Mr. Justice Marshall

delivered the opinion of the Court.

Twenty-two coal mine operators (Operators) brought this suit to test the constitutionality of certain aspects of Title IY of the Federal Coal Mine Health and Safety Act of 1969, 83 Stat. 792, as amended by the Black Lung Benefits Act of 1972, 86 Stat. 150, 30 U. S. C. § 901 et seq. (1970 ed. and Supp. IV). The Operators, potentially liable under the amended Act to compensate certain miners, former miners, and their survivors for death or total disability due to pneumoconiosis arising out of employment in coal mines, sought declaratory and in-junctive relief against the Secretary of Labor and the *6Secretary of Health, Education, and Welfare, who are responsible for the administration of the Act and the promulgation of regulations under the Act.

On cross-motions for summary judgment, a three-judge District Court for the Eastern District of Kentucky, convened pursuant to 28 U. S. C. §§ 2282 and 2284, found the amended Act constitutional on its face, except in regard to two provisions concerning the determination of a miner's total disability due to pneumoconiosis. The court enjoined the Secretary of Labor from further application of those two provisions. 385 F. Supp. 424 (1974). After granting a stay of the three-judge court's order, 421 U. S. 944 (1975), we noted probable jurisdiction of the cross-appeals. 421 U. S. 1010 (1975). We conclude that the amended Act, as interpreted, is constitutionally sound against the Operators' challenges.

I

Coal workers’ pneumoconiosis — black lung disease— affects a high percentage of American coal miners with severe, and frequently crippling, chronic respiratory impairment.1 The disease is caused by long-term inhalation of coal dust.2 Coal workers’ pneumoconiosis (here*7after pneumoconiosis) is generally diagnosed on the basis of X-ray opacities indicating nodular lesions on the lungs of a patient with a long history of coal dust exposure. As the Surgeon General has stated, however, post-mortem examination data have indicated a greater prevalence of the disease than X-ray diagnosis reveals.

According to the Surgeon General, pneumoconiosis is customarily classified as “simple” or “complicated.”3 Simple pneumoconiosis, ordinarily identified by X-ray opacities of a limited extent, is generally regarded by physicians as seldom productive of significant respiratory impairment. Complicated pneumoconiosis, generally far more serious, involves progressive massive fibrosis as a complex reaction to dust and other factors (which may include tuberculosis or other infection), and usually4 produces significant pulmonary impairment and marked respiratory disability. This disability limits the victim's physical capabilities, may induce death by cardiac failure, and may contribute to other causes of death.5

Removing the miner from the source of coal dust has so far proved the only effective means of preventing the contraction of pneumoconiosis, and once contracted the disease is irreversible in both its simple and complicated stages. No therapy has been developed. Finally, because the disease is progressive,6 at least in its com*8plicated stage, its symptoms may become apparent only after a miner has left the coal mines.

In order to curb the incidence of pneumoconiosis, Congress provided in Title II of the Federal Coal Mine Health and Safety Act of 1969, § 201 et seq., 30 U. S. C. § 841 et seq., for limits on the amount of dust to be permitted in the ambient air of coal mines. Additionally, in view of the then-established prevalence of irreversible pneumoconiosis among miners, and the insufficiency of state compensation programs, Congress passed Title IV of the 1969 Act, § 401 et seq., 30 U. S. C. § 901 et seq., to provide benefits to afflicted miners and their survivors. These benefit provisions were subsequently broadened by the Black Lung Benefits Act of 1972. 30 U. S. C. § 901 et seq. (1970 ed., Supp. IV).

As amended, the Act divides the financial responsibility for payment of benefits into three parts. Under Part B of Title IV, §§ 411-414, 30 U. S. C. §§ 921-924 (1970 ed. and Supp. IV), claims filed between December 30, 1969, the date of enactment, and June 30, 1973, are adjudicated by the Secretary of Health, Education, and Welfare and paid by the United States.7

Under Part C of Title IV, §§ 421-431, 30 U. S. C. §§931-941 (1970 ed. and Supp. IV), claims filed after December 31, 1973, are to be processed under an applicable state workmen's compensation law approved by the Secretary of Labor under the standards set forth in §421, 30 U. S. C. §931 (1970 ed. and Supp, IV). In *9the absence of such an .approved state program, and to date no state program has been approved, claims are to be filed with and adjudicated by the Secretary of Labor, and paid by the mine operators. § 422, 30 U. S. C. §932 (1970 ed. and Supp. IV). Under §422 an operator who is entitled to a hearing in connection with these claims is liable for Part C benefits with respect to death or total disability due to pneumoconiosis arising out of employment in a mine for which the operator is responsible. The operator’s liability for Part C benefits covers the period from January 1, 1974, to December 30, 1981. Payments of benefits under Part C are to the same categories of persons — a miner or certain survivors — and in the same amounts, as under Part B. §§ 422 (c), (d); see § 412 (a), 30 U. S. C. § 922 (a) (1970 ed. and Supp. IV).8

Claims filed during the transition period between the Federal Government benefit provision under Part B, and state plan or operator benefit provision under Part C— that is, July 1 to December 31, 1973 — are adjudicated *10under § 415 of Part B, 30 U. S. C. § 925 (1970 ed., Supp. IV), by the Secretary of Labor. The United States is responsible for payment of these claims until December 31, 1973. Responsible operators, having been notified of a claim and entitled to participate in a hearing thereon, are thereafter liable for benefits as if the claim had been filed pursuant to Part C and § 422 had been applicable to the operator.

The Act provides that a miner shall be considered "totally disabled,” and consequently entitled to compensation, "when pneumoconiosis prevents him from engaging in gainful employment requiring the skills and abilities comparable to those of any employment in a mine or mines in which he previously engaged with some regularity and over a substantial period of time.” § 402 (f), 30 U. S. C. § 902 (f) (1970 ed., Supp. IV).9 The Act also prescribes several “presumptions” for use in determining compensable disability.10 Under § 411(c) (3), a miner *11shown by X-ray or other clinical evidence to be afflicted with complicated pneumoconiosis is “irrebuttably presumed” to be totally disabled due to pneumoconiosis; if he has died, it is irrebuttably presumed that he was totally disabled by pneumoconiosis at the time of his death, and that his death was due to pneumoconiosis. 30 U. S. C. §921 (c)(3) (1970 ed., Supp. IY). In any event, the presumption operates conclusively to establish entitlement to benefits.

The other presumptions are each explicitly rebuttable by an operator seeking to avoid liability. There are three such presumptions. First, if a miner with 10 or more years’ employment in the mines contracts pneumoconiosis, it is rebuttably presumed that the disease arose out of such employment. §411 (c)(1), 30 U. S. C. §921 (c)(1) (1970 ed., Supp. IV). Second, if a miner with 10 or more years’ employment in the mines died from a “respirable disease,” it is rebuttably presumed that his death was due to pneumoconiosis. § 411 (c)(2), 30 U. S. C. § 921 (c) (2) (1970 ed., Supp. IV). Finally, if a miner, or the survivor of a miner, with 15 or more years’ employment in underground coal mines is able, despite the absence of clinical evidence of complicated pneumoconiosis, to demonstrate a totally disabling respiratory or pulmonary impairment, the Act rebuttably presumes that the total disability is due to pneumoconiosis, that the miner was totally disabled by pneumoconiosis when he died, and that the miner’s death was due to pneumoconiosis. § 411 (c)(4), 30 U. S. C. § 921 (c)(4) (1970 ed., Supp. IV).11 Section 411(c)(4) specifically provides: “The Secre*12tary may rebut [this latter] presumption only by establishing that (A) such miner does not, or did not, have pneumoconiosis, or that (B) his respiratory or pulmonary impairment did not arise out of, or in connection with, employment in a coal mine.” Moreover, under § 413(b), 30 U. S. C. § 923 (b) (1970 ed., Supp. IV), none of these three rebuttable presumptions may be defeated solely on the basis of a chest X-ray.12

II

In initiating this suit against the defendant Secretaries (hereafter Federal Parties), the Operators contended that the amended Act is unconstitutional insofar as it requires the payment of benefits with respect to miners who left employment in the industry before the effective date of the Act; that the Act’s definitions, presumptions, and limitations on rebuttal evidence unconstitutionally impair the operators’ ability to defend against benefit claims; and that certain regulations promulgated by the Secretary of Labor regarding the apportionment of liability for benefits among operators, and the provision of medical benefits, are inconsistent with the Act and constitutionally defective.

*13The three-judge District Court held that all issues as to the validity of the challenged regulations were within the jurisdiction of a single district judge, and the court entered an order so remanding them. 385 F. Supp., at 426. The District Court upheld each challenged statutory provision as constitutional, with two exceptions. First, the District Court held that § 411 (c) (3)’s irrebut-table presumption is unconstitutional as an unreasonable and arbitrary legislative finding of total disability “in terms other than those provided by the Act as standards for total disability.” 385 F. Supp., at 430. Second, reading the limitation on evidence in rebuttal to § 411 (c) (4)’s presumption of total disability due to pneumo-coniosis to apply to an operator’s defense in a § 415 transition-period case, the District Court found thát limitation unconstitutional in two respects. It held the limitation arbitrary and unreasonable in not permitting a rebuttal showing that the case of pneumo-coniosis afflicting the miner was not disabling. 385 F. Supp., at 430. And taking the provision to mean that an operator may defend against liability only on the ground that the pneumoconiosis did not arise out of employment in any coal mine, rather than on the ground that it did not arise out of employment in a coal mine for which the operator was responsible, the District Court found the provision an unreasonable and arbitrary limitation on rebuttal evidence relevant and proper under § 422 (c), 30 U. S. C. § 932 (c). 385 F. Supp., at 430-431. The District Court accordingly entered an order declaring unconstitutional, and enjoining the Secretary of Labor from seeking to apply, §411 (c)(3)’s irrebut-table presumption and §411(c)(4)’s limitation on rebuttable evidence.

The Operators’ appeal, No. 74-1316, reasserts the constitutional challenges rejected by the District Court. *14The appeal of the Federal Parties, No. 7-D1302, seeks reversal of the declaration and injunction respecting the constitutionality of §§411 (c)(3) and (4). Neither side here questions the District Court’s decision not to address the issues raised with respect to the Secretary of Labor’s regulations. As we have already noted, we uphold the statute against all the constitutional contentions properly presented here. Because we read the limitation on rebuttal evidence in §411 (c)(4) as inapplicable to the Operators, however, we vacate that portion of the District Court’s order which invalidates that limitation.

III

The Federal Parties direct our attention initially to National Independent Coal Operators Assn. v. Brennan, 372 F. Supp. 16 (DC), summarily aff’d, 419 U. S. 955 (1974), which raised a number of issues identical to those presented here. Our summary affirmance in that case did not foreclose the District Court’s determination of unconstitutionality regarding §§411 (c)(3) and (4), those issues not having been before us on the appeal. Several questions presented here — most notably those of retroactivity and preclusion of sole reliance on X-ray testimony evidence — were raised and decided in National Independent Coal Operators Assn. v. Brennan, but having heard oral argument and entertained full briefing on these issues together with the other questions raised in the case, we proceed to treat them here more fully. Cf. Edelman v. Jordan, 415 U. S. 651, 670-671 (1974).

IV

The Operators contend that the amended Act violates the Fifth Amendment Due Process Clause by requiring them to compensate former employees who terminated their work in the industry before the Act was passed, *15and the survivors of such employees.13 The Operators accept the liability imposed upon them to compensate employees working in coal mines now and in the future who are disabled by pneumoconiosis; and they recognize Congress’ power to create a program for compensation of disabled inactive coal miners. But the Operators complain that to impose liability upon them for former employees’ disabilities is impermissibly to charge them with an unexpected liability for past, completed acts that were legally proper and, at least in part, unknown to be dangerous at the time.

It is by now well established that legislative Acts adjusting the burdens and benefits of economic life come to the Court with a presumption of constitutionality, and that the burden is on one complaining of a due process violation to establish that the legislature has acted in an arbitrary and irrational way. See, e. g., Ferguson v. Skrupa, 372 U. S. 726 (1963); Williamson v. Lee Optical Co., 348 U. S. 483, 487-488 (1955). And this Court long ago upheld against due process attack the competence of Congress to allocate the interlocking economic rights and duties of employers and employees upon workmen’s compensation principles analogous to those enacted here, regardless of contravening arrangements between employer and employee. New York Central R. Co. v. White, 243 U. S. 188 (1917); see also Philadelphia, B. & W. R. Co. v. Schubert, 224 U. S. 603 (1912).

To be sure, insofar as the Act requires compensation for disabilities bred during employment terminated *16before the date of enactment, the Act has some retrospective effect — although, as we have noted, the Act imposed no liability on operators until 1974.14 And it may be that the liability imposed by the Act for disabilities suffered by former employees was not anticipated at the time of actual employment.15 But our cases are clear that legislation readjusting rights and burdens is not unlawful solely because it upsets otherwise settled expectations. See Fleming v. Rhodes, 331 U. S. 100 (1947); Carpenter v. Wabash R. Co., 309 U. S. 23 (1940); Norman v. Baltimore & Ohio R. Co., 294 U. S. 240 (1935); Home Bldg. & Loan Assn. v. Blaisdell, 290 U. S. 398 (1934); Louisville & Nashville R. Co. v. Mottley, 219 U. S. 467 (1911). This is true even though the effect of the legislation is to impose a new duty or liability based on past acts. See Lichter v. United States, 334 U. S. 742 (1948); Welch v. Henry, 305 U. S. 134 (1938); Funkhouser v. Preston Co., 290 U. S. 163 (1933).

It does not follow, however, that what Congress can legislate prospectively it can legislate retrospectively. *17The retrospective aspects of legislation, as well as the prospective aspects, must meet the test of due process, and the justifications for the latter may not suffice for the former. Thus, in this case the justification for the retrospective imposition of liability must take into account the possibilities that the Operators may not have known of the danger of their employees’ contracting pneumoconiosis, and that even if they did know of the danger their conduct may have been taken in reliance upon the current state of the law, which imposed no liability on them for disabling pneumoconiosis.16 While the Operators have clearly been aware of the danger of pneumoconiosis for at least 20 years,17 and while they have not specifically pressed the contention that they would have taken steps to reduce or eliminate the incidence of pneumoconiosis had the law imposed liability upon them, we would nevertheless hesitate to approve the retrospective imposition of liability on any theory of deterrence, cf. United States v. Peltier, 422 U. S. 531, 542 *18(1975), or blameworthiness, cf. ibid.; De Veau v. Braisted, 363 U. S. 144, 160 (1960).

We find, however, that the imposition of liability for the effects of disabilities bred in the past is justified as a rational measure to spread the costs of the employees' disabilities to those who have profited from the fruits of their labor — the operators and the coal consumers. The Operators do not challenge Congress’ power to impose the burden of past mine working conditions on the industry. They do claim, however, that the Act spreads costs in an arbitrary and irrational manner by basing liability upon past employment relationships, rather than taxing all coal mine operators presently in business. The Operators note that a coal mine operator whose work force has declined may be faced with a total liability that is disproportionate to the number of miners currently employed. And they argue that the liability scheme gives an unfair competitive advantage to new entrants into the industry, who are not saddled with the burden of compensation for inactive miners’ disabilities. In essence the Operators contend that competitive forces will prevent them from effectively passing on to the consumer the costs of compensation for inactive miners’ disabilities, and will unfairly leave the burden on the early operators alone.

Of course, as we have already indicated, a substantial portion of the burden for disabilities stemming from the period prior to enactment is borne by the Federal Government. But even taking the Operators’ argument at face value, it is for Congress to choose between imposing the burden of inactive miners’ disabilities on all operators, including new entrants and farsighted early operators who might have taken steps to minimize black lung dangers, or to impose that liability solely on those early operators whose profits may have been increased at the expense of their employees’ health. We are unwilling to assess the *19wisdom of Congress’ chosen scheme by examining the degree to which the “cost-savings” enjoyed by operators in the pre-enactment period produced “excess” profits, or the degree to which the retrospective liability imposed on the early operators can now be passed on to the consumer. It is enough to say that the Act approaches the problem of cost spreading rationally; whether a broader cost-spreading scheme would have been wiser or more practical under the circumstances is not a question of constitutional dimension. See, e. g., Ferguson v. Skrupa, 372 U. S., at 730-732; Williamson v. Lee Optical Co., 348 U. S., at 488.

