Opinion ID: 186132
Heading Depth: 4
Heading Rank: 2

Heading: Subcategorization by Aggregate Plant Size

Text: We now turn to Industry Petitioners’ second substantive claim, that even if EPA may subcategorize when setting MACT floors, the Clean Air Act does not permit it to do so on the basis of aggregate plant capacity. This inquiry centers on § 129(a)(2)’s second sentence, which provides: ‘‘The Administrator may distinguish among classes, types (including mass-burn, refuse-derived fuel, modular and other types of units), and sizes of units within a category in establishing such standards.’’ 42 U.S.C. § 7429(a)(2). According to Industry Petitioners, aggregate plant capacity is not encompassed within any of the sentence’s three permissible grounds of distinction: class, type and size of unit. Once again, Industry Petitioners insist that their position is compelled by dicta in this court’s opinion in Davis. In support, they point to a fragment of a sentence in a footnote that states: ‘‘EPA cannot use location to override the MWC unit categories established by Congress.’’ Davis, 101 F.3d at 1405 n.11. But even if the word ‘‘location’’ is correctly read as a reference to a unit’s location at a plant of a specified aggregate capacity, the complete footnote is at least equally supportive of EPA’s position: that while location may not be used to combine statutory categories, it may be used to subcategorize within each category. The footnote states: That provision is CAA § 112(d)(3), which governs standards for emissions from major stationary sources, and provides: Emission standards promulgated under this subsection for existing sources TTT shall not be less stringent TTT than — (A) the average emission limitation achieved by the best performing 12 percent of the existing sources TTT in the category or subcategoryTTTT 42 U.S.C. § 7412(d)(3). But the fact that Congress had available a clearer way of expressing what EPA believes the legislature said in § 129(a)(2) does not compel us to reject EPA’s interpretation. Although § 112(d)(3)’s single-sentence formulation is clearer, we cannot conclude that EPA was unreasonable in relying on two of § 129(a)(2)’s sentences to do the same work. 16 We emphasize that we do not hold that the EPA is precluded from ever taking a unit’s location into account, but simply that EPA cannot use location to override the MWC unit categories established by Congress. Section 129(a)(2) gives the EPA broad discretion to differentiate among units in a category, and there is nothing in the text of section 129(a)(2) that would prevent the EPA from subcategorizing within the two categories of MWC units TTT on the basis of the units’ location, provided the EPA indicated why such a subcategorization was appropriate. Id. (emphasis added); see also id. at 1411. As before, we need not spend time deconstructing Davis’ dicta, because the words of the statute must ultimately decide the issue. See Ernst & Ernst v. Hochfelder, 425 U.S. 185, 201 (1976). As we have noted, § 129(a)(2) authorizes EPA to ‘‘distinguish among classes.’’ ‘‘Class’’ is an ambiguous term. It is not defined in the Clean Air Act, and the dictionary definition — ‘‘a group, set, or kind marked by common attributes’’ — could hardly be more flexible. WEBSTER’S THIRD NEW INTERNATIONAL DICTIONARY 416 (1976) (3rd meaning). There is certainly nothing about the term or its dictionary definition that precludes the use of aggregate plant capacity as a factor for drawing distinctions among units. Because the term ‘‘class’’ is ambiguous, we would now ordinarily take Chevron’s second step and ask whether it was reasonable for the Agency to construe that term as permitting subcategorization based on aggregate plant capacity. But because Industry Petitioners regard this case as governed by step one of Chevron, their briefs do not dispute that, assuming subcategorization is permitted at all, aggregate capacity is a reasonable criterion. Petitioners’ Br. at 11, 16. Instead, they contend that EPA failed to provide any explanation at all for subcategorizing on that basis. Because we ultimately find that argument dispositive, we pretermit our discussion of Chevron and proceed directly to that challenge.11 11Industry Petitioners also contend, somewhat elliptically, that the 2000 Rule is inconsistent with the statute because the emission 17