United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued November 18, 2022 Decided June 20, 2023

No. 21-1251

HEATING, AIR CONDITIONING & REFRIGERATION 

DISTRIBUTORS INTERNATIONAL, ET AL.,

PETITIONERS

v.

ENVIRONMENTAL PROTECTION AGENCY AND MICHAEL S.

REGAN, IN HIS OFFICIAL CAPACITY AS ADMINISTRATOR OF THE 

U.S. ENVIRONMENTAL PROTECTION AGENCY,

RESPONDENTS

Consolidated with 21-1252, 21-1253

On Petitions for Review of a Final Action

of the Environmental Protection Agency

Stephen K. Wirth and Wayne J. D’Angelo argued the 

causes for Association Petitioners and Petitioner Worthington 

Industries, Inc. With them on the briefs were Ethan G. 

Shenkman and Jonathan S. Martel. Zachary J. Lee entered an 

appearance.
2

David M. Williamson argued the cause and filed the briefs 

for petitioner Choice Refrigerants.

Andrew S. Coghlan, Attorney, U.S. Department of Justice, 

argued the cause for respondents. On the brief were Todd Kim, 

Assistant Attorney General, and Eric G. Hostetler, Attorney.

Melissa J. Lynch and David Doniger were on the brief for 

amicus curiae Natural Resources Defense Council in support 

of respondents.

Before: HENDERSON, PILLARD and WALKER, Circuit 

Judges.

Opinion for the Court filed by Circuit Judge WALKER. 

Opinion concurring in part and dissenting in part filed by 

Circuit Judge PILLARD.

WALKER, Circuit Judge: Fridges, freezers, and airconditioning are technological marvels, making our lives much 

more comfortable. But those amenities rely on harmful 

greenhouse gases called hydrofluorocarbons — HFCs for 

short.

According to the Environmental Protection Agency, those 

gases threaten the environment because they “can be hundreds 

to thousands of times more potent than carbon dioxide.” 86 

Fed. Reg. 55,123 (Oct. 5, 2021). To reduce their use, Congress 

enacted the American Innovation and Manufacturing Act. 42 

U.S.C. § 7675. The Act directs the EPA to pass a rule phasing

them out. Id. § 7675(e).

After the EPA passed that rule, two regulated companies 

and three trade associations sought judicial review. They say 
3

that the agency exceeded its statutory authority in two different 

ways, and that the Act violates the nondelegation doctrine. 

One of the statutory arguments fails, as does the 

nondelegation challenge. But the remaining argument has 

merit: The EPA lacked statutory authority to pass two measures

regulating the distribution of HFCs. So we vacate those parts 

of the EPA’s rule and remand to the agency. 

I. Background

A. Congress Tasked the EPA with Reducing HFC Use 

The United States has long struggled with the

environmental impact of refrigeration technology. Before 

fridges, freezers, and air conditioners used hydrofluorocarbons

as coolants, they used chlorofluorocarbons. But 

chlorofluorocarbons deplete the ozone layer. So in 1990 

Congress started to phase them out. 42 U.S.C. §§ 7671a, 

7671c. 

That prompted a shift to HFCs. But Congress’s change

swapped one environmental hazard for another. HFCs, the 

EPA says, are harmful greenhouse gases — “hundreds to 

thousands of times more potent than carbon dioxide.” 86 Fed. 

Reg. at 55,123.

In 2020, Congress intervened again, this time passing the 

American Innovation and Manufacturing Act to phase out 

HFCs. 42 U.S.C. § 7675. The Act directs the EPA to “issue a 

final rule . . . phasing down” HFCs “through an allowance

allocation and trading program.” Id. § 7675(e)(3). The Act 

provides the outline for how that program will work, leaving 

the agency to fill in the details. 
4

Here’s how it works. The EPA first calculates the baseline 

levels of HFC production and consumption in the United 

States. Id. § 7675(e)(1)(C). The agency then caps maximum 

annual HFC production and consumption at a percentage of 

those baselines — for instance, ninety percent in 2023. Id. 

§ 7675(e)(2)(B), (C). Over time, the caps come down, 

eventually reaching fifteen percent in 2036. Id. 

To ensure that production and consumption stay under the

respective caps, the Act puts in place a system of “allowances.”

Id. § 7675(e)(2)(D). An allowance is like a license; without 

one, “no person shall . . . produce” or “consume” HFCs. Id.

§ 7675(e)(2)(A).

Allowances are initially distributed to HFC users by the 

EPA. Once allocated, HFC users can buy and sell allowances 

from one another to adjust their production or consumption 

capacity. Id. § 7675(g). The total number of allowances in 

circulation corresponds to the current HFC production or

consumption cap. 

Late last year, the EPA issued its final Phasedown Rule,

implementing the cap-and-trade program. 40 C.F.R. pt. 84. 

Among other things, the Phasedown Rule calculates the annual 

production and consumption caps, explains how the agency 

will distribute allowances, and establishes reporting and 

auditing requirements for HFC consumers. Id.

B. The Petitioners Make Three Challenges to the Rule

The petitioners challenge three different aspects of the 

Phasedown Rule. 
5

First, Choice Refrigerants, a manufacturer of heating and 

cooling chemicals, challenges the EPA’s authority to regulate 

HFCs within blends. 

An HFC blend is a mix of HFCs and other chemicals.

Blends are better than plain-vanilla HFCs for some heating and 

cooling applications. Choice’s flagship product is an HFC 

blend that it manufactures abroad and imports into the United 

States.