The Operators ultimately rest their due process argument on Railroad Retirement Board v. Alton R. Co., 295 U. S. 330 (1935), in which the Court found the Railroad Retirement Act of 1934 to be unconstitutional. Among the provisions specifically invalidated as arbitrary was .a provision for employer-financed pensions for former employees who, though not in the employ of the railroads at the time of enactment, had been so employed within the year. Assuming that the portion of Alton invalidating this provision retains vitality,18 we find it distinguishable from this case. The point of the black lung benefit provisions is not simply to increase or supplement a former employee’s salary to meet his generalized need for funds. Rather, the purpose of the Act is to satisfy a specific need created by the dangerous conditions under which the former employee labored — to allocate to the mine operator an actual, measurable cost of his business.

In sum, the Due Process Clause poses no bar to requiring an operator to provide compensation for a *20former employee's death or disability due to pneumo-coniosis arising out of employment in its mines, even if the former employee terminated his employment in the industry before the Act was passed.

V

We turn next to a consideration of the Operators' challenge to the “presumptions” and evidentiary rules governing adjudications of compensable disability under the Act.

A

The Act prescribes two alternative methods for showing “total disability,” which is a prerequisite to compensation. First, a miner is “totally disabled” under the definition contained in § 402 (f), if pneumoconiosis, simple or complicated,

“prevents him from engaging in gainful employment requiring the skills and abilities comparable to those of any employment in a mine or mines in which he previously engaged with some regularity and over a substantial period of time.” 19

Second, if a miner can show by clinical evidence (ordinarily X-ray evidence) that he is afflicted with complicated pneumoconiosis, the incurable and final stage of the disease, then the miner is deemed to be totally disabled under § 411 (c) (3).20 Thus, Congress has mandated that *21the final stage of the disease is always compensable if its existence can be shown by positive clinical evidence, and that any stage of the disease is compensable when physically disabling under the terms of § 402 (f). The Operators maintain that both of these standards are constitutionally untenable.

(1)

The Operators contend that the definition of “total disability” set up in § 402 (f) is unconstitutionally arbitrary and irrational, because it provides for the compensation of former miners who might well be employable in other lines of work, and who therefore are not truly disabled by their mining-generated afflictions. We think it patent that this attack on § 402 (f) must fail. A miner disabled under § 402 (f) standards has suffered in at least two ways: His health is impaired, and he has been rendered unable to perform the kind of work to which, he has adapted himself. Whether these interferences merit compensation is a public policy matter left primarily to the determination of the legislature. Cf. Geduldig v. Aiello, 417 U. S. 484 (1974). We cannot say that they are so insignificant as not to be a rational basis for compensation. Indeed, we long ago upheld against similar attack a workmen's compensation scheme providing benefits for injuries not depriving the employee of his ability to work. See New York Central R. Co. v. Bianc, 250 U. S. 596 (1919); cf. Urie v. Thompson, 337 U. S. 163, 181-187 (1949).

*22(2)

The District Court, relying on such cases as Stanley v. Illinois, 405 U. S. 645 (1972), and Vlandis v. Kline, 412 U. S. 441 (1973), invalidated §411(c)(3)’s “irrebut-table presumption” of total disability due to pneumo-coniosis based on clinical evidence of complicated pneu-moconiosis. The presumption, the court explained,

“forecloses all fact finding as to the effect of that disease upon a particular coal miner .... To the extent that such presumption purports to making a finding of total disability in terms other than those provided by [§402 (f)] as standards for total disability, it is unreasonable and arbitrary. As written, section [411 (c)(3)] is violative of due process in precluding the opportunity to present evidence as to the effect of a chronic dust disease upon an individual in determining whether or not he is disabled.” 385 F. Supp., at 429-430.

We think the District Court erred in equating this case with those in the mold of Stanley and Vlandis.

As an operational matter, the effect of §411 (c) (3)’s “irrebuttable presumption” of total disability is simply to establish entitlement in the case of a miner who is clinically diagnosable as extremely ill with pneumoconi-osis arising out of coal mine employment.21 Indeed, the *23legislative history discloses that it was precisely this advanced and progressive stage of the disease that Congress sought most certainly to compensate.22 Were the Act phrased simply and directly to provide that operators were bound to provide benefits for all miners clinically demonstrating their affliction with complicated pneu-moconiosis arising out of employment in the mines, we think it clear that there could be no due process objection to it. For, as we have already observed, destruction of earning capacity is not the sole legitimate basis for compulsory compensation of employees by their employers. New York Central R. Co. v. Bianc, supra. We cannot say that it would be irrational for Congress to conclude that impairment of health alone warrants compensation. Since Congress can clearly draft a statute to accomplish precisely what it has accomplished through § 411 (c) (3)’s presumption of disability, the argument is essentially that Congress has accomplished its result in an impermissible manner — by defining eligibility in terms of “total disability” and erecting an “irrebuttable presumption” of total disability upon a factual showing that does not necessarily satisfy the statutory definition of total disability. But in a statute such as this, regulat*24ing purely economic matters, we do not think that Congress’ choice of statutory language can invalidate the enactment when its operation and effect are clearly permissible, Cf. Weinberger v. Salfi, 422 U. S. 749, 767-785 (1975); McDonald v. Board of Election, 394 U. S. 802, 809 (1969); United States v. Carolene Products Co., 304 U. S. 144, 154 (1938).

(3)

In addition to creating an irrebuttable presumption of total disability, § 411 (c) (3) provides that clinical evidence of a miner’s complicated pneumoconiosis gives rise to an irrebuttable presumption that he was totahy disabled by pneumoconiosis at the time of his death, and that his death was due to pneumoconiosis. The effect of these presumptions, in particular the presumption of death due to pneumoconiosis, is to grant benefits to the survivors of any miner who during his lifetime had complicated-pneumoconiosis arising out of employment in the mines, regardless of whether the miner’s death was caused by pneumoconiosis. The Operators raise no separate challenge to these presumptions, and we would have no occasion to comment separately on them were it not for the Operators’ general complaint against the application of the Act to employees who terminated their employment before the Act was passed. To the extent that the presumption of death due to pneumoconiosis is viewed as requiring compensation for damages resulting from death unrelated to the operator’s conduct, its application to employees who terminated ■ their employment before the Act was passed would present difficulties not encountered in our prior discussion of retroactivity. The justification we found for the retrospective application of the Act is that it serves to spread costs in a rational manner — by allocating to the operator an actual cost of his *25business, the avoidance of which might be thought to have enlarged the operator’s profits. The damage resulting from a miner’s death that is due to causes other than the operator’s conduct can hardly be termed a “cost” of the operator’s business.

We think it clear, however, that the benefits authorized by § 411 (c) (3)’s presumption of death due to pneu-moconiosis were intended not simply as compensation for damages due to the miner’s death, but as deferred compensation for injury suffered during the miner’s lifetime as a result of his illness itself. Thus, the Senate Report accompanying the 1972 amendments makes clear Congress’ purpose to award benefits not only to widows whose husbands “[gave] their lives,” but also to widows whose husbands “gave their health ... ha the service of the nation’s critical coal needs.” 23

In the case of a miner who died with, but not from, pneumoconiosis before the Act was passed, the benefits serve as deferred compensation for the suffering endured by his dependents by virtue of his illness. And in the case of a miner who died with, but not from, pneumo-coniosis after the Act was passed, the benefits serve an additional purpose: The miner’s knowledge that his dependent survivors would receive benefits serves to compensate him for the suffering he endures. In short, § 411 (e)(3)’s presumption of death due to pneumoconiosis authorizes compensation for injury attributable to the operator’s business, and viewed as such it poses no retro-activity problems distinct from those considered in our prior discussion.

It might be suggested that the payment of benefits to dependent survivors is irrational as a scheme of compensation for injury suffered as a result of a miner’s disability. But we cannot say that the scheme is wholly *26unreasonable in providing, benefits for those who were most likely to have shared the miner’s suffering. Nor can we say that the scheme is arbitrary simply because it spreads the payment of benefits over a period of time.24

We might face a more difficult problem in applying § 411 (c) (3)’s presumption of death due to pneumo-coniosis on a retrospective basis if the presumption authorized benefits to the survivors of a miner who did not die from pneumoconiosis, and who during his life was completely unaware of and unaffected by his illness; or, in the case of a miner who died before the Act was passed, if the presumption authorized benefits to the survivors of a miner who did not die from pneumoconio-sis, who nevertheless was aware of and affected by his illness, but whose dependents were completely unaware of and unaffected by his illness. But the Operators in their facial attack on the Act have not suggested that a miner whose condition was serious enough to activate the §411 (c)(3) presumptions might not have been affected in any way by his condition, or that the family of such a miner might not have noticed it. Under the *27circumstances, we decline to engage in speculation as to whether such cases may arise.25

B

Turning our attention to the statutory regulations of proof of § 402 (f) disability, we focus initially on the Operators’ challenge to the presumptions contained in §§411 (c)(1) and (2). Section 411 (c)(1) provides that a coal miner with 10 years’ employment in the mines who suffers from pneumoconiosis will be presumed to have contracted the disease from his employment.26 Section 411 (c)(2) provides that if a coal miner with 10 years’ employment in the mines dies from a respiratory disease, his death will be presumed to have been due to pneumoconiosis.27 Each presumption is explicitly rebuttable, and the effect of each is simply to shift the burden of going forward with evidence from the claimant to the operator. See Fed. Rule Evid. 301.

*28We have consistently tested presumptions arising in civil statutes such as this, involving matters of economic regulation, against the standard articulated in Mobile, J. & K. C. 22. Co. v. Turnipseed, 219 U. S. 35, 43 (1910):

“That a legislative presumption of one fact from evidence of another may not constitute a denial of due process of law or a denial of the equal protection of the law it is only essential that there shall be some rational connection between the fact proved and the ultimate fact presumed, and that the inference of one fact from proof of another shall not be so unreasonable as to be a purely arbitrary mandate.”

See Atlantic Coast Line R. Co. v. Ford, 287 U. S. 502 (1933); Bandini Petroleum Co. v. Superior Court, 284 U. S. 8, 19 (1931). See also Leary v. United States, 395 U. S. 6, 29-53 (1969); Tot v. United States, 319 U. S. 463, 467-468 (1943). Moreover, as we have recognized:

“The process of making the determination of rationality is, by its nature, highly empirical, and in matters not within specialized judicial competence or completely commonplace, significant weight should be accorded the capacity of Congress to amass the stuff of actual experience and cull conclusions from it.” United States v. Gainey, 380 U. S. 63, 67 (1965).

Judged by these standards, the presumptions contained in §§ 411 (c)(1) and (2) are constitutionally valid. The Operators focus their attack on the rationality of the presumptions’ bases in duration of employment. But it is agreed~here that pneumoconiosis is caused by breathing coal dust, and that the likelihood of a miner’s developing the disease rests upon both the concentration of dust to which he was exposed and the duration of his exposure. Against this scientific background, it was not *29beyond Congress' authority to refer to exposure factors in establishing a presumption that throws the burden of going forward on the operators. And in view of the medical evidence before Congress indicating the noticeable incidence of pneumoconiosis in cases of miners with 10 years' employment in the mines,28 we cannot say that it was “purely arbitrary” for Congress to select the 10-year figure as a point of reference for these presumptions. No greater mathematical precision is required. Cf. Lindsley v. Natural Carbonic Gas Co., 220 U. S. 61, 78 (1911).

The Operators insist, however, that the 10-year presumptions are arbitrary, because they fail to account for varying degrees of exposure, some of which would pose lesser dangers than others. We reject this contention. In providing for a shifting of the burden of going forward to the operators, Congress was no more constrained to require a preliminary showing of the degree of dust concentration to which a miner was exposed, a historical fact difficult for the miner to prove, than it was to require a preliminary showing with respect to all other factors that might bear on the danger of infection. It is worth repeating that mine employment for 10 years does not serve by itself to activate any presumption of pneumoconiosis; it simply serves along with proof of pneumoconiosis under §411 (c)(1) to presumptively establish the cause of pneumoconiosis, and along with proof of death from a respiratory disease under § 411 (c) (2) to presumptively establish that death was due to pneumoconiosis. In its “rough accommodations,” Metropolis Theatre Co. v. Chicago, 228 U. S. 61, 69 (1913), Congress was surely entitled to select duration of em*30ployment, to the exclusion of the degree of dust exposure and other relevant factors, as signaling the point at which the operator must come forward with evidence of the cause of pneumoconiosis or death, as the case may be. We certainly cannot say that the presumptions, by excluding other relevant factors, operate in a “purely arbitrary” manner. Mobile, J. & K. C. R. Co. v. Turnipseed, supra, at 43.

The Operators press the same due process attack upon the durational basis of the rebuttable presumption in §411 (c)(4), which provides, inter alia, that a miner employed for 15 years in underground mines, who is able to marshal evidence demonstrating a totally disabling respiratory or pulmonary impairment, shall be rebuttably presumed to be totally disabled by pneumoconiosis.29 Par*31ticularly in light of the Surgeon General’s testimony at the Senate hearings on the 1969 Act to the effect that the 15-year point marks the beginning of linear increase in the prevalence of the disease with years spent underground,30 we think it clear that the durational basis of this presumption is equally unassailable.

C

The Operators also challenge § 413 (b) of the Act, which provides that “no claim for benefits . . . shall be denied solely on the basis of the results of a chest roent-genogram [X-ray].” 31 Congress, of course, has plenary authority over the promulgation of evidentiary rules for the federal courts. See, e. g., Hawkins v. United States, 358 U. S. 74, 78 (1958); Tot v. United States, 319 U. S., at 467; cf. Lindsley v. Natural Carbonic Gas Co., supra, at 81. The Operators contend, however, that § 413 (b) denies them due process because X-ray evidence is frequently the sole evidence they can marshal to rebut a claim of pneumoconiosis.32 We conclude that, given Congress’ reasoned reservations regarding the reliability of negative X-ray evidence, it was entitled to preclude exclusive reliance on such evidence.

Congress was presented with significant evidence demonstrating that X-ray testing that fails to disclose pneumoconiosis cannot be depended upon as a trust*32worthy indicator of the absence of the disease.33 In particular, the findings of the Surgeon General and others indicated that although X-ray evidence was generally the most important diagnostic tool in identifying the presence or absence of pneumoconiosis, when considered alone it was not a wholly reliable indicator of the absence of the disease; that autopsy frequently disclosed pneumo-coniosis where X-ray evidence had disclosed none;34 and that pneumoconiosis may be masked from X-ray detection by other disease.35

Taking these indications of the unreliability of negative X-ray diagnosis at face value, Congress was faced with the problem of determining which side should bear the burden of the unreliability. On the one hand, preclusion of any reliance on negative X-ray evidence would risk the success of some nonmeritorious claims; on the other hand, reliance on uncorroborated negative X-ray evidence would risk the denial of benefits in a significant number of meritorious cases. Congress addressed the problem by adopting a rule which, while preserving some of the utility, avoided the worst dangers of X-ray evidence. Section 413 (b) does not make negative X-ray evidence inadmissible, or ineligible to be considered as ultimately persuasive evidence when taken together with other factors — for example, a low level of coal dust concentration in the operator’s mine, a relatively short dura*33tion of exposure to coal dust, or the likelihood that the miner is disabled by some other cause.36 The prohibition is only against sole reliance upon negative X-ray evidence in rejecting a claim.

The Operators attack the limitation on the use of negative X-ray evidence by suggesting that Congress’ conclusion as to the unreliability of negative X-ray evidence is constitutionally unsupportable. Relying on other evidence submitted to Congress in 1972,37 the Operators contend that the consensus of medical judgment on the question is that good quality X-ray evidence does reliably indicate the presence or absence of pneumoconiosis. In essence, the Operators seek a judicial reconsideration of the judgment of Congress on this issue. But the reliability of negative X-ray evidence was debated forcefully on both sides before the Congress, and the Operators here suggest nothing new to add to the debate; they are simply dissatisfied with Congress’ conclusion. As we have recognized in the past, however, when it comes to evidentiary rules in matters “not within specialized judicial competence or completely commonplace,” it is primarily for Congress “to amass the stuff of actual ex*34perience and cull conclusions from it.” United States v. Gainey, 380 U. S., at 67. It is sufficient that the evidence before Congress showed doubts about the reliability of negative X-ray evidence. That Congress ultimately determined “to resolve doubts in favor of the disabled miner” 38 does not render the enactment arbitrary under the standard of rationality appropriate to this legislation.

