West Virginia v. EPA (2022)

(Slip Opinion) OCTOBER TERM, 2021 1 Syllabus NOTE: Where it is feasible, a syllabus (headnote) will be released, as is being done in connection with this case, at the time the opinion is issued. The syllabus constitutes no part of the opinion of the Court but has been prepared by the Reporter of Decisions for the convenience of the reader. See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337 . SUPREME COURT OF THE UNITED STATES Syllabus WEST VIRGINIA ET AL. v. ENVIRONMENTAL PROTECTION AGENCY ET AL. CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT No. 20–1530. Argued February 28, 2022—Decided June 30, 2022* In 2015, the Environmental Protection Agency (EPA) promulgated the Clean Power Plan rule, which addressed carbon dioxide emissions from existing coal- and natural-gas-fired power plants. For authority, the Agency cited Section 111 of the Clean Air Act, which, although known as the New Source Performance Standards program, also au- thorizes regulation of certain pollutants from existing sources under Section 111(d). 42 U. S. C. §7411 (d). Prior to the Clean Power Plan, EPA had used Section 111(d) only a handful of times since its enact- ment in 1970. Under that provision, although the States set the actual enforceable rules governing existing sources (such as power plants), EPA determines the emissions limit with which they will have to com- ply. The Agency derives that limit by determining the “best system of emission reduction . . . that has been adequately demonstrated,” or the BSER, for the kind of existing source at issue. §7411(a)(1). The limit then reflects the amount of pollution reduction “achievable through the application of” that system. Ibid. In the Clean Power Plan, EPA determined that the BSER for exist- ing coal and natural gas plants included three types of measures, which the Agency called “building blocks.” 80 Fed. Reg. 64667 . The first building block was “heat rate improvements” at coal-fired plants—essentially practices such plants could undertake to burn coal —————— * Together with No. 20–1531, North American Coal Corp. v. Environ- mental Protection Agency et al., No. 20–1778, Westmoreland Mining Holdings LLC v. Environmental Protection Agency et al., and No. 20– 1780, North Dakota v. Environmental Protection Agency et al., also on certiorari to the same court. 2 WEST VIRGINIA v. EPA Syllabus more cleanly. Id., at 64727 . This sort of source-specific, efficiency- improving measure was similar in kind to those that EPA had previ- ously identified as the BSER in other Section 111 rules. Building blocks two and three were quite different, as both involved what EPA called “generation shifting” at the grid level—i.e., a shift in electricity production from higher-emitting to lower-emitting produc- ers. Building block two was a shift in generation from existing coal- fired power plants, which would make less power, to natural-gas-fired plants, which would make more. Ibid. This would reduce carbon di- oxide emissions because natural gas plants produce less carbon dioxide per unit of electricity generated than coal plants. Building block three worked like building block two, except that the shift was from both coal and gas plants to renewables, mostly wind and solar. Id., at 64729, 64748 . The Agency explained that, to implement the needed shift in generation to cleaner sources, an operator could reduce the regulated plant’s own production of electricity, build or invest in a new or exist- ing natural gas plant, wind farm, or solar installation, or purchase emission allowances or credits as part of a cap-and-trade regime. Id., at 64731–64732. Taking any of these steps would implement a sector- wide shift in electricity production from coal to natural gas and renew- ables. Id., at 64731 . Having decided that the BSER was one that would reduce carbon pollution mostly by moving production to cleaner sources, EPA then set about determining “the degree of emission limitation achievable through the application” of that system. §7411(a)(1). The Agency rec- ognized that, in translating the BSER into an operational emissions limit, it could choose whether to require anything from a little genera- tion shifting to a great deal. It settled on what it regarded as a “rea- sonable” amount of shift, which it based on modeling how much more electricity both natural gas and renewable sources could supply with- out causing undue cost increases or reducing the overall power supply. Id., at 64797–64811. The Agency ultimately projected, for instance, that it would be feasible to have coal provide 27% of national electricity generation by 2030, down from 38% in 2014. From these projected changes, EPA determined the applicable emissions performance rates, which were so strict that no existing coal plant would have been able to achieve them without engaging in one of the three means of gener- ation shifting. The Government projected that the rule would impose billions in compliance costs, raise retail electricity prices, require the retirement of dozens of coal plants, and eliminate tens of thousands of jobs. This Court stayed the Clean Power Plan in 2016, preventing the rule from taking effect. It was later repealed after a change in Presidential administrations. Specifically, in 2019, EPA found that the Clean Cite as: 597 U. S. ____ (2022) 3 Syllabus Power Plan had exceeded the Agency’s statutory authority under Sec- tion 111(d), which it interpreted to “limit[ ] the BSER to those systems that can be put into operation at a building, structure, facility, or in- stallation.” 