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California respondents opposition to 26A305

State of California · 2026-09-09

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No. 26A305

In the Supreme Court of the United States

UNITED STATES POSTAL SERVICE, et al.,
Applicants,

CALIFORNIA, et al.,
Respondents.

DONALD J. TRUMP, et al.,
Applicants,

LEAGUE OF WOMEN VOTERS OF MASSACHUSETTS, et al.,
Respondents.

OPPOSITION TO APPLICATION

ANDREA JOY CAMPBELL ROB BONTA
Attorney General of Attorney General of California
Massachusetts SAMUEL T. HARBOURT
Solicitor General
NICHOLAS W. BROWN HELEN H. HONG
Attorney General of Principal Deputy Solicitor General
Washington AARON D. PENNEKAMP
Supervising Deputy Solicitor General
AARON D. FORD IAN FEIN*
Attorney General of Nevada L. NICOLE ALLAN
Deputy Solicitors General
(Additional counsel listed
STATE OF CALIFORNIA
on signature pages)
DEPARTMENT OF JUSTICE
455 Golden Gate Avenue, Suite 11000
San Francisco, CA 94102-7004
(415) 510-3466
Ian.Fein@doj.ca.gov
September 9, 2026 *Counsel of Record

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TABLE OF CONTENTS
Page

Introduction ......................................................................................................... 1
Statement ............................................................................................................ 5
Argument ........................................................................................................... 10
I. Defendants are unlikely to succeed on the merits...................... 10
A. USPS lacks statutory and constitutional authority for
its unprecedented interference with state elections
administration on the eve of a major election .................. 10
B. The USPS rule is also procedurally defective .................. 24
II. Equitable considerations weigh heavily against a stay ............. 30
Conclusion.......................................................................................................... 41

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INTRODUCTION

Allowing the challenged USPS rule to take effect for this year’s imminent

November elections would “be an unmitigated disaster.” Those were the words

recently used by Utah’s Lieutenant Governor and top elections official when

raising alarm bells over the catastrophic harms threatened by USPS’ new

rule. 1 Officials in Florida and Ohio have voiced similar concerns. 2 And

declarations in the record from over two dozen other senior elections officials,

see Dkt. 4—including the Republican-appointed Chair of the Wisconsin

Elections Commission, see Dkt. 100-1—confirm those fears.3 In some States,

unrebutted evidence establishes that compliance with USPS’ rule would be

impossible ahead of the midterms, meaning that millions of voters would be

unable to vote by mail and some would not be able to vote at all. In the

remaining States, there would be chaos—and a significant risk that millions

more voters would be denied the ability to vote.

1 McKellar, Utah Clerks Don’t Expect Lawsuits Over Trump’s Mail-In Voting

Rule to Impact Elections This Year, Utah News Dispatch (updated Aug. 28,
2026), https://perma.cc/64E6-GYFU.
2 Griffin et al., Trump’s War on Mail-In Ballots Has Voters Baffled, N.Y. Times

(Sept. 6, 2026), https://perma.cc/3HF3-EQVD; Trau, Ohio Election Officials
Warn Against Trump’s Mail-In Ballot Changes, News 5 Cleveland (Aug. 28,
2026), https://perma.cc/77D8-P6MV; Rich, It’s Too Late to Implement the USPS
Ballot-Mailing Rule for This Election, NYU Law Democracy Project (Sept. 9,
2026), https://perma.cc/R9G4-5RWS (views of Ohio county elections official).
3 All citations to the docket are to the district court docket in the case filed by

the plaintiff States, California v. USPS, No. 26-cv-13917 (D. Mass.).

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There is nothing “modest” (e.g., Appl. 2), equitable, or lawful about USPS’

new ballot-mail restrictions. Tens of millions of Americans will likely wish to

vote by mail this year. Under the challenged rule, ballots will not be delivered

to those voters unless each is registered in USPS’ new, not-yet-functional

online portal; a voter-specific Intelligent Mail barcode (IMb) is printed on

outgoing and return ballot envelopes; and those barcodes are accurately tied to

each voter and uploaded to that same portal. The efforts that state and local

elections officials would have to undertake to even begin an attempt at

compliance are herculean. Among other things, officials would have to obtain

USPS approval of new ballot-envelope designs on an unprecedented timetable;

purchase new envelopes to replace those already ordered (if they can find

vendors who can fulfill last-minute orders, which is doubtful); develop and

upgrade technological systems to generate IMbs; upload voter-specific

information to the portal; ensure that ballots have the proper IMb for each

recipient; and train state and local officials on how to undertake these tasks.

Each step of this process is fraught with an extreme risk of error. And

even if state and local officials were somehow able to implement the new rule

perfectly, there is a high risk of technical breakdown, ineptitude, and delay on

the part of USPS. Recent reports from a USPS whistleblower and others about

the agency’s “sloppy and rushed” development of its new online portal and

ballot-scanning process, e.g., Dkt. 115 at 13, call to mind the disastrous rollout

of Healthcare.gov in 2013. Similarly here, the federal government is relying

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on “slapdash software development,” id. at 15; “insufficient internal testing,”

id. at 16; and “‘siloed’ . . . teams of developers . . . working independently

without any effort towards interoperability,” id. at 17. USPS also apparently

plans to use a “batch” scanning protocol—called a “zero-percent failure policy,”

id. at 19—whereby thousands or tens of thousands of ballots will be processed

simultaneously, and “if even one bar code on one single ballot . . . fails to

properly scan,” “the entire batch is rejected and sent back to the state,” id. at

10. Scanning failures “are predictable—and likely,” in light of the many

“scanning problems” recently experienced by USPS. Id. at 20.

USPS’ unprecedented experiment with our Nation’s most cherished

franchise—the right to vote—is unlawful. When an agency “‘claim[s] to

discover in a long-extant statute an unheralded power’ representing a

‘transformative expansion in [its] regulatory authority’” on a matter of political

significance, West Virginia v. EPA, 597 U.S. 697, 724 (2022), the Court

“‘typically greet[s]’” such claims “with at least some ‘measure of skepticism,’”

Biden v. Nebraska, 600 U.S. 477, 516 (2023) (Barrett, J., concurring).

Skepticism is warranted here. Never before has USPS attempted to interfere

with elections in this way, let alone a fast-approaching election. And nothing

in federal law authorizes USPS to refuse to deliver ballots. To the contrary,

Congress has exhaustively enumerated the types of materials that USPS can

lawfully refuse to deliver. Ballots are not among them. Congress has also

repeatedly enacted measures to facilitate delivery and return of mail ballots.

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It has never tried to make it harder to vote by mail. And where Congress has

not authorized federal control over the “Times, Places and Manner” of

elections, U.S. Const., art. I, § 4, cl. 1, it is off limits to executive-branch

bureaucrats. In our constitutional system, that task is left to the States.

USPS’ novel ballot-mail requirements are also procedurally defective.

When unveiling new rules, agencies must acknowledge and take accountability

for the consequences of their actions. See, e.g., Encino Motorcars v. Navarro,

579 U.S. 211, 222 (2016). Here, USPS said almost nothing about the States’

reliance on existing mail-voting systems or the disruptive consequences of

rushing out a new set of requirements mere weeks before the November

elections. Nor did USPS provide more than vague, conclusory assertions about

its justification for this new measure. USPS also violated its duty to seek an

opinion from the Postal Regulatory Commission before making major service

changes. Had USPS complied, it is not difficult to imagine what the

Commission would have said. One commissioner recently criticized USPS for

failing to “run the tests to give us the validity that the damn thing will work.”

Katz, Postal Officials Say Trump’s Mail-Ballot Push Will Create Widespread

Errors, NOTUS (Aug. 27, 2026), https://perma.cc/SFX9-BZBD. “To do it in

three weeks,” he emphasized, “my God, there’s no way.” Id.

Given the new rule’s serious legal defects and threatened interference

with the ability of millions of people to vote, the request for a stay should be

denied. Mail-voting laws have made voting easier for millions of Americans,

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especially rural and disabled voters, as well as those traveling during the

election season. Indeed, in November 2024, roughly one in three American

voters cast mail ballots. States have also come to depend on mail voting. In

some cases, they have virtually eliminated in-person voting and lack the

infrastructure or resources to overhaul their systems by November. Whatever

else may be said of USPS’ new rule, it would wreak havoc on States and their

voters if it takes effect at this late point—when some States, including North

Carolina and Wisconsin, have already begun to mail out ballots. This Court

has repeatedly refused to allow far less disruptive changes to take effect on the

“the eve of an election.” E.g., Republican Nat’l Comm. v. Democratic Nat’l

Comm., 589 U.S. 423, 424 (2020) (per curiam). The Court should follow the

same course here by denying the stay application.

