Appellant Keith Fulton & Sons, Inc. (Fulton) originally challenged the constitutionality of the Multiemployer Pension Plan Amendments Act of 1980 (MPPAA), 29 U.S.C. §§ 1381, et seq., Pub.L. No. 96-364, 94 Stat. 1208 (1980), on a number of grounds. A panel of this court upheld most of the act, but found that certain presumptions in the statute, 29 U.S.C. § 1401(a)(3), deprived employers of procedural due process. Because of the importance of the issue, the unanimous authority of other circuits against the panel’s view,1 *1139and the questions raised by the parties following the panel decision, we decided to reconsider whether the prescribed method of assessing withdrawal liability, with its statutory presumptions, is constitutional. After a careful review of the statute, its legislative history, and the opposing arguments, we have concluded that the statute' does meet the requirements of procedural due process.
I. BACKGROUND
The facts surrounding Fulton’s withdrawal from the New England Teamsters and Trucking Industry Pension Fund (the Fund) are set out in the opinion of the panel at 762 F.2d 1124 (1st Cir.1984). Although that opinion also describes the history of the MPPAA and some of its provisions, we believe it necessary to review certain aspects of that discussion as background for this decision.
The MPPAA was enacted as an amendment to the Employee Retirement Income Security Act of 1974 (ERISA), 29 U.S.C. §§ 1001, et seq., and was designed, in part, to strengthen multiemployer pension plans financially by discouraging employers from withdrawing and leaving a plan with unfunded liabilities. H.R.Rep. No. 869, 96th Cong., 2d Sess. 67, reprinted in 1980 U.S. Code Cong. & Ad.News 2918, 2935 [hereinafter House Report]. It does so by requiring a withdrawing employer to pay its share of the shortfall; this payment is known as the “withdrawal liability”. The statute provides that the amount of withdrawal liability is calculated by the trustees of the pension plan. If an employer disputes either the amount or the fact of liability, it can negotiate with the pension plan and, if there is no resolution, the dispute must be arbitrated. 29 U.S.C. § 1401(a)(1). Either party to the arbitration may appeal that decision to a district court. 29 U.S.C. § 1401(b)(2).
The constitutional objections which we consider at this time focus on the method of calculating the withdrawal liability and the deference accorded that calculation. Fulton argues that it is a violation of due process for the trustees to determine an employer’s withdrawal liability in the first instance, since their goal always would be to maximize the amount in order to swell the pension fund’s coffers. The trustees’ natural bias is compounded, it is argued, by the statutory presumptions of correctness given to that initial determination. Subsection A of 29 U.S.C. § 1401(a)(3) provides that, for purposes of arbitration proceedings under the MPPAA, “any determination made by a plan sponsor under sections 1381 through 1399 of this title and section 1405 of this title [all relating to calculation of withdrawal liability] is presumed correct unless the party contesting the determination shows by a preponderance of the evidence that the determination was unreasonable or clearly erroneous.” Subsection B of § 1401(a)(3) provides that:
“In the case of the determination of a plan’s unfunded vested benefits for a plan year, the determination is presumed correct unless a party contesting the determination shows by a preponderance of evidence that—
(i) the actuarial assumptions and methods used in the determination were, in the aggregate, unreasonable (taking into account the experience of the plan and reasonable expectations), or
(ii) the plan’s actuary made a significant error in applying the actuarial assumptions or methods.”
A district court reviewing the arbitrator’s award must then presume the arbitrator’s findings of fact to be correct unless they *1140are rebutted by “a clear preponderance of the evidence.” 29 U.S.C. § 1401(c). Fulton contends that these presumptions make the trustees’ determinations “virtually unassailable”, and they argue that the inability to meaningfully challenge the initial calculation is a denial I of due process.
II. DISCUSSION
We begin our analysis with the recognition that:
“ ‘[i]t 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 [83 S.Ct. 1028, 10 L.Ed.2d 1347] (1963); Williamson v. Lee Optical Co., 348 U.S. 483, 487-488 [75 S.Ct. 461, 464, 99 L.Ed. 563] (1955).’ ” Usery v. Turner Elkhorn Mining Co., 428 U.S. 1, 15, 98 S.Ct. 2882, 2892, 49 L.Ed.2d 752 (1976).
