Reply Brief — William Trevor Case, Petitioner v. Montana

No. 24-624

In the Supreme Court of the United States

WILLIAM TREVOR CASE, PETITIONER

v.

STATE OF MONTANA, RESPONDENT.

ON WRIT OF CERTIORARI TO THE

SUPREME COURT OF THE STATE OF MONTANA

REPLY BRIEF FOR PETITIONER

ELIZABETH NIELSON

FRED A. ROWLEY, JR.

Wilson Sonsini

Counsel of Record

Goodrich & Rosati, P.C.

MARK R. YOHALEM

95 S. State St., Ste 1000

Wilson Sonsini

Salt Lake City, UT 84111 Goodrich & Rosati, P.C.

953 E. Third St., Ste 100

CHRISTOPHER R. BETCHIE

Los Angeles, CA 90013

Hull, Swingley &

(323) 210-2900

Betchie, P.C.

fred.rowley@wsgr.com

P.O. Box 534

Helena, MT 59624

JOHN B. KENNEY

Wilson Sonsini

NATHAN D. ELLIS

Goodrich & Rosati, P.C.

2047 N. Last Chance

1700 K Street NW

Gulch #482

Washington, D.C. 20006

Helena, MT 59601

Counsel for Petitioner

(Additional counsel listed on next page)

KELSEY C. CATINA

MADISON J. WELSH

Wilson Sonsini

Goodrich & Rosati, P.C.

701 Fifth Avenue

Ste 5100

Seattle, WA 98104

ERIC O. BRAVIN

New York University

School of Law

245 Sullivan St.,

Ste C-20

New York, NY 10012

Counsel for Petitioner

i

TABLE OF CONTENTS

Page

INTRODUCTION ....................................................... 1

ARGUMENT .............................................................. 3

I.

The Fourth Amendment requires probable

cause for emergency-aid home entries. ............... 3

A. Nonconsensual warrantless home entries

implicate core Fourth Amendment

interests, not the lesser interests the

State invokes. ................................................ 3

B. This Court’s exigency precedents support

a probable cause standard. ........................... 6

C. The affray rule is the most analogous

common law rule. .......................................... 8

D. A probable cause standard best balances

liberty interests in the home and public

safety concerns. ........................................... 12

II. Montana’s intermediate reasonableness

standard contravenes precedent and would

sow confusion. .................................................... 17

III. The officers here lacked probable cause—or

reasonable grounds—of an emergency

justifying warrantless entry into Case’s home. 23

CONCLUSION ......................................................... 24

ii

TABLE OF AUTHORITIES

Page(s)

Cases:

44 Liquormart, Inc. v. Rhode Island,

517 U.S. 484 (1996)......................................... 14

Arizona v. Hicks,

480 U.S. 321 (1987)........................................... 3

Atwater v. City of Lago Vista,

532 U.S. 318 (2001).............................. 16, 21-22

Boyd v. United States,

116 U.S. 616 (1886)......................................... 13

Brigham City v. Stuart,

547 U.S. 398 (2006)....... 2-3, 8, 13-14, 16, 19-20

Camara v. Mun. Ct. of City & Cnty. of

San Francisco,

387 U.S. 523 (1967)......................................... 15

Caniglia v. Strom,

593 U.S. 194 (2021)......................................... 13

City of Los Angeles v. Patel,

576 U.S. 409 (2015)..................................... 4, 13

Colorado v. Bertine,

479 U.S. 367 (1987)........................................... 4

Coolidge v. New Hampshire,

403 U.S. 443 (1971)........................................... 5

iii

District of Columbia v. Wesby,

583 U.S. 48 (2018) ............................................ 8

Dunaway v. New York,

442 U.S. 200 (1979).................1-3, 16, 18, 21-22

Florida v. Jardines,

569 U.S. 1 (2013) .............................................. 4

Georgia v. Randolph,

547 U.S. 103 (2006)........................................... 1

Graham v. Barnette,

5 F.4th 872 (8th Cir. 2021) ............................. 15

Griffin v. Wisconsin,

483 U.S. 868 (1987)........................................... 4

Handcock v. Baker,

126 Eng.Rep. 1270 (1800)............................... 12

Illinois v. Gates,

462 U.S. 213 (1983)..................... 1, 8, 16, 19, 22

Lange v. California,

594 U.S. 295 (2021)...................3-4, 9, 12-13, 20

Locke v. United States,

11 U.S. (7 Cranch) 339 (1813) ........................ 15

Maleverer v. Spinke,

73 Eng.Rep. 79 (1537)..................................... 12

Marshall v. Barlow’s, Inc.,

436 U.S. 307 (1978)......................................... 15

iv

Michigan v. Fisher,

558 U.S. 45 (2009) ........................................ 6, 8

Michigan v. Tyler,

436 U.S. 499 (1978)....................................13-14

Minnesota v. Olson

495 U.S. 91 (1990) .........................................6-7

Nat’l Treasury Emps. Union v. Von Raab,

489 U.S. 656 (1989)........................................... 4

New Jersey v. T.L.O.,

469 U.S. 325 (1985)................................ 4, 18-19

O’Connor v. Ortega,

480 U.S. 709 (1987)......................................... 20

Ornelas v. United States,

517 U.S. 690 (1996)......................................... 24

Payton v. New York,

445 U.S. 573 (1980)................................... 11, 13

Rex v. Coate,

98 Eng.Rep. 539 (1772)................................... 12

Riley v. California,

573 U.S. 373 (2014)......................................... 12

Safford Unified Sch. Dist. No. 1 v.

