule violated the ADEA. 667 F.Supp. at 23.
As illustrated by the hypothetical example set forth at the outset of this dissent in Part II, no other conclusion can logically be reached. If the “senior-first” rule violates the ADEA and therefore is tainted, its taint cannot be sanitized by the remaining innocuous provisions of the Postal Service policy. Indeed, nowhere in the majority opinion is it ever suggested that the “senior-first” rule by itself does not violate the ADEA. Nor is it an answer to the district court’s finding of illegality, that Arnold has focused on only one provision of the three-part CPP as the majority argues.
D.
I am not convinced by the Postal Service’s contention, accepted by the majority, that disparate impact may not be established by isolating one component of the CPP, rather than considering its overall effect on the protected class of Level 23 inspectors. The gravamen of the majority’s position is that the district court erred in rejecting Postal Service’s statistical evidence as to the effect of the CPP with respect to all postal inspectors (both above and below the age of 40), in favor of Arnold’s proofs which focused on the effect of the “senior-first” rule on Level 23 inspectors over the age of 40. The majority claims that, when viewed in terms of its three component parts — (1) voluntary transfers of Level 23 inspectors; (2) voluntary transfers of Level 21 inspectors who are promoted to fill Level 23 vacancies; and (3) senior-first directed transfers — the CPP does not impact unfavorably on older Level 23 inspectors. In so concluding, the majority reasons that when one examines the pool of all Level 23 postal inspectors who have been transferred, both voluntarily and involuntarily, there is no disproportionate representation of inspectors aged 40 and older.
I believe that the majority has missed the point of Arnold’s complaint. No objection has ever been lodged against the policy component of voluntary transfers. Arnold’s only complaint is with the involuntary transfers. When the district court examined the pool of inspectors, who had been subject to involuntary transfers, it found that it was “1.9 to 2 times more likely that a postal inspector 40 years of age and above will be directed to transfer than a postal inspector under 40 years of age.” 667 F.Supp. at 23.
In order to reach its conclusion, the majority attempts to distinguish Connecticut v. Teal, 457 U.S. 440, 102 S.Ct. 2525, 73 L.Ed.2d 130 (1982). Maj. op. at 999. I find the distinction wholly unpersuasive. I read Teal as being inconsistent with the Postal Service’s argument that the “senior-first” rule must be analyzed as part of the CPP “package” and may not be evaluated in isolation. My understanding of Teal is consistent with that expressed by the Third Circuit in Massarsky v. General Motors Corp., 706 F.2d 111 (3d Cir.1983), cert. denied, 464 U.S. 937, 104 S.Ct. 348, 78 L.Ed.2d 314 (1983), in which the court characterized Teal as standing for the proposition that “an employment practice must be analyzed at the first step in the employment process that produces an adverse impact on a [protected group], not the end result of the employment process as a whole.” Id. at 122.
In Teal, Connecticut required all employees to pass a written examination prior to becoming eligible for permanent supervisory positions. Pass rates on the examination were significantly lower for black employees than for white employees, thus excluding a disproportionately high number of black candidates from further consideration. A number of black employees brought suit under Title VII, claiming that the examination had a discriminatory impact on black employees and was not job related. The state answered these allegations by arguing that while proportionately fewer blacks became eligible for promotion as a result of the examination, a disproportionately higher number of blacks who were eligible were ultimately given pro*1007motions to supervisory positions. The state argued that the “bottom-line” result, which was more favorable to blacks than to whites, constituted a complete defense to the putative Title VII violations.
The Supreme Court rejected Connecticut’s “bottom-line” rationale on the ground that Title VII protects individuals, not classes, from discrimination. The Court made clear that fairness to a group as a whole cannot justify unfairness to individual employees because Title VIPs “focus on the individual is unambiguous.” Id. at 455, 102 S.Ct. at 2534-35. Although the Teal Court recognized that a nondiscriminatory “bottom-line” might assist an employer in rebutting an inference of discrimination, the Court noted that “[a] racially balanced work force cannot immunize an employer from liability for specific acts of discrimination.” Id. at 454, 102 S.Ct. at 2534-35.