Fulton’s argument that 29 U.S.C. § 1401(a)(3) is unconstitutional must, therefore, receive rigorous scrutiny. In determining whether due process is satisfied, we are required to balance the private interest that will be affected, the risk of error inherent in the challenged procedure, and the government’s interest in using the procedure, Mathews v. Eldridge, 424 U.S. 319, 335, 96 S.Ct. 893, 903, 47 L.Ed.2d 18 (1976), but we also “are mindful that ‘due process is flexible and calls for such procedural protections as the particular situation demands,’ ” Republic Industries v. Teamsters Joint Council, 718 F.2d 628, 640, (quoting Morrissey v. Brewer, 408 U.S. 471, 481, 92 S.Ct. 2593, 2600, 33 L.Ed.2d 484 (1972)). Thus, our inquiry is not whether there is a fairer method for assessing withdrawal liability, but only whether the method Congress chose is fair enough. The statute can not be arbitrary, but it need not be perfect.
In a sense, Fulton takes issue with two separate aspects of the MPPAA arbitration procedures: the use of a non-neutral party, the fund trustees, to calculate the liability in the first instance, and the use of presumptions to support that initial calculation. While statutory presumptions are not uncommon and have been upheld frequently,2 the original panel in this case was concerned about the due process implications of granting the presumptions on behalf of apparently non-neutral trustees. Although we recognize that the trustees come to their task of calculating withdrawal liability with a bias, we do not believe that their lack of neutrality, even when aided with the statutory presumptions, deprives Fulton and other employers of due process. We do not minimize the hardship to Fulton, a sole stockholder corporation assessed a withdrawal liability of $468,637 when it withdrew from the Fund after the City of Cambridge acquired its land in a federally subsidized taking for a public transportation project. We simply rule that the action Congress took was within its discretion.
We emphasize first that we do not perceive the trustees to be performing an adjudicatory role when they calculate the withdrawal liability, and so we do not believe we in any way mar the purity of the judicial process in deciding that their bias is not of constitutional dimension. Rather than serving as judicial decisionmakers, the trustees are simply part of an administrative procedure set up by Congress for reaching an initial determination of withdrawal liability which is then challengeable in arbitration and in court. “If there is a liability, someone has to fix it”, Shelter Framing Corp. v. Carpenters Pension Trust, 543 F.Supp. 1234, 1244 (C.D.Cal.1982), aff'd in part and rev’d in part on other grounds, 705 F.2d 1502 (9th Cir.1983), rev’d sub nom. Pension Benefit Guaranty *1141Corp. v. R.A. Gray & Co., — U.S.-, 104 S.Ct. 2709, 81 L.Ed.2d 601 (1984), and Congress simply assigned the duty to the persons with the most information. See Republic Industries, 718 F.2d at 640 n. 13. The trustees, moreover, do not have unbridled discretion in fixing the amount of liability. They are required to compute the employer’s debt according to “detailed and explicit statutory guides”, Textile Workers Pension v. Standard Dye & Finishing, 725 F.2d at 855.
A brief description of how the trustees determine withdrawal liability underscores the difference between their work and that of a judge. The trustees must use an accepted actuarial method for computing the unfunded vested liability of a plan, 29 U.S.C. § 1393(a), which is the total amount owed to participating employees at the time of the withdrawal.3 The Act also sets out four methods which may be used for allocating this amount among employers. 29 U.S.C. § 1391(c). Although the trustees unquestionably are allowed to make initial choices for allocating the fund shortfall, and the choices they make unquestionably can have the effect of increasing or decreasing the amount of withdrawal liability, their discretion is primarily that of selecting one from a number of procedures prescribed by Congress the first time a withdrawal issue arises. The Act specifically requires that a plan’s rules for determining withdrawal liability “operate and be applied uniformly with respect to each employer.” 29 U.S.C. § 1394(b). Uniformity would seem to require that a rule applying to all employers (should they withdraw) in Year One also would apply to all employers in subsequent years, in the absence of significant changes of circumstance.4 Thus, in future years, the trustee’s function is likely to become that of simply applying a designated method of computation to all later withdrawals. In addition, their knowledge that they must act uniformly over time, treating like cases alike, significantly cabins their discretion, for it tends to create a uniform employer interest in favor of fair rules and, given the need to maintain employer membership and satisfaction, it entails a trustee obligation of fair treatment to withdrawing employers as part of their obligation to the fund.
