2006 Decisions

Opinions of the United

States Court of Appeals

for the Third Circuit

7-21-2006

USA v. Mosley

Precedential or Non-Precedential: Precedential

Docket No. 05-1519

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Recommended Citation

"USA v. Mosley" (2006). 2006 Decisions. Paper 649.

http://digitalcommons.law.villanova.edu/thirdcircuit_2006/649
The Honorable Thomas M. Reavley, United States *

Circuit Judge for the Fifth Circuit, sitting by designation.

PRECEDENTIAL

UNITED STATES COURT OF APPEALS

FOR THE THIRD CIRCUIT

 

No. 05-1519

 

UNITED STATES OF AMERICA

 v.

ROBERT MOSLEY,

 Appellant

 

On Appeal from the United States District Court

for the Eastern District of Pennsylvania

(D.C. No. 04-cr-00190)

District Judge: Honorable John R. Padova

 

Argued June 15, 2006

Before: FISHER, CHAGARES and

REAVLEY, Circuit Judges.

*

(Filed: July 21, 2006)
2

David L. McColgin

Brett G. Sweitzer (Argued)

Defender Association of Philadelphia

Federal Court Division

601 Walnut Street

The Curtis Center, Suite 540 West

Philadelphia, PA 19106

Attorneys for Appellant

Jennifer A. Williams (Argued)

Office of United States Attorney

615 Chestnut Street, Suite 1250

Philadelphia, PA 19106

Attorney for Appellee

 

OPINION OF THE COURT

 

FISHER, Circuit Judge.

We are presented here with a casebook-ready fact pattern

implicating an area of Fourth Amendment law that has long

been a source of confusion. Today we explain, as clearly as we

can, how the exclusionary rule applies in cases in which

evidence obtained during an illegal traffic stop is introduced

against a passenger with no possessory interest in the vehicle.

We hold that when a vehicle is illegally stopped by the

police, no evidence found during the stop may be used by the
3

government against any occupant of the vehicle unless the

government can show that the taint of the illegal stop was

purged. The metaphorical bubble of causation encapsulates the

entire vehicle and links the illegality of the stop to the Fourth

Amendment rights of all of the occupants.

In so holding, we join all of our sister circuits that have

directly faced this issue. We will canvass that caselaw, and

explain why we agree with it.

I.

On the night of October 28, 2003, Robert Mosley went to

the Diamond Dolls nightclub in Philadelphia with his nephew

Jerome Small, who drove. While they were at the club, Small

received a telephone call from a romantic acquaintance, and told

Mosley that he was leaving the club to go meet her. Not

wanting to leave Mosley without a ride home, Small introduced

Mosley to his friend Julian Hayes, who agreed to drop Mosley

off on his way home. At around 1:30 a.m., Mosley left the club

with Hayes and Erica Scott, a dancer at the club who was

accompanying Hayes. Hayes and Scott got in the front seat of

Hayes’ vehicle, a green Suzuki SUV, and Mosley got in the

back.

At about the same time, a police radio call went out

advising officers to be on the lookout for a black man with

dreadlocks driving a green SUV. The source of the information

relayed in the radio call is not reflected in the record. Police

officers on patrol in the neighborhood of the nightclub heard the

call and shortly thereafter saw Hayes’ SUV, a green SUV with
The jury specially found that Mosley had possessed only 1

the gun that was on the seat itself, and not the two that were on

the floor.

4

a black driver, as it was pulling away from the nightclub. They

immediately pulled the car over. Upon approaching the car, the

responding officers observed a gun on the floor under the

driver’s seat. They then ordered Hayes, Scott, and Mosley to get

out of the car, and searched it, recovering a second gun from

the front seat, two from the floorboards of the back seat area,

and one from the back seat itself. Hayes and Mosley were

arrested and charged with gun possession.

However, the Supreme Court has held that anonymous

tips do not provide sufficient justification for an investigatory

stop, see Florida v. J.L., 529 U.S. 266 (2000), and the officers

did not observe Hayes committing any traffic violation that

would have justified the stop under Whren v. United States, 517

U.S. 806 (1996). The government conceded that the stop was

illegal, and dropped all charges against Hayes.

The government proceeded, however, with the gun

possession case against Mosley, arguing that because he was a

passenger in the vehicle, he could not seek to suppress the guns,

notwithstanding the illegality of the stop. Mosley contended

that insofar as he had been illegally seized by the traffic stop, he

should have the same suppression claim as Hayes. The District

Court agreed with the government, and admitted into evidence

the guns found in the back seat of the vehicle. Mosley was 1

convicted under 18 U.S.C. § 922(g) for possessing a firearm
Mosley had a prior felony conviction for burglary, which 2

supplied the predicate for the § 922(g) charge.

Mosley also contends, first, that the evidence of 3

constructive possession was insufficient; second, that the

District Court erroneously sentenced him under the “armed

career criminal” enhancement provisions of 18 U.S.C. § 924(e);

third, that the District Court failed adequately to determine

whether Mosley’s prior convictions were “related” for purposes

of calculating his criminal history under the Guidelines; and

fourth, that § 924(g), the felon-in-possession statute, is

unconstitutional under the Commerce Clause. As to these, the

government concedes error on the § 924(e) issue, and does not

object to reconsideration of the Guidelines criminal history

calculation. Because we will order suppression of the guns, we

deem it unnecessary to decide the sufficiency question. And we

acknowledge that the Federal Public Defender’s office preserves

the Commerce Clause challenge to § 922(g) in order to pursue

certiorari in the Supreme Court; we are bound by our prior case,

United States v. Singletary, 268 F.3d 196 (3d Cir. 2001), in

which we upheld the constitutionality of the statute.

5

following a felony conviction. He appeals on several grounds; 2

we will decide the case on the suppression issue. “We review 3

the denial of a motion to suppress for clear error as to the

underlying factual determinations and exercise plenary review

over the application of the law to those facts.” United States v.

Williams, 417 F.3d 373, 376 (3d Cir. 2005).
Consider this scenario: the police mount an operation in 4

which they erect a fake “drug checkpoint” (which are flatly

illegal under Indianapolis v. Edmond, 531 U.S. 32 (2000)) and

then stake out the highway exit just before the fake checkpoint,

videotape all vehicles exiting there, and pull over any vehicle

that violates a traffic law (for example, failing to signal at the

exit turn). The practice was upheld this year in United States v.

Rodriguez-Lopez, 444 F.3d 1020 (8th Cir. 2006). More

6

II.

