Potter Stewart

“ 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, or 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. ”

“ 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. ”

“ 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. ”