D

Finally, the Operators challenge the limitation on rebuttal evidence contained in § 411 (c) (4). That section, as we have indicated, provides that a miner employed for 15 years in underground mines who is able to demonstrate a totally disabling respiratory or pulmonary impairment shall be rebuttably presumed to be totally disabled by pneumoconiosis, and his death shall be rebut-tably presumed to be due to pneumoconiosis. The final sentence of § 411 (c) (4) provides that

“[t]he Secretary may rebut [the presumption provided herein] only by establishing that (A) such miner does not, or did not, have pneumoconiosis, or that (B) his respiratory or pulmonary impairment did not arise out of, or in connection with, employment in a coal mine.”

The effect of this limitation on rebuttal evidence is, inter'alia, to grant benefits to any miner with 15 years’ employment in the mines, if he is totally disabled by some respiratory or pulmonary impairment arising in connection with his employment, and has a case of pneu-moconiosis. The Operators contend that this limitation erects an impermissible irrebuttable presumption, because it establishes liability even though it might be medically demonstrable in an individual case that the miner’s *35pneumoconiosis was mild and did not cause the disability — that the disability was wholly a product of other disease, such as tuberculosis or emphysema. Disability due to these diseases, as the Operators note, is not otherwise compensable under the Act.

The District Court, concluding that the quoted limitation on rebuttal evidence applied against an operator in a § 415 transition-period case, and recognizing that pneu-moconiosis is not inherently disabling in the § 402 (f) sense, judged this limitation unconstitutional on the ground that it deprived an operator of a factual defense — that the miner is not “totally disabled” due to pneumoconiosis under § 402 (f). Additionally, reading the second part of the § 411 (c) (4) limitation on rebuttal to preclude an operator’s defense that the disease did not arise out of employment in the particular mines for which it was responsible, the District Court found this aspect of §411 (c)(4) unconstitutional as well.

The Federal Parties urge on their cross-appeal that these constitutional judgments are erroneous. We need not inquire into the constitutional questions raised by the District Court, however, because we think it clear as a matter of statutory construction that the § 411 (c) (4) limitation on rebuttal evidence is inapplicable to operators. By the language of §411 (c)(4), the limitation applies only to “the Secretary” and not to an operator seeking to avoid liability under § 415 or § 422. And this plain language is fortified by the legislative history. The Senate Report on § 411 (c) (4) specifically states that the limitation on rebuttal applies to the Secretary of Health, Education, and Welfare, but nowhere suggests that it binds an operator.39 - \

*36While apparently recognizing that the §411 (c)(4) limitation on rebuttal evidence could not apply against an operator in a Part C determination, the District Court believed that the limitation bound an operator in the determination of a claim filed during the § 415 transition period, “[s]ince under section [415] the operator is bound by the Secretary's finding of liability under Part B.” 385 F. Supp., at 430. In so concluding, the District Court was in error. First, it would appear, again from the plain language of the statute, that the reference to “the Secretary” in § 411 (c) (4) does not refer to the Secretary of Labor. On the contrary, § 402 (c), 30 U. S. C. § 902 (c), quite plainly defines “Secretary” when used in Part B, including § 411, as meaning the Secretary of Health, Education, and Welfare, not the Secretary of Labor. The Senate Report referred to above confirms this conclusion. Even assuming, however, that the § 411 (c)(4) limitation on rebuttal by “the Secretary” may be taken to bind the Secretary of Labor insofar as he was required to pay benefits for which the United States was liable during the transition period, § 415 (a)(1), we have found nothing in the statute or in its legislative history to suggest that an operator is similarly bound because the Secretary of Labor is also to adjudicate the operator’s liability. §415 (a) (5). Indeed, such a reading would render a mine operator bound by the rebuttal limitation in § 415 transition-period cases, although not so bound in cases filed thereafter under Part C. And that result would be contrary to the language of § 415 (a) (5), which prescribes that an operator “shall be bound by the determination of the Secretary of Labor [on a § 415 transition-period claim] as if the claim had been filed pursuant to part C.”

In short, we conclude that the Act does not itself limit the evidence with which an operator may rebut the *37§411 (c)(4) presumption. Accordingly, we vacate the order of the District Court declaring the §411 (c)(4) limitation on rebuttal evidence unconstitutional and enjoining the Secretary of Labor from limiting evidence in rebuttal to the § 411 (c) (4) presumption. Cf. Van Lare v. Hurley, 421 U. S. 338, 344 (1975); United States v. Munsingwear, Inc., 340 U. S. 36 (1950).

We are aware that regulations promulgated in 1972 by the Secretary of Health, Education, and Welfare under his §411 (b) authorization, 20 CFR §§410.414, 410.454 (1975), applicable to Part C determinations under §422 (h), and expressly adopted in 1973 by the Secretary of Labor, 20 CFR pt. 718 (1975), authorize limitations on rebuttal evidence similar to those contained in § 411 (c) (4), and appear to apply in determinations of an operator’s liability. But the Operators’ amended complaint never challenged the statutory or constitutional validity of these regulations.40 Particularly in the absence of any mention of the regulations in the opinion and judgment of the District Court, or in the briefs and oral arguments of the parties, we find it inappropriate to consider their statutory or constitutional validity at this stage.41

*38VI

In sum, the challenged provisions, as construed, are constitutionally sound against the Operators’ facial attack. The judgment of the District Court as appealed from in No. 74-1316 is affirmed. The judgment of the District Court as appealed from in No. 74 — 1302 is reversed, except insofar as it declares unconstitutional, and enjoins the operation of, the limitation on rebuttal evidence contained in §411 (c)(4) of the Act. In this latter respect, the judgment in No. 74-1302 is vacated, and the case remanded with directions to dismiss.

It is so ordered.

The Chief Justice concurs in the judgment.

Mr. Justice Stevens took no part in the consideration or decision of these cases.

Mr. Justice Powell,

concurring in part and concurring in the judgment in part.

Appellants in No. 74-1316, the Operators, challenge as unconstitutional the retroactive obligations imposed on them by the Federal Coal Mine Health and Safety Act of 1969 (Act), 83 Stat. 792, as amended by the Black Lung Benefits Act of 1972, 86 Stat. 150, 30 TJ. S. C. § 901 et seq. (1970 ed. and Supp. IV). The Court rejects their contention in Part IV of its opinion. I concur in the judgment as to Part IV, and concur in other portions of the opinion not inconsistent with the views herein expressed.

I

Coal miner’s pneumoconiosis was not recognized in the United States until the 1950’s, and there was no federal *39legislation providing benefits to its victims until the enactment of this statute in 1969. In Title IV of the Act, Congress significantly redefined the respective rights and obligations of miners and their employers in regard to this disease by establishing a benefits scheme to compensate victims of pneumoconiosis.1 Under Title IV miners who filed claims before July 1, 1973, are to collect benefits from the Federal Government, §§411-414, 30 U. S. C. §§ 921-924 (1970 ed. and Supp. IV).2 Miners filing claims after June 30, 1973, are to collect benefits-until 1981, see ante, at 26 n. 24, from their individual employers. §§ 415, 421-431, 30 U. S. C. §§ 925, 931-941 (1970 ed. and Supp. IV).3 Under the statute, the class of claimants to which individual employers are liable includes both (i) miners employed at the time of or after enactment and (ii) miners no longer employed in the industry at the time of enactment (former miners).

The unprecedented feature of the Act is that miners may be eligible to receive benefits from a particular coal-mining concern even if the miner was no longer employed in the industry at the time of enactment. The *40Department of Labor already has made initial determinations of liability against one of the Operators and in favor of claimants whose employment terminated decades ago.4

II

The Operators do not challenge their liability to miners employed at the time of or after enactment, a liability which accords with familiar principles of workmen’s compensation.5 They contend, however, that a statutory liability to former miners has been imposed in violation of the Fifth Amendment guarantee against arbitrary, irrational, or discriminatory legislation, see, e. g., Richardson v. Belcher, 404 U. S. 78, 81 (1971), as there *41is no rational justification for imposing liability to former miners upon individual mine owners.

The Court recognizes that its evaluation of the rationality of the employers’ challenged liability must take into account the retroactive nature of the liability:

“The retrospective aspects of legislation, as well as the prospective aspects, must meet the test of due process, and the justifications for the latter may not suffice for the former. Thus, in this case the justification for the retrospective imposition of liability must take into account the possibilities that the Operators may not have known of the danger of their employees’ contracting pneumoconiosis, and that even if they did know of the danger their conduct may have been taken in reliance upon the current state of the law . . . .” Ante, at 17.

The Court then acknowledges that the Act would not be justified “on any theory of deterrence ... or blameworthiness.” Ante, at 17-18. It nonetheless sustains the provision for retroactive liability, reasoning as follows:

“We find . . . that the imposition of liability for the effects of disabilities bred in the past is justified as a rational measure to spread the costs of the employees’ disabilities to those who have profited from the fruits of their labor — the operators and the coal consumers.” Ante, at 18.

“We are unwilling to assess the wisdom of Congress’ chosen scheme by examining the degree to which the 'cost-savings’ enjoyed by operators in the pre-enactment period produced 'excess’ profits, or the degree to which the retrospective liability imposed on the early operators can now be passed on to the consumer. It is enough to say that the Act approaches the problem of cost-spreading rationally Ante, at 18-19.

*42In my view whether the retroactive liability is constitutional is a considerably closer question than the Court’s treatment suggests. The rationality of retrospective liability as a cost-spreading device is highly questionable.

If coal-mining concerns actually enjoyed “excess” profits in the pre-enactment period by virtue of their nonliability for pneumoconiosis, and if such profits could be quantified in some discernible way, Congress rationally could impose retrospective liability for the benefit of the miners concerned. But, in this context, the term “excess profits” must mean profits over and above those that operators would have made in years and decades past if they had set aside from current operations funds sufficient to provide compensation, although under no obligation to do so. It is unlikely that such profits existed. The coal industry is highly competitive and prices normally are determined by market forces. One therefore would expect that, had a compensation increment been added to operating costs, the operators over the long term simply would have passed most of it on to consumers, thereby leaving their profitability relatively unaffected. In short, the talk of “excess profits” in any realistic sense is wholly speculative.

Nor can I accept without serious question the Court’s view that the costs now imposed by the Act may be passed on to consumers. Firms burdened with retroactive payments must meet that expense from current production and current sales in a market where prices must be competitive with the prices of firms not so burdened. One ordinarily would expect that if burdened firms are to meet both competitive prices and their retroactive obligations, their profits necessarily will be less than those of their competitors. Thus, the burdened firms in all likelihood will have to bear the costs of the *43retroactive liability rather than pass those costs on to consumers. And they must bear such costs quite without regard to whether “excess profits” may have been made in some earlier years.6

In some industries conditions might be such that the cost of retroactively imposed benefits could be spread to consumers. It seems most unlikely, however, that the coal industry is such an industry. A notable fact about coal mining is that the industry currently employs only about 150,000 persons, whereas in 1939 it employed nearly 450,000. Brief for Operators 24. The reduced scale of employment in the coal industry, combined with the liability to former miners and their survivors, means that retroactive obligations almost certainly will be disproportionate to the scale of current operations.7 Moreover, it is unlikely that liability to former miners will be distributed randomly across the industry, as it is dictated by historical patterns that may be wholly unrelated to the present contours of the industry. Two examples are illustrative: (i) Some coal-mining concerns have been in the mining business for decades, while some competitors have commenced operation more recently. The exposure of the former group to claims of employees long separated from active employment is likely to be significantly *44greater than that of their competitors, (ii) Some companies engaged in coal mining in years past on a much larger scale and with many more employees than currently. This is not an unusual situation in a “depleting asset” industry, where smaller companies often lack the resources with which to continue the acquisition and development of new properties. Stronger competitors, on the other hand, may have operated on a constant or an increasingly large scale.8 In each case the competitively disadvantaged companies may be unable to spread a substantial portion of their costs to consumers. In view of these considerations it is unrealistic to think that the Act will spread costs to “the operators and the coal consumers,” ante, at 18, and thus I question the Court’s conclusion that the Act is rational in imposing retroactive liability.

Ill

Despite the foregoing, I must concur in the judgment on the record before us. Congress had broad discretion in formulating a statute to deal with the serious problem of pneumoconiosis affecting former miners. E. g., Richardson v. Belcher, 404 U. S. 78 (1971); cf. Williamson v. Lee Optical Co., 348 U. S. 483 (1955). Nor does the Constitution require that legislation on economic matters be compatible with sound economics or even with normal fairness. As a result, economic and remedial social enactments carry a strong presumption of constitutionality, e. g., United States v. Carolene Products Co., 304 U. S. 144, 148 (1938), and the Operators had the heavy burden of showing the Act to be unconstitutional.

*45The constitutionality of the retrospective liability in question here ultimately turns on the sophisticated questions of economic fact suggested above, and these facts are likely to vary widely among the Operators.9 In this case, however, decided on the cross-motions for summary judgment, the Operators have failed to make any factual showings that support their sweeping assertions of irrationality. Although I find these assertions strongly suggestive that Congress has acted irrationally hi pursuing a legitimate end, I am not satisfied that they are sufficient — in the absence of appropriate factual support — to override the presumption of constitutionality. Accordingly, I agree that the federal parties were entitled to summary judgment on this record.

Mr. Justice Stewart,

with whom Mr. Justice Rehnquist joins,

concurring in part and dissenting in part.

While in all other respects joining the opinion and judgment of the Court, I cannot accept the Court’s conclusion, ante, at 36-37, that the limitation on rebuttal evidence in § 411 (c)(4), 30 U. S. C. § 921 (c)(4) (1970 ed., Supp. IV), is inapplicable to “transition” determinations under § 415 insofar as those determinations bind operators. Section 415 (a) (5), as set forth in 30 U. S. C. § 925 (a) (5) (1970 ed., Supp. IV), provides that an “operator . . . shall be bound by the determination of the Secretary of Labor [on a transition] claim as if the claim had been filed pursuant to part C of this subchap-ter and section 932 of this title had been applicable to such operator.” As the Court correctly observes, the critical question is thus whether the §411 (c)(4) limi*46tation would apply “if the claim had been filed pursuant to part C . . . and section 932 . . . .”

The Court reads the “plain language” of § 411 (c) (4), and in particular the reference to “the Secretary [of Health, Education, and Welfare],” to mean that “the limitation applies only to 'the Secretary’ and not to an operator seeking to avoid liability under § 415 [30 U. S. C. § 925] or § 422 [30 U. S. C. § 932].” Ante, at 35. This reading, the Court concludes, is “fortified by the legislative history” and in particular by the “Senate Report on § 411 (c) (4) [which] specifically states that the limitation on rebuttal applies to the Secretary of Health, Education, and Welfare, but nowhere suggests that it binds an operator.” Ibid.

The Court’s analysis omits any consideration of the effect of § 430, as set forth in 30 U. S. C. § 940 (1970 ed., Supp. IV), which provides as follows:

“The amendments made by the Black Lung Benefits Act of 1972 to part B of this subchapter shall, to the extent appropriate, also apply to [Part C]: Provided, That for the purpose of determining the applicability of the presumption established by section 921 (c) (4) of this title to claims filed under this part, no period of employment after June 30, 1971, shall be considered in determining whether a miner was employed at least fifteen years in one or more underground mines.”

Since the limitation on rebuttal evidence in § 411 (c) (4) was created by the “amendments made by the Black Lung Benefits Act of 1972,” it would seem to follow that the limitation applies to Part C determinations. This inference is reinforced by the Senate Report, which stated:

“New section 430 requires that amendments to *47part B be applied, wherever appropriate, to part C. . . .

“Questions were raised during the Committee deliberations over whether the amendments to part B would automatically be applicable, where appropriate, to part C.

“Although it would appear clear that the same standards are to govern, the Committee concluded that it would be best to so specify.