This case, therefore, is unlike Ward v. Village of Monroeville, 409 U.S, 57, 93 S.Ct. 80, 34 L.Ed.2d 267 (1972), in which the town mayor also acted as the initial judge for certain minor violations. The Supreme Court in Ward found a due process violation because the mayor had an obvious interest in increasing town revenues and the “[petitioner [was] entitled to a neutral and detached judge in the first instance.” Id. at 61-62, 93 S.Ct. at 84. Unlike the mayor in Ward, whose role was to adjudi*1142cate traffic offenses and impose fines on a case-by-case basis, “the trustees play a mixed role since much, but admittedly not all, of their task is ministerial in nature,” Republic Industries, 718 F.2d at 640 n. 13.
On this issue, then, we are in accord with the court in Dorn’s Transp., Inc. v. I.A.M. Nat. Pension Fund, 578 F.Supp. 1222, 1237-38 (D.D.C.1984):
“[T]he role they perform in the statutory scheme is one of administration or enforcement rather than of adjudication. Both the fact and the degree of liability are determined by the trustees according to statutorily mandated standards and methods which otherwise satisfy the requirements of due process____ In this respect, the precision of the Congressionally-prescribed standards cures the process of the innate taint of partiality.” See also Textile Workers Pension, 725 F.2d at 855; Republic Industries, 718 F.2d at 640-41 and 640 n. 13; Shelter Framing Corp., 543 F.Supp. at 1244.
Even if the trustees need not be as neutral as judges, their decisions must nevertheless provide due process to the employers. Fulton believes the trustees can not calculate liabilities in a constitutional manner because of their institutional bias and the presumptions which reinforce their biased decisions. We disagree for two reasons. First, we do not believe the trustees are as biased against the employers as Fulton suggests; and, second, we believe the statutory procedure lawfully envisions a less perfect calculation than Fulton demands. We discuss each of these points separately below.
Trustee Bias
An equal number of trustees are chosen by the participating employers and the participating unions, and so their allegiances are not uniformly against the withdrawing employer. Although it has been argued that even employer trustees would be inclined to inflate the withdrawal liability to lessen the burden on employers who remain in the plan, Republic Industries, 718 F.2d at 640; Shelter Framing, 543 F.Supp. at 1244, such an approach is unlikely since the initial choice of a method for calculating the liability will be used on all subsequent withdrawals from that fund, possibly including withdrawal of the trustees’ own employers. Although the trustees are fiduciaries to the fund, and must consider the fund’s interest above all else, that does not mean always choosing the highest withdrawal liability:
“Plan fiduciaries are given a great deal of flexibility to strike a balance among the competing considerations of encouraging new entrants, discouraging withdrawals, easing administrative burdens, and protecting the financial soundness of a fund. The committee wishes to make it clear that in choosing the rules that would eliminate or reduce liability, the choice of such a rule is not per se a violation of fiduciary standards; the determination must be made as to whether the fiduciary has acted reasonably and in the interests of plan participants and beneficiaries and otherwise in accordance with the fiduciary standards.” H.R.Rep. No. 869, 96th Cong., 2d Sess. 67, reprinted in 1980 U.S.Code Cong. & Ad.News 2935.5
This commentary makes it clear that the trustees’ role is not simply to find the highest value for withdrawal liability; they would not meet their fiduciary duty to the fund, for example, if they set excessively high withdrawal liabilities which would have the effect of discouraging future par*1143ticipation. Shelter Framing, 543 F.Supp. at 1244.
It also must be remembered that the trustees’ determination is not, in fact, irrebuttable. The employer always has the opportunity to demonstrate that the trustees’ calculation is unreasonable or erroneous,6’ and presumably the employer could also challenge the trustees’ determination by showing how bias in a particular case affected the decisionmaking process and produced a result that was unreasonable.
Thus, we can not say that an institutional bias on the part of the trustees makes unconstitutional the MPPAA’s procedure for calculating withdrawal liability.'