The EPA says mixing an HFC with another chemical does 

not exempt the HFC from the cap-and-trade program. So 

importing blends “requires expenditure of allowances,” with 

the number of “allowances necessary” determined according to 

the “components of the blend that are regulated HFCs.” JA 

1112; see also 86 Fed. Reg. at 55,133, 55,142. If that’s correct, 

Choice must buy allowances to import its blend, and its 

production costs will go up.

Second, Choice claims that Congress impermissibly 

delegated legislative power to the EPA by giving it unguided 

discretion to distribute HFC allowances. 

The Act lists six types of HFC users — including 

“mission-critical military” users — who get preferential access 

to the pool of allowances. 42 U.S.C. 

§ 7675(e)(4)(B)(iv)(I)(ee). The Act also lets the agency 

designate other “essential” users who should get allowances.

Id. § 7675(e)(4)(B)(i)-(ii). But beyond that, Choice argues, the 

Act lets the EPA decide who should get the remaining 

allowances. And because the statute gives no additional 

guidance, Choice says it violates the nondelegation doctrine.

Third, three trade associations challenge two HFCdistribution regulations in the EPA’s rule. The first regulation
6

mandates refillable cylinders to transport HFCs, thus banning 

the disposable cylinders used by the industry today. 40 C.F.R. 

§ 84.5(h). The second regulation establishes a certification and 

tracking system for HFC distribution. Id. § 84.23(a). Under 

that system, “any person who imports, sells, or distributes” 

HFCs “must permanently affix a QR code to the [HFC’s] 

container that documents a valid certification identification.” 

Id. § 84.23(c)(2).

The trade associations argue that the Act does not give the 

EPA authority to pass those regulations — nowhere does the 

Act say anything about QR codes or refillable cylinders. That 

challenge is joined by Worthington Industries, the only 

domestic manufacturer of refillable and disposable cylinders.

II. Analysis

Under the Clean Air Act, this Court may set aside the 

EPA’s Phasedown Rule if it is “arbitrary, capricious, an abuse 

of discretion, or otherwise not in accordance with law.” 42 

U.S.C. § 7607(d)(9)(A); see id. §§ 7607(d)(1)(I), 

7675(k)(1)(C). We “apply the same standard of review under 

the Clean Air Act as we do under the Administrative Procedure 

Act.” Maryland v. EPA, 958 F.3d 1185, 1196 (D.C. Cir. 2020)

(cleaned up).

Applying that standard, we vacate in part the EPA’s 

Phasedown Rule. Choice’s challenges fail: The AIM Act gives 

the EPA authority to regulate HFCs within blends, and we may 

not consider Choice’s nondelegation argument because Choice

failed to exhaust it before the agency. But the trade 

associations’ petition fares better: The EPA does not identify a 

statutory provision authorizing its QR-code and refillablecylinder rules. So we vacate those parts of the Phasedown Rule 

and remand to the agency. 
7

A. The EPA May Regulate HFCs Within Blends

The EPA has statutory authority to regulate HFCs within 

blends. That’s because an HFC within a blend remains a 

regulated HFC under the Act. 

Start with the EPA’s statutory authority. The AIM Act 

directs the EPA to “phas[e] down the production [and 

consumption] of regulated substances . . . through an 

allowance allocation and trading program.” 42 U.S.C.

§ 7675(e)(3)(A)-(B). So the EPA has authority to require 

allowances for any regulated substance. Id. § 7675(e)(2)(A).

The Act defines a “regulated substance” to include HFCs

“listed” in a statutory table. Id. § 7675(b)(11), (c)(1) (table of 

regulated substances). The HFCs listed in the table are 

identified by their molecular formulas. Id. 

Under that definition, an HFC within a blend is still a 

“regulated substance” because it is chemically identical to an 

HFC outside of a blend. Both have the same molecular 

structure. As the EPA put it during notice and comment, “[t]he 

components [of a blend] are not chemically altered in [the 

blending] process.” JA 1112. 

In other words, an HFC in a blend of other chemicals is 

like a blue M&M in a bag of red M&Ms. The blue one does 

not stop being blue just because it is tossed in with a bunch of 

red ones. In the same way, an HFC mixed with other chemicals 

does not stop being a regulated substance under the Act. Cf. 42 

U.S.C. § 7675(e)(4)(A)(i) (when a chemical process 

“consume[s]” an HFC to create some other chemically-distinct 

product, that product is not covered by the allowance-trading 

program). 
8

In response, Choice argues that blended HFCs are different 

enough from unblended HFCs that they are not regulated 

substances. It says “blended products . . . have distinct 

physical and chemical properties” and “cannot be readily 

separated into their component[s] . . . without complex 

fractionation equipment.” Choice Br. 4.

That may be true. But it does not go to whether an HFC 

within a blend has a different molecular composition than an 

unblended HFC. And when pressed at argument, Choice 

repeatedly conceded that HFCs within blends are chemically 

identical to HFCs outside of a blend. 

Finally, Choice notes that under the Act, the EPA may not 

“designate as a regulated substance a blend of substances that 

includes a[n] [HFC] for purposes of phasing down production 

or consumption of regulated substances.” 42 U.S.C. 

§ 7675(c)(3)(B)(i). But that provision conditions the 

Administrator’s authority to list new HFCs as “regulated 

substances” subject to the allowance-trading program. Id.