STATEMENT

1. The Constitution entrusts States with responsibility for regulating

federal elections unless Congress—not the Executive Branch—preempts their

legislative choices. E.g., U.S. Const. art. I, § 4, cl. 1. That was by design. The

Framers were intimately familiar with the British system, where “the

influence of the Crown on elections was most dangerously exerted.” 2 The

Records of the Federal Convention of 1787, at 204 (M. Farrand ed., 1911) (J.

Madison). The wisdom of the Framers’ decision has been validated over time.

As members of Congress recognized when overwhelmingly voting to enact the

Help America Vote Act of 2002, the Constitution’s “dispersal of responsibility

for election administration has made it impossible for a single centrally

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controlled authority to dictate how elections will be run, and thereby be able

to control the outcome.” H.R. Rep. No. 107-329, pt. 1, at 32 (2001).

One way that States have exercised their authority over federal elections

is by allowing mail voting. Mail voting increases turnout across political

parties and is especially helpful for rural and disabled voters.4 Today, “every

State lets at least some residents vote” by mail. Watson v. RNC, 146 S. Ct.

2165, 2171 (2026). Of those, 29 States mail a ballot to any voter who requests

one, while 8 States plus the District of Columbia mail a ballot to every

registered, active voter. See Nat’l Conf. of State Legislatures, Table 1: States

with No-Excuse Absentee Voting (updated July 17, 2026),

https://perma.cc/65CU-8UP3. Some States, such as Washington and Oregon,

have virtually eliminated in-person voting and use mail ballots for nearly all

voters (98.5% and 99.3% respectively). See, e.g., Dkt. 4-4 ¶ 9; Dkt. 4-19 ¶ 4.

And in many other States, large portions of the population vote by mail—for

example, 91.5% in Utah, 74.7% in Arizona, and 53.7% in Indiana.5 In the 2024

general election, roughly 30% of voters nationwide cast their ballots by mail.

See U.S. Election Assistance Comm’n, Election Admin. and Voting Survey, at

ii (June 2025), https://perma.cc/8J5Y-5TVN.

4 See, e.g., Angel et al., Mail Voting in the US: Data Points to Very Low Fraud

and Significant Benefits to Voters, Brookings (Nov. 6, 2025),
https://perma.cc/E3WD-8AN7.
5 See Stevenson, Map Shows States Most Affected by Trump’s Mail Ballot
Rules, Newsweek (Sept. 4, 2026), https://perma.cc/HK5E-4BUX.

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2. In March 2026, President Trump issued Executive Order 14399. 91

Fed. Reg. 17125 (Mar. 31, 2026). Among other things, Section 3 of the EO

required USPS to develop a new set of ballot delivery restrictions before the

November midterm elections. EO § 3(b). Plaintiffs challenged the EO’s

directive to USPS as ultra vires because Congress had not authorized any such

program. The district court agreed and enjoined USPS from implementing the

EO as to plaintiff States for the November midterm elections. See California

v. Trump, 2026 WL 1826490, at *15-18 (D. Mass. June 25, 2026). This Court

stayed the injunction. Trump v. California, 609 U.S. __, 2026 WL 2473573, *5

(2026) (per curiam). It deemed plaintiffs’ challenge to the EO nonjusticiable,

but made clear that they could challenge the final USPS rule and that nothing

in the Court’s decision suggested the rule “will necessarily be lawful.” Id.

In late August, USPS issued its final rule. 91 Fed. Reg. 54966 (Aug. 26,

2026). It provides for USPS to refuse to deliver ballots unless state and local

elections officials comply with multiple new requirements. Mail ballot

envelopes must now meet design standards that include, among other things,

full automation compatibility and a voter-specific IMb printed on outgoing and

return envelopes. Id. at 54990-54991 (§ 705.24.3). After elections officials

submit their designs for USPS review and obtain approval, id. at 54979, they

must upload voter information, including IMbs, to a new online portal, id. at

54991 (§ 705.24.4). Elections officials must then bring their mail ballots to

USPS for a “verification” process in which USPS will scan the IMbs before

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accepting the ballots for delivery. Id. at 54991 (§ 705.24.5); see id. at 54981-

54982. If the IMb on an envelope does not match the information in the portal,

the ballot “will be returned” and not delivered. Id. at 54991 (§ 705.24.5.3).

The rule was finalized just weeks before the November elections and only

days before ballots had to be sent in some States. See, e.g., N.C. Gen. Stat.

§ 163-227.10(a) (September 4 deadline to begin mailing ballots). USPS

nonetheless assigned the rule an “immediate effective date”—five days before

its publication in the Federal Register—to facilitate “implementation of this

rule in time for the 2026 general election.” 91 Fed. Reg. at 54966. The agency

only briefly addressed its decision to apply the rule to the imminent elections.

Id. at 54985. USPS noted “logistical or financial difficulties [that] states may

face complying with the rule, including some claims that immediate

implementation would prove impossible.” Id. But it brushed aside those

concerns and concluded “there is no compelling reason for any delay.” Id.

3. Plaintiff States filed this lawsuit challenging the rule, see Dkt. 1, and

moved for a temporary restraining order and preliminary injunction in light of

the rapidly approaching November elections, see Dkt. 5. On August 27, the

district court granted a TRO while the expedited preliminary injunction

proceedings continued. Dkt. 31. Defendants and intervenors appealed the

TRO and moved for a stay pending appeal. See Dkts. 58, 61. The district court

denied those motions. Dkt. 72. Briefing on defendants’ and intervenors’ stay

motions concluded in the court of appeals on September 2.

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The district court held its preliminary injunction hearing on September 3

and indicated that it intended to rule promptly. A few hours later, defendants

filed an application with this Court to stay the TRO. No. 26A297. The next

day, the district court granted plaintiffs’ motions for a preliminary injunction

and dissolved the TRO. App’x 47a-49a. The court concluded that plaintiffs

were likely to succeed on their claims that the rule exceeded USPS’

constitutional and statutory authority, id. at 25a-31a; that plaintiffs were

irreparably harmed by the rule, id. at 32a-43a; and that “immediate

implementation . . . threatens disenfranchisement of millions of United States

citizens,” whereas “the record includes no evidence relating to fraudulent mail

voting to support [USPS’] rushed implementation” of the rule, id. at 45a-46a.

The court enjoined the rule’s provisions only “to the extent [they are]

mandatory.” Id. at 48a. The court also limited the preliminary injunction to

the November elections. Id. at 47a-48a.

In its decision, the district court denied defendants’ request for a stay of

the preliminary injunction. App’x 46a-47a. Defendants and intervenors

appealed the injunction, Dkts. 158, 159, and moved for a stay before the court

of appeals. Defendants then withdrew their earlier application for this Court

to stay the (now-dissolved) TRO and filed this application to stay the

preliminary injunction. Plaintiffs filed their response to the stay motions in

the court of appeals on Monday of this week. As of the time of this filing, the

court of appeals has not yet ruled on the stay requests.

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ARGUMENT

Defendants bear “an ‘especially heavy burden’” in seeking emergency

relief from this Court. Little v. Reclaim Idaho, 591 U.S. 1060, 1063 (2020)

(Roberts, C.J., concurring in grant of a stay); see, e.g., Trump v. Illinois, 146 S.

Ct. 432 (2025). They must make “‘a strong showing that [they are] likely to

succeed on the merits’” and that the equitable considerations weigh in their

favor. Nken v. Holder, 556 U.S. 418, 434 (2009). They cannot do so. Indeed,

while defendants are exceedingly unlikely to prevail on the merits, the

equitable considerations make the relief sought by defendants unthinkable:

allowing USPS’ new rule to take effect would be virtually certain to prevent

many millions of Americans from casting mail ballots in this fall’s elections.

I. DEFENDANTS ARE UNLIKELY TO SUCCEED ON THE MERITS

A. USPS Lacks Statutory and Constitutional Authority for
Its Unprecedented Interference with State Elections
Administration on the Eve of a Major Election

1. A federal agency “‘literally has no power to act’ . . . unless and until

Congress authorizes it to do so.” FEC v. Cruz, 596 U.S. 289, 301 (2022). That

principle is especially clear in the context of federal elections because the

Constitution commits control to Congress and the States, not the Executive.

See U.S. Const. art. I, § 4, cl. 1. Here, none of the statutes invoked by

defendants even mention mail ballots. Nor do they confer on USPS authority

to virtually eliminate mail voting on the eve of a major election in States where

compliance with the rule’s requirements would be infeasible. Infra pp. 33-37.