When one peruses the traffic-stop suppression caselaw,

one is struck by how rarely a traffic stop is found to have been

illegal. In United States v. Whren, 517 U.S. 806 (1996), the

Supreme Court established a bright-line rule that any technical

violation of a traffic code legitimizes a stop, even if the stop is

merely pretext for an investigation of some other crime. And

once a car has been legally stopped, the police may “escalate”

the encounter by visually inspecting the interior of the car, and

checking credentials and asking questions of the occupants. See

United States v. Givan, 320 F.3d 452, 458 (3d Cir. 2003) (“After

a traffic stop that was justified at its inception, an officer who

develops a reasonable, articulable suspicion of criminal activity

may expand the scope of an inquiry beyond the reason for the

stop and detain the vehicle and its occupants for further

investigation.”). Courts give considerable deference to police

officers’ determinations of reasonable suspicion, see, e.g.,

United States v. Nelson 284 F.3d 472, 482 (3d Cir. 2002), and

the cases are steadily increasing the constitutional latitude of the

police to pull over vehicles.4
famously, in United States v. Arvizu, 534 U.S. 266 (2002), the

Supreme Court reversed the Ninth Circuit’s determination that

a Border Patrol officer had gone too far in basing a traffic stop

of a family van on his observation that the kids had waved at

him “mechanically.”

The “standing” inquiry, in the Fourth Amendment 5

context, is shorthand for the determination of whether a

litigant’s Fourth Amendment rights have been implicated. See

United States v. Kimball, 25 F.3d 1, 5 (1st Cir. 1994) (“We use

the term ‘standing’ as a shorthand method of referring to the

issue of whether the defendant’s own Fourth Amendment

interests were implicated by the challenged governmental action.

‘Technically, the concept of “standing” has not had a place in

Fourth Amendment jurisprudence for more than a decade, since

the Supreme Court in Rakas v. Illinois, 439 U.S. 128, 58 L. Ed.

2d 387, 99 S. Ct. 421 (1978), indicated that matters of standing

in the context of searches and seizures actually involved

substantive Fourth Amendment law.’ United States v. Sanchez,

943 F.2d 110, 113 n.1 (1st Cir. 1991).”).

7

Passengers in cars, unlike owners or licensees, have no

reasonable expectation of privacy in the interior of the vehicle

in which they are riding. Because the Fourth Amendment’s

protection against unreasonable searches is predicated on the

invasion by the government of a person’s reasonable expectation

of privacy, passengers are generally held to lack “standing” to 5

object to evidence discovered in a search of a vehicle. See

Rakas v. Illinois, 439 U.S. 128 (1978). Fourth Amendment

rights are personal rights, and a search of a car does not
While the District Court’s opinion is not entirely clear on 6

this point, we read it to suggest that the District Court

analytically separated the detention of the vehicle from the

removal and detention of Mosley’s person, and believed that

only the latter constituted a seizure of Mosley for Fourth

Amendment purposes. The District Court stated, for example,

that “[f]or purposes of the instant Motion [to suppress], the

Government concedes that the officers violated Defendant’s

Fourth Amendment rights by removing him from the vehicle and

detaining him in connection with the stop of the vehicle.”

The Fourth Amendment violation, however, was the

traffic stop itself, and not just Mosley’s removal from the car.

We wish to reiterate this point for the benefit of future litigants:

a Fourth Amendment seizure of every occupant of a vehicle

occurs the moment that vehicle is pulled over by the police. The

legality of the seizure depends upon the legality of the traffic

stop.

8

implicate the rights of non-owner passengers: the car is treated

conceptually like a large piece of clothing worn by the driver.

But we should not be distracted by the fact that this case

involves evidence found in a car. This is not an “auto search”

case. The search of the car is not before us; the seizure of

Mosley is. This case is about an illegal seizure by the police of

the defendant, pursuant to which evidence was discovered. The

violation of Mosley’s Fourth Amendment rights was the traffic

stop itself, and it is settled law that a traffic stop is a seizure of

everyone in the stopped vehicle, see Delaware v. Prouse, 440

U.S. 648, 653 (1979). Thus passengers in an illegally stopped 6
For the most comprehensive collection of cases, see 6 7

Wayne R. LaFave, Search and Seizure § 11.3 (4th ed. 2004)

(citing, inter alia, United States v. Grant, 349 F.3d 192 (5th Cir.

2003); United States v. Ameling, 328 F.3d 443 (8th Cir. 2003);

United States v. Gama-Bastidas, 142 F.3d 1233 (10th Cir.

1998); United States v. Sowers, 136 F.3d 24 (1st Cir. 1998);

United States v. Rusher, 966 F.2d 868 (4th Cir. 1992)).

9

vehicle have “standing” to object to the stop, and may seek to 7

suppress the evidentiary fruits of that illegal seizure under the

fruit of the poisonous tree doctrine, as expounded in the line of

cases following Wong Sun v. United States, 371 U.S. 471

(1963). The dispositive legal issue is the causal relationship

between the traffic stop and the discovery of the evidence:

whether the evidence found in the car was “fruit” of the illegal

stop. The question that bedeviled the proceedings below is

whether the evidence found in the car was causally linked to the

illegal seizure of Mosley, the passenger.

In analyzing that causal connection, the District Court

relied on a Tenth Circuit case, United States v. DeLuca, 269

F.3d 1128 (10th Cir. 2001), in which a passenger sought to

suppress evidence found during a traffic stop. Taking its cue

from that case, the District Court proposed various hypotheticals

to test the “factual nexus” between the violation of Mosley’s

Fourth Amendment rights and the discovery of the evidence.

Specifically, the District Court pondered whether, if Mosley had

asked for and received permission to leave the scene

immediately after the car was stopped, the evidence in the car

would still have been discovered. Since the answer to that
10

question is obviously “yes,” the District Court ruled that Mosley

had failed to demonstrate an adequate “factual nexus” between

the illegal government action and the discovery of the

challenged evidence. Although the government had clearly

violated Mosley’s Fourth Amendment rights, the District Court

determined that the specific violation of Mosley’s rights – as

opposed to Hayes’ rights – did not have a sufficiently close

causal connection, or “factual nexus,” to the discovery of the

evidence to support Mosley’s suppression claim.

The general requirement of a “factual nexus” between a

specific Fourth Amendment violation and a specific piece of

evidence derives from two Supreme Court cases on wiretap

evidence. In those cases, the government had gathered

thousands of discrete pieces of evidence over many months of

investigation. Over the course of the investigation, the

government committed various illegal acts, and the question for

the Court was how to determine which pieces of evidence were

tainted by the particular illegal actions. See United States v.

Nardone, 308 U.S. 338, 341 (1939); United States v. Alderman,

394 U.S. 165, 183 (1969). Because of the multiplicity and

complexity of the investigation and the evidence, there was no

commonsense causal relationship between any given Fourth

Amendment violation and any given piece of evidence. Rather

than hold all the evidence to have been tainted by the violations,

the Court held that the proper course is for district courts to

probe more deeply, and employ thought experiments to

determine which violation was causally connected to which
The test has since been applied by the Ninth Circuit in

8

complex cases involving ongoing police investigations. See,

e.g., United States v. Kandik, 633 F.2d 1334 (9th Cir. 1980);

United States v. Allard, 600 F.2d 1301 (9th Cir. 1979); United

States v. Cella, 568 F.2d 1266 (9th Cir. 1977).

