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 authorizes 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 enactment 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 comply. 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 existing 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 more cleanly. Id., at 64727. This sort of source-specific, efficiency-improving measure was similar in kind to those that EPA had previously 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 producers. 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 dioxide 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 existing 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 renewables. 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 recognized that, in translating the BSER into an operational emissions limit, it could choose whether to require anything from a little generation shifting to a great deal. It settled on what it regarded as a “reasonable” amount of shift, which it based on modeling how much more electricity both natural gas and renewable sources could supply without 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 generation 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 Power Plan had exceeded the Agency’s statutory authority under Section 111(d), which it interpreted to “limit[ ] the BSER to those systems that can be put into operation at a building, structure, facility, or installation.” 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 instead 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 necessary for a court to conclude that Congress intended to delegate authority “of this breadth to regulate a fundamental sector of the economy.” 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 upgrades 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 reduction” 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 vacatur 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 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 distinction 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 “determines” the BSER that—taking into account cost, health, and other factors—it finds “has been adequately demonstrated,” and then quantifies “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 generation, 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 asserted,” 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. Department of Health and Human Servs., 594 U. S. ___, ___; Utility Air Regulatory 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 questions doctrine, given both separation of powers principles and a practical 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 unheralded power representing a transformative expansion of its regulatory 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 pollution simply by “shifting” polluting activity “from dirtier to cleaner sources.” 80 Fed. Reg. 64726. The Government quibbles with this history, 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] installed 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. Indeed, the Agency nodded to the novelty of its approach when it explained 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 Telecommunications 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 . . . 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 & Williamson, 529 U. S., at 160. Nor can the Court ignore that the regulatory 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 provisions 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 pertinent 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” identified 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.

Notes
<sup>1

2</sup> Together with No. 20–1531, North American Coal Corp. v. Environmental 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.

In January 2019, the Department of Homeland Security began to implement the Migrant Protection Protocols (MPP). Under MPP, certain non-Mexican nationals arriving by land from Mexico were returned to Mexico to await the results of their removal proceedings under section 1229a of the Immigration and Nationality Act (INA). MPP was implemented pursuant to a provision of the INA that applies to aliens “arriving on land . . . from a foreign territory contiguous to the United States” and provides that the Secretary of Homeland Security “may return the alien to that territory pending a proceeding under section 1229a.” 8 U. S. C. §1225(b)(2)(C). Following a change in Presidential administrations, the Biden administration announced that it would suspend the program, and on June 1, 2021, the Secretary of Homeland Security issued a memorandum officially terminating it.

   The States of Texas and Missouri (respondents) brought suit in the Northern District of Texas against the Secretary and others, asserting that the June 1 Memorandum violated the INA and the Administrative Procedure Act (APA). The District Court entered judgment for respondents. The court first concluded that terminating MPP would violate the INA, reasoning that section 1225 of the INA “provides the government two options” with respect to illegal entrants: mandatory detention pursuant to section 1225(b)(2)(A) or contiguous-territory return pursuant to section 1225(b)(2)(C). 554 F. Supp. 3d 818, 852. Because the Government was unable to meet its mandatory detention obligations under section 1225(b)(2)(A) due to resource constraints, the court reasoned, terminating MPP would necessarily lead to the systemic violation of section 1225 as illegal entrants were released into the United States. Second, the District Court concluded that the June 1 Memorandum was arbitrary and capricious in violation of the APA. The District Court vacated the June 1 Memorandum and remanded to DHS. It also imposed a nationwide injunction ordering the Government to “enforce and implement MPP in good faith until such a time as it has been lawfully rescinded in compliance with the APA and until such a time as the federal government has sufficient detention capacity to detain all aliens subject to mandatory detention under [section 1225] without releasing any aliens because of a lack of detention resources.” Id., at 857 (emphasis in original).

   While the Government’s appeal was pending, the Secretary released the October 29 Memoranda, which again announced the termination of MPP and explained anew his reasons for doing so. The Government then moved to vacate the injunction on the ground that the October 29 Memoranda had superseded the June 1 Memorandum. But the Court of Appeals denied the motion and instead affirmed the District Court’s judgment in full. With respect to the INA question, the Court of Appeals agreed with the District Court’s analysis that terminating the program would violate the INA, concluding that the return policy was mandatory so long as illegal entrants were being released into the United States. The Court of Appeals also held that “[t]he October 29 Memoranda did not constitute a new and separately reviewable ‘final agency action.’ ” 20 F. 4th 928, 951.

Held: The Government’s rescission of MPP did not violate section 1225 of the INA, and the October 29 Memoranda constituted final agency action. Pp. 8–25.

  (a) Beginning with jurisdiction, the injunction that the District Court entered in this case violated 8 U. S. C. §1252(f )(1). See Garland v. Aleman Gonzalez, 596 U. S. ___, ___. But section 1252(f )(1) does not deprive this Court of jurisdiction to reach the merits of an appeal even where a lower court enters a form of relief barred by that provision. Section 1252(f )(1) withdraws a district court’s “jurisdiction or authority” to grant a particular form of relief. It does not deprive lower courts of all subject matter jurisdiction over claims brought under sections 1221 through 1232 of the INA.

  The text of the provision makes that clear. Section 1252(f )(1) deprives courts of the power to issue a specific category of remedies: those that “enjoin or restrain the operation of ” the relevant sections of the statute. And Congress included that language in a provision whose title—“Limit on injunctive relief ”—makes clear the narrowness of its scope. Moreover, the provision contains a parenthetical that explicitly preserves this Court’s power to enter injunctive relief. If section 1252(f )(1) deprived lower courts of subject matter jurisdiction to adjudicate any non-individual claims under sections 1221 through 1232, no such claims could ever arrive at this Court, rendering the specific carveout for Supreme Court injunctive relief nugatory.