The relevant provisions instead use generic language to grant USPS authority

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to adopt “rules and regulations . . . as may be necessary in the execution of its

functions”; engage in “powers incidental, necessary, or appropriate to the

carrying on of its functions”; and “provide for the collection, handling,

transportation, [and] delivery” of mail. 39 U.S.C. § 401(2), (10); id. § 404(a)(1).

Such “humdrum” provisions, Biden v. Nebraska, 600 U.S. 477, 499 (2023),

cannot support USPS’ exercise of sweeping power over elections. Defendants’

interpretation of those provisions would grant USPS “virtually unlimited

power,” id. at 502, to severely restrict mail voting—not just for this year’s

upcoming elections (when compliance is impossible or virtually impossible in

many States, infra pp. 33-37), but in all future elections. Under USPS’ novel

understanding of the postal statutes, its authority would allow it to impose any

conditions on mail voting, up to and including conditions that would effectively

abolish voting by mail. Cf. Dkt. 1 ¶ 4 (President Trump commenting that he

wants to “get rid of MAIL-IN BALLOTS”). For instance, USPS could require

a notarized signature on the ballot envelope; require voters to deliver their

ballots to a mail-processing facility in person; or accept mail ballots only during

a short period, perhaps just a single day. And under USPS’ theory, it could

take any of these steps mere days before mail voting begins in any election

cycle—without even being subject to basic arbitrary-and-capricious review

under the APA. Compare, e.g., Appl. 33, with infra p. 22. Such sweeping power

would enable USPS to effectively enact a nationwide policy against mail voting

that “Congress has chosen not to enact itself.” Biden, 600 U.S. at 503.

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Congress has hardly been silent on the subject of mail voting. It has

addressed the issue multiple times—but only by requiring USPS to make mail

voting easier for States and voters. The National Voter Registration Act

(NVRA) requires USPS to afford favorable postage rates to certain election

mail. 39 U.S.C. § 3629. And the Uniformed and Overseas Citizens Absentee

Voting Act (UOCAVA) requires USPS to deliver ballots “expeditiously and free

of postage.” Id. § 3406(a)(1). At the same time, Congress has declined to enact

legislation that would allow USPS to treat ballots as “nonmailable” if they do

not have barcodes like those required by the rule here. See, e.g., Vote by Mail

Tracking Act, H.R. 5658, 118th Cong. (2023), https://perma.cc/9PXA-A4TS. 6

And when Congress has made major changes to voting laws, it has been careful

to provide sufficient lead time to prevent interference with elections. See, e.g.,

107 Stat. 77, 89 (1993) (NVRA enacted 1993, but effective 1995).

There is no “historical precedent” for “the breadth of authority that the

[USPS] now claims,” “a telling indication that the [challenged rule] extends

beyond the agency’s legitimate reach.” NFIB v. OSHA, 595 U.S. 109, 119 (2022)

(per curiam) (internal quotation marks omitted); see, e.g., Dkt. 119-1 ¶ 17.

USPS’ prior exercises of statutory authority have involved mundane topics like

making sure “[a] clear space [is] available on all mail for the address,” Domestic

6 Under the “Vote by Mail Tracking Act”—a legislative proposal introduced in

several recent congressional sessions—States would be required to add
barcodes to mail ballots to enable voters to track their own ballots upon
submission. That legislative proposal does not provide for a portal or data-
matching scheme akin to what the challenged USPS rule requires.

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Mail Manual, 602.1.1; setting special “[p]eriodicals prices” for “publisher[s] or

registered news agent[s],” id. at 207.1.1; and allowing customers to “file an

indemnity claim for insured mail,” id. at 609.1.1. Even the examples of

election-specific policies discussed by defendants—such as optional “design

elements,” “prioritization” of ballot mail, and delivery of “absentee balloting

materials” if a mailer does not “affix the necessary postage,” Appl. 20 (internal

quotation marks omitted)—lack the sweeping features and disruptive

consequences of the rule challenged here. Indeed, none of those examples allow

USPS to refuse to deliver ballots. To the contrary, they make it easier for

ballots to be delivered and returned. That is consistent with Congress’

judgment and the bipartisan judgment of many States, that mail voting should

be encouraged. See, e.g., supra pp. 6, 12.

Defendants assert that plaintiffs draw an “illusory distinction” between

“rules that facilitate voting and rules that burden voting.” Appl. 21. But as

discussed above, it is Congress that has historically drawn that distinction. In

any case, plaintiffs can certainly conceive of “rules that facilitate voting” in far-

reaching ways that would exceed USPS’ powers. For example, without express

congressional authorization, USPS would not enjoy authority to mandate, as a

condition of delivering ballots, that States significantly expand the time

available for mail voting. Nor could USPS direct States to allow all of their

voters to cast ballots by mail, on a no-excuse basis, as a condition of accepting

ballots for delivery. It is not difficult to imagine a future presidential

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administration wanting to adopt such policies. Under defendants’ limitless

theory, those policies would presumably be valid. Under plaintiffs’ narrower,

more constrained view of USPS’ power, they would not.

Defendants also try to depict the USPS rule as “modest.” E.g., Appl. 2.

They assert that the rule “regulates only how States must prepare, design, and

present [ballot] envelopes,” id. at 18, and “requires States to upload . . .

information,” id. at 3. But “[l]abeling” the rule as modest “does not lessen [its]

effect.” Biden, 600 U.S. at 496. And USPS’ focus on “envelope-design and

addressee-information requirements” (e.g., Appl. 19) omits the rule’s most

significant feature: USPS will refuse to deliver ballots that do not satisfy its

untested protocol for matching ballot mail with information in its new, not-yet-

functional portal. Defendants likewise ignore the overwhelming record

evidence that the rule risks denying mail ballots to millions of voters. Infra

pp. 33-40. In light of that evidence, USPS has effectively “seize[d] control of

States’ administration of elections,” contra Appl. 3, at least for purposes of the

upcoming elections. Giving USPS the power to interfere with imminent

elections in this way would represent “‘a transformative expansion in [its]

regulatory authority.’” West Virginia v. EPA, 597 U.S. 697, 724 (2022).

For similar reasons, defendants are wrong to deny that this case poses a

“major question” of “political significance.” 91 Fed. Reg. at 54973; see Appl. 23-

24. The rule challenged here arguably has greater political significance than

the subject of any of the Court’s prior major-questions cases. Roughly one in

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three voters cast ballots by mail in the November 2024 election. Supra p. 6.

Because USPS’ new requirements will likely make mail voting impossible in

some States while depriving many voters of mail ballots in others, infra pp. 33-

40, the rule threatens to have a profound, calamitous impact on voting rights

and elections administration. If that does not make this case one of “‘political

significance,’” Biden, 600 U.S. at 502, it is hard to see what would. Cf. Bost v.

Ill. State Bd. of Elections, 607 U.S. 71, 77 (2026) (“electoral process” is “‘of the

most fundamental significance under our constitutional structure’”).

Yet another “telltale sign” that USPS has “transgressed its statutory

authority” is that it is regulating well “outside its wheelhouse.” Biden, 600 U.S.

at 518 (Barrett, J., concurring). USPS’ “day-in, day-out work,” id. at 519, of

ensuring “efficient postal services at fair and reasonable rates and fees,” 39

U.S.C. § 403(a), hardly qualifies it to make complex judgments about election

administration. Compare 52 U.S.C. § 20921 (establishing Election Assistance

Commission). Yet in the final rule’s text, USPS repeatedly invokes policy

concerns about “protect[ing] the integrity of federal elections.” E.g., 91 Fed.

Reg. at 54969. USPS’ application likewise portrays the rule as a “significant

federal election-integrity measure.” Appl. 13. In fact, that is the only asserted

basis USPS has ever provided for the rule. Plaintiffs now contend that the rule

is best understood as “regulat[ing] the U.S. mail” rather than “regulat[ing]

elections.” Id. at 19. But given the rule’s undeniable impacts on the

availability of mail voting in the upcoming election—and the rule’s origins in

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an elections-focused executive order, supra p. 7—it is difficult to see how

anyone could conceive of the rule as anything other than an elections

regulation, which has always been its sole purported policy justification.

The Court should thus be especially hesitant to conclude that Congress

intended to “delegate[] [the] ‘highly consequential power’” that USPS now

claims. Learning Res., Inc. v. Trump, 607 U.S. 229, 243 (2026) (plurality op.).