The Presumption of Reasonableness
Fulton argued in its supplemental brief that we should find the MPPAA’s presumptions of correctness unconstitutional because “an employer simply has no financial incentive to go to arbitration solely over the issue of actuarial assumptions unless there is something so utterly aberrant about the case that no person could seriously doubt that the trustee erred.” Although we think Fulton overstated the likely impact of the presumptions on employers, we also think it is true that the presumptions discourage litigation. That, however, is precisely their point:
“These rules are necessary in order to ensure the enforcability [sic] of employer liability. In the absence of these presumptions, employers could effectively nullify their obligation by refusing to pay and forcing the plan sponsor to prove every element involved in making an actuarial determination.” House Report at 86, U.S.Code Cong. & Admin.News 1980, p. 2954.
We think it is not irrational for Congress to impose presumptions as a disincentive to challenging the trustees’ determination precisely because of circumstances which Fulton emphasizes, namely that the uncertainties inherent in making actuarial assumptions mean that there is a range of “reasonable” withdrawal liability amounts. Fulton uses the fact that there are a number of reasonable values for withdrawal liability to argue that one figure must be the best, or the fairest; that the trustees will not be looking for that figure but for the highest figure; that the presumptions operate to sustain that figure; and that that is a denial of due process. What must not be overlooked, however, as Fulton concedes, is that “virtually any of the available methods of valuing the Fund’s assets and liabilities may well be ‘reasonable’ in an actuarial sense”, and that the nature of the “actuarial art” enables the trustees “to choose from a wide range of assumptions, all of which are, in some sense, ‘reasonable’ ” (emphasis added).
We think this factually compelled concession gives the game away. Fulton concedes there are several “correct” methods, yet insists it is entitled to a better “correct” method than the Fund chose. We do not think due process requires this much. Congress apparently recognized the imprecision of forecasting a plan’s financial future, and created the presumptions to avoid “[l]engthy, futile and costly bickering over the adequacy of the methods chosen.” Dorn’s, 578 F.Supp. at 1239.7 We think a convincing test of the constitutionality of this approach is to ask if Congress could have enacted a flat requirement that would have been even harsher on employers. We *1144have no doubt that in furtherance of its objective of shoring up financially troubled multiemployer pension plans, see House Report at 54-55, reprinted in 1980 U.S. Code Cong. & Ad.News 2922-23, Congress could have unilaterally imposed the highest reasonable withdrawal liability, since Congress need not have a perfect fit in matching economic legislation with its purpose. Turner Elkhorn, 428 U.S. at 19, 96 S.Ct. at 2894; Ferguson v. Skrupa, 372 U.S. 726, 730-32, 83 S.Ct. 1028, 1031-32, 10 L.Ed.2d 93 (1963); Williamson v. Lee Optical, 348 U.S. 483, 487-88, 75 S.Ct. 461, 464, 99 L.Ed. 563 (1955). If the imposition of withdrawal liability is constitutional, and we have held that it is, 762 F.2d 1124, then Congress’ decision to impose any reasonable amount must also be constitutional. Thus, instead of a flexible system with presumptions, Congress could have constitutionally required the trustees or even an independent agency to use the actuarial method which would produce the highest reasonable withdrawal liability. A rigid system imposing the highest reasonable amount would do the job of minimizing disputes over withdrawal liability amounts even better than presumptions since it would avoid arguments, like Fulton’s, over what amount is “most reasonable”. Since Congress could draft a statute to accomplish precisely what it has accomplished through the presumptions, but with less responsiveness to individual cases, “we do not think that Congress’ choice of statutory language can invalidate the enactment when its operation and effect are clearly permissible.” Turner Elkhorn, 428 U.S. at 23, 96 S.Ct. at 2896. We think it aids a proper sense of perspective to reflect that, after all, the Supreme Court upheld the retroactive application of the MPPAA, Pension Benefit Guaranty Corp. v. R.A. Gray & Co., — U.S. -, 104 S.Ct. 2709, 81 L.Ed.2d 601. Certainly, if due process allows the retroactive imposition of this potentially substantial liability, it must allow deference to a calculation of that liability which even Fulton admits is likely to be reasonable, and which can be struck down if shown to be unreasonable.