§ 7675(c)(3)(A). Here, the EPA has not exercised that 

authority, let alone used it to list a blend as a regulated HFC. It 

has instead regulated already-listed HFCs within a blend. And 

the Act confirms that the prohibition on listing blends “does

not affect the authority of the Administrator to regulate under 

this Act a regulated substance within a blend of substances.” 

Id. § 7675(c)(3)(B)(ii) (emphasis added). 

B. Choice Failed to Exhaust Its Nondelegation Challenge

Next, Choice says Congress impermissibly delegated its 

legislative authority to the EPA. See 86 Fed. Reg. at 55,142

(noting EPA’s “considerable discretion” in allocating 

allowances under the AIM Act), 55,203 (final rule allocating 
9

allowances). But because Choice failed to make its 

nondelegation argument to the EPA during notice and 

comment, Choice may not raise that argument now.

Choice sues under § 307 of the Clean Air Act, which 

“appl[ies] to” the AIM Act. 42 U.S.C. § 7675(k)(1)(C). That 

cause of action has an exhaustion requirement: a litigant may 

raise in court only “an objection to a rule or procedure which 

was raised with reasonable specificity during the period for 

public comment.” Id. § 7607(d)(7)(B). 

Choice concedes that it did not raise its nondelegation 

argument during notice and comment. Instead, it says it did not 

need to exhaust its nondelegation argument because it is an 

objection to the statute and not an “objection to a rule or 

procedure” subject to exhaustion. Id. § 7607(d)(7)(B). 

That argument collapses under scrutiny. The Clean Air 

Act’s cause of action authorizes only a limited category of 

suits: “petition[s] for review of action of the Administrator [of 

the EPA].” Id. § 7607(b)(1) (emphasis added). So litigants 

using the Clean Air Act’s cause of action must bring challenges 

to agency action, not free-floating challenges to statutes. 

Statutes are passed by Congress, not the “Administrator [of the 

EPA].” Id. 

Thus, to the extent that Choice’s suit is an objection to the 

AIM Act alone, Choice fails to state a claim under the Clean 

Air Act. And to the extent Choice is challenging the 

Phasedown Rule, the Clean Air Act’s exhaustion requirement 

applies. 42 U.S.C. § 7607(d)(7)(B). Either way, Choice’s 

nondelegation claim is not properly before us. 

That said, Choice’s petition is best read as a challenge to 

the EPA’s rule. In substance, its argument is that the EPA’s 
10

rule is unlawful because the statute authorizing it is an 

unconstitutional delegation of legislative power. Indeed, 

Choice characterizes its argument that way in its brief. It lists 

the “ruling[ ] under review” as the “Cap-and-Trade Rule” and 

it asserts that “[t]his Court has jurisdiction . . . to review EPA’s 

final rule.” Choice Br. ii, 1. Because Choice’s challenge is to 

the Phasedown Rule, any objections to that rule had to be made

first to the EPA. 42 U.S.C. § 7607(d)(7)(B). Choice did not 

do that here. So we may not consider its nondelegation claim

now. 

Requiring litigants to first bring nondelegation challenges 

to the EPA may seem futile. After all, the agency cannot 

change Congress’s grant of broad discretion.1

 But the Clean 

Air Act’s exhaustion rule has no exception for futile 

challenges. Texas Municipal Power Agency v. EPA, 89 F.3d 

858, 876 (D.C. Cir. 1996) (per curiam) (no futility exception); 

see also Lead Industry Association Inc. v. EPA, 647 F.2d 1130, 

1172-74 (D.C. Cir. 1980) (no exception for constitutional 

challenges to the rulemaking process).

2

1 The agency could, in the rulemaking process, decide for itself that 

a statute unconstitutionally delegates too much power, rendering a 

rule unlawful. Cf. U.S. Const., art. II (the executive branch, acting 

under the President, has a duty to “take Care that the Laws be 

faithfully executed”). 

2 True, some constitutional challenges to agency action may be 

brought directly in district court — even if a statute requires other 

run-of-the-mill challenges to be first litigated before the agency. See 

Axon Enterprise, Inc. v. Federal Trade Commission, 143 S. Ct. 890 

(2023). But that doesn’t excuse Choice from the Clean Air Act’s 

exhaustion requirement here. When litigants choose to use a 

statutory review mechanism like the Clean Air Act’s, they must still 

meet its strictures. So even if Choice could have bypassed the Act’s 

exhaustion requirement by bringing its nondelegation claim directly 
11

C. The Refillable-Cylinder and QR-Code Rules Lack 

Statutory Basis

Finally, the trade associations and Worthington argue that 

the EPA’s refillable-cylinder and QR-code rules lack a 

statutory basis. We agree. The EPA has not identified a 

provision of the AIM Act giving it the authority to require 

refillable cylinders or a QR-code tracking system. 40 C.F.R. 

§§ 84.5(h), 84.23(a). 

To support those regulations, the EPA attempts to rely on 

two provisions of the AIM Act. It initially points to Section 

7675(k)(1)(A), which gives the agency authority to 

“promulgate . . . such regulations as are necessary to carry out 

the functions of the [EPA] under [the AIM Act].” The EPA 

recognizes that (k)(1)(A) is a source of procedural not 

substantive authority — it lets the agency pass rules to carry 

out powers granted by other provisions of the statute. 