As discussed above, supra p. 5, the Framers deliberately entrusted power over

elections to Congress and the States, not the Executive. And where a case

involves a “core congressional power,” Learning Res., 607 U.S. at 243, or

threatens to “‘significantly alter the balance between federal and state power,’”

the Court generally “‘require[s] Congress to enact exceedingly clear language,’”

Ala. Ass’n of Realtors v. Dep’t of Health & Hum. Servs., 594 U.S. 758, 764 (2021)

(per curiam). That is the case here: the “policy of Congress for so great a part

of our constitutional life has been, and now is, to leave the conduct of the

election of its members to state laws, administered by state officers.” United

States v. Gradwell, 243 U.S. 476, 485 (1917). “[W]henever [Congress] has

assumed to regulate such elections it has done so by positive and clear statutes.”

Id. Defendants identify nothing “positive and clear” in support of USPS’ ballot-

verification and non-delivery rule—certainly nothing authorizing USPS to

adopt such a rule on the eve of a major election.

2. There is a second, independent statutory basis to invalidate USPS’

new rule. As USPS has acknowledged, only Congress has “authority to create

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new categories of ‘nonmailable matter.’” 91 Fed. Reg. at 54974; see Ex parte

Jackson, 96 U.S. 727, 732 (1877). That is because Congress has exhaustively

delineated the categories of materials that USPS can lawfully refuse to deliver.

See, e.g., 39 U.S.C. §§ 3001-3018; see also id. § 3001(a). And when Congress

enumerates an “‘established series,’” “any ‘omission’ from that series

necessarily ‘bespeaks a negative implication.’” Esteras v. United States, 606

U.S. 185, 195 (2024); see id. (“expressio unius est exclusio alterius”).

Consistent with that principle, the Court long ago held that USPS “cannot

exclude or refuse to deliver” mail unless authorized by “some law of Congress.”

Am. Sch. of Magnetic Healing v. McAnnulty, 187 U.S. 94, 109 (1902). “[P]ostal

laws make a clear-cut division between mailable and nonmailable material,”

Hannegan v. Esquire, Inc., 327 U.S. 146, 152 (1946), and the power to define

new categories of nonmailable material “has been zealously watched and

strictly confined” by Congress, id. at 156 n.18. Critically here, Congress has

not authorized USPS to treat ballots as nonmailable.

Defendants respond that the new data-matching and non-delivery

requirements do not qualify as “mailability” restrictions because they impose

“conditions on the acceptance of mailable matter” without “prohibit[ing]

[anything] from being mailed altogether.” 91 Fed. Reg. at 54973-54974; see

Appl. 22. But the same could be said of many restrictions expressly treated as

“mailability” rules by Congress. See, e.g., 39 U.S.C. § 3001(n)(1) (“hazardous

material is nonmailable” unless “authorized by” conditions imposed by USPS);

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id. § 3001(g) (fragrance ad samples nonmailable unless sealed in certain way);

id. § 3010 (conditions on mailing of sexually oriented ads). USPS cannot invent

a definition of “mailability” that ignores the way Congress has used the term.

And it is telling that, when members of Congress recently proposed legislation

conditioning the delivery of ballot mail on States’ use of trackable barcodes,

they did so by proposing to amend Title 39’s central mailability provision and

designating noncompliant ballots as “nonmailable.” Vote by Mail Tracking Act,

H.R. 5658, 118th Cong. (2023), https://perma.cc/9PXA-A4TS.

Defendants argue that, if the new ballot-mail restrictions are treated as

unlawful mailability regulations, then USPS would lack the ability to address

several other issues, ranging from the dangers of replica explosives to the

failure of senders to affix proper postage. See Appl. 17-23. Defendants are

wrong. Their examples only illustrate ways in which Congress has—unlike

here—given USPS express authority to adopt limits on mailability. Take, for

example, the two restrictions most heavily featured in defendants’ application:

restrictions governing replica explosives and cremated remains. E.g., id. at 16-

17. In 18 U.S.C. § 1716, Congress provided that all “mechanical, chemical, or

other devices or compositions . . . and all other natural or artificial articles,

compositions, or material which may kill or injure another, or injure the mails

or other property” “are nonmailable,” id. § 1716(a), unless mailed “in

accordance with the rules . . . prescribed by the Postal Service,” id. § 1716(j)(1).

Congress also provided that USPS can impose conditions on the mailing of “any

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such articles” that “are not outwardly or of their own force dangerous or

injurious.” Id. § 1716(b); see also 39 U.S.C. § 3001(a).

USPS has long taken the position that Section 1716 authorizes its

restrictions on replica explosives and cremated remains.7 That longstanding

position—which defendants apparently now disavow, see Appl. 17—was

plainly correct. Replica explosives are “devices or compositions” that threaten

to “injure” USPS workers or “injure the mails or other property,” 18 U.S.C.

§ 1716(a), because “postal operations have been disrupted and facilities have

been evacuated when replica or inert explosive devices have been discovered

in the mail,” 75 Fed. Reg. 30300, 30300 (June 1, 2010). Cremated remains, like

other “[p]owders” subject to USPS mailability restrictions, threaten to “cause

soiling, damage, discomfort or destruction, upon escape (leakage).” 90 Fed.

Reg. 9843, 9843 (Feb. 19, 2025). They therefore qualify as “compositions” or

“material” which may “injure the mails or other property.” 18 U.S.C. § 1716(a);

see 83 Fed. Reg. 1189, 1190 (Jan. 10, 2018) (explaining that these and other

related rules mitigate “the potential for serious injury to Postal Service

employees and the general public, as well as the potential for damage to USPS

equipment”). To say that ballot mail “does not present the same operational

7 The cremated-remains and replica-explosives rules are USPS regulations on

“Restricted Matter,” defined to include materials “restricted by 18 U.S.C.
§ 1716(a).” USPS, Publication 52, ch. 1, § 122, https://perma.cc/R95W-BAXS;
see id., ch. 2, § 211, https://perma.cc/2J4D-GJQ3 (invoking 18 U.S.C. § 1716);
id., ch. 4, § 434 (Replica or Inert Explosive Devices), https://perma.cc/YMA6-
GHQY; id., ch. 4, § 451.22 (Cremated Remains), https://perma.cc/RK6T-ET8B.

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issues” (Appl. 17) as materials that threaten panic, evacuations, massive

postal-service disruptions, and property damage is “a delicately put

understatement.” Watson v. RNC, 146 S. Ct. 2165, 2175 (2026).

Congress has also given USPS ample authority to address other examples

discussed in the application—for example, restrictions on delivery of

“unstamped” mail or “a heavy package if the customer failed to pay sufficient

postage.” Appl. 22. Under 39 U.S.C. § 404(a)(2), USPS may “prescribe . . . the

amount of postage and the manner in which it is to be paid.” That express

grant of authority plainly encompasses the power not to deliver mail lacking

proper postage. And under 39 U.S.C. § 3001(c)(1)(A), “[m]atter which . . .

exceeds [USPS-devised] size and weight limits . . . is nonmailable.” USPS

likewise has congressionally authorized tools to address “elder-abuse mail

scams.” Appl. 18; see, e.g., 39 U.S.C. § 3001(d); id. § 3005(a)(1).8

The only other specific restriction discussed in the application reveals just

how far defendants have to stretch in their attempt to identify an analogue for

USPS’ new ballot-mail policy. Defendants analogize to a rule requiring that

mail include a “visible and legible” delivery address. Appl. 21. They assert

that “there does not appear to be any specific statutory authority” for that

policy. Id. Of course, an identifiable delivery address is necessary for USPS

8 The “election-specific mail-preparation policies” described by defendants
(Appl. 19) are not restrictions on mailability. As defendants acknowledge,
many such policies are recommended, not mandatory. Id. at 3, 20. And none
bars USPS from delivering ballot mail. See, e.g., id. at 20 (discussing policies
designed to “prioritize” ballot mail and ensure delivery).

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“to provide for the . . . delivery . . . of mail.” 39 U.S.C. § 404(a)(1). And basic

postage formatting requirements have always been treated as different in kind

from restrictions concerning the mailability of specific materials. Otherwise,

USPS would have unlimited power to devise any new mailability restriction it

wishes without explicit statutory authority. It is “a basic logical fallacy”

(Appl. 22) for USPS to assume that, just because it has authority to prescribe

unexceptional postage formatting requirements, it necessarily also has the

power to adopt any nonmailability restrictions under the sun. That has not

been the law for over a century, see McAnnulty, 187 U.S. at 109, and as

discussed above, USPS has already acknowledged that it lacks such power, see

91 Fed. Reg. at 54974 (describing “Congress’s authority to create new categories

of ‘nonmailable matter’” (emphasis added)).