Our rejection of Fulton’s argument does not mean that we believe Congress picked the best method for ascertaining an employer’s withdrawal liability. It is quite likely that an expert arbitrator who would handle all disputes concerning a specific pension fund’s withdrawal liability would be “fairer” than a set of trustees who, to one extent or another, have an interest in the calculation. See Note, Trading Fairness for Efficiency: Constitutionality of the Dispute Resolution Procedures of the Multiemployer Pension Plan Amendments Act of 1980, 71 Geo.LJ. 161, 190-91 (1982). Finding the best method, however, is not our function; under the due process precedents which guide us, we must only find that Congress acted rationally in designing the procedure for calculating withdrawal liability.
We acknowledge that the system of presumptions means that, at times, a “reasonable” calculation by the trustees will prevail over the “most reasonable” calculation to which Fulton argues it is entitled. Congress could rationally have decided, however, that the search for the “most reasonable” withdrawal liability figure would undermine its goal of securing financial stability for multiemployer pension plans and so, in the balance, a procedure that in most cases will produce at least a reasonable assessment is good enough.8 Moreover, if an injustice does occur, the procedure provides for relief in arbitration or in federal court.
It is also instructive to consider the impact of a decision for Fulton. Without the presumption in favor of the trustees’ determination, results in arbitration are likely to vary for withdrawals even in the same year from a given plan, undermining Congress’ evident intent that plan rules be administered uniformly with respect to each employer, 29 U.S.C. § 1394(b). Elimination of *1145the presumption will also lead to an increase in litigation over.the withdrawal liability assessments, even in cases when the amount apparently is correct but the employer hopes it can slip a marginal case for another amount past a sympathetic arbitrator. Fulton concedes the presumptions now discourage such wistful litigation. Congress passed this legislation to protect financially shaky pension plans, and we would be stripping a layer of lawful protection from the plans by removing the presumption and opening them up to an increased load of litigation.
We recognize that there are no precise analogies to the type of delegation Congress made to pension fund trustees in the MPPAA. Perhaps this is because it is a further extension of a growing trend of delegating to those closer to a problem the difficult task of unraveling conflicting facts and assumptions, a trend already amply reflected by the work of administrative agencies. Its emergence in the area of multiemployer pension funds is perhaps brought about by the nature and impact of the task; calculating withdrawal liabilities is a highly technical endeavor, affecting many thousands of employees, in which certainty is lacking and litigation expenses are likely to impose precisely the economic harm which Congress is trying to avoid. It is in such circumstances that the detached view of the judge is least helpful.
We are not without some comparisons, however, and those we have found convince us that we have reached the correct resolution of this case. In Turner Elkhorn, 428 U.S. 1, 96 S.Ct. 2882, the Supreme Court upheld a number of evidentiary presumptions in the Black Lung Benefits Act of 1972, including two irrebuttable ones, establishing coal miners’ entitlement to death or disability benefits for pneumoconiosis, or black lung disease. In finding the statute constitutional, the Court noted that presumptions arising in civil statutes involving matters of economic regulation do not violate due process as long as there is a “ ‘rational connection between the fact proved and the ultimate fact presumed’ ”, id. at 28, 96 S.Ct. at 2898, quoting Mobile, J. & K.C.R. Co. v. Turnipseed, 219 U.S. 35, 43, 31 S.Ct. 136, 138, 55 L.Ed. 78 (1910). The Court also stated:
“ ‘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.’ ” 428 U.S. at 28, 96 S.Ct. at 2898, quoting United States v. Gainey, 380 U.S. 63, 67, 85 S.Ct. 754, 757, 13 L.Ed.2d 658 (1965).
We recognize the difference between the type of evidentiary presumption at issue in Turner Elkhorn, involving inferences from one set of facts to another, and the presumptions at issue here, which allocate the burden of proof. We do not think the difference is of significance, however, in determining the appropriate deference to pay to Congress’ judgment on an issue unquestionably outside of “specialized judicial competence”. As we discussed above, Congress’ goal of protecting multiemployer pension plans is rationally related to its decision to presume the correctness of a calculation of withdrawal liability which almost certainly will fall within a range of reasonableness. In this context, moreover, the employers have the ability to challenge the trustees’ determinations; in Turner Elkhorn, certain of the presumptions were irrebuttable.