 Statutory structure likewise confirms this conclusion. Elsewhere in section 1252, where Congress intended to deny subject matter jurisdiction over a particular class of claims, it did so unambiguously. See, e.g., §1252(a)(2) (entitled “Matters not subject to judicial review”). Finally, this Court previously encountered a virtually identical situation in Nielsen v. Preap, 586 U. S. ___, and proceeded to reach the merits of the suit notwithstanding the District Court’s apparent violation of section 1252(f )(1). Pp. 8–13.

  (b) Turning to the merits, section 1225(b)(2)(C) provides: “In the case of an alien . . . who is arriving on land . . . from a foreign territory contiguous to the United States, the [Secretary] may return the alien to that territory pending a proceeding under section 1229a.” Section 1225(b)(2)(C) plainly confers a discretionary authority to return aliens to Mexico. This Court has “repeatedly observed” that “the word ‘may’ clearly connotes discretion.” Opati v. Republic of Sudan, 590 U. S. ___, ___.

  Respondents and the Court of Appeals concede that point, but urge an inference from the statutory structure: because section 1225(b)(2)(A) makes detention mandatory, they argue, the otherwise-discretionary return authority in section 1225(b)(2)(C) becomes mandatory when the Secretary violates that mandate. The problem is that the statute does not say anything like that. The statute says “may.” If Congress had intended section 1225(b)(2)(C) to operate as a mandatory cure of any noncompliance with the Government’s detention obligations, it would not have conveyed that intention through an unspoken inference in conflict with the unambiguous, express term “may.” The contiguous-territory return authority in section 1225(b)(2)(C) is discretionary—and remains discretionary notwithstanding any violation of section 1225(b)(2)(A).

  The historical context in which section 1225(b)(2)(C) was adopted confirms the plain import of its text. Section 1225(b)(2)(C) was added to the statute more than 90 years after the “shall be detained” language that appears in section 1225(b)(2)(A). And the provision was enacted in response to a BIA decision that had questioned the legality of the contiguous-territory return practice. Moreover, since its enactment, every Presidential administration has interpreted section 1225(b)(2)(C) as purely discretionary, notwithstanding the consistent shortfall of funds to comply with section 1225(b)(2)(A).

  The foreign affairs consequences of mandating the exercise of contiguous-territory return likewise confirm that the Court of Appeals erred. Interpreting section 1225(b)(2)(C) as a mandate imposes a significant burden upon the Executive’s ability to conduct diplomatic relations with Mexico, one that Congress likely did not intend section 1225(b)(2)(C) to impose. And finally, the availability of parole as an alternative means of processing applicants for admission, see 8 U. S. C. §1182(d)(5)(A), additionally makes clear that the Court of Appeals erred in holding that the INA required the Government to continue implementing MPP. Pp. 13–18.

  (c) The Court of Appeals also erred in holding that “[t]he October 29 Memoranda did not constitute a new and separately reviewable ‘final agency action.’ ” 20 F. 4th, at 951. Once the District Court vacated the June 1 Memorandum and remanded to DHS for further consideration, DHS had two options: elaborate on its original reasons for taking action or “ ‘deal with the problem afresh’ by taking new agency action.” Department of Homeland Security v. Regents of Univ. of Cal., 591 U. S. ___, ___. The Secretary selected the second option from Regents: He accepted the District Court’s vacatur and dealt with the problem afresh. The October 29 Memoranda were therefore final agency action for the same reasons that the June 1 Memorandum was final agency action: Both “mark[ed] the ‘consummation’ of the agency’s decisionmaking process” and resulted in “rights and obligations [being] determined.” Bennett v. Spear, 520 U. S. 154, 178.

  The various rationales offered by respondents and the Court of Appeals in support of the contrary conclusion lack merit. First, the Court of Appeals erred to the extent it understood itself to be reviewing an abstract decision apart from the specific agency actions contained in the June 1 Memorandum and October 29 Memoranda. Second, and relatedly, the October 29 Memoranda were not a mere post hoc rationalization of the June 1 Memorandum. The prohibition on post hoc rationalization applies only when the agency proceeds by the first option from Regents. Here, the Secretary chose the second option from Regents and “issue[d] a new rescission bolstered by new reasons absent from the [June 1] Memorandum.” 591 U. S., at ___. Having returned to the drawing table, the Secretary was not subject to the charge of post hoc rationalization.

  Third, respondents invoke Department of Commerce v. New York, 588 U. S. ___. But nothing in this record suggests a “significant mismatch between the decision the Secretary made and the rationale he provided.” Id., at ___. Relatedly, the Court of Appeals charged that the Secretary failed to proceed with a sufficiently open mind. But this Court has previously rejected criticisms of agency closemindedness based on an identity between proposed and final agency action. See Little Sisters of the Poor Saints Peter and Paul Home v. Pennsylvania, 591 U. S. ___, ___. Finally, the Court of Appeals erred to the extent it viewed the Government’s decision to appeal the District Court’s injunction as relevant to the question of the October 29 Memoranda’s status as final agency action. Nothing prevents an agency from undertaking new agency action while simultaneously appealing an adverse judgment against its original action. Pp. 18–25.

20 F. 4th 928, reversed and remanded.

 Roberts, C. J., delivered the opinion of the Court, in which Breyer, Sotomayor, Kagan, and Kavanaugh, JJ., joined. Kavanaugh, J., filed a concurring opinion. Alito, J., filed a dissenting opinion, in which Thomas and Gorsuch, JJ., joined. Barrett, J., filed a dissenting opinion, in which Thomas, Alito, and Gorsuch, JJ., joined as to all but the first sentence.