For substantive authority, the EPA relies on Section 

7675(e)(2)(B):

(B) Compliance

For each year [of the phasedown period], 

the Administrator shall ensure that the 

annual quantity of all regulated substances 

produced or consumed in the United States 

does not exceed the product obtained by 

multiplying —

in district court (we take no position on whether it could), it did not 

do that here. 
12

(i) the production baseline or 

consumption baseline, as applicable; 

and

(ii) the applicable percentage listed on the 

table contained in subparagraph (C).

Relying on Congress’s instruction to “ensure” that HFC 

production and consumption “do[] not exceed” the phasedown 

cap, the EPA’s final rule claimed the “authority to establish 

complementary measures . . . [to] meet the statutory reduction 

[target],” 86 Fed. Reg. at 55,172 (citing 42 U.S.C. 

§ 7675(e)(2)(B)).

But the EPA’s reading has two major problems: It ignores 

the role that subsection (e)(2)(B) plays in the statutory scheme 

and it reads too much into the word “ensure.”

To start, subsection (e)(2)(B) is a math equation, not a 

grant of regulatory power. It tells the agency how to calculate 

the production and consumption cap for each year of the 

phasedown. To calculate the cap, the agency must 

“multiply[]” the “production baseline or consumption 

baseline” by the “applicable percentage listed on the table” in 

(e)(2)(C). 42 U.S.C. § 7675(e)(2)(B). 

Confirming that reading, statutory cross-references treat 

(e)(2)(B) as a formula setting the cap for each year of the 

phasedown. For example, subsection (e)(2)(D)(i) instructs the 

EPA to “determine the quantity of allowances . . . that may be 

used for the following calendar year” by referring to the cap 

“calculated under” (e)(2)(B). Id. § 7675(e)(2)(D)(i). 

Similarly, under (e)(5), the EPA may allow an HFC producer 

to make more HFCs than authorized by his “production 

allowances” if doing so “would not violate” the cap in 

(e)(2)(B). Id. § 7675(e)(5), (B)(iii).
13

Given the role that (e)(2)(B) plays in the statutory scheme, 

that subsection would be an odd place for Congress to locate a 

grant of sweeping regulatory power letting the agency pass 

additional measures to phasedown HFCs. True, the placement 

of statutory language is only one part of the puzzle. Courts 

must vindicate the plain meaning of the text wherever it is 

placed in the statute. But here the statutory text does not 

support the EPA’s assertion of power.

Reading subsection (e)(2)(B) to grant the EPA authority to 

pass complementary measures leans heavily on the word 

“ensure.” The EPA asserts that (e)(2)(B)’s use of “shall 

ensure” reflects Congress’s “intentional effort to confer the 

flexibility necessary [for] the agency to accomplish the 

statute’s aims” and so gives the EPA “more general authority 

to establish complementary measures to ensure that the 

statutory phasedown is achieved.” EPA Br. 52 (cleaned up).

We disagree. To “ensure” is “to make sure, certain, or 

safe.” Ensure (def. 1), Merriam-Webster (2023). So when 

Congress told the EPA to “ensure” that the annual HFC 

consumption cap is not “exceed[ed],” all it said was that the 

agency should guarantee that result. 42 U.S.C. § (e)(2)(B). 

Subsection (e)(2)(B) does not tell the agency anything about 

how to “ensure” the cap is met. 

The rest of the statute does that job. Congress gave the 

EPA the power to ensure the cap is met by using the allowancetrading program, id. § 7675(e), detailed statutory auditing and 

reporting requirements, id. § 7675(d), and the EPA’s power to 

pass rules regulating “practice[s], process[es], or activit[ies]” 

for “servicing, repair[ing], dispos[ing of], or install[ing] [HFC] 

equipment,” id. § 7675(h)(1). 
14

Those detailed instructions undercut the agency’s claim

that (e)(2)(B) gives it power to pass other measures. When 

“draftsmen[] mention . . . one thing, like a grant of authority” 

it “necessarily, or at least reasonably, impl[ies] the preclusion 

of alternatives.” Shook v. D.C. Financial Responsibility and 

Management Assistance Authority, 132 F.3d 775, 782 (D.C. 

Cir. 1998). Congress’s exhaustive instructions to the agency 

throughout the AIM Act make it less plausible that Congress 

meant the words “shall ensure” in (e)(2)(B) to give the EPA

broad power to pass new rules. 

That intuition becomes even stronger when we consider 

the breadth of the EPA’s claimed power. The refillablecylinder rule alone is likely to impose between $ 441 million

and $2 billion in costs on the regulated industry. 86 Fed. Reg. 

at 55,174 ($ 441 million estimate); JA 119 ($ 2 billion

estimate). It is unlikely that Congress would have granted the 

agency authority to pass a rule of that magnitude in a provision 

of the statute that says nothing about complementary measures, 

refillable cylinders, or QR Codes.

To be clear, we do not decide this case under the majorquestions doctrine. That doctrine holds that courts “expect 

Congress to speak clearly if it wishes to assign to an agency 

decisions of vast economic and political significance.” West 

Virginia v. EPA, 142 S. Ct. 2587, 2605 (2022) (cleaned up). 

And the EPA’s QR-code and refillable-cylinder rules are less

important and expensive than other regulations to which the 

Supreme Court has applied that doctrine. See id. at 2609; NFIB 

v. OSHA, 142 S. Ct. 661, 666 (2022). 