Thus, I would hold that the district court was correct in analyzing and separating out the discrete effects of the “senior-first” rule, and finding that the CPP had a disparate impact on senior-Level 23 inspectors.
E.
The implication of the majority’s opinion is that the district court erred in rejecting the Postal Service’s statistical data in favor of the data submitted by Arnold.
The Postal Service’s statistics analyzed the affect of the “senior-first” rule on all postal inspectors, including those who were and are temporarily or permanently exempt from the “senior-first” rule. By using average data and binomial distribution analysis (which predicts the probability of transferring a postal inspector 40 years of age and older when chosen from the entire pool of eligible postal inspectors both over, and under, 40), the Postal Service was able to demonstrate that those over 40 did not stand a significantly higher chance of being transferred, than those under 40.
Arnold’s proofs, on the other hand, analyzed the affect of the “senior-first” rule on those to whom the rule applies — non-exempt, Level 23 inspectors. The district court properly concluded that the relevant pool from which to measure the effect of the “senior-first” rule should include only those who are eligible for directed transfer. This conclusion was supported by the testimony of Chief Postal Inspector Clauson who testified that the CPP necessarily affected the older inspectors adversely. Upon questioning by the court, Chief Clau-son testified as follows:
THE COURT: Now, by the use of the seniority system, it’s far more likely than not that that is going to have an effect upon the more senior, older employees, is it not?
THE WITNESS: Yes, your honor. Particularly the directed transfer portion.
THE COURT: That is what I am talking about.
THE WITNESS: Yes.
THE COURT: The directed transfer.
THE WITNESS: Yes.
THE COURT: And that is going to happen in most every case in the directed transfer situation, is it not?
THE WITNESS: Senior person; yes, sir.
THE COURT: And the only way, Chief Clauson, that could be corrected would be to go to a random system of selecting people for directed transfer in order to avoid the impact on age of your seniority system. Isn’t that right?
THE WITNESS: That is one way; yes, sir.
THE COURT: It’s the only way, isn’t it?
THE WITNESS: Well, the other option was to go like the junior and probably the reverse.
THE COURT: That wouldn’t have accomplished your mission.
THE WITNESS: That’s right. That’s right.
THE COURT: But by using seniority, it does have an effect, an adverse effect, by reason of a person’s age. Doesn’t it?
THE WITNESS: Yes, your honor.
Supp.App. at 52-3.
The district court made a factual finding that Arnold’s data and evidence better reflected the effect of the “senior-first” rule *1008on the protected class of postal inspectors. In light of the evidence of record there can be no doubt that the district court’s finding was not clearly erroneous. Because our review of the district court’s factual findings is governed by this highly deferential standard, I perceive no principled basis by which to justify the majority’s holding that no disparate impact was demonstrated.
F.
In its final argument, with respect to disparate impact, the Postal Service contended that, even if the district court’s finding of disparate impact is correct, the court applied the wrong legal standard in holding that no valid “job relatedness” had been demonstrated by the Postal Service with respect to the directed transfer component of the CPP. Although the majority did not find it necessary to discuss this issue because of its holding that the district court had erred, my analysis, which would sustain the district court’s findings, obliges me to discuss this issue.
As the Postal Service correctly points out, when disparate impact has been established, an employer’s burden of rebuttal has been described by the Supreme Court as showing that the challenged practice is “job related,” New York Transit Authority v. Beazer, 440 U.S. 568, 587, 99 S.Ct. 1355, 1366, 59 L.Ed.2d 587 (1979); that it bears a “manifest relationship” to the job in question, Griggs v. Duke Power Co., 401 U.S. at 432, 91 S.Ct. at 854; or that it is justified by “business necessity,” Albemarle Paper Co. v. Moody, 422 U.S. 405, 425, 95 S.Ct. 2362, 2375, 45 L.Ed.2d 280 (1975).