84 Fed. Reg. 32524 . EPA explained that the Clean Power Plan, rather than setting the standard “based on the application of equipment and practices at the level of an individual facility,” had in- stead based it on “a shift in the energy generation mix at the grid level,” id., at 32523 . The Agency determined that the interpretive question raised by the Clean Power Plan fell under the major questions doctrine. Under that doctrine, it determined, a clear statement is nec- essary for a court to conclude that Congress intended to delegate au- thority “of this breadth to regulate a fundamental sector of the econ- omy.” Id., at 32529 . It found none. The Agency replaced the Clean Power Plan by promulgating a different Section 111(d) regulation, known as the Affordable Clean Energy (ACE) rule. Id., at 32532 . In that rule, EPA determined that the BSER would be akin to building block one of the Clean Power Plan: a combination of equipment up- grades and operating practices that would improve facilities’ heat rates. Id., at 32522, 32537 . A number of States and private parties filed petitions for review in the D. C. Circuit, challenging EPA’s repeal of the Clean Power Plan and its enactment of the replacement ACE rule. The Court of Appeals consolidated the cases and held that EPA’s “repeal of the Clean Power Plan rested critically on a mistaken reading of the Clean Air Act”— namely, that generation shifting cannot be a “system of emission re- duction” under Section 111. 985 F. 3d 914, 995 . The court vacated the Agency’s repeal of the Clean Power Plan and remanded to the Agency for further consideration. It also vacated and remanded the ACE rule for the same reason. The court’s decision was followed by another change in Presidential administrations, and EPA moved the court to partially stay its mandate as to the Clean Power Plan while the Agency considered whether to promulgate a new Section 111(d) rule. No party opposed the motion, and the Court of Appeals agreed to stay its vaca- tur of the Agency’s repeal of the Clean Power Plan. Held: 1. This case remains justiciable notwithstanding the Government’s contention that no petitioner has Article III standing, given EPA’s stated intention not to enforce the Clean Power Plan and to instead engage in new rulemaking. In considering standing to appeal, the question is whether the appellant has experienced an injury “fairly traceable to the judgment below.” Food Marketing Institute v. Argus Leader Media, 588 U. S. ___ , ___. If so, and a “favorable ruling” from the appellate court “would redress [that] injury,” then the appellant has a cognizable Article III stake. Ibid. Here, the judgment below 4 WEST VIRGINIA v. EPA Syllabus vacated the ACE rule and its embedded repeal of the Clean Power Plan, and accordingly purports to bring the Clean Power Plan back into legal effect. There is little question that the petitioner States are injured, since the rule requires them to more stringently regulate power plant emissions within their borders. The Government counters that EPA’s current posture has mooted the prior dispute. The distinc- tion between mootness and standing matters, however, because the Government bears the burden to establish that a once-live case has become moot. The Government’s argument in this case boils down to its representation that EPA does not intend to enforce the Clean Power Plan prior to promulgating a new Section 111(d) rule. But “voluntary cessation does not moot a case” unless it is “absolutely clear that the allegedly wrongful behavior could not reasonably be expected to recur.” Parents Involved in Community Schools v. Seattle School Dist. No. 1, 551 U. S. 701, 719 . Here, the Government “nowhere suggests that if this litigation is resolved in its favor it will not” reimpose emissions limits predicated on generation shifting. Ibid. Pp. 14–16. 