Instead, we rely on another long-standing rule of 

interpretation: “Congress . . . does not alter the fundamental 

details of a regulatory scheme in vague terms or ancillary 

provisions.” Whitman v. American Trucking Associations, 531 
15

U.S. 457, 468 (2001). Whereas the major-questions doctrine 

has a constitutional basis — safeguarding the “separation of 

powers” by ensuring that agencies do not use statutory 

ambiguities to make decisions vested in our elected

representatives — the American Trucking rule rests on a more 

modest intuition about how we use language. West Virginia, 

142 S. Ct. at 2609. The touchstone of statutory interpretation

is always to “interpret the words consistent with their ordinary

meaning at the time Congress enacted the statute.” Wisconsin 

Central Ltd. v. United States, 138 S. Ct. 2067, 2070 (2018)

(cleaned up). Ordinary readers of English do not expect 

provisions setting out math equations to empower an agency to 

prescribe other “fundamental details of a regulatory scheme.” 

Whitman, 531 U.S. at 468. 

Because the EPA’s interpretation of (e)(2)(B) seeks to do 

just that, it strains against the ordinary use of language. That 

is an important clue that the EPA advances an implausible 

reading of the statute. 

* * *

The EPA has not identified a statute authorizing its QRcode and refillable-cylinder regulations. We therefore vacate 

those parts of the Phasedown Rule and remand to the agency.

We deny Choice’s challenges to other aspects of the rule.

So ordered.
PILLARD, Circuit Judge, concurring in part and dissenting 

in part:

I agree with my colleagues that EPA has the statutory 

authority to regulate hydrofluorocarbons (HFCs) that are 

contained within blends. I also agree that we may not hear 

Choice’s nondelegation argument because Choice failed to 

exhaust it before the agency. 

I write separately to explain why EPA has the authority to 

require refillable cylinders for regulated HFCs and to

implement a QR-code tracking system to trace the import, sale, 

and distribution of HFCs through the supply chain. In the 

American Innovation and Manufacturing Act, Congress 

imposed on EPA a duty to “ensure” compliance with the

schedule Congress mandated for phasing down HFC 

production and consumption. 42 U.S.C. § 7675(e)(2)(B). The 

Act makes clear that Congress intended its phasedown 

schedule to be met. To that end, it empowered EPA to 

“promulgate such regulations as are necessary” to effect 

compliance. Id. § 7675(k)(1)(A).

The rule under review falls squarely within EPA’s 

congressionally delegated authority: The agency determined 

that, to accomplish the HFC phasedown, it was necessary to 

require refillable cylinders with unique, trackable QR codes, so 

it promulgated a final rule to that effect. After all, requiring 

refillable and trackable cylinders is a straightforward way to 

“ensure” that the regulated substances they contain correspond 

to allowances the statute requires. Without such tools, it is hard 

to see how EPA can ensure the phasedown.

My colleagues’ conclusion that EPA’s duty to ensure 

compliance is nothing more than a “math equation,” Maj. Op. 

12, understates and undercuts the responsibility Congress gave 

the agency. Their reading runs counter to the statute’s text and 

structure. It will hamstring EPA’s efforts to combat illicit trade 
2

in HFCs, making it less likely that the United States 

accomplishes the HFC reductions Congress mandated. And 

the majority’s interpretation will have unfortunate side effects

for domestic industry and law enforcement: Even as it places 

law-abiding U.S. importers and producers at a competitive 

disadvantage by making the United States market an easy 

target for illegal HFCs, it will help the illegal product to 

circulate unseen by U.S. law enforcement. 

I.

HFCs are highly potent greenhouse gases with global 

warming potentials “that can be hundreds to thousands of times 

more potent than carbon dioxide.” 86 Fed. Reg. 55,116, 

55,123/3 (Oct. 5, 2021). “[T]heir use is growing worldwide,” 

in part due to “the increasing use of refrigeration and air 

conditioning equipment globally.” Id. The amount of HFCs in 

the global atmosphere is thus increasing at “accelerating rates.”

Id. “[E]levated concentrations of [greenhouse gases] including 

HFCs have been warming the planet, leading to changes in the 

Earth’s climate,” such as “in the frequency and intensity of heat 

waves, precipitation, and extreme weather events.” Id. at 

55,124/2. 

Recognizing that releases of these potent greenhouse gases

are projected to continue accelerating rapidly, the United States 

joined with more than 140 countries to ratify the so-called 

Kigali Amendment to the Montreal Protocol on Substances that 

Deplete the Ozone Layer. The signatories to the 2016 Kigali 

Amendment committed to a “global phasedown of the 

production and consumption of HFCs.” Id. at 55,123/3-24/1; 

see id. at 55,139/1-2. If fully implemented, the Kigali 
3

Amendment “is expected to avoid up to 0.5 °C of warming by 

2100.” Id. at 55,124/1. 

In keeping with that international commitment to phase 

down HFCs, Congress enacted the bipartisan American 

Innovation and Manufacturing (AIM) Act. Pub. L. No. 116-

260, div. S, § 103, 134 Stat. 2255, 2255-71 (2020) (codified at 

42 U.S.C. § 7675). Under the Act, HFC production and 

consumption in the United States must be phased down to 15 

percent of baseline levels by 2036. 42 U.S.C. § 7675(e)(2). 

The Act imposes those steep restrictions on HFC supply while 

other parties to the Kigali Amendment are also limiting the 

supply of HFCs in “ways that are similar.” 86 Fed. Reg. at 

55,139/1. 