In this case, the district court stated that in order to “establish a business necessity defendant must have had no other choice but to transfer the most senior Level 23 postal inspectors to fill the vacancies in Major Metropolitan Areas.” 667 F.Supp. at 23-24 (emphasis added). The Postal Service argued that the district court’s “no other choice” standard was unfairly harsh and placed too great a burden on the Postal Service to prove business necessity.
While I agree that the district court's standard was perhaps demanding in view of the Supreme Court’s test as enunciated in Griggs, I am convinced that, given the testimony adduced by the Postal Service at trial, see 667 F.Supp. at 24, the Postal Service would not have prevailed even under the less stringent standard set forth in Griggs v. Duke Power. Thus, if the district court did in fact utilize too demanding a standard, its use of that standard constituted harmless error. In Griggs, the Court stated that:
[t]he touchstone is business necessity. If an employment practice which operates to exclude [the protected class] cannot be shown to be related to job performance, the practice is prohibited .... [that employment practice must] bear a demonstrable relationship to successful performance of the jobs for which it was used.
Id. at 431, 91 S.Ct. at 853.
Under this standard, which appears to be somewhat more permissive than the standard used by the district court, the business necessity defense of the Postal Service would also fail. The district court noted that in the Postal Service’s Chief Inspector’s testimony that the “senior-first” rule was justified by the Service’s need for:
(1) more experienced postal inspectors in major metropolitan areas, (2) a perpetual system for remedying the shortage of experienced postal inspectors in major metropolitan areas, and (3) a predictable system for directing transfers of experienced postal inspectors to major metropolitan areas.
667 F.Supp. at 24.
As the district court logically found, these reasons fail to satisfy the “no other choice” test used by the district court and, in my view, these reasons would also fail the somewhat less demanding “demonstrably related to job performance” test enunciated in Griggs. Randomly selecting Level 23 inspectors, rather than requiring “senior-first” transfers, would satisfy the Service’s need for a “perpetual,” “predictable” system that ensured the placement of “ex*1009perienced postal inspectors” in major metropolitan areas. This is borne out by the fact that the Service allowed any Level 23 inspector to voluntarily transfer, and even allowed less experienced Level 21 inspectors to transfer to fill MMA vacancies. As the district court observed, “there was more than ample evidence in the record to show that defendant’s alleged need for ‘experienced’ postal inspectors was no more than a need for Level 21 and higher inspectors.” 667 F.Supp. at 24.
Indeed, the district court discounted the Postal Service’s justification when it found, “[ajlthough defendant attempts to justify the senior-first rule by arguing that it has a business need for the most senior postal inspectors in the major metropolitan areas, the evidence before the Court clearly shows that defendant’s real business need was for Level 21 or higher postal inspectors of any seniority.” Id. at 19. Thus, whatever standard was utilized, it was evident under the district court findings, all of which were supported by evidence, that the Postal Service’s business necessity defense was unavailing.
Accordingly, I am satisfied that the district court’s reasoning in this respect was sound, its findings were not clearly erroneous, and, each finding was fully supported by evidence.
G.
Overall therefore, I am satisfied that the district court correctly applied a theory of disparate impact. The district court findings were supported by evidence that the Postal Service had violated the ADEA by the “senior-first” component of the CPP. Those findings must be upheld when reviewed under our clearly erroneous standard.
I turn next to a consideration of disparate treatment.
IV
It has been established under Title VII that disparate treatment claims can involve an isolated incident of discrimination against a single individual, or, allegations of a “pattern of practice” of discrimination affecting an entire class of individuals. Palmer v. Schultz, 815 F.2d 84, 90 (D.C.Cir.1987); International Brotherhood of Teamsters v. United States, 431 U.S. 324, 335, 97 S.Ct. 1843, 1854, 52 L.Ed.2d 396 (1977). I see no reason why the district court should not have followed this approach in the ADEA context.