11

piece of evidence. These cases express the commonsense 8

proposition that a single Fourth Amendment violation does not

taint an entire case, but only the evidence uncovered as a result

of that violation.

Prior to DeLuca, courts had not generally thought that

traffic stops presented sufficiently complex investigatory

contexts to warrant such an added layer of causal analysis. In

DeLuca, however, a panel of the Tenth Circuit, over a heated

dissent by former Chief Judge Seymour, applied that

counterfactual – “What if?” – approach to a suppression motion

brought by a passenger who was illegally detained during a

traffic stop. The application of “factual nexus” hypotheticals to

a traffic stop suppression case was a novel idea. The majority

view in the circuits was and remains that in a traffic stop, there

will always be a sufficient “nexus” between the stop and the

search, unless there are significant intervening events that sever

or attenuate the causal chain. There is generally no “nexus”

problem in illegal traffic stop cases, as the leading treatise puts

it, because the connection between the illegal action and the

discovery of the evidence is straightforward: If the police had

not pulled over the vehicle, they would not have discovered the

evidence. See 6 Wayne R. LaFave, Search and Seizure

§ 11.4(d) (4th ed. 2004) (summarizing caselaw).
In fact this is not such an unusual occurrence. A traffic 9

stop requires only reasonable suspicion to believe that a traffic

violation has been committed. But detaining the vehicle longer

than is necessary to effectuate the legitimate response to that

traffic violation requires independent suspicion that some other

crime is afoot. The transition from traffic stop to investigatory

stop is the focal point of many suppression cases. See, e.g.,

Illinois v. Caballes, 543 U.S. 405, 407 (U.S. 2005) (“A seizure

that is justified solely by the interest in issuing a warning ticket

to the driver can become unlawful if it is prolonged beyond the

time reasonably required to complete that mission.”).

12

We can understand why the DeLuca majority thought that

the case required some revision to the traditional fruits analytical

apparatus. DeLuca did not involve an illegal traffic stop. It

involved instead a legal traffic stop that became illegal when the

police continued to detain the vehicle and its occupants after the

legitimate purposes of the stop had been completed. Because 9

the stop itself was legal, the court reasoned that whatever

government actions violated the defendant’s rights must be

analytically separable from the traffic stop. The Fourth

Amendment violation in DeLuca was the detention of the

defendant passenger, along with the other occupants of the car,

beyond the period necessary to complete the legitimate purposes

of the stop. But at the point that the detention of the defendant

passenger became illegal, the police already had control over the

vehicle. The court therefore tried to tease out the causal efficacy

of the precise illegality raised by the defendant passenger. The

court asked whether, if the passenger had been allowed to leave

the scene before the detention became illegal, the incriminating
Even on its limited facts, DeLuca was not 10

uncontroversial. Former Chief Judge Seymour issued a

blistering dissent, calling the majority’s reasoning “ludicrous,”

and Professor LaFave concurred in that assessment. The most

serious criticism is that the counterfactual methodology “forces

the defendant to disprove inevitable discovery and does an end

run around the government’s burden of proof on inevitable

discovery.” DeLuca, at 269 F.3d at 1145 n.1 (Seymour, J.,

dissenting).

13

evidence would still have been discovered. The answer was

“yes”: it wasn’t his car, so his leaving would not have removed

the evidence.

The question in DeLuca was thus whether the police

would still have discovered the challenged evidence if they had

let the passenger go before doing anything illegal to him. On

the DeLuca facts, if the police had let the passenger go after the

initial legal stop but before the subsequent illegal prolongation

of the stop, then nothing illegal would have been done to him –

and the evidence would still have been discovered. Therefore

the passenger had no suppression claim. So reasoned the Tenth

Circuit.10

But we agree with Mosley that DeLuca is inapposite here.

The hypothetical, and the holding, are relevant only to situations

in which the initial traffic stop is legal, and that is not our case.

We express no opinion on the viability in this Circuit of the

DeLuca test on DeLuca facts; we decide the case before us, not
We will not be overly coy, though: we recognize that 11

the rationale for our holding might be thought to undermine the

DeLuca rationale even on DeLuca facts. But the preceding

sentence is dicta; when an appropriate case arises, the parties

may do what they will with our decision here.

14

a different one. But whatever its viability on appropriate facts,

11

this case does not present such facts. If the initial traffic stop is

illegal, then even if the passenger is allowed to leave the scene

before the search, it will not be the case that the police have not

violated his Fourth Amendment rights. Where the traffic stop

itself is illegal, it is simply impossible for the police to obtain

the challenged evidence without violating the passenger’s

Fourth Amendment rights. DeLuca says nothing about such

situations.

The Tenth Circuit itself has addressed the question

whether DeLuca applies to traffic stops illegal from their

inception, and stated clearly that it does not. It applies, the court

explained in a recent suppression case applying DeLuca, only to

cases in which the illegal police conduct occurred after the
And the same is true of an earlier Tenth Circuit case, 12

United States v. Nava-Ramirez, 210 F.3d 1128 (10th Cir. 2000),

cited in DeLuca: “Nava-Ramirez does not contest the legality

of the initial stop. Rather, he argues that at the moment [the

officer] concluded his search of the passenger compartment

without finding any evidence indicating Nava-Ramirez was

involved in illegal activity, his continued detention became

unlawful.” That factual setting – initially legal stop, subsequent

illegal detention of passenger – is the underpinning and

necessary condition for the DeLuca-type “factual nexus” test.

It has absolutely no application to situations where the passenger

challenges the legality of the initial stop.

15

police had legally gained control of the vehicle. The temporal

12

sequence of events makes all the difference, said the court:

[Wong Sun] and its progeny, see, e.g., United

States v. Melendez-Garcia, 28 F.3d 1046,

1053-54 (10th Cir. 1994), are readily

distinguishable insofar asin those casesthe illegal

police conduct preceded the means by which the

evidence was obtained, thus establishing the

requisite factual nexus between the evidence and

the illegal conduct. By contrast, any unlawful

police activity here occurred after voluntary

consent had been obtained. Consequently, [the

defendant] could not establish that, but for the

alleged illegal seizure, the evidence would not

have come to light as required by DeLuca.
The Roberts case, to be sure, is unpublished, but we 13

think the recently adopted amendment to Fed. R. App. Proc.