Redding,

557 U.S. 364 (2009)....................................18-19

Scott v. Wakem,

176 Eng.Rep. 147 (1862)................................. 12

v

South Dakota v. Opperman,

428 U.S. 364 (1976)........................................... 4

United States v. Carter,

601 F.3d 252 (4th Cir. 2010) .......................... 17

United States v. Jackson,

415 F.3d 88 (D.C. Cir. 2005)........................... 24

United States v. Melvin,

596 F.2d 492 (1st Cir. 1979) ........................... 22

United States v. Montoya de Hernandez,

473 U.S. 531 (1985)..................................... 2, 18

United States v. Santana,

427 U.S. 38 (1976) ............................................ 7

United States v. Watson,

423 U.S. 411 (1976)........................................... 6

United States v. Winsor,

846 F.2d 1569 (9th Cir. 1988) ...................21-22

Vernonia Sch. Dist. 47J v. Acton,

515 U.S. 646 (1995)........................................... 4

Warden v. Hayden,

387 U.S. 294 (1967)........................................... 7

Welsh v. Wisconsin,

466 U.S. 740 (1984)....................................20-21

Whren v. United States,

517 U.S. 806 (1996)......................................... 15

vi

Wilson v. Arkansas,

514 U.S. 927 (1995)......................................8-11

Wyman v. James,

400 U.S. 309 (1971)........................................... 4

Other Authorities:

Akhil Amar,

Fourth Amendment First Principles, 107 Harv. L. Rev. 757 (1994) ............. 5, 21

Akhil Amar,

The Bill of Rights as a

Constitution, 100 Yale L.J. 1131

(1991)................................................................. 5

J. Chitty,

Criminal Law (1816)..................................10-11

M. Dalton,

The Country Justice (1705) ............................ 10

Thomas Y. Davies,

Recovering the Original Fourth

Amendment, 98 Mich. L. Rev. 547

(1999)................................................................. 6

Hale,

Historia Placitorum Coronæ

(1736)........................................................ 6, 9-11

Hawkins,

Pleas of the Crown (1797) ................................ 9

vii

Ronald Reagan,

The President’s News Conference,

Aug. 12, 1986,

https://www.reaganlibrary.gov/ar

chives/speech/presidents-newsconference-23 .................................................. 14

Wayne R. LaFave,

Search and Seizure: A Treatise on

the Fourth Amendment (6th ed.

2020) ...........................................................19-20

INTRODUCTION

In its BIO, Montana rightly conceded that

“Brigham City’s ‘objectively reasonable basis’ standard requires, in function if not in form, that officers

have probable cause to believe someone is in danger

and requires immediate assistance.” BIO2. Now, remarkably, Montana contends that requiring probable

cause would “necessitate overruling Brigham City”

and “reimagine the Fourth Amendment.” Resp.Br.1-2.

Montana was right the first time. “The requirement of probable cause has roots that are deep in our

history.” Dunaway v. New York, 442 U.S. 200, 213

(1979). The liberty interest at stake in emergency-aid

situations is equally venerable, for we have “lived our

whole national history” with the understanding “that

a man’s house is his castle.” Georgia v. Randolph, 547

U.S. 103, 115 (2006). And because probable cause is “a

fluid concept,” Illinois v. Gates, 462 U.S. 213, 232

(1983), it has long been applied to “noncriminal” inquiries (Resp.Br.13-14). Indeed, as Montana has

noted, courts around the country already “routinely

apply the probable cause standard” to emergency-aid

entries. BIO2-3. Confirming probable cause as the

emergency-aid standard requires no imagination;

merely respect for well-founded constitutional law.

Montana and the U.S. insist probable cause cannot

be detached from “criminality” (Resp.Br.27), making

it “poorly suited, at best, for the context of emergency

aid” (U.S.Br.14). But it is this position, not Case’s,

that “reimagine[s]” Fourth Amendment protections.

Resp.Br.1. On the State and Government’s theory, the

citizen in his home is not a man in his castle, but

equivalent to a schoolchild in the classroom or a probationer, once the state invokes a “noninvestigatory”

2

purpose. Resp.Br.46-48; U.S.Br.20. On their theory,

the established baseline rule requiring a warrant and

probable cause should be cast aside in favor of an academic theory that, on its own terms, departs from

this Court’s precedent. And on their theory, the apt

historical principle is not the common law affray rule,

which applied in the very situation presented in

Brigham City v. Stuart, 547 U.S. 398 (2006), but a “necessity” tort defense (Resp.Br.24-25) that no searchor-seizure treatise mentions and that required greater

certainty than probable cause.

Based on these reimagined tenets, Montana and

the U.S. urge the Court to replace the “familiar

threshold standard” of probable cause, Dunaway, 442

U.S. at 213, with a “reasonableness” standard that is

hopelessly indeterminate. The State and Government

cannot even settle on a single standard within their

own briefs, disclaiming reasonable suspicion while

simultaneously invoking precedent applying that

standard. They offer no guidance on how certain a

first responder must be that someone inside a home

urgently needs help. The upshot is that first responders would need to ponder incommensurate “social and

individual interests” amidst the chaos and danger of

emergency situations. Cf. id. at 214.

This Court has refused to adopt “a third Fourth

Amendment threshold” between probable cause and

reasonable suspicion, United States v. Montoya de

Hernandez, 473 U.S. 531, 540 (1985), and a vague

“reasonableness” test is an especially poor candidate.

The officers, “firefighters, social workers, and paramedics” who assess emergencies (U.S.Br.29) need “the

relative simplicity and clarity” provided by probable

3

cause, Dunaway, 442 U.S. at 213—not a rule that confuses even its own proponents. This Court should “adhere to the textual and traditional standard of probable cause.” Arizona v. Hicks, 480 U.S. 321, 329 (1987).

ARGUMENT

I. The Fourth Amendment requires probable

cause for emergency-aid home entries.

A. Nonconsensual warrantless home entries

implicate core Fourth Amendment interests, not the lesser interests the State invokes.