2. Congress did not grant EPA in Section 111(d) of the Clean Air Act the authority to devise emissions caps based on the generation shifting approach the Agency took in the Clean Power Plan. Pp. 16–31. (a) In devising emissions limits for power plants, EPA “deter- mines” the BSER that—taking into account cost, health, and other fac- tors—it finds “has been adequately demonstrated,” and then quanti- fies “the degree of emission limitation achievable” if that best system were applied to the covered source. §7411(a)(1). The issue here is whether restructuring the Nation’s overall mix of electricity genera- tion, to transition from 38% to 27% coal by 2030, can be the BSER within the meaning of Section 111. Precedent teaches that there are “extraordinary cases” in which the “history and the breadth of the authority that [the agency] has as- serted,” and the “economic and political significance” of that assertion, provide a “reason to hesitate before concluding that Congress” meant to confer such authority. FDA v. Brown & Williamson Tobacco Corp., 529 U. S. 120 , 159–160. See, e.g., Alabama Assn. of Realtors v. Depart- ment of Health and Human Servs., 594 U. S. ___ , ___; Utility Air Reg- ulatory Group v. EPA, 573 U. S. 302 , 324; Gonzales v. Oregon, 546 U. S. 243, 267 ; National Federation of Independent Business v. OSHA, 595 U. S. ___ , ___. Under this body of law, known as the major ques- tions doctrine, given both separation of powers principles and a prac- tical understanding of legislative intent, the agency must point to “clear congressional authorization” for the authority it claims. Utility Air, 573 U. S., at 324. Pp. 16–20. (b) This is a major questions case. EPA claimed to discover an Cite as: 597 U. S. ____ (2022) 5 Syllabus unheralded power representing a transformative expansion of its reg- ulatory authority in the vague language of a long-extant, but rarely used, statute designed as a gap filler. That discovery allowed it to adopt a regulatory program that Congress had conspicuously declined to enact itself. Given these circumstances, there is every reason to “hesitate before concluding that Congress” meant to confer on EPA the authority it claims under Section 111(d). Brown & Williamson, 529 U. S., at 160 . Prior to 2015, EPA had always set Section 111 emissions limits based on the application of measures that would reduce pollution by causing the regulated source to operate more cleanly, see, e.g., 41 Fed. Reg. 48706—never by looking to a “system” that would reduce pollu- tion simply by “shifting” polluting activity “from dirtier to cleaner sources.” 80 Fed. Reg. 64726 . The Government quibbles with this his- tory, pointing to the 2005 Mercury Rule as one Section 111 rule that it says relied upon a cap-and-trade mechanism to reduce emissions. See 70 Fed. Reg. 28616 . But in that regulation, EPA set the emissions limit—the “cap”—based on the use of “technologies [that could be] in- stalled and operational on a nationwide basis” in the relevant timeframe. Id., at 28620–28621. By contrast, and by design, there are no particular controls a coal plant operator can install and operate to attain the emissions limits established by the Clean Power Plan. In- deed, the Agency nodded to the novelty of its approach when it ex- plained that it was pursuing a “broader, forward-thinking approach to the design” of Section 111 regulations that would “improve the overall power system,” rather than the emissions performance of individual sources, by forcing a shift throughout the power grid from one type of energy source to another. 80 Fed. Reg. 64703 (emphasis added). This view of EPA’s authority was not only unprecedented; it also effected a “fundamental revision of the statute, changing it from [one sort of] scheme of . . . regulation” into an entirely different kind. MCI Tele- communications Corp. v. American Telephone & Telegraph Co., 512 U. S. 218, 231 . The Government attempts to downplay matters, noting that the Agency must limit the magnitude of generation shift it demands to a level that will not be “exorbitantly costly” or “threaten the reliability of the grid.” Brief for Federal Respondents 42. This argument does not limit the breadth of EPA’s claimed authority so much as reveal it: On EPA’s view of Section 111(d), Congress implicitly tasked it, and it alone, with balancing the many vital considerations of national policy implicated in the basic regulation of how Americans get their energy. There is little reason to think Congress did so. EPA has admitted that issues of electricity transmission, distribution, and storage are not within its traditional expertise. And this Court doubts that “Congress 6 WEST VIRGINIA v. EPA Syllabus . . . intended to delegate . . . decision[s] of such economic and political significance,” i.e., how much coal-based generation there should be over the coming decades, to any administrative agency. Brown & Wil- liamson, 529 U. S., at 160 . Nor can the Court ignore that the regula- tory writ EPA newly uncovered in Section 111(d) conveniently enabled it to enact a program, namely, cap-and-trade for carbon, that Congress had already considered and rejected numerous times. The importance of the policy issue and ongoing debate over its merits “makes the oblique form of the claimed delegation all the more suspect.” Gonzales, 546 U. S., at 267–268. Pp. 20–28. (c) Given