Other cases of which we take note include Vance v. Terrazas, 444 U.S. 252, 100 S.Ct. 540, 62 L.Ed.2d 461 (1980), in which the Supreme Court upheld an evidentiary presumption that a U.S. citizen who declares allegiance to a foreign state intended the expatriating conduct. Despite a recognized preference for requiring clear and convincing evidence to prove expatriation, the Court upheld the presumption because the proceeding involved was civil in nature and did not threaten a loss of liberty. Again, while we recognize the distinction between the presumption at issue in this case and the presumption in Vance, we *1146contrast the importance of the matter at issue there, an individual’s citizenship, with the economic interest at stake here.
The Supreme Court itself made a similar contrast when it upheld the constitutionality of duration-of-relationship requirements for Social Security benefit eligibility for surviving wives and stepchildren of deceased wage earners:
“The Constitution does not preclude such policy choices as a price for conducting programs for the distribution of social insurance benefits. [Citation omitted.] Unlike criminal prosecutions, or the custody proceedings at issue in Stanley v. Illinois [405 U.S. 645, 92 S.Ct. 1208, 31 L.Ed.2d 551 (1972) ], such programs do not involve affirmative Government action which seriously curtails important liberties cognizable under the Constitution. There is thus no basis for our requiring individualized determinations when Congress can rationally conclude not only that generalized rules are appropriate to its purposes and concerns, but also that the difficulties of individual determinations outweigh the marginal increments in the precise effectuation of congressional concern which they might be expected to produce.” Weinberger v. Salfi, 422 U.S. 749, 785, 95 S.Ct. 2457, 2476, 45 L.Ed.2d 522 (1975).
While Salfi, too, provides an imperfect analogy with the issue of Congress’ prescribed method for computing withdrawal liability, it, like Vance, suggests to us that the present case falls even more clearly within the bounds of due process. Unlike Salfi, which reflected a generalized, irrebuttable presumption that recent marriages were more likely than not shams designed specifically to secure Social Security benefits, this case involves only a rebut-table presumption that a calculation which probably will be within a range of reasonableness is an appropriate withdrawal liability.
Although we concede that Congress may not have prescribed the fairest plan for assessing withdrawal liability, our review of the statute in light of the standard of due process convinces us that the provisions of 29 U.S.C. § 1401(a)(3) are not constitutionally deficient. “Read together ... these provisions do little more than allocate the burden of proof to the challenger and direct that issues which are close be resolved in favor of the nonjudicial dispute resolver”, Republic Industries, 718 F.2d at 640-41.
The district court’s denial of Fulton’s motion for summary judgment on this issue is affirmed.
. Textile Workers Pension v. Standard Dye & Finishing Co., 725 F.2d 843, 854-55 (2d Cir.1984), cert. denied sub nom. Sibley, Lindsay & Curr Co. v. Bakery, Confectionery & Tobacco Workers Int'l, — U.S. -, 104 S.Ct. 3554, 82 L.Ed.2d 856 (1984); Washington Star Co. v. Typographical Union Negotiated Pension Plan, 729 F.2d 1502, 1511 (D.C.Cir.1984); Republic Indus*1139tries, Inc. v. Teamsters Joint Council No. 83, 718 F.2d 628, 640-41 (4th Cir.1983), cert. denied, — U.S.-, 104 S.Ct. 3553, 82 L.Ed.2d 855 (1984). Cf. Peick v. Pension Ben. Guar. Corp., 539 F.Supp. 1025, 1047-49 (N.D.Ill.1982), aff'd, 724 F.2d 1247, 1268 (7th Cir.1983), cert. denied, — U.S.-, 104 S.Ct. 3554, 82 L.Ed.2d 855 (1984) (appeals court upholds constitutionality of MPPAA without expressly addressing the specific issues we consider here, the role of the pension plan trustees and the presumptions supporting their actions, although the district court did consider the trustees' role); Terson Co. v. Bakery Drivers & Salesmen Local 194, 739 F.2d 118, 121 (3rd Cir.1984) (concluding generally that MPPAA does not violate due process).