“It is contemplated by the Committee that the applicable portions of following sections of part B, as amended, would apply to part C: section 411, section 412 (except the last sentence of subsection (b) thereof), section 413, and section 414.” S. Rep. No. 92-743, p. 21 (1972).

See also id., at 33.

The only play in the tight linkage of Part C to the amendments to Part B is that afforded by the proviso in § 430 and by the phrase “to the extent appropriate” which appears in that section. The proviso does not remove the rebuttal limitation, but it does alter § 411 (c) (4)’s allocation of the burden of proof in another crucial respect: It limits the period of employment which may be considered for purposes of determining the applicability of the presumption. The presence of the proviso is relevant in two respects. First, it underscores the basic applicability to Part C determinations of the § 411 (c) (4) rebuttal presumption. Second, it demonstrates that Congress knew how to place a significant limitation on the applicability of that presumption when it chose to do so.

The care and precision which Congress used in drafting this qualifying language bears on the propriety of reading the phrase “to the extent appropriate” as obliquely qualifying the applicability of the rebuttal limitation to *48Part C determinations. That limitation is part and parcel of an elaborate reallocation of the burden of proving disability resulting from pneumoconiosis. Under prior Social Security procedure “if an X-ray [did] not show totally disabling pneumoconiosis, no further processing of a claim [was] allowed. Thus, any further evidence of disability [was] not allowed if the X-ray show[ed] negative.” S. Rep. No. 92-743, supra, at 11. This heavy reliance on X-ray evidence had unfortunate consequences for coal miners because of the inability of X-ray examinations to detect pneumoconiosis in some instances. Congress responded to this particular problem by

“prohibiting denial of a claim solely on the basis of an X-ray, by providing a presumption of pneumo-coniosis for miners with respiratory or pulmonary disability where they have worked 15 years or more in a coal mine, and by requiring the Social Security Administration to use tests other than the X-ray to establish the basis for a judgment that a miner is or is not totally disabled due to pneumoconiosis.” Ibid.

The 15-year rebuttable presumption embodied in § 411 (c) (4) was perhaps the most significant feature of Congress’ response. Based in part on testimony of the Surgeon General that “[f]or work periods greater than 15 years underground, there was a linear increase in the prevalence of the disease with years spent underground,” S. Rep. No. 92-743, supra, at 13, the presumption embodied a congressional decision to “giv[e] the benefit of the doubt,” id., at 11, to a specific class of claimants totally disabled by respiratory or pulmonary impairments who could not prove by X-ray evidence that the impairment resulted from pneu-moconiosis. The presumption was rebuttable only if the respondent could show either that “(A) such miner does not, or did not, have pneumoconiosis, or that (B) his respiratory or pulmonary impairment did not arise out of, *49or in connection with, employment in a coal mine.” §411 (c)(4), 30 U. S. C. §921 (c)(4) (1970 ed., Supp. IV).

It is difficult to believe that Congress would have used the phrase “to the extent appropriate” in § 430 to withdraw the protection of the rebuttal limitation under Part C while retaining the rebuttable presumption of which it is an integral part. Such an interpretation is inconsistent with the care Congress displayed in drafting the § 430 proviso. Moreover, it leads necessarily to other improbable results. The Court’s approach, for instance, necessarily implies that Congress extended the benefit of the §411 (c)(4) presumption to “surface, as well as underground, miners [in specified circumstances],” S. Rep. No. 92-743, supra, at 2, with the intention that the protection would lapse as soon as Part C came into play. The relevant sentence in §411 (c)(4) states that “[t]he Secretary [of Health, Education, and Welfare] shall not apply all or a portion of the requirement of this paragraph that the miner work in an underground mine where he determines that conditions of a miner’s employment in a coal mine other than an underground mine were substantially similar to conditions in an underground mine.” (Emphasis added.) If the operative principle is that provisions in §411 (c)(4) which bind “the Secretary [of Health, Education, and Welfare]” are automatically “inappropriate” for Part C proceedings, then surface miners would be stripped of the benefits of § 411 (c) (4) as soon as the legislative scheme enters its transitional stage.

Moreover, the Court’s reading of the statute is anomalous in terms of the overall structure of Part C. The primary goal of Congress in framing Part C was to transfer adjudicatory responsibilities over coal miners’ pneumoconiosis claims to state workmen’s compensation tribunals, but only if the state compensation law was *50found by the Secretary of Labor to provide “standards for determining death or total disability due to pneu-moconiosis . . . substantially equivalent to . . . those standards established under part B of this subchap-ter .. . .” § 421 (b)(2)(C), as set forth in 30 U. S. C. §931 (b)(2)(C) (1970 ed., Supp. IV). One of the Part B standards is the rebuttal limitation in § 411 (c)(4). Thus, the Secretary of Labor would not be empowered to approve a state law which did not contain a “substantially equivalent” evidentiary limitation.

The delegation of adjudicatory responsibility to the Secretary of Labor under Part C was a backstop measure, intended to provide a forum for presentation of claims during any period after January 1, 1974, when a state workmen’s compensation law was not included on the Secretary of Labor’s list of state laws with provisions “substantially equivalent” to those in Part B. § 421 (a), 30 IT. S. C. § 931 (a) (1970 ed., Supp. IV). See S. Rep. No. 92-743, supra, at 19-21. Since the very reason for withholding approval of a state law and providing an alternative federal forum is lack of “substantial equivalence” between the state-law provisions and the “standards established under part B,” including the rebuttal limitation in § 411 (c)(4), it would be anomalous if the substitute federal forum could employ evidentiary rules which deviate substantially from those in Part B.

The statutory language and legislative history simply will not yield such an unlikely result. The phrase “to the extent appropriate” in § 430, 30 U. S. C. § 940 (1970 ed., Supp. IV), plainly refers to language in Part B which has no relevance to Part C, notably the language that specifies that “the Secretary [of Health, Education, and Welfare]” is to have certain adjudicative responsibilities. These are the references that are not “appropriate” under Part C, because Part C transfers adjudicative responsibilities to the States or, in the alternative, *51to the Secretary of Labor. The obvious purpose of the phrase “to the extent appropriate” is to accommodate minor linguistic variations resulting from this transfer of responsibility. Thus, the interaction of the phrase “to the extent appropriate” and the reference to “the Secretary” in the rebuttal limitation of §411 (c)(4) does not render the entire limitation “inappropriate” to Part C proceedings; it merely renders the reference to “the Secretary” inappropriate under Part C.

It is significant that the Court’s interpretation of §411 (c)(4)’s rebuttal limitation is not urged or even suggested by any party to this suit. The Federal Parties’ position is that the District Court erred by reading § 411 (c)(4) to foreclose a showing that would refute total disability. That position is clearly correct. The § 411 (c) (4) presumption comes into play only after the claimant establishes total disability. See §411 (c)(4), 30 U. S. C. § 921 (c)(4) (1970 ed., Supp. IV) (“and if other evidence demonstrates the existence of a totally disabling respiratory or pulmonary impairment, then there shall be a rebuttable presumption . . .”). In addition, the District Court ruled that § 411 (c)(4) places upon a specific coal mine owner the burden of proving that the respiratory or pulmonary disease did not arise out of coal mine employment. The Federal Parties urge that this construction is erroneous, because it overlooks the fact that under § 422 (c), 30 U. S. C. § 932 (c), a specific operator can also defeat liability by showing that the disability did not arise, even in part, out of employment in his mine during the period when he operated it. Again, the Federal Parties are clearly correct. If the operator makes the § 422 (c) showing, then the §411 (c)(4) presumption — and the rebuttal limitation — is irrelevant. Accordingly, I would reverse the District Court’s ruling that the §411 (c)(4) rebuttal limitation violates the Constitution.

OPINION OF THE COURT

GREENBERG, Circuit Judge.

I. INTRODUCTION

In 1992, Congress enacted the Coal Industry Retiree Health Benefit Act (“Coal Act”), 26 U.S.C. §§ 9701-9722, to ensure that retired coal miners and their dependents would continue to receive the health *164and death benefits they had been receiving since the 1940s pursuant to a series of collective bargaining agreements. By the late 1980s, problems had arisen that caused serious under-funding to the two benefit plans funding the miners’ benefits. Fearing that the miners and their families would be left with no health or death benefits, Congress stepped in and passed the Coal Act, which provided a new funding mechanism under which the Commissioner of Social Security (“Commissioner”) would assign miners to a coal industry employer based on the recency and longevity of a miner’s employment. That employer then would be responsible for providing the funds for those miners’ benefits.

The Coal Act has led to a flood of litigation challenging the Commissioner’s assignments of liability under the Act, as well as Takings and Due Process challenges to the constitutional validity of the Act’s imposition of retroactive liability. Following this legal trend, Anker Energy Corp. (“Anker”) filed this action in the United States District Court for the Western District of Pennsylvania seeking declaratory and injunctive relief that the Commissioner improperly assigned it responsibility for funding certain miners’ benefits and that these assignments violated the Takings and Due Process Clauses of the Fifth Amendment to the United States Constitution. Anker also asserted that appellee Consolidation Coal Co. (“Consol”) had agreed to assume liability for any payments due for miners’ benefits and to reimburse Anker for any such payments Anker made, and thus was hable to it for the monies attributable to the assignments.

The district court dismissed all of these claims at the pleadings and summary judgment stages of litigation. First, the court granted Consol’s motion for judgment on the pleadings pursuant to Fed.R.Civ.P. 12(c) on Anker’s claims that the Commissioner should have assigned the miners to Consol, and that Consol had agreed to indemnify Anker for any liability it incurred for the payment of miners’ benefits. See Anker Energy Corp. v. Consolidation Coal Co., Civ. No. 96-1938 (W.D.Pa. July 25, 1997) (Anker I). Subsequently, the district court upheld the constitutionality of the application of the Coal Act to Anker on a motion for summary judgment. See Anker Energy Corp. v. Consolidation Coal Co., Civ. No. 96-1938 (W.D.Pa. Mar. 11, 1998) {Anker II). FinaUy, inasmuch as it had affirmed the imposition of liability against Anker and had determined that Anker was delinquent in its payments under the Act, the district court entered a judgment of $1,180,489.06 against Anker for annual premiums, interest, liquidated damages, attorney’s fees, and costs. See Anker Energy Corp. v. Consolidation Coal Co., Civ. No. 96-1938 (W.D.Pa. July 21, 1998) (Anker III). This appeal followed.

II. FACTUAL AND PROCEDURAL HISTORY

A. Factual History

The courts have well-chronicled the history of the coal industry’s struggles to provide retirement and health benefits to miners. See, e.g., Unity Real Estate Co. v. Hudson, 178 F.3d 649, 653-55 (3d Cir.1999); Eastern Enters. v. Apfel, 524 U.S. 498,-, 118 S.Ct. 2131, 2137-42, 141 L.Ed.2d 451 (1998) (plurality opinion). Therefore, we only briefly will summarize this chronology and outline the parties’ roles within that larger story.

In 1947, the United Mine Workers of America (“UMWA”) and the Bituminous Coal Operators’ Association (“BCOA”) agreed upon the first of a series of National Bituminous Coal Wage Agreements (“NBCWA” or “wage agreement”), which specified the terms and conditions of employment and provided health and pension benefits for miners. The 1947 NBCWA established the United Mine Workers of America Welfare and Retirement Fund, which used the proceeds of a royalty on coal production to provide pension and *165medical benefits for miners and their families. The 1947 NBCWA did not specify the benefits to which miners and their families were entitled, instead leaving this task to three trustees in charge of the Fund. In 1950 the union and the industry association agreed upon a new NBCWA that created a new Fund financed by a per ton levy on coal mined by signatory operators. Like the 1947 Fund, the 1950 version did not promise specific benefits, and the benefits were always subject to cancellation or change.

This system did not change significantly until 1974 when, to comply with the newly enacted ERISA, the UMWA and the BCOA negotiated a new wage agreement that created four trusts funded by royalties on coal production and premiums based on hours worked by miners. Under the new agreement, the 1950 Benefit Plan covered miners who retired before January 1, 1976, and their dependents, while the 1974 Benefit Plan covered miners who retired after 1975 and their dependents. Both Plans provided nonpension benefits, including medical benefits.

The 1974 NBCWA explained that it was amending the previous system to provide health benefits for retired miners “for life,” and to their widows until death or remarriage. Because of this broadened coverage the number of eligible benefit recipients increased dramatically, and the Plans began losing money.

In response, the 1978 NBCWA assigned responsibility to signatory employers for the health care of their own active and retired employees. The 1978 agreement also restricted the 1974 Plan so that it would provide health benefits only for “orphaned” retirees, those whose last employer had gone out of business or otherwise ceased contributing to the Plans. To ensure the Plans’ solvency, the 1978 NBCWA included a “guarantee” clause that obligated signatories' to make sufficient contributions to maintain benefits during that agreement, and the union and operators amended the Plans to include “evergreen clauses” that required signatories to contribute to the Plans if they remained in the coal business even if they never signed another wage agreement.

Despite the 1978 NBCWA and subsequent attempts to improve the Plans, they continued to lose money because of the increase in beneficiaries, the escalating costs of health care, and the flood of signatory companies abandoning the Plans. In 1992 Congress responded by passing the Coal Act. The Act merged the 1950 and 1974 Benefit Plans into a new multi-em- • ployer plan called the United Mine Workers of America Combined Benefit Fund (“Combined Fund”). The Combined Fund provides “substantially the same” health benefits to retirees and their dependents that the 1950 and 1974 Plans provided. 26 U.S.C. § 9703(b)(1), (f). However, Congress altered the funding mechanism, an action that has led to the overflow of litigation.

The Act finances the Combined Fund with annual premiums assessed against signatory operators, which are companies that were or are signatories to a “coal wage agreement.” 26 U.S.C. § 9701(c)(1). The Act defines a “coal wage agreement” as an NBCWA, or “any other agreement entered into between an employer in the coal industry and the United Mine Workers of America that required” the provision of health benefits to its retirees or contributions to the 1950,1974 or any prior Benefit Plan. 26 U.S.C. § 9701(b)(1)(A), (B). Any signatory operator who “conducts' or derives revenue from any business activity, whether or not in the coal industry,” may be required to contribute to the Combined Fund. 26 U.S.C. §§ 9701(c)(7), 9706(a). Where a signatory operator is no longer involved in any business activity, premiums may be assessed against “related person[s]” including “successors in interest and businesses or corporations under common control.” Eastern Enters., 524 U.S. at , 118 S.Ct. at 2142 (discussing 26 U.S.C. §§ 9701(c)(2)(A), 9706(a)).

*166The Commissioner of Social Security assigns retirees to particular signatory operators, and calculates premiums according to these assignments based on the following formula:

(a) In general. — For purposes of this chapter, the Commissioner of Social Security shall ... assign each coal industry retiree who is an eligible beneficiary to a signatory operator which (or any related person with respect to which) remains in business in the following order:

(1) First, to the signatory operator which—

(A) was a signatory to the 1978 coal wage agreement or any subsequent coal wage agreement, and

(B) was the most recent signatory operator to employ the coal industry retiree in the coal industry for at least 2 years.

(2) Second, if the retiree is not assigned under paragraph (1), to the signatory operator which—

(A) was a signatory to the 1978 coal wage agreement or any subsequent coal wage agreement, and

(B) was the most recent signatory operator to employ the coal industry retiree in the coal industry.

(3) Third, if the retiree is not assigned under paragraph (1) or (2), to the signatory operator which employed the coal industry retiree in the coal industry for a longer period of time than any other signatory operator prior to the effective date of the 1978 coal wage agreement.

26 U.S.C. § 9706(a).

The surge of litigation attacking the Coal Act began shortly after the Commissioner began assigning retirees to signatory operators. In Lindsey Coal Mining Co. v. Chater, 90 F.3d 688 (3d Cir.1996), we held the Act constitutional as applied to a coal company to which the Commissioner had assigned retirees through section 9706(a)(3) concerning those signatory operators who had not signed the 1978 agreement. See id. at 695. However, the Supreme Court’s decision in Eastern Enterprises, 524 U.S. 498, 118 S.Ct. 2131, calls the continuing vitality of Lindsey Coal Mining into question, as the Court found the Act unconstitutional as applied to a coal company that had ceased mining in 1965 and never signed the 1974 or subsequent wage agreements. Id. at 2153 (plurality opinion); id. at 2154 (Kennedy, J., concurring in judgment).