Montana concedes that “searches and seizures inside a home without a warrant are presumptively unreasonable.” Resp.Br.26 (quoting Brigham City, 547

U.S. at 403). Because the Fourth Amendment makes

a warrant supported by probable cause the constitutional baseline for “entering a home without permission,” the Court has “jealously” guarded the few exceptions for “warrantless intrusions.” Lange v. California, 594 U.S. 295, 298, 303 (2021). Under those exceptions, it has never held that the state can breach

“the sanctity of a person’s living space,” ibid., on less

than probable cause. As Justice Scalia explained,

“[d]ispensing with the need for a warrant is worlds

apart from permitting a lesser standard of cause.”

Hicks, 480 U.S. at 327. So a “dwelling-place search”—

warrant or no—“requires probable cause.” Id. at 328.

1. Despite allowing that “the sanctity of the home

is an important Fourth Amendment value”

(Resp.Br.46), Montana contends there is no “mechanical requirement of warrants or probable cause” for

home entries (id. at 25). Yet neither Montana nor the

U.S. can cite a single decision of this Court holding

4

that a “quantum of knowledge” (Resp.Br.23) less than

probable cause suffices to enter an ordinary citizen’s

home. Instead, they ground their theory that “probable cause is not invariably required” (Resp.Br.17;

U.S.Br.13 (quoting Vernonia Sch. Dist. 47J v. Acton,

515 U.S. 646, 653 (1995))), in cases involving liberty

interests far removed from the “core” interest in the

home, Lange, 594 U.S. at 303. See Resp.Br.17, 41, 4748; U.S.Br.13-14, 18.

A warrant or probable cause may not be an “irreducible requirement of a valid search” when officials

search students at school, New Jersey v. T.L.O., 469

U.S. 325, 340 (1985); Acton, 515 U.S. at 653, government employees in the workplace, Nat’l Treasury

Emps. Union v. Von Raab, 489 U.S. 656, 665 (1989),

or impounded vehicles, South Dakota v. Opperman,

428 U.S. 364, 372 (1976); Colorado v. Bertine, 479 U.S.

367, 374 (1987). But these intrusions do not implicate

a citizen’s liberty interest in his home, “the archetype

of [Fourth Amendment] privacy protection.” Lange,

594 U.S. at 303; cf. City of Los Angeles v. Patel, 576

U.S. 409, 420 (2015) (“administrative search[es]” of

hotel’s records). And entering the homes of “probationers in the legal custody of the State,” Griffin v. Wisconsin, 483 U.S. 868, 870 (1987), or benefit recipients

who have consented to such searches, Wyman v.

James, 400 U.S. 309, 317-318 (1971), bears no constitutional comparison to entering a non-consenting person’s home with “long barrel guns” drawn

(Pet.App.5a).

This approach would topple the home’s constitutional status as “first among equals.” Florida v.

Jardines, 569 U.S. 1, 6 (2013). In place of the baseline

warrant and probable cause requirements for home

5

searches, Montana would substitute the weaker protections afforded places the state controls or has custodial power. If anything “reimagine[s]” the Fourth

Amendment (Resp.Br.1), it is equating the citizen in

his home with a schoolchild; a public employee; a probationer; a dependent.

2. To justify this doctrinal inversion, Montana proposes displacing precedent with academic theory. Relying on articles by Professor Akhil Amar, Montana

argues that the Framers “bifurcat[ed]” the Fourth

Amendment into the Warrant Clause and the Reasonableness Clause, creating “two different commands.”

Resp.Br.16. Per this notion, neither the warrant requirement nor probable cause establishes a constitutional baseline for Fourth Amendment “reasonableness”; rather, reasonableness is wholly “separate” and

“distinct.” Resp.Br.16-17, 25.

The precise relationship between the Warrant

Clause and Reasonableness Clause is a matter of “disagreement” running back “over a hundred years,”

Coolidge v. New Hampshire, 403 U.S. 443, 474 (1971),

which this Court has never definitively resolved. But

as Amar recognizes, his view that the protections of

warrants and probable cause do not inform the Reasonableness Clause is contravened by “modern Supreme Court” precedent. The Bill of Rights as a Constitution, 100 Yale L.J. 1131, 1178-1179 (1991). That

precedent “routinely sa[ys] that even warrantless

searches and seizures ordinarily must be backed by

‘probable cause.’” Amar, Fourth Amendment First

Principles, 107 Harv. L. Rev. 757, 782 (1994). So whatever the merits of the “bifurcation” theory, endorsing

6

it would require upending decades of binding precedent, see supra § I.A.1, and raise questions far beyond

this case’s scope.1

B. This Court’s exigency precedents support

a probable cause standard.

This Court’s exigent-circumstances precedents reflect the general requirement that officials have probable cause before making warrantless entries.

Pet.Br.22-25. And while the Court did not use “‘probable cause’ language” in Brigham City or Michigan v.

Fisher, 558 U.S. 45 (2009) (Resp.Br.43), the standard

it did apply is consistent with probable cause.

1. The language and reasoning of the Court’s exigent-circumstances precedents refute Montana’s contention that the Court “has never required officers to

have probable cause of the exigency.” Resp.Br.29.

a. Montana insists Minnesota v. Olson, 495 U.S. 91

(1990), “did not say that the state court actually applied the correct standard” (Resp.Br.45). That ignores

the Court’s holding that the lower court applied “the

1 Further, Professor Amar’s strict “bifurcation” theory

(Resp.Br.16) is hardly the prevailing historical view. See,

e.g., Thomas Y. Davies, Recovering the Original Fourth

Amendment, 98 Mich. L. Rev. 547, 618 (1999) (“[N]one [of

the early constitutional commentaries] identified a reasonableness standard distinct from the standards for a valid

warrant.”). Rather, the requirement of probable cause has

long been tied to the reasonableness of a search or seizure.

The concept evolved independently of, and predates, warrants (see CAC.Br.20-23), and the common law required

“probable cause of suspicion” for warrantless felony arrests,

1 Hale, Historia Placitorum Coronæ 588 (1736); accord

United States v. Watson, 423 U.S. 411, 420-421 (1976).