that precedent counsels skepticism toward EPA’s claim that Section 111 empowers it to devise carbon emissions caps based on a generation shifting approach, the Government must point to “clear congressional authorization” to regulate in that manner. Utility Air, 573 U. S., at 324. The Government can offer only EPA’s authority to establish emissions caps at a level reflecting “the application of the best system of emission reduction . . . adequately demonstrated.” §7411(a)(1). The word “system” shorn of all context, however, is an empty vessel. Such a vague statutory grant is not close to the sort of clear authorization required. The Government points to other provi- sions of the Clean Air Act—specifically the Acid Rain and National Ambient Air Quality Standards (NAAQS) programs—that use the word “system” or “similar words” to describe sector-wide mechanisms for reducing pollution. But just because a cap-and-trade “system” can be used to reduce emissions does not mean that it is the kind of “system of emission reduction” referred to in Section 111. Finally, the Court has no occasion to decide whether the statutory phrase “system of emission reduction” refers exclusively to measures that improve the pollution performance of individual sources, such that all other actions are ineligible to qualify as the BSER. It is perti- nent to the Court’s analysis that EPA has acted consistent with such a limitation for four decades. But the only question before the Court is more narrow: whether the “best system of emission reduction” iden- tified by EPA in the Clean Power Plan was within the authority granted to the Agency in Section 111(d) of the Clean Air Act. For the reasons given, the answer is no. Pp. 28–31. 985 F. 3d 914 , reversed and remanded. ROBERTS, C. J., delivered the opinion of the Court, in which THOMAS, ALITO, GORSUCH, KAVANAUGH, and BARRETT, JJ., joined. GORSUCH, J., filed a concurring opinion, in which ALITO, J., joined. KAGAN, J., filed a dissenting opinion, in which BREYER and SOTOMAYOR, JJ., joined. Cite as: 597 U. S. ____ (2022) 1 Opinion of the Court NOTICE: This opinion is subject to formal revision before publication in the preliminary print of the United States Reports. Readers are requested to notify the Reporter of Decisions, Supreme Court of the United States, Wash- ington, D. C. 20543, of any typographical or other formal errors, in order that corrections may be made before the preliminary print goes to press. SUPREME COURT OF THE UNITED STATES _________________ Nos. 20–1530, 20–1531, 20–1778 and 20–1780 _________________ WEST VIRGINIA, ET AL., PETITIONERS 20–1530 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. THE NORTH AMERICAN COAL CORPORATION, PETITIONER 20–1531 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. WESTMORELAND MINING HOLDINGS LLC, PETITIONER 20–1778 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. NORTH DAKOTA, PETITIONER 20–1780 v. ENVIRONMENTAL PROTECTION AGENCY, ET AL. ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT [June 30, 2022] CHIEF JUSTICE ROBERTS delivered the opinion of the Court. The Clean Air Act authorizes the Environmental Protec- tion Agency to regulate power plants by setting a “standard of performance” for their emission of certain pollutants into 2 WEST VIRGINIA v. EPA Opinion of the Court the air. 84 Stat. 1683 , 42 U. S. C. §7411 (a)(1). That stand- ard may be different for new and existing plants, but in each case it must reflect the “best system of emission reduc- tion” that the Agency has determined to be “adequately demonstrated” for the particular category. §§7411(a)(1), (b)(1), (d). For existing plants, the States then implement that requirement by issuing rules restricting emissions from sources within their borders. Since passage of the Act 50 years ago, EPA has exercised this authority by setting performance standards based on measures that would reduce pollution by causing plants to operate more cleanly. In 2015, however, EPA issued a new rule concluding that the “best system of emission reduction” for existing coal-fired power plants included a requirement that such facilities reduce their own production of electric- ity, or subsidize increased generation by natural gas, wind, or solar sources. The question before us is whether this broader conception of EPA’s authority is within the power granted to it by the Clean Air Act. I A The Clean Air Act establishes three main regulatory pro- grams to control air pollution from stationary sources such as power plants. Clean Air Amendments of 1970, 84 Stat. 1676 , 42 U. S. C. §7401 et seq. One program is the New Source Performance Standards program of Section 111, at issue here. The other two are the National Ambient Air Quality Standards (NAAQS) program, set out in Sections 108 through 110 of the Act, 42 U. S. C. §§7408–7410, and the Hazardous Air Pollutants (HAP) program, set out in Section 112, §7412. To understand the place and