We recently have had the opportunity to apply the fragmented Eastern Enterprises decision to facts similar to those here. In Unity Real Estate, 178 F.3d 649, we upheld the Commissioner’s assessment of liability against two companies that had signed the 1974 and 1978 wage agreements and later NBCWAs as constitutional in the face of takings and due process challenges. Id. at 675-76, 677-78.

B. Procedural History

The seeds of discontent that led to this suit were sown on March 30, 1994, when the Commissioner informed Anker that she was assigning it liability for certain retired miners, surviving spouses and dependents, and several orphaned miners due to its relationship with King Knob Coal Co. (“King Knob”) which no longer was in business. From 1967 until 1982, Consol had contracted with King Knob for it to extract coal on certain of Consol’s properties. As part of these contracts, King Knob agreed that “its employees shall be members of the United Mine Workers of America and it shall be a signatory to the then current National Bituminous Coal Wage Agreement.” App. at 75.

To achieve this end, King Knob signed “me too” agreements during the 1970s and 1980s, the last in 1984. See app. at 8. Anker characterizes a “me too” agreement as an agreement between an employer who was not a member of the BCOA nor an NBCWA signatory yet who agreed by sep*167arate instrument with the UMWA to “be bound by the terms of the NBCWAs.” App. at 8.

An affiliate of Anker acquired King Knob in 1975. The parties’ relationship continued uneventfully until Consol canceled its contracts with King Knob following which they entered into a settlement agreement on July 23, 1982. Paragraph 4(b) of the settlement required Consol to

promptly reimburse King Knob for all subsequent payments due to the UMWA Fund or any successor fund attributable to (i) tonnage of coal produced under the contracts, (ii) hours worked at the mine operated under the Robinson Run contract on or before August 31, 1982, and. (iii) hours worked at the mines operated under the Booth contract on or before June 30,1982.

App. at 17, 97.

In 1994 and 1995, the Commissioner informed Anker that it was a related person to King Knob and was being assigned liability for a number of beneficiaries under the Coal Act. Arguing that Consol was the proper signatory operator responsible for some of these retirees under the Act as they worked at Consol’s properties and Consol was responsible for them, Anker protested this assignment. The Commissioner responded that Anker’s liability was based upon the fact that King Knob (not Consol) was the signatory employer of the eligible retirees. Moreover, the Commissioner determined that she was not authorized to assign Anker’s premiums to Con-sol despite the parties’ possible contractual agreement for reimbursement of future benefits because the Social Security Administration “is not bound by any private agreements made between companies, nor does the Coal Act allow for pro-ration of premium payments between companies.” App. at 33.

Anker and King Knob responded by filing this action seeking declaratory and injunctive relief that Consol is liable for any premiums due the Combined Fund, and that the Commissioner’s assessment of liability to the Combined Fund under the Coal Act violates' the Due Process and Takings Clauses of the Fifth Amendment to the United States Constitution. As a matter of convenience we usually refer to Anker alone as the plaintiff and appellant. Besides Consol, Anker named the UMWA Combined Fund, its Trustees and the Commissioner as defendants.

In an unpublished disposition, the district court granted Consol’s motion for judgment on the pleadings pursuant to Fed.R.Civ.P. 12(c) as to Counts One and Two of Anker’s complaint. Anker I at 2. In Count One, Anker alleged that Consol had agreed with King Knob and the UMWA that it would pay the premiums owed to the 1950 and 1974 Plans based upon the amount of coal produced and the hours worked by King Knob’s employees. Id. at 13. Anker contended that because of these agreements, Consol became the signatory operator responsible for King Knob’s employees’ benefits under the 1950 and 1974 Plans, and thus was the proper party to which the Commissioner should assign King Knob’s retirees. Id. at 14.

The district court held that Anker could not support this claim and granted Consol judgment as a matter of law on Count One. Id. The court recognized that “it is undisputed that King Knob was a signatory to one or more coal wage agreements covering its employees at Consol’s Booth and Robinson Rim properties, and that Anker is a ‘related person’ to King Knob as defined in the Coal Act.” Id. at 15. King Knob was also clearly the employer of the miners. Id. at 20. Thus, the Commissioner’s assignment of beneficiaries and liability under the Act to Anker as a related person to King Knob was correct. Id. at 21. Moreover, the court refuted Anker’s argument that Consol had agreed in 1982 to be responsible for any future contributions owed to a subsequent benefit plan, and agreed with the Commissioner that the Coal Act does not allow for the assess*168ment of liability based upon private contracts. Id. at 15-16.

The court also granted Consol’s motion for judgment on the pleadings on Count Two, which alleged that pursuant to their settlement agreement Consol was liable to Anker for all premiums for which Anker is responsible under the Act. Id. at 21. The court rejected Anker’s argument that paragraph 4(b) of the settlement agreement bound Consol to reimburse King Knob, and thus Anker, for its liability under the Coal Act, reasoning that premiums under the Act are not

‘attributable to’ the tonnage of coal produced and the number of hours worked under the contract mining agreements, and the Combined Fund is not a successor fund which requires premium payments based on the tonnage of coal produced or the number of hours worked by a signatory operator’s employees. Rather, under the Coal Act, health benefits are funded by the imposition of what is, in essence, a tax.

Id. at 22-23. Finally, the court relied upon Carbon Fuel Co. v. USX Corp., 100 F.3d 1124 (4th Cir.1996), when it held that even if Anker was entitled to reimbursement under its contract with Consol, Con-sol still would be entitled to judgment as a matter of law because “the Coal Act abrogated pre-act contracts reallocating mining companies’ obligations to pre-Act benefit plans.” Id. at 24 n. 17. Next the district court upheld the constitutionality of the application of the Coal Act to Anker in a second unpublished decision, and, relying upon our holding in Lindsey Coal Mining, 90 F.3d 688, granted summary judgment in favor of the Combined Fund, its Trustees, and the Commissioner on Count Three which sought a finding of unconstitutionality. Anker II at 6.

Finally, on July 21, 1998, the district court granted summary judgment on the Combined Fund’s counterclaim for entry of a judgment against Anker and King Knob for annual premiums, interest, liquidated damages, attorney’s fees, and costs. Anker III at 10-11. Anker did not contest the assessment of annual premiums. Id. at 6 n. 3. Considering this fact and Congress’s clear intent to provide for liquidated damages, interest, attorney’s fees, and costs if an employer fails to make timely payments, the court entered judgment for $1,180,489.06 against Anker and King Knob in a third unpublished disposition. Id. at 11. Anker and King Knob then appealed.

III. DISCUSSION

Anker argues that the Coal Act is unconstitutional as applied to it according to the Supreme Court’s decision in Eastern Enterprises, 524 U.S. 498, 118 S.Ct. 2131. Appellants’ Brief at 19-26. Alternatively, Anker urges us to reverse the district court’s grant of judgment on the pleadings against it on Counts One and Two of its complaint. Id. at 26-37. Anker repeats its position concerning Count One that the Commissioner should have assigned the miners at issue to Consol. As to Count Two, Anker contends that the district court erroneously found paragraph 4(b) of the settlement agreement between King Knob and Consol clear and unambiguous. Consequently, Anker believes that the district court erred in not considering its parol evidence, and that under our precedent, parol evidence is essential to interpreting the parties’ intent correctly. Moreover, Anker argues that the district court’s interpretation of paragraph 4(b) of the settlement agreement was simply wrong. Id. at 28-37. Finally, Anker contests the district court’s awarding the Combined Fund interest, liquidated damages, attorney’s fees, and costs, arguing that the Act does not provide for the assessment of these items. Id. at 37-48.

We will affirm the district court’s decisions regarding the constitutionality of the Act, the correctness of the Commissioner’s assignments, and the award of interest, liquidated damages, fees and costs against Anker. However, we will reverse the court’s order granting judgment on the *169pleadings on Count Two, Anker’s contract claim for reimbursement from Consol, and will remand to the district court for further proceedings on that count.1

A. Standard of Review

In reviewing the district court’s order, we examine the Commissioner’s action under the same standard of review properly applied by the district court. See Florida Power & Light Co. v. Lorion, 470 U.S. 729, 744, 105 S.Ct. 1598, 1607, 84 L.Ed.2d 648 (1985). Thus, we review the Commissioner’s decision as a final agency action brought under the Administrative Procedure Act. See Lindsey Coal Mining, 90 F.3d at 691; 5 U.S.C. § 704. Accordingly, the issue is whether the administrative determination was “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A).2 See C.K v. New Jersey Dep’t of Health and Human Servs., 92 F.3d 171, 182 (3d Cir.1996).

We review the district court’s decision as to the constitutionality of the Coal Act as applied to Anker de novo. See Dyszel v. Marks, 6 F.3d 116, 123 (3d Cir.1993). Similarly, our review of the district court’s granting of judgment on the pleadings and summary judgment where the district court was not reviewing the Commissioner’s decisions is plenary. , See Smith v. National Collegiate Athletic Ass’n, 139 F.3d 180, 183 (3d Cir.1998), rev’d on other grounds, — U.S.-, 119 S.Ct. 924, 142 L.Ed.2d 929 (1999); Petruzzi’s IGA Supermarkets, Inc. v. Darling-Delaware Co., 998 F.2d 1224, 1230 (3d Cir.1993).

B. Takings and Due Process Challenges

Our discussion of Anker’s, constitutional challenge begins with Eastern Enterprises, 524 U.S. 498, 118 S.Ct. 2131, where a fragmented Supreme Court considered the constitutionality of the Coal Act as applied to a company whose coal operations had ceased in 1965. Id. at-, 118 S.Ct. at 2143. A majority of the Court struck down the law as applied to Eastern Enterprises by relying on two distinct theories. The four-justice plurality held that application of the Coal Act to Eastern Enterprises violated the Fifth Amendment as an unconstitutional taking. Id. at-, 118 S.Ct. at 2149. Justice Kennedy, who provided ¡the fifth vote striking down the application of the Act, disagreed with the plurality’s takings reasoning, but found that the Act’s retroactivity violated due process. Id. at -, 118 S.Ct. at 2154 (Kennedy, J., concurring in judgment and dissenting in part). The four dissenting justices agreed with Justice Kennedy that application of the statute did not violate the Takings Clause, yet disagreed with his opinion that the Act violated due process. Id. at-, 118 S.Ct. at 2161 (Breyer, J., dissenting).

To consider Anker’s takings and due process claims, we first must decide what, if any, holding in Eastern Enterprises binds our decision. “When a fragmented Court decides a case and no single rationale explaining the result enjoys the assent of five Justices, ‘the holding of the Court may be viewed as that position taken by those Members who concurred in the judgment on the narrowest grounds.’ ” Marks v. United States, 430 U.S. 188, 193, *17097 S.Ct. 990, 993, 51 L.Ed.2d 260 (1977) (quoting Gregg v. Georgia, 428 U.S. 153, 169 n. 15, 96 S.Ct. 2909, 2923 n. 15, 49 L.Ed.2d 859 (1976)). However, as we recognized in Rappa v. New Castle County, 18 F.3d 1043 (3d Cir.1994), and reaffirmed in Unity Real Estate, 178 F.3d at 658, the Marks rule is applicable only where “one opinion can be meaningfully regarded as ‘narrower’ than another” and can “represent a common denominator of the Court’s reasoning.” Rappa, 18 F.3d at 1057 (quoting King v. Palmer, 950 F.2d 771, 781 (D.C.Cir.1991) (en banc)). Thus, in cases where approaches differ, no particular standard is binding on an inferior court because none has received the support of a majority of the Supreme Court. Id. at 1058.

As to the immediate situation, we recognized in Unity Real Estate that “Justice Kennedy’s substantive due process reasoning is not a ‘narrower’ ground that we might take to constitute the controlling holding.” 178 F.3d at 658. In such a ease, then, the only binding aspect of a splintered decision is its specific result, in Eastern Enterprises the Court’s “holding the Coal Act unconstitutional as applied to Eastern Enterprises.” Association of Bituminous Contractors, Inc. v. Apfel, 156 F.3d 1246, 1255 (D.C.Cir.1998). Eastern Enterprises requires a finding that the Coal Act is unconstitutional as applied to Anker, then, only if Anker “standfs] in a substantially identical position to Eastern Enterprises with respect to both the plurality and Justice Kennedy’s concurrence.” Unity Real Estate, 178 F.3d at 659.3

Applying Eastern Enterprises in accordance with the foregoing methodology is not difficult inasmuch as its plurality and concurrence both found significant the fact that Eastern Enterprises was not a signatory to either the 1974 or 1978 NBCWAs, and thus it did not contemplate either being responsible for or contributing to the miners’ expectation of lifetime benefits. The plurality recognized that while the takings inquiry is “essentially ad hoc and fact intensive” the Court, in prior decisions, had identified three factors that are particularly significant: “ ‘the economic impact of the regulation, its interference with reasonable investment backed expectations, and the character of the governmental action.’ ” 524 U.S. at -, 118 S.Ct. at 2146 (quoting Kaiser Aetna v. United States, 444 U.S. 164, 175, 100 S.Ct. 383, 390, 62 L.Ed.2d 332 (1979)). The plurality then summarized its takings case law as follows:

Our opinions ... make clear that Congress has considerable leeway to fashion economic legislation, including the power to affect contractual commitments between private parties. Congress also may impose retroactive liability to some degree particularly where it is ‘confined to short and limited periods required by the practicalities of producing national legislation.’ Our decisions, however, have left open the possibility that legislation might be unconstitutional if it imposes severe retroactive liability on a limited class of parties that could not have anticipated the liability, and the extent of that liability is substantially disproportionate to the parties’ experience.

*171 Id. at -, 118 S.Ct. at 2149 (quoting Pension Benefit Guar. Corp. v. R.A. Gray & Co., 467 U.S. 717, 731, 104 S.Ct. 2709, 2719, 81 L.Ed.2d 601 (1984)) (internal quotation marks omitted) (emphasis added) (citation omitted).

Applying these precepts, the plurality held that the Coal Act placed a “considerable financial burden” upon Eastern Enterprises, which was liable for between $50 and $100 million in cumulative payments. Id. at-, 118 S.Ct. at 2149. The plurality acknowledged that this type of financial burden was not a per se taking — “a permanent physical occupation of ... property” — yet noted that the Court’s decisions upholding the Multiemployer Pension Amendments Act of 1980 to supplement ERISA suggested that “an employer’s statutory liability for multiemployer plan benefits should reflect some ‘proportion[ality] to its experience with the plan.’ ” Id. at-, 118 S.Ct. at 2149 (quoting Concrete Pipe & Prods. of Cal., Inc. v. Construction Laborers Pension Trust for S. Cal., 508 U.S. 602, 645, 113 S.Ct. 2264, 2291, 124 L.Ed.2d 539 (1993)). The plurality found this proportionality lacking because “while Eastern contributed to the 1947 and 1950 W & R Funds, it ceased its coal mining operations in 1965 and neither participated in negotiations nor agreed to make contributions in connection with the Benefit Plans under the 197k, 1978, or subsequent NBCWA’s.” Id. at'-, 118 S.Ct. at 2150 (emphasis added). This was significant because the 1974 and subsequent agreements “first suggest[ed] an industry commitment to the funding of lifetime health benefits for both retirees and their family members.” Id. at-, 118 S.Ct. at 2150. Thus, because Eastern Enterprises never had contemplated liability nor contributed to the miners’ expectation of lifetime benefits, the plurality held that “the correlation between Eastern and its liability to the Combined Fund is tenuous, and the amount assessed against Eastern resembles a calculation ‘made in a vacuum.’ ” Id. at-, 118 S.Ct. at 2150 (quoting Connolly v. Pension Benefit Guar. Corp., 475 U.S. 211, 225, 106 S.Ct. 1018, 1026, 89 L.Ed.2d 166 (1986)).