. See, e.g., Vance v. Terrazas, 444 U.S. 252, 100 S.Ct. 540, 62 L.Ed.2d 461 (1980); Usery v. Turner Elkhorn Mining Co., 428 U.S. 1, 96 S.Ct. 2882, 49 L.Ed.2d 752 (1976); Mathews v. Lucas, 427 U.S. 495, 96 S.Ct. 2755, 49 L.Ed.2d 651 (1976); Weinberger v. Salfi, 422 U.S. 749, 95 S.Ct. 2457, 45 L.Ed.2d 522 (1975); Welch v. Helvering, 290 U.S. 111, 54 S.Ct. 8, 78 L.Ed. 212 (1933).
. Calculation of this amount requires the use of actuarial assumptions about such things as employee life expectancy and future rates of return on the plan’s assets. The MPPAA requires that plans use actuarial assumptions and methods that "in the aggregate, are reasonable” and that "in combination, offer the actuary’s best estimate of anticipated experience under the plan____’’ 29 U.S.C. § 1393(a)(1). It is also worth noting that this calculation is made by an actuary, a professional consultant to the plan, and not by the trustees themselves. Although the trustees have the option of accepting or rejecting a given projection, the trustees’ actions with regard to the actuary’s estimate can be used in challenging the reasonableness of the withdrawal liability calculations. In Woodward Sand Co. and Operating Engineers Pension Trust, 3 E.B.C. (BNA) (Employee Benefits Cases) (Kaufman, Arb.) 2351 (1982), the plan trustees had rejected the actuary’s recommended assumptions and the arbitrator found the plan’s substitute assumptions to be unreasonable. The arbitrator reduced the employer's liability by more than 20% and awarded the employer $10,-000 in attorney's fees.
. It appears to us that, under 29 U.S.C. § 1394(b), the same figures would be used for all employers withdrawing in a given year. Although we assume the precise numbers on some variables — for example, interest rates — might change from year-to-year to reflect changing economic conditions, it also appears to us that § 1394(b) would require use of the same figures for unchanging variables such as mortality rates. In any case, we do not believe the trustees have any significant flexibility after the first employer withdraws from a fund and the procedures for calculating withdrawal are chosen. Any deviation from the original procedure to reach a result that harms the employer could well be found unreasonable if challenged.
. We agree with the observation of the court in Peick v. Pension Ben. Guaranty Corp., 539 F.Supp. at 1048 n. 48, quoting N.L.R.B. v. Amax Coal Co., 453 U.S. 322, 343, 101 S.Ct. 2789, 2801, 69 L.Ed.2d 672 (1981) (Stevens, J., dissenting), that "[e]mpIoyer-appointed trustees do not violate their fiduciary duties simply because they are sensitive to the management perspective of what is best for the plan:
‘[T]he administration of a trust fund often gives rise to questions over which representatives of management and representatives of labor may have legitimate differences of opinion that are entirely consistent with their fiduciary duties.' ’’
The majority holding in Amax is not to the contrary.
. This is not pure theory. See, e.g., Classic Coal Corp. v. U.M.W. 1950 and 1974 Pension Plans, 5 E.B.C. (BNA) (Employee Benefits Cases) 1449 (1984) (Nagle, Arb.); Perkins Trucking Co. and Local 807 Pension Fund, 4 E.B.C. (BNA) 1489 (1983) (O’Loughlin, Arb.).
. A committee report on the MPPAA explained that the presumptions were created “to reduce the likelihood of dispute and delay over technical actuarial matters with respect to which there arc often several equally ‘correct approaches'. Without such a presumption, a plan would be helpless to resist dilatory tactics by a withdrawing employer — tactics that could, and could be intended to, result in prohibitive collection costs to the plan. The presumptions can be rebutted in those cases where injustice would otherwise resült to the withdrawing employer." Senate Committee on Labor and Human Resources, 96th Cong., 2d Sess., § 1076, The Multiemployer Pension Plan Amendments Act of 1980: Summary and Analysis of Consideration, 21 (1980).
. "While additional procedural safeguards might contribute to the perception of the withdrawn contributors that justice had been equitably served, the extensive cost to the taxpayer and to the fund far outweighs the benefit to be gained." Dorn's, 578 F.Supp. at 1239.