Ensuring compliance with that HFC phasedown will be no 

small feat. As countries around the world tighten restrictions 

on HFCs, incentives to trade illegally are surging. In EPA’s

experience—including during the United States’ participation 

in the global phasedown of ozone-depleting substances and in 

the early stages of the HFC phasedown elsewhere—declining 

allowances for lawful import and production of a substance 

tend to increase its illegal trade. See id. at 55,166/2-68/1, 

55,166/2 n.63. Indeed, observed rates of noncompliance with 

HFC quota systems have been dramatic. One study found that 

even those imports that were reported to European customs 

officials “exceeded the quota amount by 16 percent in 2019 and 

33 percent in 2020.” Id. at 55,167/1. In another study, 72 

percent of surveyed companies in Europe, where disposable 

cylinders are illegal, “had seen or been offered refrigerants in 

disposable cylinders.” Id. at 55,166/3. The United States faces 

similar pressures. Id. at 55,167/2. Without appropriate 

compliance measures to enable vigorous enforcement, illegal 

trade will likely swamp the congressionally mandated 

phasedown. Left unchecked, illicit trade in HFCs threatens to 
4

“significantly harm the environment, the United States 

economy, and consumer and worker safety.” Id. at 55,168/1. 

In promulgating the phasedown rule mandated by the Act, 

EPA thus took a “multifaceted approach . . . to deter, identify, 

and penalize illegal activity.” Id. EPA adopted sensible 

compliance measures to ensure the HFC phasedown and “to 

create a level playing field for the regulated community.” Id. 

Two such compliance measures are at issue here: first, a 

prohibition on single-use cylinders for regulated HFCs and,

second, a container-tracking system requiring QR codes to 

provide visibility into the import, sale, and distribution of 

HFCs. 

II.

Two provisions of the AIM Act work in tandem to 

authorize EPA’s refillable-cylinder and QR-code regulations. 

First is subsection 7675(k)(1)(A), which empowers EPA to 

“promulgate such regulations as are necessary to carry out the 

functions of the Administrator” under the Act. 42 U.S.C. 

§ 7675(k)(1)(A). The majority explains that “(k)(1)(A) is a 

source of procedural not substantive authority – it lets the 

agency pass rules to carry out powers granted by other 

provisions of the statute.” Maj. Op. 11. So far, so good. On 

this much the majority and I agree: Whenever the Act assigns 

to EPA a substantive responsibility or function, EPA may also 

promulgate rules “as necessary” to carry out that function. 

The second provision—and source of EPA’s substantive 

responsibility—is subsection 7675(e)(2)(B). Recall that 

subsection (e)(2)(B), entitled “Compliance,” says that EPA 

“shall ensure” that annual HFC production or consumption

“does not exceed” the congressionally mandated cap for any

given year. 42 U.S.C. § 7675(e)(2)(B). On the meaning of that 

provision, the majority and I part ways. To be sure, the 
5

majority starts off on the right foot: Subsection (e)(2)(B) does 

set out the production and consumption caps and provide the 

formula for calculating them. But, while it includes a formula, 

subsection (e)(2)(B) is not just a “math equation.” Maj. Op. 

12. 

In subsection (e)(2)(B), Congress called on EPA to make 

certain that the HFC phasedown is achieved. That duty flows 

from the plain text of the provision. The operative words are

“shall ensure.” “The first sign that the statute impose[s] an 

obligation is its mandatory language: ‘shall.’” Me. Cmty. 

Health Options v. United States, 140 S. Ct. 1308, 1320 (2020). 

“[T]he word ‘shall’ usually connotes a requirement.” Id. 

(quoting Kingdomware Techs., Inc. v. United States, 579 U.S. 

162, 171 (2016)). The duty subsection (e)(2)(B) places on EPA 

is to “ensure”—that is, to guarantee—that annual HFC 

production or consumption “does not exceed” the 

congressionally mandated cap for any given year. 42 U.S.C. 

§ 7675(e)(2)(B). In other words, as EPA put it, the agency has 

“the responsibility to ensure that the statutorily required 

phasedown occurs.” 86 Fed. Reg. at 55,172/3. 

Congress supplied another cue as to the intended meaning 

of subsection (e)(2)(B): its heading. See Merit Mgmt. Grp., LP 

v. FTI Consulting, Inc., 138 S. Ct. 883, 893 (2018). In 

subsection (e)(2)(B), Congress described EPA’s authority as 

one of “Compliance”—not just “Calculation.” That choice of 

heading underscores that Congress intended to impose on EPA 

a duty to guard against non-compliance with the 

congressionally mandated phasedown. 

As the majority recognizes, however, subsection (e)(2)(B) 

does not spell out in detail how the agency is to ensure the cap 

is met. Maj. Op. 13. For that, we return to EPA’s procedural 

authority found in subsection (k)(1)(A). Because one of the 
6

Administrator’s functions under the Act is to “ensure” 

compliance with the phasedown, 42 U.S.C. § 7675(e)(2)(B), 

EPA may issue appropriate rules as necessary to do so, id. 

§ 7675(k)(1)(A). That is, Congress delegated to EPA the 

authority to promulgate reasonable compliance measures, so 

long as they are necessary to guaranteeing that the phasedown 

is met (and do not conflict with any other provision of the Act). 