Finally, defendants point to 18 U.S.C. § 1341 as support for the

challenged rule. See Appl. 17. But read alongside 39 U.S.C. §§ 3001(d) and

3005(a)(1), Section 1341 merely authorizes USPS to refuse to transmit

materials that serve a “scheme or artifice to defraud.” Construing similar

language, the Court long ago held that the postal service may refuse to deliver

mail on grounds of fraud only in “cases of actual fraud in fact.” McAnnulty,

187 U.S. at 106. State officials sending ballots to voters pursuant to state law

are obviously not engaging in fraud. To the extent USPS wants to obtain more

expansive power to address purported fraud in the mail-voting context, cf. 91

Fed. Reg. at 54969, it should direct its concerns to “the people’s elected

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representatives in Congress,” NFIB, 595 U.S. at 121 (Gorsuch, J., concurring).

As a “creature[] of statute,” id. at 117 (majority op.), USPS has no power to act

without congressional authority. And without such authority, the Executive

Branch cannot wield power over federal elections. Our constitutional system

commits that power exclusively to Congress and the States. Supra p. 5.

3. Defendants do not dispute that plaintiffs may bring the foregoing

challenge to USPS’ authority, but argue that judicial review of the claim must

be “narrowly circumscribed” because the agency is “exempted . . . from

ordinary APA review.” Appl. 14 (citing 39 U.S.C. § 410(a)). Even if that were

true as a general matter, but cf. Air Courier Conf. of Am. v. Am. Postal Workers

Union, 498 U.S. 517, 522-523 (1991) (reserving the question), it is not the case

here. Review under the APA is plainly available for “proceedings concerning

the mailability of matter.” 39 U.S.C. § 3001(m). And as USPS has repeatedly

acknowledged, e.g., 91 Fed. Reg. at 54967-59468, this rulemaking is a

“proceeding,” cf. 5 U.S.C. § 551(5), (12) (“agency proceeding” includes “rule

making”). The rulemaking also concerned “the mailability of matter” because

the rule imposes restrictions on whether ballots can be mailed and delivered.

Supra pp. 16-18; see App’x 31a (holding plaintiffs are likely to succeed on their

claim that the challenged rule is contrary to law under 5 U.S.C. § 706(2)(A)).

Regardless of the APA’s applicability here, USPS’ authority to issue the

challenged rule would still be subject to review. This Court has repeatedly

held that “plaintiffs may sue ‘in equity’ without a congressionally-provided

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cause of action ‘to prevent an injurious action by a public officer.’” Trump v.

Cook, 146 S. Ct. 2234, 2251 n.2 (2026) (quoting Armstrong v. Exceptional Child

Ctr., Inc., 575 U.S. 320, 327 (2015)). The decision in Youngstown Sheet & Tube

Co. v. Sawyer, 343 U.S. 579 (1952), provides a classic illustration: plaintiffs

argued that the President’s seizure of steel mills was ultra vires because it was

“not authorized by an act of Congress or by any constitutional provisions.” Id.

at 583. Plaintiffs’ argument here—that USPS lacks any statutory or

constitutional basis for its rule—is materially indistinguishable.

According to USPS, plaintiffs can succeed on an ultra vires claim only by

showing that the rule is “entirely in excess of [USPS’] delegated powers and

contrary to a specific prohibition.” Appl. 14 (quoting NRC v. Texas, 605 U.S.

665, 681 (2025)). If that standard actually applied, plaintiffs would satisfy it:

the rule against adopting mailability restrictions without congressional

authorization has been clear and settled for over a century. Supra pp. 16-22.

But the NRC standard does not apply. This Court has applied it only in cases

where plaintiffs sued outside an otherwise available judicial review scheme.

See NRC, 605 U.S. at 680-682 (Hobbs Act); Leedom v. Kyne, 358 U.S. 184, 187-

188 (1958) (Wagner Act). In NRC, for example, Congress had provided for

judicial review of certain agency orders under the Hobbs Act. 605 U.S. at 674.

But the challengers could not satisfy the Hobbs Act’s requirements, so they

sought to make an “end-run around [its] limitations” by pursuing “ultra vires

review.” Id. at 681. By contrast, where no alternative statutory review scheme

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is available, the Court has addressed statutory and constitutional claims

without applying the NRC standard. See, e.g., Cook, 146 S. Ct. at 2246-2251

& n.2; Learning Res., 607 U.S. at 248-255; Trump v. Illinois, 146 S. Ct. at 434.

In those cases, the limit on APA review was the reasoning of Franklin v.

Massachusetts, 505 U.S. 788 (1992), which held that the President is not an

“agency” subject to the APA. Here, if the APA were unavailable, but see supra

p. 22, the relevant limitation would be 39 U.S.C. § 410(a). But USPS identifies

no sensible reason why that should make any difference. It would be highly

anomalous for actions of the President to be subject to greater judicial scrutiny

than those of the U.S. Postal Service. Cf. Franklin, 505 U.S. at 800 (discussing

the “unique constitutional position of the President”). Defendants’ contrary

view—that Congress effectively “eliminated judicial review” of USPS actions,

Appl. 15—would also mean that USPS could engage in hugely consequential

actions, and the judiciary—including this Court—would be virtually powerless

to stop them. It would not be enough for the Court to hold that an agency acted

“entirely in excess of [its] delegated powers”; it would also have to conclude that

the agency acted “contrary to a specific prohibition.” NRC, 605 U.S. at 681

(emphases added). The Court should reject that remarkable contention.

B. The USPS Rule Is Also Procedurally Defective

Serious procedural flaws provide additional reasons to enjoin the new

rule—in particular for this year’s impending midterm elections. Defendants

overlook these arguments when they assert that plaintiffs raise “no claim” that

the rule is unlawful based on its rushed implementation for the imminent

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elections. Appl. 7. As discussed below, that is the core of plaintiffs’ procedural

challenges. And although the district court did not reach these arguments,

e.g., App’x 31a n.36, they nonetheless offer alternative grounds to deny the

stay. This Court “‘revie[ws] judgments, not statements in opinions,’” and so—

even when considering an application to stay a preliminary injunction pending

appeal—it does not limit its review to only “the reasons given by the lower

courts.” Cook, 146 S. Ct. at 2251 n.3. The Court considers “any argument

presented below that supports the judgment of the lower court.” Hankerson v.

North Carolina, 432 U.S. 233, 240 n.6 (1977).

1. “One of the basic procedural requirements of administrative

rulemaking is that an agency must give adequate reasons for its decisions.”

Encino Motorcars, LLC v. Navarro, 579 U.S. 211, 221 (2016). An agency’s

decision must be both “‘reasonable and reasonably explained.’” Ohio v. EPA,

603 U.S. 279, 292 (2024). USPS flouted that requirement here by saying

“almost nothing” about its consequential decision to apply the rule to the

imminent November elections. Encino Motorcars, 579 U.S. at 223. Although

the agency briefly noted the “logistical or financial difficulties [that] states may

face complying with the rule,” 91 Fed. Reg. at 54985, the agency nowhere

acknowledged the consequences of States’ inability to comply in time for the

November elections: namely, that millions of Americans will be deprived of

their ability to vote by mail and, in many cases, their ability to vote at all. Infra

pp. 33-40. “[A]n agency cannot simply ignore” such “‘an important aspect of

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the problem’ before it.” Ohio, 603 U.S. at 293, 294. USPS had an obligation to

address that problem and take “‘accountability’” for the consequences of its

decision. DHS v. Regents of the Univ. of Cal., 591 U.S. 1, 22 (2020).

Instead, USPS gave only passing mention to States’ “claims that

immediate implementation would prove impossible.” 91 Fed. Reg. at 54985.

Nothing in the final rulemaking suggests that the agency made any effort to

evaluate the plausibility of those serious claims. Rather, the rulemaking’s

reference to “potential[] . . . new costs,” id. (emphasis added), suggests that

USPS failed to actually evaluate States’ arguments about the threatened

consequences for elections administration and voting rights. See Ohio, 603

U.S. at 295 (“awareness” of a concern “is not itself [a sufficient] explanation”).

USPS’ failure to address the impact on mail voting in this fall’s elections

“alone renders” its decision “arbitrary and capricious.” Regents, 591 U.S. at 30.

“But it is not the only defect.” Id. The agency also failed to address “serious

reliance interests” upended by its decision. Encino Motorcars, 579 U.S. at 224.

For example, because States “have long organized their election systems

around existing mail ballot procedures” and relied on USPS to deliver their

ballots, those that are unable to comply with the rule this fall will face

“substantial financial and administrative burdens” in trying to quickly return

to in-person voting. Dkt. 1-1 at 22. In States that “no longer ha[ve] the

infrastructure to accommodate a last-minute reversion to in-person voting,”

immediate implementation of the rule would be “catastrophic.” E.g., Dkt. 4-4

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¶ 42; see also infra p. 39. USPS “offered no reasoned response” to these

important concerns. Ohio, 603 U.S. at 293.