function of Section 111 in the statutory scheme, some background on the other two programs is in order. The NAAQS program addresses air pollutants that “may Cite as: 597 U. S. ____ (2022) 3 Opinion of the Court reasonably be anticipated to endanger public health or wel- fare,” and “the presence of which in the ambient air results from numerous or diverse mobile or stationary sources.” §7408(a)(1). After identifying such pollutants, EPA estab- lishes a NAAQS for each. The NAAQS represents “the max- imum airborne concentration of [the] pollutant that the public health can tolerate.” Whitman v. American Trucking Assns., Inc., 531 U. S. 457, 465 (2001); see §7409(b). EPA, though, does not choose which sources must reduce their pollution and by how much to meet the ambient pollution target. Instead, Section 110 of the Act leaves that task in the first instance to the States, requiring each “to submit to [EPA] a plan designed to implement and maintain such standards within its boundaries.” Train v. Natural Re- sources Defense Council, Inc., 421 U. S. 60, 65 (1975); §7410. The second major program governing stationary sources is the HAP program. The HAP program primarily targets pollutants, other than those already covered by a NAAQS, that present “a threat of adverse human health effects,” in- cluding substances known or anticipated to be “carcino- genic, mutagenic, teratogenic, neurotoxic,” or otherwise “acutely or chronically toxic.” §7412(b)(2). EPA’s regulatory role with respect to these toxic pollu- tants is different in kind from its role in administering the NAAQS program. There, EPA is generally limited to deter- mining the maximum safe amount of covered pollutants in the air. As to each hazardous pollutant, by contrast, the Agency must promulgate emissions standards for both new and existing major sources. §7412(d)(1). Those standards must “require the maximum degree of reduction in emis- sions . . . that the [EPA] Administrator, taking into consid- eration the cost of achieving such emission reduction, and any non-air quality health and environmental impacts and energy requirements, determines is achievable . . . through application of measures, processes, methods, systems or techniques” of emission reduction. §7412(d)(2). In other 4 WEST VIRGINIA v. EPA Opinion of the Court words, EPA must directly require all covered sources to re- duce their emissions to a certain level. And it chooses that level by determining the “maximum degree of reduction” it considers “achievable” in practice by using the best existing technologies and methods. §7412(d)(3). Thus, in the parlance of environmental law, Section 112 directs the Agency to impose “technology-based standard[s] for hazardous emissions,” Alaska Dept. of Environmental Conservation v. EPA, 540 U. S. 461, 485, n. 12 (2004) (em- phasis added). This sort of “ ‘technology-based’ approach fo- cuses upon the control technologies that are available to in- dustrial entities and requires the agency to . . . ensur[e] that regulated firms adopt the appropriate cleanup technol- ogy.” T. McGarity, Media-Quality, Technology, and Cost- Benefit Balancing Strategies for Health and Environmen- tal Regulation, 46 Law & Contemp. Prob. 159, 160 (Summer 1983) (McGarity). (Such “technologies” are not limited to literal technology, such as scrubbers; “changes in the design and operation” of the facility, or “in the way that employees perform their tasks,” are also available options. Id., at 163, n. 18.) The third air pollution control scheme is the New Source Performance Standards program of Section 111. §7411. That section directs EPA to list “categories of stationary sources” that it determines “cause[], or contribute[ ] signifi- cantly to, air pollution which may reasonably be anticipated to endanger public health or welfare.” §7411(b)(1)(A). Un- der Section 111(b), the Agency must then promulgate for each category “Federal standards of performance for new sources,” §7411(b)(1)(B). A “standard of performance” is one that “reflects the degree of emission limitation achievable through the application of the best system of emission reduction which (taking into account the cost of achiev- ing such reduction and any nonair quality health and Cite as: 597 U. S. ____ (2022) 5 Opinion of the Court environmental impact and energy requirements) the [EPA] Administrator determines has been adequately demonstrated.” §7411(a)(1). Thus, the statute directs EPA to (1) “determine[ ],” taking into account various factors, the “best system of emission reduction which . . . has been adequately demonstrated,” (2) ascertain the “degree of emission limitation achievable through the application” of that system, and (3) impose an emissions limit on new stationary sources that “reflects” that amount. Ibid.; see also 80 Fed. Reg. 64538 (2015). Generally speaking, a source may achieve that emissions cap any way it chooses; the key is that its pollution be no more