The question before us therefore, is whether the district court improperly found that the CPP was designed and implemented with full knowledge that it intentionally discriminated against Level 23 inspectors aged 40 and above. In Palmer, the court stated that plaintiffs in Title VII pattern and practice cases need not rely on statistical evidence alone, to establish intentional discrimination:
Because the ultimate issue in a disparate treatment case is whether the disparity resulted from unlawful discriminatory animus, plaintiffs may introduce any additional evidence which is probative on this issue.... When plaintiffs in a Title VII pattern or practice case rely on evidence in addition to the evidence of the disparity itself, the issue for the trier of fact in determining whether the plaintiffs have established a prima facie case must be whether the totality of plaintiff’s evidence (again including the evidence of the disparity itself) demonstrates that, more likely than not, the disparity resulted from an unlawful animus ....
815 F.2d at 96-7.
Courts generally apply the tripartite evi-dentiary scheme developed in the context of Title VII litigation to suits brought under the ADEA. See Coburn v. Pan American World Airways, Inc., 711 F.2d 339, 342-43 (D.C.Cir.), cert. denied, 464 U.S. 994, 104 S.Ct. 488, 78 L.Ed.2d 683 (1983). Under these guidelines, an individual claiming disparate treatment must make out a pri-ma facie case using sufficient facts to give rise to a reasonable inference that race, sex or age was a factor in the employment decision at issue. Krodel v. Young, 748 F.2d 701, 705 (D.C.Cir.1984), cert. denied, 474 U.S. 817, 106 S.Ct. 62, 88 L.Ed.2d 51 *1010(1985). “Once a prima facie case has been established, the employer bears a minimal burden of “producing evidence” tending to show that the plaintiff was denied employment or promotion for a legitimate nondiscriminatory reason.” Id. If the employer successfully produces credible evidence to this effect, the burden shifts back to the plaintiff to show by a preponderance of the evidence that the employer’s asserted legitimate reason is a “pretext” for discrimination. Id. (citing McDonnell Douglas Corp. v. Green, 411 U.S. 792, 800-02, 93 S.Ct. 1817, 1823-24, 36 L.Ed.2d 668 (1973)).
In clarifying exactly what type of action rises to the level of disparate treatment, this court has stated:
In an ADEA case, the plaintiffs ultimate burden is to prove that age was ‘a determining factor’ in the challenged employment decision.... The plaintiff must prove that ‘age made a difference in the employer’s decision,’ ... in the sense that, ‘but for’ the discriminatory motive, the employee would have been hired, promoted or retained.... The question of discriminatory intent, moreover, is a finding of fact subject to the ‘clearly erroneous’ standard of review.... [A] district court's ADEA ruling .... can thus only be overturned if the court committed legal error or if we are ‘left with the definite and firm conviction that a mistake has been committed.’
Krodel, 748 F.2d at 706.
In the present case, there can be no question but that the district court utilized the proper legal standard when analyzing the effect of the CPP on Level 23 senior inspectors. The district court’s analytical framework virtually tracks the framework set forth in McDonnell Douglas, 411 U.S. at 800-02, 93 S.Ct. at 1823-24 — a framework subsequently adopted by our court as a model for analyzing disparate treatment claims under the ADEA. See Krodel, 748 F.2d at 705-06. The district court methodically analyzed whether the plaintiffs had established a prima facie case against the Postal Service; whether the defendant had produced evidence of a legitimate, non-discriminatory reason for the senior-first rule; and whether the plaintiffs proved by a preponderance of the evidence that the Postal Service’s reason for the senior-first rule was a pretext for its discriminatory animus.