USPS’ only explanation for applying the rule to the November elections

was its assertion that “the visibility and law-enforcement benefits of the rule”

justified immediate implementation. 91 Fed. Reg. at 54985. But “conclusory

statements do not suffice to explain” an agency’s decision. Encino Motorcars,

579 U.S. at 224. And elsewhere in the rulemaking, USPS expressly declined

to make any findings about “the incidence of [mail] voter fraud.” 91 Fed. Reg.

at 54969. The agency’s explanation for immediate implementation therefore

does not provide “‘a rational connection between the facts found and the choice

made.’” Ohio, 603 U.S. at 292. And that is particularly so because USPS did

not account for the fact that the purported “visibility and law-enforcement

benefits” will not—and cannot—materialize in States that are unable to

comply with the rule for the fall elections. 91 Fed. Reg. at 59485. “Perhaps

there is some explanation why the number and identity of participating States”

would not change USPS’ calculus about the respective benefits and costs of

immediate implementation, “[b]ut if there is,” “it does not appear in the final

rule.” Ohio, 603 U.S. at 293-294. Plaintiffs are thus “likely to prevail” on the

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claim that USPS “failed to supply ‘a satisfactory explanation’” for its decision

to apply the new rule to the November elections. Id. at 294.9

2. USPS also failed to seek an advisory opinion from the Postal

Regulatory Commission before making “a change in the nature of postal

services” that will “generally affect service on a nationwide or substantially

nationwide basis.” 39 U.S.C. § 3661(b). In the final rule, USPS asserted that

it had no obligation to consult with the Commission because the rule will not

have a “meaningful impact” on—or change the nature of—postal services. 91

Fed. Reg. at 54976 (quoting Buchanan v. USPS, 508 F.2d 259, 262 (5th Cir.

1975)). But the rule’s operational changes to how USPS processes mail ballots

will have a meaningful impact on USPS’ delivery of ballots nationwide. See,

e.g., Dkt. 119-1 ¶¶ 108-121 (rule is “incredibly time-consuming,” “burdensome”

on “USPS employees,” and “exacerbate[s] existing [USPS] challenges”). That

such ballots are a “subset” of the mailstream is irrelevant. 91 Fed. Reg. at

54976. USPS has previously requested advisory opinions for proposed changes

that affected only a subset of mail. See, e.g., 87 Fed. Reg. 18044 (Mar. 29, 2022)

9 Even if the Court concluded that the APA is inapplicable here, but see supra

p. 22, it would not make a difference to this claim. The arbitrary-and-
capricious standard predates the APA, which merely “restate[d] the present
law as to the scope of judicial review.” U.S. Dep’t of Just., Att’y Gen. Manual
on Admin. Proc. Act 108 (1947). Courts “have always exercised the power in
appropriate cases to set aside agency action which they found to be . . .
arbitrary [or] capricious.” Id. So even in contexts where courts have treated
USPS as exempt from Section 706(2)(A), they have subjected the agency to a
“reasoned decision-making” requirement. Sears, Roebuck & Co. v. USPS, 844
F.3d 260, 265 (D.C. Cir. 2016); see also Nat’l Ass’n of Postal Supervisors v.
USPS, 26 F.4th 960, 975-976 (D.C. Cir. 2022).

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(requesting advisory opinion on changes to retail ground and parcel select

ground mail). And the changes at issue in the rule challenged here are of far

greater “significance” than those. Buchanan, 508 F.2d at 263.

The rule will also change the “nature” of USPS services because the

agency has never before embarked on a ballot-scanning and verification

program or refused to deliver mail ballots to voters. 39 U.S.C. § 3661(b); supra

pp. 12-13. USPS’ conclusory assertion that the rule would not affect the

“experience of the individual postal consumer,” 91 Fed. Reg. at 54976 (quoting

Pennsylvania v. DeJoy, 490 F. Supp. 3d 833, 885 (E.D. Pa. 2020)), ignores that

compliance will be impossible for many States this fall. For that reason, and

because of USPS’ own technological feasibility challenges, infra pp. 33-40,

millions of voters across the Nation likely will not receive the mail ballots to

which they are entitled under state law and by which they exercise their right

to vote—thereby unquestionably affecting the “experience” of those “individual

postal consumer[s].” Had USPS consulted with the Commission, as Congress

intended, the agency would have had to address the technological and

feasibility challenges that are likely to result in an implementation “disaster.”

Katz, Postal Officials Say Trump’s Mail-Ballot Push Will Create Widespread

Errors, NOTUS (Aug. 27, 2026), https://perma.cc/SFX9-BZBD; see also Stmt.

of Comm’r Day, Dkt. C2026-27 (Postal Regul. Comm’n Sept. 3, 2026),

https://perma.cc/YG9P-TDEK (reiterating concerns about USPS’ inadequate

“advance testing and validation”).

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USPS argued below that plaintiffs were required to exhaust this claim

with the Commission and then bring it in the D.C. Circuit. See Dkt. 17 at 12

(citing 39 U.S.C. §§ 3662, 3663). That is incorrect. See Washington v. Trump,

487 F. Supp. 3d 976, 981 n.1 (E.D. Wash. 2020); Pennsylvania, 490 F. Supp. 3d

at 856-857 (rejecting similar contention and noting the “irony” of USPS

“bypassing the Commission” and then arguing that it is “Plaintiffs who must

resort to the Commission in order to obtain relief ”). Indeed, that argument is

especially flawed in the circumstances here because plaintiffs’ “‘here-and-now

injur[ies]’” ahead of the imminent November elections would be “impossible to

remedy” through the Commission’s administrative review process. Axon

Enter., Inc. v. FTC, 598 U.S. 175, 191 (2023); see New York v. Trump, 181 F.4th

132, 140 n.3 (D.C. Cir. 2026).

II. EQUITABLE CONSIDERATIONS WEIGH HEAVILY AGAINST A STAY

Defendants fail to show irreparable harm from the preliminary

injunction—certainly nothing comparable to the catastrophic harm that

plaintiffs and the public would suffer if the challenged rule took effect before

this year’s midterms. Defendants’ principal argument is that none of plaintiffs’

evidence of harm—and none of the district court’s extensive findings about

infeasibility—make any difference. “[T]here is no basis,” defendants assert, “to

hold that an otherwise-valid rule . . . becomes invalid simply because it is

adopted sufficiently close to an election,” such that compliance becomes

difficult or infeasible. Appl. 32-33. That assertion is contrary to both settled

law, see, e.g., NetChoice, LLC v. Fitch, 145 S. Ct. 2658, 2658 (2025) (Kavanaugh,

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J., concurring), and common sense: it would mean that the federal government

could rush out any election-related policy on the eve of an election, and no

matter how disastrous the consequences for voting rights and elections

administration, no one would have a remedy in court. The Court should reject

that astonishing proposition.

1. Defendants’ assertions of harm are in substantial tension with the

narrow scope of the preliminary injunction. Because the injunction is

inapplicable to “elections after the November 2026 election,” App’x 46a

(emphasis added), it merely preserves the status quo ahead of elections that

are now only 55 days away. For that reason, defendants are mistaken that

“the injunction bars USPS from training its employees to conduct the

verification process.” Appl. 30; see id. at 12. There is nothing blocking USPS

from training employees on the scanning, data-matching, and verification

protocol prescribed by the rule, so long as such training is geared toward future

elections (or even voluntary participation in this year’s elections). App’x 46a.

The injunction is also limited to “the Final Rule’s mandatory provisions”

and thus does not “preclude[] States from voluntarily complying with the Final

Rule.” App’x 46a (emphases added). USPS remains free to continue to develop

the portal, train its employees, and work with States on the design of their

mail ballots on a voluntary basis. States may also choose to seek approval of

their envelopes and upload voter data into the portal whenever it becomes

operational. Cf. App’x 38a (portal “is not . . . operational” as of September 4).

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That period of voluntary compliance could prove valuable to USPS, as it would

offer the agency a trial run of its untested technology and data-matching

features and help the agency address serious concerns raised by USPS officials

and postal experts. See, e.g., Dkt. 115 at 15-16 (warning about “slapdash

software development” and “insufficient internal testing”); App’x 41a (noting

“the unproven nature of the [portal’s] new technology”); supra pp. 2-3 (similar).