than the amount “achievable through the application of the best system of emission reduction . . . adequately demonstrated,” or the BSER. §7411(a)(1); see §7411(b)(5). EPA undertakes this analysis on a pollutant-by-pollutant basis, establishing different standards of performance with respect to different pollutants emitted from the same source category. See, e.g., 73 Fed. Reg. 35838 (2008); 42 Fed. Reg. 22510 (1977). Although the thrust of Section 111 focuses on emissions limits for new and modified sources—as its title indicates— the statute also authorizes regulation of certain pollutants from existing sources. Under Section 111(d), once EPA “has set new source standards addressing emissions of a partic- ular pollutant under . . . section 111(b),” 80 Fed. Reg. 64711 , it must then address emissions of that same pollutant by existing sources—but only if they are not already regulated under the NAAQS or HAP programs. §7411(d)(1). Existing power plants, for example, emit many pollutants covered by a NAAQS or HAP standard. Section 111(d) thus “operates as a gap-filler,” empowering EPA to regulate harmful emis- sions not already controlled under the Agency’s other au- thorities. American Lung Assn. v. EPA, 985 F. 3d 914, 932 (CADC 2021). 6 WEST VIRGINIA v. EPA Opinion of the Court Although the States set the actual rules governing exist- ing power plants, EPA itself still retains the primary regu- latory role in Section 111(d). The Agency, not the States, decides the amount of pollution reduction that must ulti- mately be achieved. It does so by again determining, as when setting the new source rules, “the best system of emis- sion reduction . . . that has been adequately demonstrated for [existing covered] facilities.” 40 CFR §60.22 (b)(5) (2021); see also 80 Fed. Reg. 64664 , and n. 1. The States then sub- mit plans containing the emissions restrictions that they intend to adopt and enforce in order not to exceed the per- missible level of pollution established by EPA. See §§60.23, 60.24; 42 U. S. C. §7411 (d)(1). Reflecting the ancillary nature of Section 111(d), EPA has used it only a handful of times since the enactment of the statute in 1970. See 80 Fed. Reg. 64703 , and n. 275 (past regulations pertained to “four pollutants from five source categories”). For instance, the Agency has established emissions limits on acid mist from sulfuric acid production, 41 Fed. Reg. 48706 (1976) (identifying “fiber mist elimina- tor” technology as BSER); sulfide gases released by kraft pulp mills, 44 Fed. Reg. 29829 (1979) (determining BSER to be a combination of scrubbers, incineration, filtration systems, and temperature control); and emissions of vari- ous harmful gases from municipal landfills, 61 Fed. Reg. 9907 (1996) (setting BSER as use of a flare to combust the gases). It was thus only a slight overstatement for one of the architects of the 1990 amendments to the Clean Air Act to refer to Section 111(d) as an “obscure, never-used section of the law.” Hearings on S. 300 et al. before the Subcom- mittee on Environmental Protection of the Senate Commit- tee on Environment and Public Works, 100th Cong., 1st Sess., 13 (1987) (remarks of Sen. Durenberger). B Things changed in October 2015, when EPA promulgated Cite as: 597 U. S. ____ (2022) 7 Opinion of the Court two rules addressing carbon dioxide pollution from power plants—one for new plants under Section 111(b), the other for existing plants under Section 111(d). Both were prem- ised on the Agency’s earlier finding that carbon dioxide is an “air pollutant” that “may reasonably be anticipated to endanger public health or welfare” by causing climate change. 80 Fed. Reg. 64530 . Carbon dioxide is not subject to a NAAQS and has not been listed as a toxic pollutant. The first rule announced by EPA established federal car- bon emissions limits for new power plants of two varieties: fossil-fuel-fired electric steam generating units (mostly coal fired) and natural-gas-fired stationary combustion tur- bines. Id., at 64512 . Following the statutory process set out above, the Agency determined the BSER for the two cat- egories of sources. For steam generating units, for instance, EPA determined that the BSER was a combination of high- efficiency production processes and carbon capture technol- ogy. See 80 Fed. Reg. 64512 . EPA then set the emissions limit based on the amount of carbon dioxide that a plant would emit with these technologies in place. Id., at 64513 . The second rule was triggered by the first: Because EPA was now regulating carbon dioxide from new coal and gas plants, Section 111(d) required EPA to also address carbon emissions from existing coal and gas plants. See §7411(d)(1). It did so through what it called the Clean Power Plan rule. In that rule, EPA established “final emission guidelines for states to follow in developing plans” to regulate existing power plants within their borders. Id., at 64662. To arrive at