A. The Prima Facie Case:
The district court held that the inspectors established a prima facie case by demonstrating that the Postal Service forced its most senior Level 23’s to transfer and that there was a statistically significant correlation between seniority and age. The district court found that, because the Service was aware of this correlation, the statistical correlation between the age and seniority was sufficient to raise an inference of disparate treatment. The district court was also persuaded by Chief Inspector Clauson’s testimony that “he knew age and seniority correlated and that the senior-first rule would adversely affect the older postal inspectors.” 667 F.Supp. at 27. Indeed, Chief Inspector Clauson, in a letter to then Chief Inspector Fletcher, wrote that he believed that any such discriminatory rule would be challenged and that a nondiscriminatory system should be used. Id. On the basis of this evidence, the district court found that “defendant’s disregard for the adverse effect of the Rule on postal inspectors 40 years of age and over and the correlation between age and seniority raise far more than an inference of age discrimination.” Id.
I have no difficulty with the district court’s finding. It is clear from the evidence produced by Arnold that inspectors over the age of 40 received a statistically disproportionate number of directed transfers. In addition, Clauson testified that when the Service adopted the “senior-first” rule it knew that such a rule was the equivalent of an “oldest-first” rule. Supp. App. at 52-3. Clauson testified that he knew that seniority and age were correlated, that he was aware of the antidiscrim-ination laws, that there was “a good chance, if not [a] certainty” that the directed transfer component of the CPP would be challenged, Supp.App. at 51, and that he knew the “senior-first” rule was “far more likely than not ... to have an effect upon *1011the more senior, older employees” and “an adverse effect, by reason of a person’s age.” Supp.App. at 52-53.
Moreover, once a correlation between seniority and age was found, the very provision of the CPP itself which mandates involuntary transfers of senior Level 23 inspectors without more, satisfies the prima, facie test. I am, therefore, satisfied, even though the majority holds otherwise, that Arnold made out a more than adequate prima facie case.
B. Was There a Legitimate, Non-Discriminatory Reason,?
In the next step of the disparate treatment analysis, the defendant must meet its burden of production by adducing evidence of a legitimate, nondiscriminatory reason for its action. See Krodel, 748 F.2d at 705.
The Postal Service claimed that its “senior-first” rule provided a perpetual and predictable system for transferring experienced postal inspectors to the major metropolitan areas. The district court rejected this “business necessity” proffer, as I do. As the district court pointed out, there was no valid need for the Postal Service to transfer the most senior Level 23 postal inspectors, particularly under a “senior-first” rule which discriminated on the basis of age. 667 F.Supp. at 27.
Moreover, the evidence was undisputed that the Postal Service’s need was for Level 21 (or higher postal) inspectors of any seniority. Id. at 19. As the record discloses the difference between Level 21 and Level 23 inspectors has little to do with familiarity with the particular tasks each is assigned. Rather, the difference is found only in the functional areas in which each operate. Id. at 11. Level 21 inspectors have assignments in four functional areas while Level 23 inspectors specialize in one of those four areas. Thus, the explanation provided by the Postal Service for mandatory and involuntary transfers of its older inspectors, when younger inspectors of equal ability were not transferred, just does not hold water.
In a pattern or practice class action case such as this one (as opposed to an individual discrimination claim),
the employer is not required to meet a burden of persuasion in rebutting the disparate treatment claim, [but] the nondiscriminatory explanation must cast sufficient doubt on the plaintiff’s proof to permit the trier of fact legitimately to decline to draw an inference of discrimination from that proof. The bare articulation of a nondiscriminatory explanation, while sufficient to rebut an individual plaintiff’s low-threshold McDonnell Douglas showing, generally will not suffice as a rebuttal to a typical class-wide showing of pervasive discrimination.
Segar, 738 F.2d at 1269. As the Burdine Court put it:
In saying that the presumption [of discrimination] drops from the case, we do not imply that the trier of fact no longer may consider evidence previously introduced by the plaintiff to establish a pri-ma facie case. A satisfactory explanation by the defendant destroys the legally mandatory inference of discrimination arising from the plaintiff’s initial evidence. Nonetheless, this evidence and inference properly drawn therefrom may be considered by the trier of fact on the issue of whether the defendant’s explanation is pretextual. Indeed, there may be some cases where the plaintiffs initial evidence, combined with effective cross-examination of the defendant, will suffice to discredit the defendant’s explanation.