7

proper legal standard” in requiring “probable cause to

believe that one or more [exigent-circumstance] factors justifying the entry were present.” Id. at 100. The

probable cause standard was “essentially the correct

standard,” ibid., even though the lower court decided

that the facts did not justify warrantless entry

(U.S.Br.28).

b. Montana is equally wrong in reading United

States v. Santana, 427 U.S. 38 (1976), as not “requir[ing] both probable cause of the underlying crime

and separate probable cause to believe that the suspect fled inside her house” (Resp.Br.45). Santana held

that the case was “clearly governed” by precedent

“recogniz[ing] the right of police, who had probable

cause to believe that an armed robber had entered a

house a few minutes before, to make a warrantless entry.” 427 U.S. at 42 (citing Warden v. Hayden, 387 U.S.

294 (1967)). Given that Santana involved the hot-pursuit exception, its language means “the officers had

probable cause to arrest Santana and to believe that

she was in the house.” Id. at 43 (White, J., concurring).

Even the U.S. does not contest Santana’s holding, arguing only that it “does not imply that officers must

always have ‘probable cause’ to believe that an exigency exists.” U.S.Br.27. But this Court has never

adopted varying standards depending on “what type

of exigency it is” (ibid.), and the U.S. offers no reasoned argument on that score.

2. In its BIO, Montana agreed that Brigham City

contemplated a probable cause standard “in function

if not in form.” BIO2. Now, however, Montana contends an “objectively reasonable belief” is formally

and functionally “different” from probable cause

8

(Resp.Br.44), such that applying probable cause

would require “overruling Brigham City” (id. at 2).

Montana’s new position is wrong. That the Court

“never used th[e] term” probable cause explains why

review is necessary here, but it hardly compels a “different meaning[].” Resp.Br.43-44. In both Brigham

City and Fisher, this Court stressed that the officers

personally observed “violent behavior” and “signs of a

recent injury.” Fisher, 558 U.S. at 48 (applying

Brigham City). These observations supported a “fair

probability” or “substantial chance” that an emergency existed, just as they might support an inference

that criminal activity was afoot. Gates, 462 U.S. at 238,

243 n.13. The resonance with probable cause is underscored, not undermined, by the “case-by-case and holistic[]” approach taken in these cases (cf. U.S.Br.21),

for probable cause “consider[s] the facts as a whole,”

District of Columbia v. Wesby, 583 U.S. 48, 60-61

(2018).

C. The affray rule is the most analogous common law rule.

Montana’s rejoinders confirm that the affray rule

is the most relevant common law analogue for emergency-aid entries. None of Montana’s search-and-seizure examples involve an emergency arising within

the home or support a warrantless entry on less than

probable cause. Nor does the “doctrine of necessity” offer proof that warrantless home entries “were governed by reasonableness” (Resp.Br.19-20; U.S.Br.25).

As the treatises confirm, established search-and-seizure rules, not a general necessity defense, defined “a

law enforcement officer’s authority to break open the

doors of a dwelling” at common law.” Wilson v. Arkansas, 514 U.S. 927, 929 (1995) (emphasis added). And

9

regardless, that defense’s requirements were more

stringent than the affray rule’s.

1. Montana pushes at an open door in arguing that

the affray rule was not the only “circumstance[] that

permitted officers of the law to ‘break [open] the

party’s house.’” Resp.Br.21. Our position is not that

the affray rule was the exclusive warrantless entry exception at common law, but that the common law “had

a rule for warrantless entries in precisely the emergency scenario presented in Brigham City.” Pet.Br.23. That affray rule shows “officials could not have entered a home without a warrant on less than probable

cause” (ibid.), not that it required “absolute certainty”

(Resp.Br.20).

Montana does not seriously dispute (Resp.20-21)

that constables could enter a home to part an affray

only if it was “made in a house in the view or hearing

of a constable,” 2 Hawkins, Pleas of the Crown 138139 (1797). The constable’s power to suppress “disorderly drinking or noise in a house at an unreasonable

time of night” was a corollary of the affray rule (2 Hale,

at 95), and nothing suggests it permitted a lesser

showing (Resp.Br.22). Nor does the constable’s duty to

part a reported affray even if “out of [his] presence”

(id. at 44), change the requirements for an in-home affray.

2. None of the other “special crimes or circumstances” identified by Montana (Resp.Br.21-22) involve the constable’s power to address an emergency

arising within a home or support a relaxed certainty

standard. While a constable could “break open the

door, tho he have no warrant” in hot pursuit of a felon,

2 Hale, at 91-92; accord Lange, 594 U.S. at 312, the

constable had to observe the felon’s flight into the

10

home, see, e.g., M. Dalton, The Country Justice 307

(1705) (permitting entry only “upon fresh Suit” of

someone who “dangerously wounded another, and

then fl[ew] into a[] house”). Similarly, while a constable could raise a hue-and-cry “in any case, where he

may arrest, tho it be only a suspicion of felony,” the

pursuers could not “break open doors” unless the suspect actually “be there,” 2 Hale, at 102-103; accord

CAC.Br.13-14 (escapees).

The U.S. tries to minimize the affray rule, casting

it as “primarily tied to arrest, rather than the emergency entry” (U.S.Br.24), but the commentators

stressed the need to “keep the peace,” 2 Hale, at 95.

And it is hardly surprising that the common law rule

on a constable’s power to address an in-home emergency was tied to crime. Constables did not have general first-responder duties; their main power, as a

“conservator of the peace,” was to arrest. 1 J. Chitty,

Criminal Law 20 (1816).

3. To find historical support, Montana reaches beyond the “common law of search and seizure” and an

“officer’s authority,” Wilson, 514 U.S. at 929, to the

law of torts. Invoking the “doctrine of necessity,” Montana argues that the common law allowed warrantless

entries “for a public good such as saving li[ves], and

required no quantum of belief” beyond “that they

[were] reasonably necessary.” Resp.Br.24.

a. As both Montana and the U.S. recognize, the

doctrine of necessity was a general tort defense, applicable to “both officers and private citizens”

(Resp.Br.20; U.S.Br.16), across a wide array of circumstances, including many far afield of an emergency entry to save someone inside a home (e.g.,

11

U.S.Br.16-17 (discussing cases involving wartime requisitioning and casting personal property out of a

barge)).