the guideline limits, EPA did the same thing it does when imposing federal regulations on new sources: It identified the BSER. The BSER that the Agency selected for existing coal-fired power plants, however, was quite different from the BSER it had chosen for new sources. The BSER for existing plants included three types of measures, which the Agency called 8 WEST VIRGINIA v. EPA Opinion of the Court “building blocks.” Id., at 64667. The first building block was “heat rate improvements” at coal-fired plants—essen- tially practices such plants could undertake to burn coal more efficiently. Id., at 64727. But such improvements, EPA stated, would “lead to only small emission reductions,” because coal-fired power plants were already operating near optimum efficiency. Ibid. On the Agency’s view, “much larger emission reductions [were] needed from [coal- fired plants] to address climate change.” Ibid. So the Agency included two additional building blocks in its BSER, both of which involve what it called “generation shifting from higher-emitting to lower-emitting” producers of electricity. Id., at 64728. Building block two was a shift in electricity production from existing coal-fired power plants to natural-gas-fired plants. Ibid. Because natural gas plants produce “typically less than half as much” carbon dioxide per unit of electricity created as coal-fired plants, the Agency explained, “this generation shift [would] re- duce[ ] CO2 emissions.” Ibid. Building block three worked the same way, except that the shift was from both coal- and gas-fired plants to “new low- or zero-carbon generating ca- pacity,” mainly wind and solar. Id., at 64729, 64748. “Most of the CO2 controls” in the rule came from the application of building blocks two and three. Id., at 64728. The Agency identified three ways in which a regulated plant operator could implement a shift in generation to cleaner sources. Id., at 64731. First, an operator could simply reduce the regulated plant’s own production of elec- tricity. Second, it could build a new natural gas plant, wind farm, or solar installation, or invest in someone else’s exist- ing facility and then increase generation there. Ibid. Fi- nally, operators could purchase emission allowances or credits as part of a cap-and-trade regime. Id., at 64731– 64732. Under such a scheme, sources that achieve a reduc- tion in their emissions can sell a credit representing the value of that reduction to others, who are able to count it Cite as: 597 U. S. ____ (2022) 9 Opinion of the Court toward their own applicable emissions caps. EPA explained that taking any of these steps would im- plement a sector-wide shift in electricity production from coal to natural gas and renewables. Id., at 64731 . Given the integrated nature of the power grid, “adding electricity to the grid from one generator will result in the instantane- ous reduction in generation from other generators,” and “re- ductions in generation from one generator lead to the in- stantaneous increase in generation” by others. Id., at 64769 . So coal plants, whether by reducing their own pro- duction, subsidizing an increase in production by cleaner sources, or both, would cause a shift toward wind, solar, and natural gas. Having decided that the “best system of emission reduc- tion . . . adequately demonstrated” was one that would re- duce carbon pollution mostly by moving production to cleaner sources, EPA then set about determining “the de- gree of emission limitation achievable through the applica- tion” of that system. 42 U. S. C. §7411 (a)(1). The Agency recognized that—given the nature of generation shifting— it could choose from “a wide range of potential stringencies for the BSER.” 80 Fed. Reg. 64730 . Put differently, in translating the BSER into an operational emissions limit, EPA could choose whether to require anything from a little generation shifting to a great deal. The Agency settled on what it regarded as a “reasonable” amount of shift, which it based on modeling of how much more electricity both natu- ral gas and renewable sources could supply without causing undue cost increases or reducing the overall power supply. Id., at 64797–64811. Based on these changes, EPA pro- jected that by 2030, it would be feasible to have coal provide 27% of national electricity generation, down from 38% in 2014. Id., at 64665, 64694 ; see Dept. of Energy, U. S. En- ergy Information Admin., Monthly Energy Review (May 2015), Electricity Net Generation: Electric Power Sector, p. 106 (Table 7.2b). 10 WEST VIRGINIA v. EPA Opinion of the Court From these significant projected reductions in genera- tion, EPA developed a series of complex equations to “deter- mine the emission performance rates” that States would be required to implement. 