Burdine, 450 U.S. at 255 n. 10, 101 S.Ct. at 1094-95 n. 10 (emphasis added). It is this underscored language that the district court appears to have relied upon. The district court found that Arnold had adequately discredited the Postal Service’s proffered reasons for adopting the “senior-first” rule and it thus concluded that the Postal Service had not sustained its burden of production. Because I am not persuaded, as apparently the majority is (Maj. Op. at 999) that we should ignore the discriminatory prong of the CPP’s three-prong policy, and because the “senior-first” prong is in my view, discriminatory and illegal *1012(as the hypothetical example in Part II of this dissent demonstrates), I would sustain, as not clearly erroneous, the district court finding that the Postal Service has not met its burden of producing evidence of a legitimate non-discriminatory business reason for adopting the CPP.
C. Was the Postal Service’s Proffered Reason a Pretext?
Although the district court need not have applied this part of the tripartite test, it nevertheless found that, even if the Postal Service had met its burden of production, the Level 23 inspectors had proved that the “senior-first” rule was a pretext for age discrimination in this case and that the service nevertheless knowingly implemented the policy. 667 F.Supp. at 27.
The district court once again noted that the Postal Service knew that seniority and age were correlated and the “senior-first” rule essentially amounted to an “older-first” rule. The district court also emphasized that the Postal Service failed to prove that it needed the most senior Level 23 inspectors to meet its requirements in the MMA’s to which they were involuntarily transferred. On the basis of these findings, the district court concluded that the “senior-first rule was a pretext to mask its discriminatory animus and motive.” 667 F.Supp. at 28.
While Arnold may not have clearly demonstrated that a discriminatory reason more likely motivated the Postal Service in this case, Arnold has succeeded in demonstrating that the Service’s proffered explanation is “unworthy of credence.” In Kro-del, the court made it clear that an ADEA plaintiff need not submit direct evidence of discriminatory intent, and that “ ‘the district court must decide which party’s explanation it believes_’” 748 F.2d at 707.
The court also stated that:
[This court] has ... not required an ADEA plaintiff to offer particularized evidence of intentional discrimination in order to prove pretext ... In Cuddy, the court indicated that age discrimination plaintiffs almost necessarily have to rely on indirect evidence, including discrepancies in the defendant’s proffered explanation, to prove that an employer was motivated by illegitimate concerns.
Krodel, 748 F.2d at 707. Applying our standard as discussed in Krodel, I conclude that the district court was not clearly erroneous in determining that the Postal Service’s announced reasons for the “senior-first” policy were pretextual.
Unlike the majority, I do not believe it appropriate to find facts at this level of review. Thus, even if the proofs were otherwise, I cannot find as the majority does, that the Postal Service’s “senior-first” policy was “universal” and “neutral.” Maj. op. at 1000.
V.
Because I cannot agree with the majority interpretation of the ADEA — an interpretation which permits adverse and undesirable employment conditions to be visited upon senior inspectors solely because of their age, and because I cannot agree that non-jury findings of the district court which are supported by evidence should be given no deference, I have been obliged to dissent.
I have gone to some length in this separate opinion to explain my disagreement with the majority’s analysis, because I am concerned that a narrow interpretation of the ADEA as the majority has construed it, together with a disregard of district court findings, may well lead to a similar result in other cases — a result, which was not intended by the Congress when it enacted ADEA to protect individuals from age discrimination.
Accordingly, giving the appropriate deference to the district court findings and giving an appropriate construction to the ADEA — a construction which implements the congressional purpose underlying the Act — I would affirm the district court which found that the CPP violates the Act under both disparate impact and disparate treatment theories.
. The clear correlation between age and seniority found to exist by the district court is binding upon us. No contention has been made that the district court’s finding was clearly erroneous. See Arnold v. Postmaster General, 667 F.Supp. 6, 27 (D.D.C.1987).