Defendants’ fears of harms to “election integrity” (Appl. 29) while the

court’s order is in place are wholly unfounded. USPS expressly declined to

resolve “[w]hether or not voter fraud is common or uncommon” when it adopted

the final rule, 91 Fed. Reg. at 54969, and “the record includes no evidence

relating to fraudulent mail voting,” App’x 45a-46a. USPS thus cannot show

that the rule’s immediate implementation is necessary to “address the risk that

the federal mails will be used to perpetrate voter fraud.” Appl. 5. No similar

USPS rule has ever existed. Yet States have long employed protocols to protect

against mail-ballot fraud. See, e.g., Nat’l Conf. of State Legislatures, How

States Verify Voted Absentee/Mail Ballots (updated May 20, 2026),

https://perma.cc/RVF3-9KAL. And studies have repeatedly demonstrated that

fraud related to mail voting is extraordinarily rare, undercutting any claim of

irreparable harm. See, e.g., Dkt. 1-1 at 19 & n.12 (collecting examples).

Nor is the injunction causing irreparable harms akin to those described

in California, 2026 WL 2473573, at *4. Contra Appl. 29. There, the Court

determined that an earlier, related injunction harmed the government because

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33

it prevented it “from even trying to lawfully implement” the President’s EO.

California, 2026 WL 2473573, at *5. But USPS has now promulgated its final

rule, and as this Court recognized, “[i]f the Postal Service’s final rule harms

the States, they may challenge that rule.” Id. at *4. Plaintiffs have

demonstrated that the rule is both extraordinarily harmful and contrary to

statute and the Constitution. See supra pp. 10-22. USPS plainly cannot suffer

irreparable harm from an injunction that merely prevents it from forcing

States to comply with an unlawful rule.10

2. Granting emergency relief would threaten catastrophic harms for

plaintiff States and the public. After considering the unrebutted declarations

in the record, the district court concluded that it would be impossible for

plaintiffs “to pivot this late in the election cycle” to come into compliance with

the rule. App’x 32a; see also Dkt. 119-1 ¶ 18 (expert concluding that “[n]one of

the Rule’s requirements can feasibly be implemented before the November 3,

2026 General Election”). As the district court explained, “[m]ost Plaintiff

10 Defendants’ request to limit the scope of relief to “the California
respondents” (Appl. 34) is perplexing. In Trump v. CASA, Inc., 606 U.S. 831,
859 n.18 (2025), the Solicitor General assured the Court that the federal
government would “respect both [its] judgments and [its] opinions.” If the
Court holds that plaintiffs have shown a likelihood of success on the merits,
supra pp. 10-30, respect for that opinion would surely require USPS to refrain
from executing the rule on a nationwide basis while this litigation proceeds.
In any event, a nationwide remedy is warranted because plaintiffs have shown
that the USPS rule violates the APA, see, e.g., supra p. 22, and Section 705 of
the APA grants courts discretion to award universal interim relief, see, e.g.,
Woonasquatucket River Watershed Council v. USDA, 2026 WL 2279789, at *20
(1st Cir. Aug. 7, 2026) (collecting cases).

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States have already ordered their mail ballots” and “have neither time nor

funds to design new mail ballots, seek approval of the new designs, order

production of mail ballots, update their own election management systems,

train election officials to use the USPS portal, and upload citizen data to the

portal, all before the midterms.” Dkt. 31 at 8, 9; see also App’x 32a-43a;

Anderson v. City of Bessemer City, 470 U.S. 564, 575 (1985) (“review of factual

findings under the clearly-erroneous standard—with its deference to the trier

of fact—is the rule, not the exception”).

Wisconsin’s experience is illustrative. As the Wisconsin Elections

Commission chair has explained, “[i]t would be virtually impossible for

Wisconsin to comply with the Rule.” Dkt. 100-1 ¶ 21. Municipal clerks are

required to mail absentee ballots to all requests on file no later than

September 17, and county clerks lack sufficient time (and funds) to reprint the

ballot envelopes they have already printed for the November elections. See id.

¶¶ 6, 13, 15, 29. Wisconsin’s envelopes could only become mailable under the

new USPS rule if the State’s elections officers could “print and hand-affix

stickers with the Rule-compliant IMb codes on” each envelope. Id. ¶ 29. But

that labor-intensive solution invites errors that risk disenfranchising voters.

See id. ¶¶ 32-34. “[A] clerk could easily place the sticker on the wrong envelope

by mistake,” for example, “or mix-up which stickers belong to which voter.” Id.

¶ 32. In any event, completing that work in time for the midterms would be

“impossib[le] for many jurisdictions”—particularly “rural municipalities,”

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35

which may not even “have the required label printing capability” and “often

have a single employee performing all elections-related work.” Id. ¶ 30.

Like many States, Wisconsin relies on thousands of municipal employees,

rather than centralized state officials, to make changes to voter databases. See

Dkt. 100-1 ¶ 5. To enroll voters with USPS’ new portal, then, those thousands

of employees “would need to be trained in how to use the new technology,

become authorized users, and then enter the data” required by the rule—all by

September 17. Id. ¶ 26. But that is wildly unrealistic. Many of the employees

responsible for completing these tasks “hold the[ir] positions on a part-time

basis, have other full-time jobs, and . . . have little to no administrative

support.” Id. Given these challenges, “full and accurate compliance [with the

rule] is extremely unlikely” in advance of the midterms. Id. The rule thus

risks “disenfranchisement for . . . eligible voter[s]” in Wisconsin—including

“populations that are particularly dependent on absentee voting, such as voters

in rural areas, voters with disabilities, and voters that lack reliable means of

transportation.” Id. ¶ 34.

Other States offer similar accounts. Washington has already printed

millions of voter ballot packets. Dkt. 4-4 ¶ 42. Two of its three printing vendors

have said that they cannot reprint ballot envelopes, and it is “very unlikely”

that the third vendor could reprint envelopes for the entire State. Id. Oregon

has “neither the time nor the money to design, review, and reorder envelopes

before ballots begin to be mailed to [the State’s approximately 3 million] voters

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in mid-September.” Dkt. 4-19 ¶ 37; see id. ¶ 35. In Colorado, nearly 1.3 million

existing ballot return envelopes will have to be discarded, and re-printing these

envelopes “may not even be possible.” Dkt. 4-6 ¶ 42. And Hawai‘i reports it

“may not be possible to get new . . . envelopes delivered to [Hawai‘i] from the

continent on such short notice.” Dkt. 4-10 ¶ 43; see also App’x 34a-36a

(surveying printing problems and concluding that the rule’s “ballot design

requirements . . . will cause Plaintiff States irreparable harm”); Dkt. 119-1

¶ 52 (expert concluding that the rule’s IMb envelope requirements are not

feasible for many jurisdictions before the 2026 election).

The record also reveals other types of serious compliance challenges. For

example, California’s statewide voter-registration system “is not currently

equipped to receive IMb information for individual voters from county election

management systems,” and those county systems are not prepared “to store

and transmit” this IMb information. Dkt. 4-1 ¶ 19. The systems in California’s

58 counties would need to be updated before the State could begin mailing

compliant ballots. Id. Similar modifications to California’s statewide system,

however, have historically “take[n] more than a year to develop, test, . . . and

deploy.” Id. Other States face similar obstacles. See, e.g., App’x 39a-40a &

nn.51-52; Dkt. 4-15 ¶ 24; Dkt. 4-21 ¶ 27; see also Dkt. 4-16 ¶ 52.

According to defendants, these “difficulties are overblown.” Appl. 31; see

id. (characterizing harms to States as “ordinary compliance costs”).

Defendants point out that the intervenor States “support the Rule and contend

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that they will be able to comply.” Id. But in contrast to plaintiff States, who

submitted some 700 pages of declarations from over two dozen senior elections

officials detailing the costs and challenges of compliance, see Dkt. 4,

intervenors submitted a single declaration, which says without detail or

explanation: “[a]lthough my staff are still figuring out some details of

implementation, I believe it is possible to implement this rule for the 2026

General Election,” Dkt. 64-1 ¶ 5. Plaintiffs’ voluminous evidentiary

submissions have also been corroborated by officials in non-plaintiff States—

Utah, in particular, which heavily relies on mail voting. Supra pp. 1, 6. And

given every opportunity to introduce responsive evidence on this point,

defendants made no effort to do so.