Because the necessity doctrine was not specific to

constables, it says little about the “the common-law

understanding of an officer’s authority,” Payton v.

New York, 445 U.S. 573, 591 (1980) (emphasis added),

or “traditional protections against unreasonable

searches,” Wilson, 514 U.S. at 931. If, as Montana suggests, the necessity doctrine were a controlling common law “guidepost” for constables (Resp.Br.24-25),

the leading search-and-seizure treatises would emphasize it. Yet neither government points to a single

such treatise even discussing the “doctrine of necessity.” Resp.Br.24. That is unsurprising; if the power of

constables to make warrantless entries were governed

by a general “necessity doctrine,” there would have

been no need for an affray or hot-pursuit rule. Whenever “safety was at stake,” the constable could have

made a warrantless entry, and the homeowners’

rights would “give way.” U.S.Br.16. The “doctrine of

necessity” is absent from these treatises because the

common law already had specific rules governing constables, who could interpose them to “justify [his

search or seizure] in an action of false imprisonment”

or trespass. 1 Hale, at 588. That also explains why

none of the governments’ necessity cases involve a

constable carrying out his duties.

At most, the affray rule could be viewed as a specific application of the general concept that the sanctity of the home “is only to be violated when absolute

necessity compels” it. Chitty, at 52. Even then, however, the general principle would hardly supplant the

specific rule for affrays.

12

b. Even if the “doctrine of necessity” bore on constabulary powers at common law, the authorities advanced by Montana and the U.S. would not support

their proposed standard. Rather, those cases confirm

that it was not enough for a tortfeasor to show his actions were “reasonably necessary.” Resp.Br.24;

U.S.Br.24. The tortfeasor had to “manifestly prove[],”

under “the strictest test,” Rex v. Coate, 98 Eng.Rep.

539, 540 (1772), that “he was right,” in fact, about the

necessity of his actions, Scott v. Wakem, 176 Eng.Rep.

147, 150 (1862). Accordingly, in the few cited cases upholding a trespass into someone’s home (Resp.Br.2425), the facts showed that the danger was publicly apparent, and thus easily cleared the probable cause

standard. See, e.g., Maleverer v. Spinke, 73 Eng.Rep.

79, 81 (1537) (“a[] house on fire”); Handcock v. Baker,

126 Eng.Rep. 1270, 1270 (1800) (wife “cried murder

and called for assistance” from within a home).

D. A probable cause standard best balances

liberty interests in the home and public

safety concerns.

A probable cause standard best balances “the degree to which [a warrantless entry] intrudes upon an

individual’s privacy” against the “legitimate governmental interests” in the safety of occupants and first

responders. Riley v. California, 573 U.S. 373, 385

(2014). To flip the constitutional baseline from a warrant supported by probable cause to a relaxed rule allowing

warrantless

“welfare

check”

entries

(Resp.Br.14), Montana and the U.S. skew the relevant

factors.

1. Montana and the U.S. blur the “firm line” drawn

by the Fourth Amendment “at the entrance to the

13

house,” Lange, 594 U.S. at 303, by equating the paramount liberty interest of a citizen in the home with

subordinate circumstances like a child at school or a

criminal on probation. See supra §I.A.1.

They contend that a citizen’s liberty interest in his

home is contingent on an official’s “purpose” in entering, and may be “diminished” if the intrusion’s purpose is “to render emergency aid.” Resp.Br.13; see also

U.S.Br.10. That reasoning is in tension with Caniglia

v. Strom, which rejected community caretaking as a

“standalone doctrine” “justif[ying] warrantless [home]

searches.” 593 U.S. 194, 196 (2021). And whether an

official claims to provide “aid” (Resp.Br.47) rather

than seek “violations of the law” (U.S.Br.15), the “intrusions share [a] fundamental characteristic: the

breach of the entrance to an individual’s home,” Payton, 445 U.S. at 589. The “essence of the offense” from

a home intrusion is “the invasion of [the occupant’s]

indefeasible right of personal security, personal liberty and private property.” Boyd v. United States, 116

U.S. 616, 630 (1886); cf. Resp.Br.46-47. That does not

change depending on whether the official’s purpose is

the collection of “evidence,” Boyd, 116 U.S. at 630, or

what “uniform” the official wears, Michigan v. Tyler,

436 U.S. 499, 506 (1978).

In focusing on the search’s “primary purpose,”

Montana invokes authority involving programmatic

searches rather than searches requiring individualized justification, like emergency-aid entries.

Resp.Br.47 (quoting Patel, 576 U.S. at 420). As this

Court explained in Brigham City, “‘an inquiry into

programmatic purpose’ is sometimes appropriate” in

assessing the reasonableness of a regime of “program-

14

matic searches conducted without individualized suspicion,” to ensure that “the purpose behind the program” is distinct from “crime control.” 547 U.S. at 405.

Emergency-aid entries, however, “are not programmatic but are responsive to individual events.” Cf. Tyler, 436 U.S. at 507.

Lowering the standard for home entries for non“adversarial” (U.S.Br.19) or “noncriminal purposes”

(Resp.Br.2) would invite courts to uphold searches

based on their post-hoc assessment of whether the

searches furthered “what the government perceives to

be [the occupant’s] own good,” cf. 44 Liquormart, Inc.

v. Rhode Island, 517 U.S. 484, 503 (1996). That is

hardly the Framers’ vision of the Fourth Amendment,

and calls to mind Ronald Reagan’s adage that “the

nine most terrifying words in the English language

are: I’m from the Government, and I’m here to help.”2

2. Nobody disputes the “strong governmental interest in … preserv[ing] life and safety.” U.S.Br.3. But

neither Montana nor the U.S. offers a coherent explanation for why this interest justifies a departure from

the traditional probable cause standard.

a. Montana’s main response is an exercise in question-begging. It insists that probable cause is “inextricably tied to criminal investigations” (Resp.Br.13), so

that “by definition, officers cannot develop probable

cause” in emergency-aid circumstances (id. at 49).