The plurality also found the lack of proportionality significant in its analysis of whether the Coal Act substantially interfered with Eastern Enterprises’ reasonable investment backed expectations, and whether the nature of the governmental action was unusual. The plurality found that the Act’s “substantial and particularly far reaching” retroactive effect interfered with Eastern Enterprises’ reasonable investment backed expectations. Id. at -, 118 S.Ct. at 2152. It noted that inasmuch as an employer in the coal industry could not have contemplated that it was promising lifetime benefits until 1974 when ERISA forced revisions to the 1950 Fund, the Coal Act’s “scheme for allocation of Combined Fund premiums is not calibrated either to Eastern’s past actions or to any agreement — implicit or otherwise — by the company.” Id. at-, 118 S.Ct. at 2152. Likewise, the plurality reasoned that the governmental action was highly unusual and implicated fundamental principles of fairness because it “single[d] out certain employers to bear a burden that is substantial in amount, based on the employers’ conduct far in the past, and unrelated to any commitment that the employers made or to any injury they caused. ...” Id. at-, 118 S.Ct. at 2153 (emphasis added). Therefore, each factor suggesting that the application of the Coal Act was an unconstitutional taking depended upon the fact that Eastern Enterprises had left the coal industry in 1965 and had not agreed to the 1974, 1978, or subsequent wage agreements.

Justice Kennedy, in finding the Coal Act’s application to Eastern Enterprises violated substantive due process, also relied upon the fact that Eastern Enterprises had not signed the 1974 or following agreements. Justice Kennedy held that “[a]ccepted principles forbidding retroactive legislation” dictated that the application of the Act to Eastern Enterprises violates the Due Process Clause. Id. at *172-, 118 S.Ct. at 2158 (Kennedy, J., concurring in judgment and dissenting in part). Applying an “arbitrary and irrational” standard of review, Justice Kennedy pointed out that the assessment of liability against Eastern Enterprises bore no legitimate relation to the government’s asserted interest in holding responsible those coal companies that created an expectation of lifetime benefits and then abandoned the industry to avoid this commitment:

As the plurality opinion discusses in detail, the expectation was created by promises and agreements made long after Eastern left the coal business. Eastern was not responsible for the resulting chaos in the funding mechanism caused by other coal companies leaving the framework of the National Bituminous Coal Wage Agreement. This case is far outside the bounds of retroactivity permissible under our law.

Id. at -, 118 S.Ct. at 2159 (citation omitted) (Kennedy, J., concurring in judgment and dissenting in part).

Thus, analysis of the decisions in Eastern Enterprises leads us to the conclusion that a majority of the Court would find the Act unconstitutional when applied to an employer that did not agree to the 1974 or subsequent NBCWAs, while application of the Act to a signatory to the 1974 or a subsequent wage agreement would be an entirely different matter.

We believe the fact that Anker was a signatory to “me too” agreements from the 1970s until 1984 factually distinguishes Anker’s situation from that of Eastern Enterprises and compels a finding that the Act is constitutional in this instance.4 This was, in fact, the Court of Appeals for the District of Columbia Circuit’s reasoning in Association of Bituminous Contractors, 156 F.3d 1246, in upholding the application of the Act to operators similarly situated to plaintiffs here. Faced with signatory operators of the 1974 and subsequent agreements by incorporation by reference in related agreements, the court noted that “the crucial fact upon which the Eastern Enterprises plurality and Justice Kennedy relied in concluding that Eastern’s Coal Act liability was disproportionate to its past conduct and thus unfairly retroactive — namely, Eastern’s departure from the coal industry in 1965 — is absent in this case.” Id. at 1256. The court continued: “The clear implication of each opinion in Eastern Enterprises is that employer participation in the 1974 and 1978 agreements represents a sufficient amount of past conduct to justify the retroactive imposition of Coal Act liability (for the dissenting justices, of course, such participation is not even necessary).” Id. at 1257. See also Unity Real Estate, 178 F.3d at 678 (Aldi-sert, J., concurring) (“The decisive material facts in Eastern Enterprises are that the company (1) left the coal industry in 1965 and (2) was never a party to the 1974 and later Wage Agreements that first suggested the commitment to lifetime benefits for retirees and family members.”). Thus, it appears that this case falls outside the specific holding of Eastern Enterprises, and we therefore find the Coal Act’s application to Anker constitutional.

However, our opinion in Unity Real Estate directs us to apply an additional level of due process analysis designed to measure “the extent of the gap between the coal companies’ contractual promises to the Funds and the requirements of the *173Coal Act.” Id. at 659. We noted there that the proper standard of review for a due process analysis is whether Congress’s action was arbitrary or irrational. Id. We concluded that Congress’s determination that the coal industry acted in a way that created the miners’ reasonable expectation of lifetime benefits, and that its finding that the coal companies were the most responsible parties for the deterioration of the Benefit Plans were “reasonable evaluations of the problem.” Id. at 670.

We then held that the Act’s retroactivity did not render it irrational in violation of due process. Id. We recognized that the “heart of retroactivity analysis is an evaluation of the extent of the burden imposed by a retroactive law in relation to the burdened parties’ prior acts” and announced that “[wjhere Congress acts reasonably to redress an injury caused or to enforce an expectation created by a party, it can do so retroactively.” Id. at 671.

In the first step of a retroactivity analysis, we measured the length of time of the retroactivity from the date the coal company’s contractual obligations ceased to the passing of the Act, and held that Unity Real Estate’s 11 years was not so extensive as to violate Justice Kennedy’s standard, although we admitted that it was a “close case.” Id. at 670. We, however, recognized that the burden the Coal Act imposes upon parties assessed liability is substantial. Id. at 671. Finally, turning to the proportionality issue, we found that the Coal Act imposes a burden justified by both the industry’s conduct that created reasonable expectations of lifetime benefits — creating a benefit fund legally obligated to pay out more funds than the operators were required to provide — and conduct that created the problem of under funding — the same initial flaws in the funding mechanism compounded by the mass exodus of operators from the industry to avoid making further contributions to the funds. Id, at 673. This analysis led us to conclude that the Coal Act did not violate the Due Process Clause because Congress was entitled to redress the problems caused by “the companies’ actions, through the BCOA through which negotiations with the unions were conducted, [which] created reasonable expectations about benefits and established a funding structure vulnerable to ‘dumping’ retirees when companies left the industry.” Id.

Applying Unity Real Estate’s retroac-tivity analysis compels us to reach a similar conclusion here. The length of time since King Knob last agreed in a “me too” contract to abide by an NBCWA was eight years, and the length of time since King Knob agreed to an NBCWA in a contract with Consol was 11 years before Congress passed the Coal Act. We found 11 years to be acceptable, although a “close case,” in Unity Real Estate. Id. at 670. Moreover, our proportionality analysis in Unity Real Estate applies full force here because King Knob was a signatory to the 1978 and subsequent NBCWAs, and thus bears the same responsibility as the plaintiffs in Unity Real Estate for creating the reasonable expectations and the problem of under-funding that the Coal Act redresses. Id. at 674.

While some language in Unity Real Estate suggests that we rested our holding on the operators’ membership in the BCOA which had negotiated the agreements that created the miners’ expectation of benefits, id. at 665-67, we will not read this language to allow “me too” signatures to avoid the application of the Act. King Knob agreed to abide by those same NBCWAs that the plaintiffs in Unity Real Estate negotiated.5 Similarly, Anker’s arr gument that its liability fails Unity Real Estate’s proportionality test since King Knob was “never” responsible for contributing to the benefit funds misses the mark. Anker fails to realize that while Consol *174may have agreed to assume King Knob’s payments to the benefit funds in its eon-tract-mining agreements spanning 1967 to 1982, King Knob, as a “me too” signatory to the NBCWAs was responsible in the first instance for the provision of these payments. King Knob’s ability to have Consol assume this obligation is simply irrelevent to the fact that by agreeing to the NBCWAs King Knob was a party to the agreements that created the miners’ expectation of lifetime benefits. King Knob benefitted as much as Consol from having the NBCWAs as those agreements kept a consistent work force in place in part by promising the provision of health and death benefits for the rest of the miners’ lives.

Overall, inasmuch as nothing germane to our holding in Unity Real Estate distinguishes Anker from the plaintiffs in Unity Real Estate, application of that case’s due process analysis leads us once again to conclude that the Act does not violate constitutional norms, this time as applied to the Anker. Thus, we find the Act constitutional as applied to Anker because of the factual distinction that makes Eastern Enterprises inapplicable, and because the case falls squarely under our analysis and holding in Unity Real Estate.

C. The Commissioner’s Assignment of Beneficiaries to Anker

In reviewing the Commissioner’s decision to assign beneficiaries to Anker, we decide whether her action was “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A). The Commissioner rejected Anker’s arguments that Consol was the entity responsible for providing the miners’ benefits. Anker had argued to the Social Security Administration

that assignments made [because of Anker’s affiliation with King Knob] should be reassigned to Consolidation Coal Co. because King Knob operated as an independent contractor mining lands owned or leased by Consol with no ownership rights in the minerals; that amounts paid by Consol to the UMWA plans were not deducted or credited against the amounts paid to King Knob for the mined coal; that upon termination of the agreement in 1982 Consol accepted responsibility for current and subsequent payments to the UMWA Welfare and Retirement Fund or any successor fund based on hours worked prior to the summer of 1982; [and] that for miners employed by King Knob after 1982, responsibility should be pro-rated....

App. at 33. The Commissioner instead determined that

Under the Coal Act, ownership of a mine is immaterial to assignment decisions. Assignments are made solely on the basis of the signatory employer who employed the eligible retiree. In the case involving King Knob, an affiliate of Anker Energy, the signatory that employed the retirees was King Knob, not Consol. Also, for Coal Act purposes, SSA is not bound by any private agreements made between companies, nor does the Coal Act allow for pro-ration of premium payments between companies. In light of the foregoing, no assignments that were made to Anker on the basis of its relationship to King Knob Coal can be reassigned to Consol.

App. at 33. We will affirm the district court’s grant of judgment on the pleadings on Count One upholding the Commissioner’s assignment of beneficiaries to Anker, because we find that her decision was not “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A).

Anker contends that King Knob was merely the “nominal” employer of the miners, while Consol was a signatory operator in its own right under the Act that had received “the entire economic benefit which those miners created,” and was “the entity which had responsibility for all payments required to be made to the UMWA Benefit Funds.” Appellants’ Brief at 26. *175We find these contentions to be without merit.

The Coal Act directs the Commissioner to assign each eligible beneficiary to a “signatory operator” who employed the beneficiary. 26 U.S.C. § 9706(a). Section 9706(a) also attempts to ensure that the specific assignment of a beneficiary is to the most recent and significant employer still in business. The Act defines a “signatory operator” as “a person which is or was a signatory to a coal wage agreement.” 26 U.S.C. § 9701(c)(1). The term “coal wage agreement” includes “the National Bituminous Coal Wage Agreement,” as well as “any other agreement entered into between an employer in the coal industry and the United Mine Workers of America that required ... the provision of health benefits to retirees of such employer ... or contributions to the 1950 UMWA Benefit Plan or the 1974 UMWA Benefit Plan, or any predecessor thereof.” 26 U.S.C. § 9701(b)(1). Finally, the Act provides that “employment of a coal industry retiree in the coal industry by a signatory operator shall be treated as employment by any related persons to such operator.” 26 U.S.C. § 9706(b)(1)(A).

Applying these terms here, we uphold the Commissioner’s conclusion that Anker is a related person to King Knob who was responsible for the provision of health benefits to the 1950 or 1974 Plans. First, King Knob was clearly a signatory operator under the Act. Anker admits that King Knob was a “me too” signatory to the 1974,1978,1981 and 1984 NBCWAs. App. at 8. Although it did not negotiate these agreements, as a “me too” signatory King Knob agreed to each of these NBCWAs, and agreed to contribute to the benefit funds. As such, King Knob falls under the Act. 26 U.S.C. § 9701.

Moreover, Anker does not contest the Commissioner’s determination that it is a “related person” to King Knob under the Act, and we find that King Knob was without question the miners’ employer. See Appellants’ Brief at 26. Anker’s pleadings and the record reveal as much. As an independent contractor, King Knob agreed in its contracts with Consol that

all parties working for it in connection with the undertaking covered by this Agreement shall be its employees subject only to its orders and supervision .... Neither Consol nor any of its agents, servants or employees shall have the right to direct, supervise or control the manner or method in which the work is to be performed.

App. at 66. Anker confuses the matter by stating that King Knob was only the miners’ “nominal” employer, and that Consol had received the entire “economic benefit” from the miners’ efforts. The Act does not mention the term “nominal” employer, nor does the term have any independent meaning in the context here. Likewise, the Act does not assess premiums based upon who received the “economic benefit” of the miners’ work. Moreover, we do not accept the accuracy of Anker’s denial that King Knob benefitted economically from its employees’ mining efforts. After all, Consol was paying King Knob for its services.

Furthermore, we find Anker’s argument unpersuasive that King Knob was not the correct signatory employer because it never had made contributions to the benefit fund inasmuch as Consol always paid King Knob’s premiums according to their mining agreements. As a “me too” signatory to the 1974, 1978,1981 and 1984 NBCWAs, King Knob was responsible for making payments for its employees to the benefit funds. Even though Consol apparently relieved King Knob of this responsibility by making all of its payments to the funds, such a contractual agreement does not lead us to conclude that King Knob was not a signatory operator responsible for making payments to the funds. Thus, we cannot say that the Commissioner’s assignment of beneficiaries to Anker is “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A).

*176D. Contract for Reimbursement

In granting Consol’s motion for judgment on the pleadings on Count Two the district court relied upon contract and statutory interpretation in holding that Consol is not liable to reimburse Anker for payments made to the Combined Fund for the eligible retirees who worked for King Knob pursuant to its mining contracts with Consol. First, the court held that the language in the settlement agreement6 was clear and unambiguous. Anker I at 22. Next, the court determined that inasmuch as the contract provides for reimbursement “attributable to” either the tonnage of coal produced or the hours miners worked for King Knob under the contracts with Consol, King Knob was entitled to reimbursement only if the premiums Anker paid to the Combined Fund were “attributable to” either factor. Id. Because the Coal Act funds health benefits, according to the district court, “by the imposition of what is, in essence, a tax,” it held that Consol was not obligated to reimburse Anker for its payments. Id. at 23. The court also held that even if Consol was contractually responsible for reimbursing Anker, Anker still could not maintain its action against Consol because the Coal Act “abrogated pre-act contracts reallocating mining companies’ obligations to preAet benefit plans.” Id. at 24 n. 17. We will reverse the district court’s order granting judgment on the pleadings in favor of Con-sol on Count.Two for reimbursement because we reject the district court’s conclusions with respect to the count.

1. Contractual liability

Anker urges us to reverse based upon the district court’s refusal to consider extrinsic evidence in light of its holding the contractual language clear and unambiguous. Appellants’ Brief at 28. Under Pennsylvania law, which is applicable here, a court can consider parol evidence only if the contractual language is ambiguous. See Allegheny Int’l, Inc. v. Allegheny Ludlum Steel Corp., 40 F.3d 1416, 1427-28 (3d Cir.1994); Langer v. Monarch Life Ins. Co., 879 F.2d 75, 81 n. 8 (3d Cir.1989).

We hold that the district court erred in deciding that paragraph 4(b) of the settlement agreement is clear and unambiguous. The provision states that Consol will reimburse King Knob for “all subsequent payments” due to the then-current “UMWA Fund” or “any successor fund.” These payments must be “attributable to” either tonnage of coal or hours worked under the contracts. Inasmuch as the Coal Act does not assign liability based upon the amount of coal mined or hours worked by miners, the court granted Consol’s motion for judgment on the pleadings.

In so doing, the court failed to acknowledge that “tonnage of coal” and “hours worked” were the methods used to determine an employer’s premiums for the 1950 and 1974 Funds. By placing this language in the agreement, the parties could have been agreeing, as Anker contends, that Consol would be responsible for any payments owed to these Funds or any successor fund arising from the work performed pursuant to the mining contracts. The district court, then, failed to read the mention of “tonnage of coal” and “hours worked” consistently with industry usage.

In fact, reading the provision to bind Consol to reimburse Bang Knob for any future benefit payments related to the work completed under the contracts would be consistent with the parties’ inclusion of the term “successor fund” in the agreement. As Anker pointed out in its brief, *177inasmuch as there was no “successor fund” to the UMWA Fund at the time of the settlement agreement, inclusion of this term signifies that the parties were contemplating possible responsibility for payment of future benefits to a future fund. Appellants’ Brief at 33. Otherwise, inclusion of this language in the contract makes no sense.