Even if plaintiffs could theoretically comply with the new rule, doing so

would present serious risks of errors and disenfranchisement. In

Massachusetts, for example, compliance would require the State’s “351 local

election offices” to “manually capture[] and update[]” the IMb information “for

each voter’s ballot envelopes.” Dkt. 4-2 ¶ 33 (emphasis added). Where

Massachusetts election officials are slated to “mail approximately 1 million

ballots to voters during the 2026 general election,” id. ¶ 43, this kind of manual

data entry creates a risk of errors that could “prevent voters from receiving

absentee or mail-in ballots,” id. ¶ 51; see also Dkt. 119-1 ¶ 112 (expert

explaining that “even a single data error would jeopardize an entire mailing

containing thousands, potentially millions, of individual ballots”). Many other

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States have expressed similar concerns.11 And in Rhode Island—where state

law requires that ballots be placed into an internal certifying envelope enclosed

in an external envelope—the State’s vendor would have to print IMbs for the

two envelopes on separate machines and then later “compile the ballot mail

package by matching the two envelopes.” Dkt. 129 ¶ 6; see id. ¶ 4. The vendor

hopes that it could “perfect[ly] match” the two envelopes, but “this process is

outside [its] established procedure” and “create[s] unnecessary risks for Rhode

Island in its election administration.” Id. ¶ 6.

USPS’ untested new technologies and processes only compound these

substantial risks of error and resulting disenfranchisement. See App’x 41a &

n.53. No one knows, for example, if USPS’ online portal for enrolling voters or

its ballot-scanning technology will actually function as intended—or at

all. E.g., Dkt. 4-1 ¶¶ 28-29. The portal “does not yet exist.” App’x 45a. And

recent revelations from a USPS whistleblower raise significant concerns that

USPS’ new systems will not work, see Dkt. 115, as do comments from an

alarmed member of the Postal Regulatory Commission, supra pp. 4, 29. Nor is

it clear that USPS can competently administer a ballot-scanning, data-

matching, and non-delivery program that is unlike anything it has ever

undertaken. Its recent performance has not been encouraging. See, e.g., Dkt.

4-2 ¶ 18 (discussing recent USPS problems with handling ballot mail); Dkt. 4-

11 See, e.g., Dkt. 4-6 ¶¶ 28, 32-33 (Colorado); Dkt. 4-11 ¶¶ 22, 25-26 (Maine);

Dkt. 4-14 ¶¶ 24, 27-28 (Minnesota); Dkt. 4-15 ¶¶ 24, 26-27 (New Jersey); Dkt.
4-19 ¶¶ 25, 27-28 (Oregon); Dkt. 4-20 ¶¶ 23, 26-27 (Pennsylvania).

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4 ¶ 22 (same); Dkt. 4-5 ¶ 18 (same); see also U.S. Gov’t Accountability Off.,

GAO-26-109008, U.S. Postal Service: Urgent Action Needed to Fix

Unsustainable Business Model and Improve Service Performance (Mar. 17,

2026), https://perma.cc/97XZ-RVW3.

For many voters, the unavailability of mail voting would make it

impossible to vote at all. Disabled voters, for example, face so many barriers

to voting in person that mail voting is often “their only option to cast a ballot.”

Davidson, American Association of People with Disabilities Applauds Supreme

Court Protecting Mail Ballot Grace Periods (June 29, 2026),

https://perma.cc/2QGV-4JV2. And in some States, a return to the prior era of

in-person voting is not an option. For example, Washington is an entirely vote-

by-mail State; it “no longer has the infrastructure to accommodate a last-

minute reversion to in-person voting.” Dkt. 4-4 ¶ 42. In Hawai‘i, there is

“insufficient time to coordinate the necessary polling places, volunteers, and

logistical framework that would be necessary to emulate the prior polling place

model that existed prior to the advent of elections by mail.” Dkt. 4-10 ¶ 24; see

also Dkt. 4-19 ¶ 18 (similar with respect to Oregon).

USPS acknowledges that this kind of disenfranchisement would harm the

public interest. See Appl. 5-6, 31. In fact, it has argued for a stay on the

grounds that if injunctive relief is later “vacated on appeal,” States may not

have “time to comply with [the rule’s] requirements, which could well end up

depriving their voters of the ability to vote by mail.” Appl. 26, USPS v.

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California, No. 26A297; see also Appl. 5-6. But that is already the case. As the

district court found based on its extensive review of the record, it is impossible

for plaintiff States to comply with the rule now, which jeopardizes their voters’

ability to vote by mail now. See App’x 44a. And plaintiff States are not alone:

Utah’s top elections official has warned that the USPS rule’s rollout would be

an “unmitigated disaster.” Officials in Ohio and Florida have raised similar

concerns. Supra p. 1 & nn.1-2. And a bipartisan coalition of elections officials

has urged USPS to give States at least one year to comply, explaining that

“changes made less than 90 days before an election risk administrative

mistakes and voter confusion.” Bipartisan Policy Ctr., Comment on USPS

Proposed Rule on Ballot Mail (July 6, 2026), https://perma.cc/DX2Y-GA3B.

At this late point, the November election is already underway. At least

two States have already begun to mail out ballots under their ordinary state

laws and processes. Dkt. 100-1 ¶ 14 (Wisconsin); Appl. 29-30 (North Carolina).

There is no good reason to deny other States the same opportunity. “When an

election is close at hand, the rules of the road should be clear and settled.”

Democratic Nat’l Comm. v. Wis. State Legislature, 592 U.S. 1039, 1043 (2020)

(Kavanaugh, J., concurring). Here, the governing rules should be those that

States long ago adopted for mail voting in this year’s election—rules that have

vastly expanded the opportunities for Americans to take part in our democracy.

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CONCLUSION

The application for a stay should be denied.

Respectfully submitted,

ANDREA JOY CAMPBELL ROB BONTA
Attorney General Attorney General of California
Commonwealth of Massachusetts SAMUEL T. HARBOURT
One Ashburton Place Solicitor General
Boston, MA 02108 HELEN H. HONG
Principal Deputy Solicitor General
AARON D. FORD THOMAS S. PATTERSON
Attorney General Senior Assistant Attorney General
State of Nevada AARON D. PENNEKAMP
1 State of Nevada Way, Suite 100 Supervising Deputy Solicitor General
Las Vegas, NV 89119 IAN FEIN
L. NICOLE ALLAN
Deputy Solicitors General
NICHOLAS W. BROWN
Attorney General SETH E. GOLDSTEIN
Supervising Deputy Attorney General
State of Washington
ANNE P. BELLOWS
1125 Washington Street SE
KEVIN L. QUADE
PO Box 40100
LISA C. EHRLICH
Olympia, WA 98504-0100
MALCOLM A. BRUDIGAM
MICHAEL S. COHEN
ROBERT WILLIAM SETRAKIAN
Deputy Attorneys General

September 9, 2026

(Counsel listing continues on next page)

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KRISTIN K. MAYES PHILIP J. WEISER
Attorney General Attorney General
State of Arizona State of Colorado
2005 North Central Avenue 1300 Broadway
Phoenix, AZ 85004 Denver, CO 80203

WILLIAM TONG KATHLEEN JENNINGS
Attorney General Attorney General
State of Connecticut State of Delaware
165 Capitol Avenue, Suite 5000 820 N. French Street
Hartford, CT 06106 Wilmington, DE 19801

BRIAN L. SCHWALB ANNE E. LOPEZ
Attorney General Attorney General
District of Columbia State of Hawai‘i
400 6th Street, NW 425 Queen Street
Washington, DC 20001 Honolulu, HI 96813

KWAME RAOUL AARON M. FREY
Attorney General Attorney General
State of Illinois State of Maine
115 S. LaSalle Street 6 State House Station
Chicago, IL 60603 Augusta, ME 04333

ANTHONY G. BROWN DANA NESSEL
Attorney General Attorney General
State of Maryland State of Michigan
200 Saint Paul Place P.O. Box 30736
Baltimore, MD 21202 Lansing, MI 48909

KEITH ELLISON JENNIFER DAVENPORT
Attorney General Attorney General
State of Minnesota State of New Jersey
445 Minnesota Street, Suite 600 124 Halsey Street, 5th Floor
St. Paul, MN 55101 Newark, NJ 07101

RAÚL TORREZ LETITIA JAMES
Attorney General Attorney General
State of New Mexico State of New York
408 Galisteo Street 28 Liberty Street
Santa Fe, NM 87501 New York, NY 10005

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JEFF JACKSON DAN RAYFIELD
Attorney General Attorney General
State of North Carolina State of Oregon
114 W. Edenton Street 1162 Court Street NE
Raleigh, NC 27603 Salem, OR 97301

PETER F. NERONHA CHARITY R. CLARK
Attorney General Attorney General
State of Rhode Island State of Vermont
150 South Main Street 109 State Street
Providence, RI 02903 Montpelier, VT 05609

JAY JONES JOSHUA L. KAUL
Attorney General Attorney General
Commonwealth of Virginia State of Wisconsin
202 North Ninth Street 17 West Main Street
Richmond, VA 23219 Madison, WI 53707

JOSH SHAPIRO
Governor
Commonwealth of Pennsylvania
30 North Third Street, Suite 200
Harrisburg, PA 17101