Montana’s premise is wrong. This Court has applied probable cause in “noncriminal context[s].”

The President’s News Conference, Aug. 12, 1986,

https://www.reaganlibrary.gov/archives/speech/presidents-news-conference-23.

2

15

Resp.Br.43. As Montana admits, in Camara v. Mun.

Ct. of City & Cnty. of San Francisco, 387 U.S. 523

(1967), this Court “held that administrative warrants

for health and safety inspections [of homes] must be

supported by probable cause.” Resp.Br.42. That

makes sense; it would be “anomalous to say that the

individual and his private property are fully protected

by the Fourth Amendment only when the individual

is suspected of criminal behavior.” Camara, 387 U.S.

at 530. Nor is Camara an outlier. Rather, because

probable cause “can take into account the nature of

the search,” id. at 538, the Court has long applied

probable cause in a variety of non-criminal contexts,

from civil forfeiture, Locke v. United States, 11 U.S. (7

Cranch) 339, 348 (1813), to “civil traffic violation[s],”

Whren v. United States, 517 U.S. 806, 808 (1996), to

workplace health-and-safety inspections, Marshall v.

Barlow’s, Inc., 436 U.S. 307, 320 (1978). And lower

courts have held that officers seizing an individual

“for a mental-health evaluation” must have “probable

cause that [the] person poses an emergent danger.”

See Graham v. Barnette, 5 F.4th 872, 886 (8th Cir.

2021) (joining “unanimous” circuit courts).

Montana tries to cabin Camara by saying it involved potential “violations of codes for which criminal

penalties applied” (Resp.Br.42-43) and thus was

“criminal-adjacent” (U.S.Br.10). But the possibility of

criminal penalties does not distinguish Camara from

many emergency-aid situations, which often involve

potential criminal activity. Pet.Br.39.

b. In any case, Montana’s reductive claim that

probable cause cannot, “by definition,” apply beyond

criminal investigations (Resp.Br.49) merely dodges

the essential question here: whether probable cause

16

supplies a “workable rule” in emergency-aid contexts,

Dunaway, 442 U.S. at 213.

On that question, Montana and the U.S. have no

substantive response. They insist that “requiring

probable cause for the exigency would make no sense”

(Resp.Br.28), because the standard is “poorly suited,

at best, for the context of emergency aid” (U.S.Br.14).

But basic probable cause principles, like the concepts

of a “fair probability” and “substantial chance,” Gates,

462 U.S. at 238, 243 n.13, apply equally to the risk

“that an occupant is seriously injured or imminently

threatened with such injury,” Brigham City, 547 U.S.

at 400. Nor is it “difficult to see” (U.S.Br.14) how the

standard’s familiar principles of corroboration would

apply to assessing the risk and gravity of an emergency, cf. Gates, 462 U.S. at 242-246. These general

principles help officers with incomplete information

assess risk and probability “on the spur (and in the

heat) of the moment.” Atwater v. City of Lago Vista,

532 U.S. 318, 347 (2001). As the U.S. explained in its

Brigham City amicus brief, “the basic requirement

that the police have an objectively reasonable belief—

i.e., probable cause—does not change, but the object of

the probable cause does change.” 2006 WL 448210, at

*18 n.18.

c. Montana and the U.S. also warn that adopting a

probable cause standard for emergency-aid situations

“would almost always prevent law enforcement from

helping” home occupants (Resp.Br.49), and “impede

first responders from saving lives” (U.S.Br.3). But neither actually explains why a probable cause standard,

in practice, would foreclose first responders from addressing “heartland” emergency-aid scenarios, including those set out by the Caniglia concurrences.

17

Pet.Br.45-48; cf. U.S.Br.30. In fact, as Montana previously recognized, lower courts already “routinely apply the probable cause standard” to emergency-aid entries (BIO2-3), without compromising their ability to

deliver urgently needed care (see Pet.Br.45-48).

3. Finally, Montana ignores the dangers of nonconsensual warrantless entries. Because “enter[ing] another’s home without permission” itself creates a “substantial risk” of violent confrontation, United States v.

Carter, 601 F.3d 252, 255 (4th Cir. 2010), the “governmental interest[] in saving li[ves]” applies to first responders and occupants alike (Resp.Br.14). This case

illustrates the point: despite being called “for ‘a welfare check’” on Case (Resp.Br.4), the officers ultimately shot him (accord NACDL.Br.17 (“[w]elfare

checks … are among the most dangerous encounters

between individuals and law enforcement”)).

II. Montana’s

intermediate

reasonableness

standard contravenes precedent and would

sow confusion.

Montana does not try to defend the reasonable suspicion standard applied below, arguing, instead, for a

vague “reasonableness” standard that “stops short of

probable cause.” Resp.Br.41. But this standard between reasonable suspicion and probable cause is at

odds with precedent and hopelessly indeterminate.

1. Unlike its amici (States.Br.3; Mannheimer.Br.16), Montana does not urge a reasonable suspicion standard (Resp.Br.39-40), and the U.S. disclaims any “equivalen[ce]” between Brigham City’s

standard and reasonable suspicion (U.S.Br.10, 21).

Both governments, however, invoke cases applying a

18

reasonable suspicion standard in their effort to minimize the intrusiveness of warrantless home entries.

E.g., T.L.O., 469 U.S. at 345-347. Indeed, in formulating its proposed reasonableness standard, the U.S.

urges applying a “lesser degree of certainty—such as

a ‘moderate chance’” to emergency-aid situations.

U.S.Br.20. But the very case it cites applied the

“standard of reasonable suspicion” to school searches.

Safford Unified Sch. Dist. No. 1 v. Redding, 557 U.S.