32(a) confirms the utility of looking to unpublished cases to

determine how precedential cases are applied. Where, as here,

an NPO clarifies the application of a prior precedent, almost all

the circuits allow its citation by the parties, and we will not

needlessly deprive ourselves of useful guidance on the scope of

the caselaw that governed this case below.

16

United States v. Roberts, 91 Fed. Appx. 645, 648 (10th Cir.

2004) (emphasis added).

The District Court’s application of DeLuca to the case at

bar, in which the illegal police conduct preceded the means by

which the evidence was obtained, was error, because even under

the Tenth Circuit’s heightened “factual nexus” test, such a

temporal scenario would appear to clearly supply the requisite

“factual nexus.”13

It is clear, so far, that an illegal traffic stop constitutes a

seizure of all occupants of a vehicle, including passengers, and

that whatever the utility of the DeLuca counterfactual analysis

to fact patterns not before us, it is not the proper analytical

model for the case that is before us.
17

III.

A.

Fourth Amendment rights are personal rights. That

proposition is not in dispute. The problem is that from that

proposition, the result in any particular case is not always

immediately obvious. Mosley does not dispute that he had no

personal expectation of privacy in the interior of the car; the

government does not dispute that he did have a reasonable

expectation that he would not be seized without probable cause.

The problem is whether the evidence in this case was discovered

as a result of his seizure.

As we will detail below, most courts treat evidence found

during an illegal traffic stop as the fruits of that stop, and see no

conceptual difficulties in suppressing such evidence when

introduced against passengers. Our most recent decision to face

such a scenario, United States v. Williams, 413 F.3d 347 (3d Cir.

2005), concerned a non-owner passenger in a parked van that

was approached by two police officers, who subsequently

observed contraband in the vehicle. The defendant claimed that

the approach constituted a seizure. We framed the suppression

issue as follows:

The central issue on appeal . . . is whether

Williams was seized within the meaning of the

Fourth Amendment when the police . . .

approached the van. If Williams was “seized” by

the police when they approached the parked van

without probable cause or reasonable suspicion to
18

do so, then the District Court correctly suppressed

all evidence obtained in connection with the

ensuing arrest under the “fruits of the poisonous

tree” doctrine.

413 F.3d at 351. Our approach can be summarized as follows:

We ask, first, whether there was a seizure. If so, then we ask

whether there was reasonable suspicion or probable cause. If

not, then suppression is proper unless the government can show

that the taint was purged. We did not even comment in Williams

on the “causal nexus” between the alleged seizure and the

discovery of evidence; on these facts we took that nexus to be

self-evident.

However, the quoted passage is dicta because we held

both that the approach was not a seizure and that the officers had

reasonable suspicion sufficient for a Terry stop in any event.

The vehicle was parked in a public place and the officers did not

make a show of force, and “law enforcement officers do not

violate the Fourth Amendment’s prohibition of unreasonable

seizures merely by approaching individuals on the street or in

other public places.” Id. at 352 (quoting United States v.

Drayton, 536 U.S. 194, 200 (2002)).

Though dicta, the analytical approach suggested by

Williams is consistent with the approach proposed by the leading

Fourth Amendment treatise.

In the typical case in which an illegal arrest is

followed by a search no “fruits” problem of any

magnitude is presented. . . . This is direct rather
19

than derivative evidence, and there is no occasion

to be concerned about the limits of the fruit of the

poisonous tree doctrine. . . . Problems of this kind

arise in the context of passengers in vehicles

attempting to have evidence found therein

suppressed . . . . [T]he passenger will claim that

the subsequent discovery of the evidence in the

vehicle was a fruit of his prior illegal detention.

It is very often the case that such a connection is

readily made out when the initial stopping of the

vehicle (and thus all of the occupants) was illegal.

6 LaFave, supra, § 11.4(d) (emphasis added).

We have not, however, yet had occasion to decide a case

requiring a precise articulation of the application of the fruit of

the poisonous tree doctrine to evidence found during illegal

traffic stops when introduced against vehicle passengers. We

will therefore state the theoretical issue as perspicuously as we

can: Is an illegal traffic stop of a car occupied by a driver and

a passenger a single constitutional violation, with two victims,

each of whom can seek to suppress all fruits of that violation?

Or is it analytically separable into two individual constitutional

violations, each with one victim, each of whom may seek to

suppress only the fruits of the violation of his individual right?

Today we endorse the former proposition, but as we

acknowledge the logical appeal of the latter proposition, we will

set out the best arguments in its favor, and then explain why we

are rejecting them.
Actually three seizures occur, because the car itself is 14

also seized. But only the personal seizures are relevant to the

argument.

20

1.

The “analytic separation” position, the position we are

rejecting, can be defended both on logical grounds and via a

reductio ad absurdum. Here are the logical grounds. Because

Fourth Amendment rights are personal rights, when the police

pull over a car with a driver and a non-owner passenger, two

individual seizures occur simultaneously: seizure of the driver,

and seizure of the passenger. Thus, we should not see the 14

traffic stop as one discrete constitutional violation (with two

victims), but rather as two separate constitutional violations

(each with one victim). Because fruits analysis always proceeds

from the specific constitutional violation inflicted on the

defendant, this analytic separation of violations necessitates a

concomitant separation of the respective fruits suppression

analyses. Because the violation of the passenger’s constitutional

rights was the seizure of the passenger (analytically separated

from the seizure of the driver), we must ask, in any fruits

analysis, whether the challenged evidence was seized as a causal

result of the seizure of the passenger. To get at the interior of

the car, where the evidence is located, the police must perforce

seize the driver and the passenger, by stopping the car. But that

one act constitutes two separate seizures. The passenger was not

in control of the car, so it is the seizure of the driver, and not the

passenger, that is required in order for the police to obtain

control over the car. The passenger’s presence has no effect on
21

the ability of the police to seize the driver and control the car.

Thus the evidence in the car would be found whether or not the

passenger was present in the car at all. Seizure of the passenger

is, accordingly, logically ancillary to the search of the vehicle.

It is logically necessary only for a search of the passenger’s

person. On this view, therefore, evidence found in the car, but

not on the passenger’s person, cannot be suppressed by the

passenger, even though the seizure of the passenger was

unconstitutional.

Some simple hypotheticals bring out the force of this

argument. Suppose that the car stops and X, a passenger, gets

out at the corner. Just as the car begins to pull away, the police,

acting on an anonymous tip, roar up and stop the car,

simultaneously ordering X, on the sidewalk, to freeze. Evidence

is found in the car but is suppressed as to the driver because the

stop was illegal. It is then introduced against X. May X

suppress? Certainly not. The two seizures are clearly separate

causal events for Fourth Amendment purposes. Nor can X

challenge a search of the car, no matter how illegal, because he

has no privacy interest in the car.