The district court also incorrectly interpreted the contract to bar reimbursement because the Coal Act does not assess premiums based upon the tonnage of coal and hours worked. While the Coal Act does not determine specifically the premiums due based upon coal tonnage and hours worked, the Act is concerned with operators who had contributed to the 1950 and 1974 Plans which were funded based on coal tonnage and hours worked. The Combined Fund, by its very terms, is a successor plan, born on February 1, 1993, when the Act mandated that “the settlors of the 1950 UMWA Benefit Plan and the 1974 UMWA Benefit Plan shall cause such plans to be merged into the Combined Fund....” 26 U.S.C. § 9702(a)(2). By concentrating on the method of funding and ignoring the industry significance of coal tonnage and hours worked, the district court incorrectly held that, as a matter of law, Consol was not liable to Anker for payments made for King Knob’s employees under its contracts with Consol. While we do not take a position as to Anker’s ultimate success in proving that Consol is in fact liable to it for the premiums for the miners assigned to it under the Act, we conclude that the district court’s disposing of the issue on the pleadings was premature, and that further proceedings with respect to it are necessary.7

2. Abrogation of contractual agreements The district court followed the decision of a divided panel of the Court of Appeals for the Fourth Circuit in Carbon Fuel Co. v. USX Corp., 100 F.3d 1124 (4th Cir.1996), when it held that the Coal Act abrogates private contracts for indemnification or reimbursement. Anker I at 24 n. 17. However, considering the Supreme Court’s statements in Eastern Enterprises concerning the language of the Act, we will not follow Carbon Fuel. Instead, we hold that the Coal Act does not prohibit indemnification or reimbursement pursuant to previous contractual arrangements.

The Eastern Enterprises plurality stated that “the Act preserves Eastern’s right to pursue indemnification,” although it does not grant any new rights, including a right to reimbursement. 524 U.S. at -, 118 S.Ct. at 2150. The Court was referring to 26 U.S.C. § 9706(f)(6) which states: “Nothing in this section shall preclude the right of any person to bring a separate civil action against another person for responsibility for assigned premiums, notwithstanding any prior decision by the Commissioner.”

In so stating, the Supreme Court (implicitly) disagreed with Carbon Fuel, 100 F.3d 1124, where the court of appeals interpreted the Act to prohibit suits for indemnification or reimbursement based upon prior private contracts. Id. at 1133. The court of appeals relied on section 9708, which states that “[a]ll liability for contributions to the Combined Fund that arises on or after February 1, 1993, shall be determined exclusively under this chapter.... ” The court also found persuasive excerpts from the legislative history stating that Congress “expressly intended to ‘reach back’ and impose obligations on signatories to the NBCWAs notwithstanding that many companies had ‘bargained out of their funding obligations.’” Carbon Fuel, 100 F.3d at 1129 (quoting 138 Cong. Rec. S17566-01, S17603). Despite the fact that no language in the Act limits the scope of *178section 9706(f)(6), the court of appeals interpreted its preservation of private actions to apply only to “post-Act private agreements and contracts.” Id. at 1134.

We cannot accept this reasoning. As the concurrence in Carbon Fuel pointed out, section 9708’s statement that all liability will be determined under the Act does not abrogate a private party’s liability to another private party for indemnification. Id. at 1140 (Williams, J., concurring in judgment). Instead, this provision provides that “[a]n operator assigned Coal Act liability by the Commissioner is primarily liable and must pay into the Combined Fund, regardless of the operator’s private, pre-Act contractual rights.” Id. Section 9706(f)(6), then, does not provide for the reassignment of primary liability for a signatory operator, but instead “preserves the right of private civil action for determining responsibility for assigned premiums as between contracting parties.” Id. at 1141.

We agree with this reading of the Act.8 Section 9706(f)(6) explicitly preserves a person’s right “to bring a separate civil action against another person for responsibility for assigned premiums.... ” This provision does not limit itself to postAct contracts, and without an explicit congressional statement otherwise, we will not construe the Act to contravene the seemingly unambiguous Congressional desire to allow for private actions between parties for reimbursement or indemnification.

Moreover, we believe that our reading of the Act is, in fact, consistent with the legislative history upon which the majority in Carbon Fuel relies. While Congress no doubt wanted to “reach back” and ensure that companies could not contract out of their obligations to the Funds, the Coal Act solves this problem by making the signatory companies responsible in the first instance for premiums. Once the Commissioner correctly assigns retirees to an operator, liability to the Funds is guaranteed. Allowing for indemnification between private parties if a previous contractual agreement so provides in no way frustrates this goal. Indeed, it may further the goal by providing for an additional entity to be liable, albeit on a contractual basis, for the payments due the Fund.

We believe the correct reading of congressional intent is that Congress desired the Act to be remedial — that Congress wanted to ensure that miners would receive the benefits the industry promised and placed liability on the parties responsible for creating the problem in the first place. Whether these parties had contracted with other private organizations for indemnification in case of future liability is irrelevant. In fact, allowing for indemnification could provide for more complete funding inasmuch as small independent contractors such as King Knob are probably more likely to have gone out of business or to have insufficient funds to pay the sometimes substantial premiums than companies similar to Consol that owned and leased the mines.

Thus, we will reverse the district court’s order granting Consol’s motion for judgment on the pleadings on Count Two for indemnification and remand the count to the district court for further proceedings. The court erroneously found the contractual language clear and unambiguous, and erroneously interpreted the Coal Act to prohibit suits for indemnification or reimbursement based upon prior contractual arrangements.

E. Interest, liquidated damages, attorney’s fees and costs

Finally, Anker contests the district court’s assessment of interest, liquidated damages, fees and costs for its failure to provide the premiums timely by arguing that the Act does not provide for *179the assessment of these costs. Appellants’ Brief at 38. We, however, will affirm the district court’s judgment against Anker for these amounts. Anker misreads the Coal Act, as it incorporates the assessment of liquidated damages and fees available in ERISA. See Holland v. Keenan Trucking Co., 102 F.3d 736, 739 (4th Cir.1996) (affirming without comment the district court’s order awarding liquidated damages, interest, fees and costs under the Coal Act); Holland v. Robert Coal Co., 986 F.Supp. 621, 633 (D.D.C.1997) (granting Combined Fund’s motion for summary judgment assessing liquidated damages, interest, fees and costs), affd, 1998 WL 794832 (D.C.Cir. Oct16, 1998); Holland v. High-Tech Collieries, Inc., 911 F.Supp. 1021, 1031-32 (N.D.W.Va.1996) (same); Holland v. Double G Coal Co., 898 F.Supp. 351, 356 (S.D.W.Va.1995) (same).

Section 9721 of the Coal Act states that “[t]he provisions of section 4301 of [ERISA] shall apply to any claim arising out of an obligation to pay any amount required to be paid by [the Coal Act] in the same manner as any claim arising out of an obligation to pay withdrawal liability under [ERISA].” 26 U.S.C. § 9721. Section 4301(b) of ERISA provides that the failure of an employer to make a timely withdrawal liability payment should be treated in the same manner as delinquent contributions. 29 U.S.C. § 1451(b). Finally, section 502 of ERISA requires a district court to award interest, liquidated damages, and reasonable attorneys’ fees and costs when a plan successfully enforces a demand for delinquent payments. 29 U.S.C. § 1132(g)(2).9

Applying this statutory scheme to Anker, the district court correctly determined that Anker had not made contributions, and thus ERISA’s enforcement provisions concerning delinquent contributions mandated the assessment of the proper fees. Anker III at 10. We find this decision clearly correct and uphold the judgment against Anker.10

IV. CONCLUSION

For the foregoing reasons, we will affirm the district court’s order granting judgment on the pleadings on Anker’s claim on Count One that the Commissioner’s assignment was erroneous, and will affirm the district court’s order granting summary judgment on the constitutionality of the Act as applied to Anker and King Knob on Count Three as well as its award of liquidated damages, interest, fees and costs on the counterclaim. However, we will reverse the district court’s order granting judgment on the pleadings on Anker’s contractual claim for reimbursement on Count Two and will remand the case to the district court for further proceedings on that count consistent with this opinion. The parties will bear their own costs on this appeal.

MARKEY, Circuit Judge.

Appeal from a judgment of the United States Claims Court (Smith, C.J.) that the United States (government) took a mineral estate (Whitney coal) from Whitney Benefits, Inc. and Peter Kiewit Sons’ Co. (PKS) (collectively Benefits) upon enactment of the Surface Mining Control and Reclamation Act of 1977, 30 U.S.C. §§ 1201 et seq. (SMCRA), and requiring payment of $60,000,000, plus interest to Benefits.1 We affirm.

I.BACKGROUND

The facts are set forth in Whitney Benefits v. U.S., 752 F.2d 1554 (Fed.Cir.1985) and in the comprehensive findings and conclusions accompanying the judgment appealed from. Whitney Benefits v. U.S., 18 Cl.Ct. 394 (Cl.Ct.1989). All of the probative facts being thus readily available to a reader of this opinion, no useful purpose would be served by a mere recast in our own words of Chief Judge Smith’s exhaustive exposition of the facts in his scholarly and well-reasoned opinion.

II.ISSUES

A. Whether the Claims Court correctly concluded, based on not-clearly-erroneous findings, that on enactment SMCRA’s prohibition of surface mining of alluvial valley floors (AVF’s) constituted a taking of the Whitney coal property.

B. Whether the Claims Court’s valuation of the coal property taken is clearly erroneous.

III.DISCUSSION

INTRODUCTION

A key element in this case is that SMCRA expressly precluded a permit for surface mining an AVF described in the statute in terms precisely applicable to, and known to be applicable to, the AVF overlying the Whitney coal property.

Contrary to the tone and tint of the government’s arguments on this appeal, the constitutionality of SMCRA is not at risk here. Benefits accepts the untrammeled right of Congress to prohibit surface mining of its Whitney coal property. All *1171Benefits seeks is the aid of the courts in forcing governmental compliance with the compensation clause of the Fifth Amendment to the Constitution. After an extended trial, the Claims Court found that Benefits had proved facts establishing its right to compensation and the amount thereof that would be just. The ease is fact-specific and basically uncomplicated, dealing only with Benefits’ property right to mine a single specific deposit of coal (Whitney coal) and the market value of that right. In attempting to shoulder the heavy appellate burden of establishing that the judgment appealed from rests on reversible error, the government proffers a plethora of attorney arguments and assertions, none of which finds adequate support in the evidence, all of which are treated and rejected in what follows.

A. Taking Upon Enactment in 1977

On this issue the government argues that: (1) the standard of review is de novo; (2) no taking could occur until Benefits had applied for and been denied a mining permit; (3) SMCRA did not prohibit Benefits from mining the “Whitney coal”; (4) SMCRA did not deprive Benefits of all economic use of its property; and (5) the Claims Court failed to consider Congress’ motivation.

1. Standard of Review

The government cites Bowen v. Public Agencies Opposed To Social Security Entrapment, 477 U.S. 41, 51-55, 106 S.Ct. 2390, 2396-98, 91 L.Ed.2d 35 (1986), but Bowen dealt only with a legal issue and did not address the standard of review. This court reviews Claims Court judgments to determine whether they are “incorrect as a matter of law” or premised on “clearly erroneous” factual determinations. Heisig v. United States, 719 F.2d 1153, 1158 (Fed.Cir.1983).

Having asserted a right to review “de novo”, the government then misconstrues the nature of such review and the posture of the case, arguing for the most part as though the Claims Court had not conducted a six-day trial and simply ignoring this court’s direction in the earlier appeal that the Claims Court make findings on the factual questions it did.2

2. Mining Permit

Calling SMCRA a “regulatory statute”, the government says it could not be deemed a taking until an expert agency applied its judgment and field reconnaissance to evaluate the surface of the land. The government does not suggest, and did not suggest at trial, any basis whatever on which a permit could be legally granted to surface mine Whitney coal. Indeed, SMCRA expressly provides that “no permit shall be approved” under conditions precisely descriptive of the Whitney coal estate.3 The Government has not shown *1172clear error in the Claims Court’s finding that any surface mining permit application would in this case have been futile. Indeed, the record is clear that any such application was obviously and absolutely foredoomed on the day SMCRA was enacted.4

The government’s facile application of the label “regulatory” and its citation of cases dealing with congressional regulation of the uses of land and other property subject to many uses are inapt here. First, as the Claims Court correctly found, the only property here involved is the right to surface mine a particular deposit of coal. The only possible use of that right is to surface mine that coal. When Congress prohibited that mining of that coal, it did not merely regulate, it took, all the property involved in this case. Second, if SMCRA could somehow be deemed “regulatory” in this case, it would avail the government nothing, for a regulatory statute that “goes too far”, will be recognized as a taking. Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 415, 43 S.Ct. 158, 160, 67 L.Ed. 322 (1922). Even if labeled “regulatory,” the present statute “went too far” in relation to Whitney coal and its circumstances, when it prohibited surface mining and provided that “No permit ... shall be approved” under those circumstances. That a permit might be obtained to mine coal properties other than Whitney coal does not change the statute to one that merely seeks to “regulate” the mining of Whitney coal for which no permit could legally be obtained. Before SMCRA was enacted, Benefits had a property right it could expect to exercise, i.e., to surface mine the Whitney coal. The moment SMCRA was enacted, Benefits no longer had that property right, for it had no permit and could not possibly under the statute obtain one for a mine that would obviously violate the conditions expressly set forth in SMCRA. 30 U.S.C. § 1260.

We are, of course, fully aware of the cases favoring administrative action. Many are here cited by the government. But in those cases administrative action might have had an effect on whether there was a taking. This is not such a case. On the contrary, this case falls among those in which the Supreme Court has found no need to exhaust administrative remedies: Weinberger v. Weisenfeld, 420 U.S. 636, 641, 95 S.Ct. 1225, 1229-30, 43 L.Ed.2d 514 (1975) (no need to exhaust because statute “on its face precludes granting benefits to men”); McKart v. United States, 395 U.S. 185, 89 S.Ct. 1657, 23 L.Ed.2d 194 (1969) (no need where facts clearly fit statutory definition). If there be coal properties to which SMCRA’s permit provision might apply, Whitney coal is not and never was such a property. Hence, the Claims Court correctly held that “it would be unreasonable under the particular facts of this case to hold that a taking could not have occurred until a subsequent administrative determination was made that mining of Whitney coal was prohibited.” 5

3. SMCRA Prohibited Mining Whitney Coal

In 1985, this Court said a taking occurs “when economic development [is] effectually prevented.” Whitney Benefits, 752 F.2d at 1559. On remand, the Claims Court carefully considered and discussed every factual and legal argument the government presented and found as a fact that in 1977 SMCRA clearly prohibited surface mining of Benefits’ coal, thereby depriving Benefits of “all economically viable use” of its property and destroying its value. That finding is not only correct and fully supported by the evidence, it is entitled to respect and may be upset only if it *1173is shown to have been clearly erroneous. Yuba Goldfields, Inc. v. United States, 723 F.2d 884, 889 (Fed.Cir.1983). The government has made no such showing, but, as in Skaw v. United States, 740 F.2d 932 (Fed.Cir.1984) and Drakes Bay Land Co. v. United States, 424 F.2d 574, 586 (Ct.Cl.1970), has on appeal carried its attempt to deny the impact of SMCRA on Whitney coal to unreasonable lengths in an apparent hope of postponing the day of reckoning into eternity. In this case, it has taken that tactic too far.

First, immediately before trial, the government stated in a Federal Register statement by BLM that “[development of the [Whitney] coal was halted by the passage of [SMCRA].” 51 Fed.Reg. 3124, 3125 (January 23,1986). Having made that concession, the government offered absolutely no evidence at trial to counter that official statement. Nor did it present a single witness to testify that there was any uncertainty whatever about SMCRA’s taking effect on Benefits’ coal property in 1977.