364, 370 (2009).

Regardless of whether these arguments are a backdoor endorsement of reasonable suspicion, a standard

“short of probable cause” (Resp.Br.41) would increase

the risk of mistaken and dangerous home entries

(Pet.Br.39-42), invite abuse in the many emergencyaid scenarios involving potential criminal activity (id.

at 39; NACDL.Br.9-14), and erode Fourth Amendment protections for the mentally ill (Pet.Br.40-41;

APA.Br.10-11).

2. Taken at their word, Montana and the U.S. argue that the emergency-aid exception should be governed by a vague “objective-reasonableness”

(Resp.Br.15) or “[g]eneral [r]easonableness” standard

(U.S.Br.12) that exceeds reasonable suspicion and

“stops short of probable cause” (Resp.Br.41). But the

Court has previously rejected attempts to “enunciate[e] still a third Fourth Amendment threshold between ‘reasonable suspicion’ and ‘probable cause,’”

Montoya de Hernandez, 473 U.S. at 540, and it should

do so again. Neither Montana nor the U.S. explains

how the standard would provide a “workable rule” for

emergency-aid situations, Dunaway, 442 U.S. at 213,

and their efforts to even enunciate an “appropriate

19

reasonableness standard” (U.S.Br.10) yield no standard at all.

a. Montana and the U.S. observe that a generalreasonableness standard is “flexible” (Resp.Br.36) and

“account[s] for all of the circumstances” (U.S.Br.17;

see also Resp.Br.34-35). But these formulations do not

distinguish that standard from probable cause or even

reasonable suspicion, both of which are also characterized by a “flexible,” Gates, 462 U.S. at 238-239, totality-of-the-circumstances assessment, ibid., Redding, 557 U.S. at 385. And apart from noting that the

standard was satisfied in this Court’s emergency-aid

cases (Resp.Br.34-35; U.S.Br.21), the State and Government offer no concrete explanation for how their

standard would guide first responders in deciding,

amidst the flux and stress of an emergency, whether

to make entry. A general reasonableness test may

make sense for assessing a regime of “programmatic

searches,” Brigham City, 547 U.S. at 405, or determining the proper standard “governing any specific class

of searches,” T.L.O., 469 U.S. at 337, but it offers little

guidance for individual home entries under exigent

circumstances.

b. The distinguishing feature of the proposed reasonableness standard only adds to the confusion: the

lack of any clear requirement of certainty. Montana

articulates no certainty requirement at all, and the

U.S. is inconsistent on the point, suggesting a “moderate chance” requirement drawn from the reasonable

suspicion standard it disavows. U.S.Br.20. It is unsurprising that the State and Government struggle to

give content to their reasonableness standard. That

standard not only “risks melding the two [established]

standards,” 2 Wayne R. LaFave, Search and Seizure:

20

A Treatise on the Fourth Amendment §3.1(a) (6th ed.

2020), but is “so devoid of content that it produces rather than eliminates uncertainty,” creating “difficulties … for courts, police, and citizens,” O’Connor v. Ortega, 480 U.S. 709, 730 (1987) (Scalia, J., concurring).

That indeterminacy is underscored by Montana’s

shifting positions on what the standard means—first

arguing that “[t]he daylight between probable cause

and an ‘objectively reasonable basis’ is difficult, if not

impossible, to see” (BIO15), but now claiming that the

standard compels something “short of probable cause”

(Resp.Br.41). Even Montana’s amici are at odds, with

some understanding an “objectively reasonable basis”

to require mere reasonable suspicion (Mannheimer.Br.16; States.Br.3), and others saying it imposes

a standard distinct from either reasonable suspicion

or probable cause (U.S.Br.10; Local.Gov.Br.3).

c. Far from solving this indeterminacy problem,

the U.S.’s proposed “sliding scale” approach, requiring

“less certain[ty]” the “more severe a danger”

(U.S.Br.22), would exacerbate it.

This Court has already built the “potential severity” of a danger (ibid.) into the emergency-aid exception’s threshold, for it applies only when there is a risk

“that an occupant is seriously injured or imminently

threatened with such injury.” Brigham City, 547 U.S.

at 400 (emphasis added). The seriousness of circumstances may bear on whether they constitute the type

of exigency justifying a warrantless entry. Ibid. This

Court has held, for example, that the hot-pursuit exception does not categorically allow officers to follow a

suspect into a house if he is suspected of a misdemeanor, Lange, 594 U.S. at 313, or was merely the

driver in a victimless crash, Welsh v. Wisconsin, 466

21

U.S. 740, 753 (1984). But the circumstances’ seriousness does not change the degree of certainty required

to invoke the exception, just as the seriousness of a

crime does not change the requirement of probable

cause. Cf. Atwater, 532 U.S. at 354.

The U.S.’s theory would allow warrantless entries

even if only “a relatively slim chance existed” of a catastrophic threat in a home. U.S.Br.22. Under such a

test, officers might not even need reasonable suspicion

to enter a home if someone reported a “highly destructive bomb” (ibid.) or similar threat. Indeed, the U.S.’s

academic authority suggests that “[s]ometimes 0.1%

is more than enough” to permit warrantless home entry. Amar, First Principles, at 801. But the U.S. cites

no case blessing such an extreme approach. And the

notion that the government could enter a home on an

anonymous tip with zero corroboration, provided the

tip involved a particularly destructive threat, would

invite even greater abuse (in cases with criminal implications) and mischief (in “swatting” cases) than a

Terry standard. It would also set at naught the government’s “heavy burden” in “demonstrat[ing] an urgent need that might justify warrantless searches.”

Welsh, 466 U.S. at 749-750.

By requiring officials to determine the severity of

a health or safety risk and then calibrate the required

level of certainty accordingly, the Government’s sliding-scale approach demands just the sort of on-thespot balancing this Court has cautioned against: “reflect[ing] on and balanc[ing] the social and individual

interests involved in the specific circumstances [officers] confront.” Dunaway, 442 U.S. at 214. Such balancing provides inadequate guidance to first responders and would inevitably lead to “more slide than

22

scale.” United States v. Winsor, 846 F.2d 1569, 1578

n.9 (9th Cir. 1988).