Now put X back in the car. What is the legal significance

of that change of place? The most obvious difference is that it

becomes physically impossible for the police to stop the car (and

detain the driver) without also seizing and detaining X. But X’s

legal situation with respect to the car and driver remains the

same: as a passenger, his privacy interest in the interior of the

car is precisely what it was when he was standing on the

sidewalk – zero. Thus, just as X’s seizure on the sidewalk

cannot logically or legally have been a cause of the discovery of
Unless, of course, the illegality is restricted to a 15

violation of the knock-and-announce rule, in which case no one,

not even the owner, can suppress. See Hudson v. Michigan, 547

U.S. --- (2006).

22

evidence inside the car, neither can his seizure while inside the

car as a passenger be a logical or legal cause of the discovery of

evidence inside the car.

The discovery of evidence inside a car simply cannot be

a violation of a passenger’s Fourth Amendment rights,

according to this argument. The passenger has a personal right

not to be seized, and that right is violated when the car is

illegally pulled over. But the illegal seizure of the passenger’s

person cannot be a legal cause of the discovery of evidence that

is not on the passenger’s person. The police may have

performed both acts at the same time, but because there was no

logical connection between the two the illegal seizure was not

a but-for cause of the discovery of the evidence.

2.

Here is the reductio ad absurdum. It is settled law that if

the police illegally enter a house and search it, the owner or

tenant of the house, or any long-term guests, may suppress

evidence found during the search. Short-term guests, however, 15

have no expectation of privacy in the house and therefore cannot

suppress the fruits of the illegal search. This is true even if the

short-term guests were seized pursuant to the illegal entry into

the house. If, for example, the police barricaded the exits to a
23

residence, entered, and ordered everyone present to freeze, they

would have thereby seized everyone present in the residence. If

their entry was illegal, for example if effected without a warrant

and absent exigent circumstances, then all of those seizures were

illegal. However, only the owner, tenant, or long-term guests

could suppress evidence found during the search. Short-term

guests would face the full evidentiary weight of any evidence

discovered. See Minnesota v. Olson, 495 U.S. 91 (1990).

Now make the house a mobile home, and drive it down

the street until it is pulled over illegally. The police again

illegally seize all the occupants and search the interior. Under

the holding we are announcing today – which conforms, as we

observed above, with those of our sister circuits – those shortterm guests are now passengers in an illegally seized vehicle,

and thus can suppress all evidence discovered during the search.

This result appears anomalous insofar as the Fourth Amendment

has been repeatedly characterized by the Supreme Court as

affording enhanced protection to the home, and diminished

protection to vehicles. Compare, e.g., Georgia v. Randolph, 547

U.S. --- (2006), slip op. at 10 (citing Wilson v. Layne, 526 U. S.

603, 610 (1999) (invoking the “centuries-old principle of respect

for the privacy of the home”); Minnesota v. Carter, 525 U.S. 83,

99 (1998) (Kennedy, J., concurring) (“[I]t is beyond dispute that

the home is entitled to special protection as the center of the

private lives of our people.”); Miller v. United States, 357 U.S.

301, 307 (1958) (noting common law tradition that a poor man

in a humble cottage might nonetheless bid defiance to all the

forces of the crown (if it is his cottage)), with, e.g., United States

v. Martinez-Fuerte, 428 U.S. 543, 561 (1976) (explaining that

Fourth Amendment protections are lessened for occupants of
The illegality of the traffic stop was caused in each case 16

by a mistake of law on the part of the police officer. (Unlike a

24

cars because cars searches do not implicate “the sanctity of

private dwellings, ordinarily afforded the most stringent Fourth

Amendment protection.”). Yet in our hypothetical, passengers

in a vehicle are afforded greater Fourth Amendment protection

than guests in a home.

B.

We have set out a coherent logical argument for an

analytic separation rule, and highlighted an apparently

anomalous contrast between vehicle and home seizure cases that

rejection of that rule might seem to entail. But we are not

persuaded. We will respond to the argument in two ways. First,

in Part III.B, we will survey the caselaw of our sister circuits, all

of which uphold passenger suppression claims following illegal

stops. Second, in Part III.C, we will reject the apparent logical

plausibility of the analytic separation argument as inconsistent

with the more pragmatic methodology exemplified by the

Supreme Court’s exclusionary rule jurisprudence.

1.

The Ninth and Eleventh Circuits have recently decided

cases with precisely analogous facts. See United States v.

Twilley, 222 F.3d 1092 (9th Cir. 2000); United States v.

Chanthasouxat, 342 F.3d 1271 (11th Cir. 2003). In each case,

the traffic stop was illegal from its inception, and evidence 16
reasonable mistake of fact, a mistake of law negates reasonable

suspicion and renders the stop illegal.) In Twilley, the officer

pulled over the car based on the California law that all vehicles

must display all plates issued by the state of registration. The

car was from Michigan, which issues only one plate. The

officer assumed that Michigan must issue two because, he said,

“an awful lot of states issue two plates.” 222 F.3d at 1094. In

Chanthasouxat, the officer pulled over the van because it lacked

an inside rearview mirror, and he thought that Alabama law

required one. It does not.

Indeed, both courts made the distinction between the 17

seizure of the passenger effected by the stop, and the subsequent

search of the car, noting that were the search the only grounds

for suppression, the passenger would lack “standing.”

Chanthasouxat, 342 F.3d at 1273 n.1; Twilley, 222 F.3d at 1095.

25

found during the traffic stop was introduced against a passenger

in the car. In each case, the government contested the

passenger’s motion to suppress by arguing that the passenger

lacked “standing” to challenge the evidence because he did not

have a reasonable expectation of privacy in the interior of the

car. In each case, the court applied a standard fruits analysis,

and suppressed the evidence as the fruit of the illegal seizure.17

The two courts treated this fact pattern as an utterly

straightforward and unremarkable application of the fruit of the

poisonous tree doctrine. Their analyses proceed precisely as

Mosley argues ours should, in the following three steps. First,

the traffic stop was a violation of the defendant’s Fourth
The parties give a fair amount of attention to United 18

States v. Pulliam, 405 F.3d 782 (9th Cir. 2005), but Pulliam is

inapposite for the same reason most of the apparently analogous

cases are: there was no determination or allegation that the

initial stop of the car was illegal. The defendant in Pulliam was

convicted based on evidence found in a search of a car in which

he was a passenger, but he challenged only his personal arrest

and search – not the initial traffic stop. He conceded that the

traffic stop was legally justified, because the car had a broken

tail light. 405 F. 3d at 785. Pulliam is just another of the many

cases where passengers lose suppression motions following

legal traffic stops. That is not our case.