Second, Benefits proved that SMCRA's AVF prohibition applied to the property because of obvious physical facts about the property. The AVF overlying most of the Whitney coal was described as plain to the eye, and farming and ranching had long operated on the surface above the Whitney coal. At trial the government stipulated the foregoing facts about the property. As the Federal Register statement reflected, the government knew SMCRA applied on enactment to Whitney coal. Benefits knew SMCRA applied; and any prospective buyer would know it applied.

Thus, the facts proven in this case are even more probative of a taking than those in Skaw. There, owners of mineral interests under Idaho’s St. Joe River alleged that their property was taken by a statute that destroyed mining rights under the St. Joe. As this Court recognized in the prior appeal of this case, it was held in Skaw, 740 F.2d at 938-40, that the plaintiffs would show a legislative taking if they “could try on the shoe and it fit” — i.e., by proving at trial that their interests lay within the boundaries of the prohibition and that they could not be mined by methods other than surface methods. As the Claims Court fully elucidated, that is just what Benefits proved here.

Third, SMCRA’s legislative history confirmed the presence of a legislative taking of the Whitney coal property. Congress was carefully attentive to the question of which particular coal properties it was affecting.6 In considering the scope of the AVF prohibition itself, and the effect of “grandfathering” mines already operating and those with de minimis AVF involvement, Wyoming’s Representative Roncalio warned that grandfathering AVF mines that had made “substantial legal and financial commitments,” but that had not yet actually received a permit to mine, presented the “strong possibility” that the “Whitney Benefits mines on the Tongue River in Sheridan County in Northern Wyoming” would be grandfathered. 123 Cong.Rec. 12638-9 (1977). He urged that the bill be revised — as it eventually was — to ensure against even the possibility that the Whitney property would escape the AVF prohibition. The government’s attack on this *1174legislative history simply ignores what Congress did. Congress revised the bill to insure that SMCRA itself would preclude the mining of Whitney coal.

Still, the government insists that uncertainty remained about SMCRA’s prohibition against mining the Whitney coal, citing Rep. Roncalio’s explanation of how the grandfather clause “might affect” certain mines. But the phrase related to “financial and legal commitments”,7 not to the prohibition of mining. Indeed, Rep. Roncalio went on to recommend an amendment that would make clear that the grandfather clause would not apply to Whitney. 123 Cong.Rec. 12,638-39 (1977). There never was any doubt that adoption of his amendment would insure that the AVF prohibition would apply with full force to the Whitney coal property. The government’s effort here to construct such a doubt is insupportable.

Oddly, while saying reliance on Rep. Roncalio’s actions is inappropriate, the government itself relies on a list offered by him. The list identified 13 mines on which AVFs represented only 0% to 3.7% of the mine area. Again, the government’s reliance is inapt, for the list covered only mines with “federal involvement” — those including federally leased coal — and by definition excluded fee coal like Whitney. Moreover, the small areas of AVF overlying the listed mines actually dramatize the taking effect of SMCRA on Benefits, whose entire coal property was either covered by an AVF or rendered unmineable by it.

The government’s argument that SMCRA did not prohibit mining Whitney coal is simply untenable. The facts correctly found by the Claims Court on Benefit’s investment and on “the economic impact of the regulation, its interference with reasonable investment-backed expectations, and the character of the governmental action,” Whitney Benefits, 752 F.2d at 1558, establish that SMCRA on enactment effected a taking of Benefits’ Whitney coal estate.

4. SMCRA Deprived Benefits of All Economic Use

On this issue, the government continues to cite language in cases in which a statute regulated but one or a few of numerous uses to which the involved properties might be put. As above indicated, the property here involved, Whitney coal, has only one use and that use is prohibited by SMCRA. In a strained effort to construct some other “economic use” or “economic benefit” remaining after enactment of SMCRA, the government says: (a) Benefits could farm some land, and (b) the coal exchange preserved the economic value of Whitney coal. Neither assertion finds a basis in the record or in law in this case, and neither renders clearly erroneous the Claims Court’s finding that the “diminution in value [of Whitney coal] was total.”

a. Farming

PKS bought a parcel of a little less than 600 of the 1327 acres overlying Whitney coal. Continuing to disregard inconvenient findings, the government ignores the Claims Court’s finding that the purchase was to facilitate PKS’ intended mining of the Whitney coal beneath the parcel and then goes on to speculate, without reference to the record, that PKS might have been able to farm that parcel. On that speculative premise, the government says SMCRA did not deprive Benefits of all economic value. The purchase of the parcel to facilitate mining was clearly a part of the investment backing for Benefits’ expectations, not unlike a purchase of mining equipment. We fully agree with the Claims Court’s evaluation of the argument as “completely off the mark”. SMCRA took Benefits’ coal rights. That is what, and only what, this suit is all about. As the Claims Court noted, Wyoming recognizes separate mineral and surface estates, Williams v. Watt, 668 P.2d 620, 624-25 (Wyo.1983) and mineral rights are clearly property subject to the taking clause of the Fifth Amendment. Skaw, 740 F.2d at 935-36.

*1175Labeling Benefits’ demand for compensation as a “facial” challenge to SMCRA, the government relies extensively on Hodel v. Virginia Surface Mining & Reclamation Ass’n, 452 U.S. 264, 101 S.Ct. 2352, 69 L.Ed.2d 1 (1981). But the demand for just compensation here is clearly distinct from the merely argumentative challenge to SMCRA rejected in Hodel. Unlike the property owners in Hodel, Benefits has presented solid proof of the impact of SMCRA, an impact that on enactment deprived Benefits of all economically viable use of its coal property. We are not at liberty to disregard, as the government would have us do, the complex and voluminous proofs presented to the Claims Court and on which that court based its detailed findings of SMCRA’s investment-destroying impact on the particular deposit known as Whitney coal. Those findings were not the result of some general discussion of the statute, but were compelled by the evidence and have not been shown to have been clearly erroneous.

b. The Coal Exchange

Choosing to disregard what this court had to say in Whitney Benefits, 752 F.2d at 1557-1559, about the coal exchange provision, 30 U.S.C. § 1260(b)(5), and this court’s language distinguishing Penn Central Transportation Co. v. New York City, 438 U.S. 104, 98 S.Ct. 2646, 57 L.Ed.2d 631 (1978), the government relies primarily on Penn Central in arguing that the coal exchange gave Benefits “something of significant value” and thus SMCRA could not have been a taking.

The government’s election to present its coal exchange argument on this appeal is difficult to understand in light of this holding of this court:

the exchange transaction is a method of ascertaining and paying just compensation for a taking, which may be negotiated and agreed upon either before or after the taking itself, and is optional with the claimants, who may reject any exchange and pursue a money award under the Tucker Act, 28 U.S.C. § 1491.

Whitney Benefits, 752 F.2d at 1560.

Though the government asserts that the possibility of an exchange represented a post-SMCRA value, it offered no evidence thereof at trial and the segment of its brief devoted to the exchange provision contains not a single record citation. When the government does not disregard the language in our earlier opinion, it manages to misinterpret it, taking this court’s distinction of Penn Central, 752 F.2d 1557, (“a regulation not meant to take an interest in land”) and the indication that in cases like Penn Central an exchange provision might be considered in determining whether and when a taking occurred, as a basis for charging error in the Claims Court’s failure to do so. The government apparently failed to notice that in Penn Central the owners retained the railroad station and that in this case the Claims Court found a total destruction of Benefits’ coal property right.

Benefits points to a district court’s May 1985 finding that the government had “unreasonably delayed” in performing an exchange, the government’s response to an order of that court in which the government said Whitney coal had no value, the government’s pretrial and post-trial switching between offers of Hidden Water and Ash Creek, and the government’s insistence on valuing any exchange at the vastly depressed coal prices in effect at the time of the exchange. Disputing none of that, the government’s reply brief says we must not look at any of it, or at any event in the last 13 years, because it all occurred after enactment of SMCRA.8 Whatever may be the validity of the government’s strident insistence that the words of the statute must serve as absolutely the sole evidence on the question of whether SMCRA was a taking, the argument avails the government nothing when one looks to the statutory words, and particularly to those relating to the exchange provision. *1176Among the portions of this court’s opinion in Whitney Benefits disregarded by the government is this:

We repeat the statutory words—

It is the policy of congress that the Secretary shall develop and carry out a coal exchange program to acquire private fee coal precluded from being mined by the restrictions of this paragraph (5) in exchange for federal coal which is not so precluded. [Emphasis supplied.]

752 F.2d at 1559.

Thus the statutory exchange provision itself in this case confirms the presence of a taking (“acquire”) of Benefits’ “fee coal precluded from being mined by the restrictions of this paragraph (5)”. That the government may in a statute take property and simultaneously offer to pay for it may evade a constitutional challenge. But a compensated taking is still a taking. An offer to pay would make no sense if nothing were taken. The exchange provision confirms the presence of a taking of coal to which it applies and the statute itself, 30 U.S.C. § 1260, supra note 2, establishes its application to Whitney coal.

As the Claims Court correctly held, SMCRA destroyed all economic value in Whitney coal. As this court held in Whitney Benefits, 752 F.2d at 1557, the exchange provision cannot be made mandatory without raising serious constitutional questions. To hold that mere presence of an exchange provision precludes a court from finding a taking on enactment in cases like this one would eviscerate the constitutional just compensation guarantee.

5. Congress’ Motivation

The government’s effort to visualize and then to apply to this case a “nuisance exception” that would justify the total uncompensated destruction of Benefits’ investment-backed expectations in its Whitney Coal property is twice-flawed: (a) there has been no showing that the facts in this case correspond to those in earlier cases dealing with injury to public health and safety; and (b) expressly recognizing the need to balance the continuing dual need for agriculture and the energy available from coal, Congress permitted continued surface mining of coal underlying some AVFs, indicating its view that all AVF mining was not in itself a “nuisance”.

a. Facts in Earlier Cases

Citing phrases from opinions in earlier cases, the government appears to have lost sight of the critical role of facts as the foundation stones on which law and precedent must stand. Relying primarily on Keystone Bituminous Coal Ass’n. v. DeBenedictis, 480 U.S. 470, 107 S.Ct. 1232, 94 L.Ed.2d 472 (1987), the government argues that SMCRA’s AVF prohibition effected no taking because it was aimed at a public purpose entitled to “deference”. Nothing in Keystone, however, supports the notion that public purpose alone permits total destruction of property rights without compensation. The government simply ignores Keystone’s analysis: a regulation effects a taking if it either (1) “does not substantially advance legitimate state interests,” or (2) “denies an owner economically viable use of his land.” 480 U.S. at 470, 107 S.Ct. at 1232-34, quoting Agins v. City of Tiburon, 447 U.S. 255, 260,100 S.Ct. 2138, 2141, 65 L.Ed.2d 106, and citing Penn Central, 438 U.S. at 124, 98 S.Ct. at 2659. See also Kaiser Aetna v. United States, 444 U.S. 164, 174, 100 S.Ct. 383, 390, 62 L.Ed.2d 332 (1979) (these are “entirely separate question[s]”).

Under the second prong of the analysis in Keystone, SMCRA denied Benefits all use of their property and completely destroyed its value. Thus Benefits is in the position occupied by the citizens in Mahon, who were denied all economically viable use of their coal, and in a fundamentally different position from that of the citizens in Keystone, who were not.9 In Keystone, the Subsidence Act simply required a small *1177portion (1.8%) of the involved coal to be left in the ground. 480 U.S. at 496, 107 S.Ct. at 1247-48. That was critical to the Court, which noted “... petitioners have not claimed, at this stage, that the Act makes it commercially impracticable for them to continue mining their bituminous coal interests in western Pennsylvania. Indeed, petitioners have not even pointed to a single mine that can no longer be mined for profit.” 480 U.S. at 495-96, 107 S.Ct. at 1247 (emphasis added). As the record here makes plain, Whitney coal is such a mine.

Thus, in the present case, as in Keystone, the surface-related purpose of the statute is valid, but not controlling. The Court in Keystone went on separately to analyze the impact of the regulation on the properties before it, and found evidence of value destruction wanting. Here the Claims Court also thoroughly analyzed the impact of SMCRA, and correctly found compelling the evidence of value destruction. The evidence having shown the total destruction of all economically viable use, the conclusion is inescapable that SMCRA constituted a taking of the Whitney coal property. That the government may certainly do, but when it does so in the circumstances of this case it is required by the Constitution to pay just compensation.

b. Congress’ Purpose

The Claims Court quoted from the statute Congress’ purpose in enacting SMCRA:10

[to] assure that the coal supply essential to the Nation’s energy requirements, and to its economic and social well-being is provided and [to] strike a balance between protection of the environment and agricultural productivity and the Nation’s need for coal as an essential source of energy.

That Congress was not in SMCRA abating a “nuisance”, within the meaning of Supreme Court and other cases discussing such abatement, is clear. In accord with the dual purpose it stated, Congress expressly permitted, in the grandfather clause, the continued mining beneath AVFs of all grandfathered mines and all mines found by State Authorities to have minimal AVF involvement, hardly the action of one out to abate a “nuisance” or anything “injurious to the health, morals, or safety of the community”, Keystone, 480 U.S. at 489, 107 S.Ct. at 1244. Congress also provided for regulations designed to restore the hydrologic balance affected by such mining, regulations Benefits proved it could have complied with in mining Whitney coal. Nonetheless, SMCRA expressly provided that “No permit ... shall be approved” for a mine such as Whitney coal which underlies the AVF precisely as described in the statute. SMCRA, as above indicated, thus destroyed all value in Whitney coal.

The Claims Court went on to note, and we agree, that the present case “presents a dispute where a proper government purpose, protecting agricultural land, must be balanced against the absolute diminution in value of the property at issue that the court has found.” The government has not cited to us a single case in which the Supreme Court has relied on the “public purpose” of a regulation or statute as a basis for finding that no taking occurred when, as here, the entire value to the owner of the involved property was destroyed. The government’s talismanie cry for reversal because “public purpose” requires “deference” is simply a too-facile misapplication of the constitutional parameters of takings law to the facts in this case.

B. Valuation

After a six-day trial, the Claims Court considered every evaluation issue addressed and all evaluation evidence sub*1178mitted at trial. It then made and explained detailed findings, some for Benefits and some for the government. On appeal, the government fails to show that any finding of the Claims Court was clearly erroneous.

We need not tarry long on the government’s evaluation arguments because: they rest basically on a complaint that the Claims Court agreed more often with Benefits’ experts than it did with the government’s; each of the challenged findings is supported in the record and citation of conflicting testimony does not establish error in the findings made 11; the Claims Court’s use of alternative assumptions, agreeing fully with neither side, represented not error, but reasoned decisionmaking12; much of the government’s attack is pure attorney argument, much is presented without reference to the record, and much is an inappropriate effort to retry the case with positions rejected by the Claims Court, but without mention of the basis for those rejections; and some of the government’s statements misinterpret and mischaracterize the record, others simply disregard the Claims Court’s expressed credibility determinations, and still others are assertions on which the government submitted no evidence at trial. In sum, the government’s attack on virtually every evaluation finding, including those in its favor, totally fails to establish reversible error.

Mindful of the Supreme Court’s admonition that an evaluation must be made “in light of all the facts affecting market value” and that inclusion of value elements dependent upon events requires that those events be “fairly shown to be reasonably probable,” Olson v. United States, 292 U.S. 246, 257, 54 S.Ct. 704, 709, 78 L.Ed. 1236 (1934), we have carefully searched the 17 pages of the government’s briefs devoted to the evaluation issue and compared them with the record without finding that any of the events involved in the Claims Court’s analysis had not been “fairly shown to be reasonably probable”. The government’s attack on the Claims Court’s acceptance of parts of the Boyd plan is merely a statement of those events government counsel thinks would have been reasonably probable — a totally inadequate basis for either reversing or, as the government suggests, remanding this case for a new evaluation.

Contrary to implications in the government’s briefs, the Claims Court did not blindly accept the Boyd plan. On the contrary, after careful review, it reduced the forecast of tons per year from 4 to 2.5 million, reduced the market value of Whitney coal by one-third, and made other findings on specific details that differed from those in the Boyd plan.

The Claims Court’s determination that Benefits is entitled to $60,296,000, plus prejudgment interest from August 3, 1977, is fully supported in the record and is not clearly erroneous.

CONCLUSION

The Claims Court’s judgment is affirmed in all respects.13