In contrast, “the requisite ‘balancing’ … is [already]

embodied in” the “single, familiar standard” of probable cause. Dunaway, 442 U.S. at 213-214. That standard permits officials to consider the specific risk at issue in making a “balanced assessment” of corroborating information and its “relative weights.” Gates, 462

U.S. at 234. Commonplace risks, like an injured child,

may require first responders to corroborate ambiguous clues like children yelling. But a more unusual

emergency, like a “highly destructive bomb” in a

house (U.S.Br.22), may be corroborated by even a few

telling clues—like an “abundance of wire” outside the

house, cf. United States v. Melvin, 596 F.2d 492, 498

(1st Cir. 1979). Police have long applied probable

cause to investigate serious crimes and forestall “severe” danger (U.S.Br.22), and that experience translates directly to assessing emergencies.

3. The “object in implementing [the Fourth Amendment’s] command of reasonableness is to draw standards sufficiently clear and simple” that officials can

make judgments in “the heat[] of the moment.” Atwater, 532 U.S. at 347. While the U.S. worries that “firefighters, social workers and paramedics … may not

apply probable-cause standards as commonly as police

officers do” (U.S.Br.29), the “relative simplicity and

clarity” of probable cause, Dunaway, 442 U.S. at 213,

make it far more manageable, and far less “unpredictable” (cf. U.S.Br.29), than the proposed balancing of

incommensurable social interests.

23

III.

The officers here lacked probable cause—or

reasonable grounds—of an emergency justifying warrantless entry into Case’s home.

Montana does not dispute that if the officers’ only

objective justification for entering Case’s home was

the threat that he would “attempt to elicit a defensive

response, i.e., a ‘suicide-by-cop” (Pet.App.5a), their entry was unconstitutional (Resp.Br.36-37). The State

argues, instead, that the officers had probable cause

(Resp.Br.51-52), or reasonable grounds to believe

“J.H.’s initial report that Case was ‘in danger’ and

might attempt suicide” (Resp.Br.37).

As the officers’ own conduct shows, the “key facts”

they knew—especially their “prior personal

knowledge” and “prior interactions” with Case

(Resp.Br.36-37)—did not support a fair probability

that Case had shot or would imminently shoot himself.

A reasonable officer who believed Case had “already

shot himself” or “might do so imminently” (U.S.Br.32)

would have entered as quickly as possible. Yet the officers waited 40 minutes before doing so.

Even allowing time to “make appropriate cautionary plans” (Resp.Br.39), it was not objectively consistent with probable cause of an exigent self-shooting

to enter after so much delay. But it was consistent

with the officers’ own on-the-scene assessment “that

it was unlikely Case required immediate aid, but rather was likely lying in wait for them to commit suicide by cop.” Pet.App.29a (McKinnon, J., dissenting).

The pivotal information, as the officers recognized,

was Case’s track record, paired with J.H.’s warning

that Case wanted to “shoot it out” with the police.

JA104. Police Chief Sather remarked that Case “ain’t

got the guts” to shoot himself (Pasha-Cam2 at 0:08:25),

24

reflecting the officers’ experience, summarized by Sergeant Pasha, that Case had “been suicidal forever and

he hasn’t done it but there have been several times

where he’s tried getting us to do it” (Pasha-Cam2 at

0:06:58). In fact, the “last time” police were called to

Case’s house, he also “said he was going to shoot it out

with [the officers].” Linsted-Cam1, at 0:02:06.

The point is not, as Montana suggests, that “the

responding officers’ supposed subjective views” control the probable cause inquiry (Resp.Br.38); rather,

their on-the-ground assessment underscores how a

reasonable officer would objectively view the situation.

After all, “a police officer may draw inferences based

on his own experience in deciding whether probable

cause exists.” Ornelas v. United States, 517 U.S. 690,

700 (1996). Even if the “trail of corroborating breadcrumbs” (Resp.Br.37) was consistent with both a risk

of suicide and a risk of suicide-by-cop, an inference

that Case was at risk of suicide was undermined here

by the officers’ experience. That experience, along

with their on-the-scene observations, made suicideby-cop a “countervailing probabilit[y],” United States

v. Jackson, 415 F.3d 88, 94 (D.C. Cir. 2005), and rendered their delayed entry unreasonable even under

Montana’s standard. Indeed, far from providing “lifesaving aid” (U.S.Br.31), the officers here shot Case.

CONCLUSION

This Court should reverse the Montana Supreme

Court.

25

Respectfully submitted,

ELIZABETH NIELSON

FRED A. ROWLEY, JR.

Wilson Sonsini

Counsel of Record

Goodrich & Rosati, P.C. MARK R. YOHALEM

95 S. State St., Ste 1000

Wilson Sonsini

Salt Lake City, UT 84111 Goodrich & Rosati, P.C.

953 E. Third St., Ste 100

CHRISTOPHER R. BETCHIE

Los Angeles, CA 90013

Hull, Swingley &

(323) 210-2900

Betchie, P.C.

fred.rowley@wsgr.com

P.O. Box 534

Helena, MT 59624

JOHN B. KENNEY

Wilson Sonsini

NATHAN D. ELLIS

Goodrich & Rosati, P.C.

2047 N. Last Chance

1700 K Street NW

Gulch #482

Washington, D.C. 20006

Helena, MT 59601

ERIC O. BRAVIN

KELSEY C. CATINA

New York University

MADISON J. WELSH

School of Law

Wilson Sonsini

245 Sullivan St.,

Goodrich & Rosati, P.C.

Ste C-20

701 Fifth Avenue

New York, NY 10012

Ste 5100

Seattle, WA 98104

Counsel for Petitioner

OCTOBER 2025