26

Amendment rights; second, the evidence was found as a direct

consequence of the stop (that is, there were no significant

intervening events); third, the government did not establish any

of the various available exceptions (attenuation, independent

source, inevitable discovery). The Twilley court held that

“[b]ecause we conclude that the stop was not supported by

reasonable suspicion, and because the subsequent search was a

product of the stop, the evidence leading to Twilley’s conviction

should have been suppressed.” Id. at 1097. The 18

Chanthasouxat court held that “[b]ecause we conclude that the

initial traffic stop violated the Fourth Amendment, the violation

was not cured by voluntary consent, and that Chanthasouxat’s

[incriminating] statements [made during the stop] were fruits of

the poisonous tree, we hold that the drug evidence and

Chanthasouxat’s statements must be suppressed.” 342 F.3d at

1281.
See also, e.g., United States v. Colin, 314 F.3d 439 (9th 19

Cir. 2002) (same analysis as Twilley, and collecting cases). In

both Twilley and Chanthasouxat, indeed, (and unlike our case)

the driver of the vehicle in fact consented to the search, but the

court ruled that the consent was not “obtained by means

sufficiently distinguishable from the illegal stop to be purged of

the primary taint.” Chanthasouxat, 342 F.3d at 1280 (internal

quotes, brackets omitted); accord Twilley, 222 F.3d at 1097

(because “the interrogation and search were a direct result of the

illegal stop . . . this is a classic case of obtaining evidence

through the exploitation of an illegal stop.”) (internal quotes

omitted).

Consent following an illegal seizure does not in itself

purge the taint of the illegality for Fourth Amendment purposes;

the government must show sufficient attenuation to causally

disconnect the consent from the seizure. See United States v.

Snype, 441 F.3d 119, 133 (2d Cir. 2006) (collecting numerous

cases).

27

What is noteworthy about these cases is that they include

no discussion whatsoever of the “factual nexus” between the

illegal stop and the discovery of the evidence. The courts see

the chain of events between the illegal stop and the subsequent

discovery of evidence to constitute such a self-evidently close

“factual nexus” that, as Professor LaFave puts it, see 6 LaFave,

supra, § 11.4(d), there is no need to probe the limits of the fruit

of the poisonous tree doctrine.19
The police officer pulled over the truck in which Reed 20

was a passenger because it was towing a horse trailer, and, the

officer testified, horse trailers are sometimes used to transport

marijuana because the smell of the horses masks the smell of the

drugs. In fact, the trailer contained horses and cash, but not

drugs. In the disputed confession, Reed admitted having been

part of a separate distribution conspiracy. 349 F.3d at 462.

28

2.

In United States v. Reed, 349 F.3d 457 (7th Cir. 2003),

the defendant passenger confessed to drug distribution after

spending several hours with police (whether in custody or not

was disputed) following a traffic stop. He contended that the

police lacked probable cause for the stop, and sought 20

suppression of the confession on fruits grounds. The district

court ruled that even if the arrest was illegal, his subsequent

confession was still voluntary. Thus the district court did not

rule on the legality of the initial stop. On appeal, the Seventh

Circuit, applying Brown v. Illinois, 422 U.S. 590 (1975), vacated

and remanded, holding that, notwithstanding the lapse of time

and the voluntariness of Reed’s confession, the confession

would have to be suppressed as fruit of the poisonous tree if the

initial stop had been illegal. The Reed court explicitly rejected

a “counterfactual purgation” analysis of the sort employed by

the Tenth Circuit in DeLuca and by the District Court in the case

at bar:

The dissent opines that Reed would have

confessed even if he had been allowed to go home
29

rather than being held for hours, because his

confession stemmed from a desire to win favor

and reward and was not a consequence of the

illegality. We cannot make that determination as

a matter of law, and the government has the

burden to prove that his confession was

attributable to a factor other than the prolonged

detention following the allegedly illegal arrest.

That Reed determined that it was in his best

interest to cooperate does not somehow divorce

his decision from the unlawful detention.

Reed, 349 F.3d at 466.

The Reed court rejects both components of the DeLuca

counterfactual analysis: first, the shifting of the explanatory

burden to the defendant, and second, the artificial “divorcing”

of the (legal) act by which the evidence was physically obtained

from its (illegal) necessary causal antecedent. If that divorce is

going to occur, the court insists, it will be through the standard

fruits exceptions, and they must be shown by the government.

3.

In United States v. Guevera-Martinez, 262 F.3d 751 (8th

Cir. 2001), the defendant was a passenger in a car pulled over in

an illegal traffic stop. During the stop, the officers searched the

car and discovered methamphetamine. On that basis they

arrested Guevera-Martinez. That night, in jail, he told an INS

agent that he was in the country illegally. Guevera-Martinez

was charged in separate indictments with both drug and
30

immigration violations. Guevera moved to suppress the drugs,

arguing that the traffic stop was illegal. The district court

granted the motion, and the drug charges were dismissed. On

the immigration charge, Guervera-Martinez sought to suppress

both the statements he made and the fingerprints taken while he

was in jail. The district court granted the suppression motion on

the same grounds, holding that both the statements and prints

were fruit of the illegal traffic stop, and the Eighth Circuit

affirmed.

The Eighth Circuit applied a straightforward fruits

analysis: “[O]fficers obtained Guevera-Martinez’s fingerprints

[and statements] by exploiting his unlawful detention, instead of

by means sufficient to have purged the taint of the initial

illegality.” Id. at 755. The court deemed it irrelevant that

Guevera-Martinez “will inevitably face” civil deportation

proceedings in which new fingerprint evidence would easily be

obtained, and which would support the reinstatement of the

criminal immigration charges: “[T]he government asks us to

ignore its use of tainted evidence in this case. We decline to [do

so] . . . The important thing is that those administering the

criminal law understand that they must obtain the evidence the

right way.” Id. at 756 (quoting Davis v. Mississippi, 394 U.S.

721, 726 n.4 (1969) (internal quotes, brackets omitted).

4.

United States v. Dortch, 199 F.3d 193 (5th Cir. 1999), is

also very close in its facts to the case at bar. In Dortch, the

defendant was the driver rather than a passenger, but this

difference is irrelevant because Dortch’s suppression claim was
31

based solely on the detention itself. Dortch was stopped for a

traffic infraction, and he did not challenge the legality of the

stop. However, the police continued to detain him (and,

obviously, his vehicle) after the legitimate purpose of the traffic

stop had been completed. Id. at 197. Instead of allowing him to

leave, the police detained him for fifteen minutes while they

summoned a drug-sniffing dog team.

The bulk of the Fifth Circuit’s analysis is devoted to the

question of whether Dortch’s continued detention, once the

purposes of the traffic stop had been completed, was legal. The

court concluded that it was not – that the police had no probable

cause to continue to detain him. The government argued that

Dortch consented to the subsequent search once the dog team

arrived, but the court held that even if he did consent, the

evidence must still be suppressed: “even if Dortch’s consent

was voluntarily given . . . the consent was not valid. Instead,

because the causal chain between the illegal detention and

Dortch’s consent . . . was not broken, the search was

nonconsensual.” Id. at 202.