The final rule under review is a run-of-the-mill exercise of 

EPA’s compliance responsibilities under the Act. EPA 

concluded that both the refillable-cylinder and QR-code

requirements were “necessary” to “ensure” annual HFC 

production and consumption do not exceed the phasedown 

limits. See id. § 7675(e)(2)(B), (k)(1)(A). As EPA explained, 

“[a] program to control the production and import of HFCs is 

only achievable to the extent it can be enforced.” 86 Fed. Reg.

at 55,175/1. Therefore, “[r]estrictions designed to deter and 

identify illegal imports . . . are a necessary component to such 

a program.” Id. (emphasis added). 

A refillable-cylinder requirement is necessary because the 

“visual differences” between disposable and refillable 

cylinders “allow Customs officials and law enforcement 

personnel to easily distinguish” between legally permitted 

refillable cylinders and disposable ones that “are favored for 

illicit trade.” Id. at 55,173/1. Indeed, refillable-cylinder 

requirements have a “proven track record of facilitating 

detection and interdiction of illegal HFCs.” Id. Several other 

jurisdictions, including the European Union, Canada, 

Australia, and India, have already adopted such requirements. 

Similarly, “a comprehensive container tracking system is 

needed” so as “[t]o help ensure the quantity of regulated 

substances produced or consumed in the United States does not 

exceed the Congressionally mandated cap.” Id. at 55,186/1. 
7

The QR-code tracking system makes it easy to spot HFCs that 

do not enter the market legally. Id. at 55,183/3. Such a system 

is also “especially important for identifying illegal production

[within the United States]—as that material will not have a 

check at the port like imports.” Id. at 55,185/3. 

Not only were both measures permissibly promulgated 

under the AIM Act, but they were also well within EPA’s 

expertise. For example, EPA has long regulated the containers 

and labeling for other substances it regulates, such as

pesticides, see, e.g., 40 C.F.R. § 156.3 et seq. (labeling 

requirements); id. § 165.1 et seq. (container requirements), and

underground storage tanks for biofuels, see id. § 280.10 et seq. 

And, in running other trading programs, EPA is familiar with 

the need for systems to track substances subject to statutory 

quantity controls. See, e.g., id. § 80.1425 et seq. (requiring 

renewable identification numbers, or RINs, to account for 

batches of qualifying renewable fuels). Furthermore, EPA has 

long partnered with other federal agencies, including U.S. 

Customs and Border Protection (CBP) and the Department of 

Justice, to help curb illicit trade in substances that it regulates. 

Since the 1990s, for instance, EPA has coordinated with CBP 

and other agencies to ensure the phaseout of ozone-depleting 

substances—an experience which informed EPA’s 

promulgation of the rule at issue here. See 86 Fed. Reg. at 

55,167/3. 

As the final rule well illustrates, EPA’s compliance 

function is vital to the statutory scheme. Ensuring compliance 

with a stringent new HFC phasedown is a daunting task, for 

which agency specialization and adaptability are paramount. 

Rather than confine EPA to any one tool, Congress left it to 

agency discretion to determine how best to root out noncompliant trade in HFCs. Given sophisticated efforts to evade 

HFC phasedowns elsewhere—as well as EPA’s own 
8

experience combatting illicit trade in ozone-depleting 

substances—it made sense for Congress not to specify precise 

methods, but to charge EPA to adopt compliance measures as 

necessitated by the circumstances, and to adapt and improve 

them based on the lessons of experience. See id. at 55,166/2-

68/1. 

The AIM Act is clear and robust on paper. But without the 

subsection (e)(2)(B) compliance function, it may prove flimsy 

in practice. As EPA explained, the steep domestic phasedown 

of HFCs will meet forceful and sophisticated efforts from 

around the globe to evade the HFC allowance system. See id. 

The court’s decision today to read out of the Act the limited but 

flexible authority to prevent such noncompliance leaves EPA 

with few and inadequate tools to ensure the HFC phasedown is 

achieved.

III.

The majority resists the plain meaning of subsection 

(e)(2)(B) by characterizing it as only “a formula setting the cap 

for each year of the phasedown.” Maj. Op. 12. That is a 

cramped reading of the language Congress used in subsection 

(e)(2)(B). 

For one, Congress’ use of the word “ensure”—which, as 

the majority agrees, means to make sure or to “guarantee,” Maj. 

Op. 13—is a perplexing one for a provision that my colleagues 

say describes only a calculation. If Congress wanted 

subsection (e)(2)(B) to provide EPA only the limited authority 

to calculate the production and consumption caps, it could 

easily have done so. Subsection (e) is littered with instructions 

for EPA to establish or calculate certain numerical values: 

Congress instructed that EPA “shall establish” production and 

consumption baselines for the phase-down of regulated 

substances, 42 U.S.C. § 7675(e)(1)(A); that each of those 
9

baselines “is the quantity equal to the sum of” certain 

statutorily enumerated calculations, id. § 7675(e)(1)(B), (C); 

and that, in calculating those baselines, “the Administrator 

shall use” certain exchange values provided in the statute, id. 

§ 7675(e)(1)(D). Put otherwise, Congress knew how to 

prescribe a mere calculation. It did more than that in subsection 

(e)(2)(B). 

Nor should we read much into the fact that the Act at times 

gives EPA “detailed instructions” regarding other agency 

responsibilities. Maj. Op. 14. The expressio unius canon on 

which the majority relies is “an especially feeble helper in the 

administrative setting, where Congress is presumed to have left 

to reasonable agency discretion questions that it has not 

directly resolved.” Cheney R.R. Co. v. ICC, 902 F.2d 66, 69 

(D.C. Cir. 1990). In the administrative context, “we have 

consistently recognized that a congressional mandate in one 

section and silence in another often ‘suggests not a prohibition 

but simply a decision not to mandate any solution in the second 

context, i.e., to leave the question to agency discretion.’” 