80 Fed. Reg. 64815 . The calcula- tions resulted in numerical emissions ceilings so strict that no existing coal plant would have been able to achieve them without engaging in one of the three means of shifting gen- eration described above. Indeed, the emissions limit the Clean Power Plan established for existing power plants was actually stricter than the cap imposed by the simultane- ously published standards for new plants. Compare id., at 64742 , with id., at 64513 . The point, after all, was to compel the transfer of power generating capacity from existing sources to wind and solar. The White House stated that the Clean Power Plan would “drive a[n] . . . aggressive transformation in the domestic energy industry.” White House Fact Sheet, App. in Ameri- can Lung Assn. v. EPA, No. 19–1140 etc. (CADC), p. 2076. EPA’s own modeling concluded that the rule would entail billions of dollars in compliance costs (to be paid in the form of higher energy prices), require the retirement of dozens of coal-fired plants, and eliminate tens of thousands of jobs across various sectors. EPA, Regulatory Impact Analysis for the Clean Power Plan Final Rule 3–22, 3–30, 3–33, 6– 24, 6–25 (2015). The Energy Information Administration reached similar conclusions, projecting that the rule would cause retail electricity prices to remain persistently 10% higher in many States, and would reduce GDP by at least a trillion 2009 dollars by 2040. Dept. of Energy, Analysis of the Impacts of the Clean Power Plan 21, 63–64 (May 2015). C These projections were never tested, because the Clean Power Plan never went into effect. The same day that EPA promulgated the rule, dozens of parties (including 27 States) petitioned for review in the D. C. Circuit. After that Cite as: 597 U. S. ____ (2022) 11 Opinion of the Court court declined to enter a stay of the rule, the challengers sought the same relief from this Court. We granted a stay, preventing the rule from taking effect. West Virginia v. EPA, 577 U. S. 1126 (2016). The Court of Appeals later heard argument on the merits en banc. But before it could issue a decision, there was a change in Presidential admin- istrations. The new administration requested that the liti- gation be held in abeyance so that EPA could reconsider the Clean Power Plan. The D. C. Circuit obliged, and later dis- missed the petitions for review as moot. EPA eventually repealed the rule in 2019, concluding that the Clean Power Plan had been “in excess of its statu- tory authority” under Section 111(d). 84 Fed. Reg. 32523 (2019). Specifically, the Agency concluded that generation shifting should not have been considered as part of the BSER. The Agency interpreted Section 111 as “limit[ing] the BSER to those systems that can be put into operation at a building, structure, facility, or installation,” such as “add-on controls” and “inherently lower-emitting pro- cesses/practices/designs.” Id., at 32524 . It then explained that the Clean Power Plan, rather than setting the stand- ard “based on the application of equipment and practices at the level of an individual facility,” had instead based it on “a shift in the energy generation mix at the grid level,” id., at 32523—not the sort of measure that has “a potential for application to an individual source.” Id., at 32524 . The Agency determined that “the interpretative question raised” by the Clean Power Plan—“i.e., whether a ‘system of emission reduction’ can consist of generation-shifting measures”—fell under the “major question doctrine.” Id., at 32529 . Under that doctrine, EPA explained, courts “ex- pect Congress to speak clearly if it wishes to assign to an agency decisions of vast economic and political signifi- cance.” Ibid. (quoting Utility Air Regulatory Group v. EPA, 573 U. S. 302 , 324 (2014) (internal quotation marks omit- ted)). The Agency concluded that the Clean Power Plan was 12 WEST VIRGINIA v. EPA Opinion of the Court such a decision, for a number of reasons. Its “generation- shifting scheme was projected to have billions of dollars of impact.” 84 Fed. Reg. 32529 . “[N]o section 111 rule of the scores issued ha[d] ever been based on generation shifting.” Ibid. And that novel reading of the statute would empower EPA “to order the wholesale restructuring of any industrial sector” based only on its discretionary assessment of “such factors as ‘cost’ and ‘feasibility.’ ” Ibid. EPA argued that under the major questions doctrine, a clear statement was necessary to conclude that Congress intended to delegate authority “of this breadth to regulate a fundamental sector of the economy.” Ibid. It found none. “Indeed,” it concluded, given the text and structure of the statute, “Congress has directly spoken to this precise ques- tion and precluded” the use of measures such as generation shifting. Ibid. In the same rulemaking, the Agency replaced the Clean Power Plan by promulgating a different Section 111(d) reg- ulation, known as the Affordable Clean Energy (ACE) Rule. Id., at 32532 . Based on its view of what measures may per- missibly make up the BSER, EPA determined that the best system would be