The court thus ordered suppression of all the evidence –

which was considerable – that had been amassed against Dortch,

and remanded not just for retrial, but with the specific order that

he be granted a judgment of acquittal. The justification was

straightforward fruits analysis: the moment the legal purposes of

the traffic stop were satisfied, any further detention of Dortch

was illegal. When the dog team arrived, the dogs were sent

around the car and alerted to it. On that basis, the police

searched the car and found drugs. And on that basis they
And indeed Dortch was neither the owner nor the 21

authorized possessor of the car. The car had been rented by a

third party (neither Dortch nor the passenger). Thus there is a

colorable argument that Dortch had no reasonable expectation

of privacy in the interior of the car whatsoever. But the court

explains that it does not need to reach that issue, because the

detention was illegal, and the fruits suppression follows directly

from that determination. See Dortch, 199 F.3d at 197-98 and

n.4 (“Given that Dortch does not challenge the legality of the

search, it is puzzling that the dissent goes to such efforts to

develop its theory that ‘because the rental agreement provided

only the renter was an authorized driver, Dortch had no right to

complain of the vehicle’s detention.’ In arguing that Dortch has

32

secured a warrant for Dortch’s home, searched it and found

more drugs and paraphernalia.

The Dortch case is particularly significant as an analogue

to the case at bar because it was governed by the twin

propositions that, first, an exterior investigation of a car by a

drug-sniffing police dog is not a search as a matter of law, see

Dortch, 199 F.3d at 198; (citing United States v. Seals, 987 F.2d

1102, 1106 (5th Cir. 1993)); see also Illinois v. Caballes, 543

U.S. 405, 409 (2005), and second, that the dog’s alerting to the

car constitutes probable cause for a search, as a matter of law.

See Dortch, 199 F.3d at 198 (citing United States v. Zucco, 71

F.3d 188, 191-92 (5th Cir. 1995). Thus, in Dortch’s case, as in

Mosley’s, there was no search to which he can object. If the dog

team had arrived while Dortch was legally detained, there would

have been no Fourth Amendment violation. The only basis for 21
no legitimate privacy interest in a rental car, the dissent seems

to miss the point. As we explain above, Dortch’s complaint is

not that the vehicle was detained or improperly searched, but

rather that he was improperly seized . . . .”).

33

Dortch’s suppression motion, as for Mosley’s, is that the

challenged evidence is the fruit of an illegal detention. Thus it

is irrelevant that Dortch was the driver rather than a passenger,

because that distinction applies only to challenges to the search

of the car, and Dortch, like Mosley, made no such challenge.

United States v. Jones, 234 F.3d 234 (5th Cir. 2000), is

similar to Dortch. In Jones, the car was validly stopped for

speeding, but the police continued to detain both driver and

passenger without probable cause after the legitimate purposes

of the stop – issuance of a citation, and computer criminal

history check – were completed. During the illegal prolongation

of the detention, the driver consented to a search of the car, and

contraband was discovered. The Fifth Circuit, upon determining

that the consent was not sufficiently attenuated from the illegal

detention to have been purged, ordered suppression of the

evidence as to both the driver and the passenger, reasoning that

although the passenger had no standing to challenge the search

of the car, he could challenge the illegal extension of the traffic

stop, and that extension was a single event which was causally

connected to the discovery of the evidence. Id. at 244.

Dortch and Jones suggest very strongly that had Mosley’s

case arisen in the Fifth Circuit, the gun would be suppressed. In

Dortch, just as here, there was no invasion of the defendant’s
34

reasonable expectation of privacy in the search that produced

the evidence. The invasion came solely in the detention (seizure

of the person), and the court applied a straightforward fruits

analysis, pursuant to which it took it as self-evident that a car

search following an illegal traffic stop is the fruit of that stop.

5.

In United States v. Kimball, 25 F.3d 1 (1st Cir. 1994), the

defendant was a passenger in a car that was stopped by the

police. All three occupants were arrested on suspicion of

burglary, and the police performed an “inventory” search of the

car upon towing it to the station. Kimball sought to suppress

evidence recovered from the car, and the court framed the issue

as follows:

A police officer’s act of stopping a vehicle

and detaining its occupants constitutes a seizure

within the meaning of the Fourth Amendment. . . .

When a police officer effects an investigatory stop

of a vehicle, all occupants of that vehicle are

subjected to a seizure, as defined by the Fourth

Amendment. The fact that a defendant is a

passenger in a vehicle as opposed to the driver is

a distinction of no consequence in this context.

The interest in freedom of movement and the

interest in being free from fear and surprise are

personal to all occupants of the vehicle, and an

individual’s interest is not diminished simply

because he is a passenger as opposed to the driver

when the stop occurred. . . . Thus, if the initial
35

stop of the vehicle was illegal, evidence seized by

virtue of that stop, such as the tools in this

instance, may be subject to exclusion under the

“fruit of the poisonous tree” doctrine.

Kimball, 25 F.3d at 5-6 (citations omitted).

The court then added, in a very significant footnote:

The Government’s reliance on Rakas v. Illinois, in

the context of a stop, is misplaced. In Rakas, the

United States Supreme Court held that a mere

passenger in an automobile ordinarily does not

have the legitimate expectation of privacy

necessary to challenge the search of that

automobile. The Supreme Court’s decision,

however, was limited to the issue of whether the

passenger’s legitimate expectation of privacy was

invaded by a search of the vehicle, and not the

stop thereof.

Id. at 6 n.3 (emphasis added, internal cites omitted).

The footnote is significant because it helps to clarify what

we think was a source of confusion in the proceedings below.

Rakas held simply that a passenger in a car has no reasonable

expectation of privacy in the interior of the car, and thus that a

search of that car does not violate any of the passenger’s Fourth

Amendment rights. But Rakassays absolutely nothing about the

scope of the exclusionary rule with respect to the fruits of an

illegal stop. The Kimball court makes it clear that the
The court ultimately affirmed the denial of Kimball’s 22

suppression motion on the grounds that the stop was reasonable.

25 F.3d at 8.

For an illustration of this methodology in practice in the

district courts, see United States v. Jones, 374 F. Supp. 2d 143

(D.D.C. 2005), which is very strongly analogous to our facts.

The district court suppressed all the challenged evidence against

the defendant after going through precisely the fruits analysis

Mosley contends for here. Jones was a non-owner passenger in

a vehicle that was illegally detained by the police. The car was

parked when officers approached, questioned, detained, and

arrested the two occupants, effecting an illegal seizure of Jones.