Catawba Cnty., N.C. v. EPA, 571 F.3d 20, 36 (D.C. Cir. 2009) 

(quoting Cheney R.R. Co., 902 F.2d at 69). 

The majority’s reliance on the expressio unius canon is

doubly irksome, however, because we normally “do not read 

the enumeration of one case to exclude another unless it is fair 

to suppose that Congress considered the unnamed possibility 

and meant to say no to it.” Barnhart v. Peabody Coal Co., 537 

U.S. 149, 168 (2003). To read the statute as the majority does,

we would have to “be confident that a normal draftsman when 

he expressed ‘the one thing’”—for example, the creation of an 

allowance-allocation-and-trading program—“would have 

likely considered the alternatives that are arguably 

precluded”—that is, refillable-cylinder and QR-code 

requirements—and by not mentioning them meant to put them 
10

off limits. Shook v. D.C. Fin. Resp. & Mgmt. Assistance Auth., 

132 F.3d 775, 782 (D.C. Cir. 1998). But neither the majority 

nor the trade associations have provided any reason to think 

that Congress considered and rejected either a refillablecylinder requirement or container-tracking system. 

Rather, recognizing that it could not foresee every way in 

which regulated entities might evade the HFC phasedown, 

Congress in subsection (e)(2)(B) stated EPA’s compliance 

duties in general terms so as “‘to confer the flexibility 

necessary’ for [EPA] to address yet unknown threats” to the 

HFC phasedown. Corbett v. TSA, 19 F.4th 478, 488 (D.C. Cir. 

2021) (quoting Massachusetts v. EPA, 549 U.S. 497, 532 

(2007)). To the extent EPA’s compliance authority might be 

viewed as “broad,” Maj. Op. 14, that reflects Congress’ 

deliberate choice to leave specific compliance measures to 

EPA’s discretion. “Congress knows to speak in plain terms 

when it wishes to circumscribe, and in capacious terms when it 

wishes to enlarge, agency discretion.” City of Arlington v. 

FCC, 569 U.S. 290, 296 (2013). 

Finally, it bears emphasis that the compliance authority 

granted and exercised here is not, relatively speaking, 

particularly broad. My colleagues’ conclusion that the 

authority EPA claims under subsection (e)(2)(B) is somehow 

disproportionate to the terms in which Congress conferred it, 

Maj. Op. 13-15, is badly misplaced. The modest regulatory 

measures EPA promulgated are a far cry from the kinds of 

sweeping or implausible measures that have triggered extra 

skepticism from the Supreme Court—whether that scrutiny 

takes the form the trade associations demand, see Association 

Reply Br. 11-13 (citing West Virginia v. United States, 142 S. 

Ct. 2587 (2022)), or the majority undertakes, see Maj. Op. 14-

15 (citing Whitman v. Am. Trucking Ass’ns, 531 U.S. 457 

(2001)). For one thing, EPA acted here within the limited 
11

ambit of a recent, pollutant-specific statute to deploy familiar 

tools to help effectuate a defined phasedown. For another, the 

ostensible “magnitude” of the compliance costs on industry is

overstated. The prohibition on single-use cylinders is projected 

to cost a mere $22 million annually on average, and the QRcode tracking system would cost even less. 86 Fed. Reg. at 

55,174/1; U.S. Env’t Prot. Agency, EPA-HQ-OAR-2021-

0044-0227-02, Regulatory Impact Analysis for Phasing Down 

Production and Consumption of Hydrofluorocarbons (HFCs) 

69 (2021) (J.A. 720). Those costs would seem to be a mere

drop in the bucket for a multi-billion-dollar regulated industry.

And they are no reason for enhanced judicial scrutiny in the 

face of the far greater health and welfare costs likely to flow 

from circumventing the phasedown. See 86 Fed. Reg. at 

55,119/1-2 & tbl.1, 55,197 tbl.8 (estimating the rule’s

annualized net benefits at more than $14 billion). 

In any case, the American Trucking decision relied on by 

the majority “stands for the rather unremarkable proposition 

that sometimes statutory silence, when viewed in context, is 

best interpreted as limiting agency discretion.” Entergy 

Corp. v. Riverkeeper, Inc., 556 U.S. 208, 223 (2009). But, as 

we have already seen, the statutory text and context here point 

in the other direction: Congress assigned to EPA the function 

of “ensur[ing]” nationwide “[c]ompliance” with the HFC 

phasedown schedule and empowered the agency to promulgate 

rules “as are necessary to carry out” that function. 42 U.S.C. 

§ 7675(e)(2)(B), (k)(1)(A). In so doing, Congress left the 

development of specific compliance measures up to EPA’s 

informed discretion. EPA’s entirely unsurprising choice to set 

up a standardized system for transporting HFCs in refillable

cylinders labeled with trackable QR-codes falls comfortably 

within that discretion. 
12

* * *

In short, EPA validly exercised its authority under the 

AIM Act to ban non-refillable cylinders and adopt a containertracking system. Because today’s decision understates and 

undercuts EPA’s statutorily imposed authority and duty to 

ensure compliance with the HFC phasedown, I respectfully 

dissent from Section II.C of the majority opinion.