The government argued first that the encounter was consensual,

and then in the alternative that it was a permissible Terry stop.

The court rejected both arguments and found the detention to be

illegal. Id. at 149, 152. Accordingly, it suppressed all evidence

subsequently recovered, including both physical evidence and

statements, because “the government failed to meet its burden

of justifying under the Fourth Amendment the police intrusion

upon Jones’ liberty.” Id. at 153. The court recognized that

Jones, as a non-owner passenger, “failed to demonstrate a

legitimate expectation of privacy in the vehicle or items

36

passenger’s reasonable expectation of privacy vis-a-vis the

search is completely irrelevant to the fruits inquiry with respect

to the stop.

We read Kimball as holding that the determinative

question in passenger suppression is the legality of the stop: if

the stop is illegal, then standard fruits suppression will apply.22
recovered from it,” id. at 154, but deemed that fact irrelevant

because the suppression claim was grounded in the illegal

detention rather than the search itself. “[The auto passenger

search cases] involve claims that the search of the vehicle or

compartments within it was unlawful. By contrast, Jones here

argues that he was unlawfully stopped and seized, and thus the

contents of the [car] should be suppressed as the result of that

unlawful seizure.” Id. The court accordingly considered

whether any “dissipating” or “purging” factors were present,

such as lapse of time or intervening circumstances. Finding

none, the court ordered all evidence recovered as a result of the

initial encounter to be suppressed.

37

6.

The government brings to our attention United States v.

Carter, 14 F.3d 1150 (6th Cir. 1994), a case in which evidence

found during a search of a vehicle was suppressed as to the

driver but admitted as to the passenger. Carter was a passenger

in a van, which the police pulled over for failure to have a valid

license plate. The crucial factual and procedural point, which

makes Carter inapposite, is that Carter did not challenge the

legality of the initial stop. Thus Carter, like DeLuca, cannot

guide the analysis in our case, because unlike in our case, the

court did not find that the initial traffic stop itself was illegal:

[W]hether or not the original traffic stop was

unconstitutional – an issue that was not preserved

in Carter’s objection to the magistrate’s report and

that we do not reach here – we shall assume for
38

purposes of analysis, not only that the subsequent

arrest of the driver was unconstitutional, but also

that the detention of Mr. Carter, if not illegal from

the outset, became illegal when the driver was

arrested.

Carter, 14 F.3d at 1154.

Note that the court does not hold that Carter’s

suppression motion would fail even if the initial traffic stop had

been illegal. The court does not assume that the initial stop was

illegal, but only that Carter’s detention “became illegal when the

driver was arrested.” That distinction (carefully preserved by

the “if not” construction) makes all the difference. As long as

the police initially obtained control over the vehicle legally, then

(on the DeLuca reasoning) no search of the vehicle after that

point, no matter how unconstitutional, will be subject to

challenge by a passenger. But Carter does not address the

situation in which the initial stop was illegal; to so treat it is to

stretch its holding not only beyond its facts but beyond its

language.

C.

As the preceding survey establishes, the prevailing rule

in the courts of appeals is that an illegal traffic stop entails a

suppression remedy for all occupants of the car. The authority

of our sister circuits is persuasive. However, we think the

interests of justice and jurisprudential clarity are best served by

giving this issue the fullest possible airing, so we think it

incumbent on us to rebut the logical argument for analytic
39

separation we presented above. We think that argument is

rebuttable independently of the persuasive weight of our sister

circuits’ decisions, for the following reasons.

First, we do not think it quite so self-evident that the

seizure of a passenger in a vehicle is not a but-for cause of the

discovery of evidence in the vehicle. The simplest statement of

the concept of but-for causation is that event A is a but-for cause

of event B if event B could not happen without event A

happening first. But-for causation is an inference drawn from

regularly observed correlation.

But it must be stressed that causation is an inference, not

an observation, as philosophers since at least Hume have

reminded us. The only empirical facts that we can discover

about the world are facts about correlation. We cannot observe

causal relationships, whether of cue ball to eight ball, of moon

to tides, or of diet-pill ingestion to heart failure. What we

observe is correlation, and when we see it regularly enough, we

hypothesize causation. Science progresses by repeated testing

and attempted invalidation of causal hypotheses. Those that

survive the process persist.

The relationship between the seizure of a passenger in a

moving vehicle, which necessarily occurs when that vehicle is

stopped by the police, and the subsequent discovery of evidence

during that stop, is one of ineluctable and undeniable

correlation. The day has not dawned when a police officer can

effectuate a traffic stop without seizing all the occupants of the
Of course, the day may dawn – perhaps it already has – 23

when police may search the interior of a moving car without

stopping it or in any way restricting the freedom of movement

of the occupants, for example by employing remote electronic

devices. In such a situation, where no seizure of the car’s

occupants is effected, Rakas would control and passengers

would lack the right to suppress evidence discovered.

40

vehicle. The correlation between that seizure and the 23

discovery of evidence during the stop is a perfect 100 percent.

As an empirical matter, therefore, the facts on the ground meet

the definition of but-for causation: you never see the one

without seeing the other first.

So should we hypothesize – or, given our institutional

position, perhaps “impose” is the better term – a causal

relationship between the seizure and the discovery of the

evidence? As detailed above, the dominant view in the circuits

is that the causal nexus between the traffic stop and the

discovery of evidence is self-evidently sufficient to support

suppression.

We agree that the causal relationship seems close, and

clear. But we will not pretend that we have no role in imposing,

as a legal matter, that causal relationship onto the fact pattern

before us, or that such judgments can be made with iron-clad

logical or empirical precision. We do not ignore the fact that the

analytic separation of individual constitutional violations is a

plausible logical deduction from the proposition that Fourth
41

Amendment rights are personal. We do, however, reject such

separation.

We think the better view is that a traffic stop is a single

act, which affects equally all occupants of a vehicle. To us, that

description of traffic stops comports with the commonsense

experience of everyone who has ever ridden in a car; we agree

with the First Circuit that the distinction between passenger and

driver “is a distinction of no consequence in this context.”

Kimball, 25 F.3d at 5. A police officer who pulls over a vehicle

does not, in the act of pulling over the vehicle, interact

separately with each occupant; rather, the officer undertakes one

action – turning on the siren and lights – which instantly affects

everyone in the targeted vehicle, signaling to them that their

freedom of movement has been restricted. It defies common

sense and common experience to transmute one action into

three, and we will not endorse a Fourth Amendment approach

that relies on such a transmutation. The government insists that

“Fourth Amendment rights are personal rights,” and we do not

contest the abstract validity of that proposition. But general

propositions do not decide concrete cases, and we reject the

practical implications the government seeks to derive from that

proposition. We reject “blind adherence to a phrase which at

most has superficial clarity and which conceals underneath that

thin veneer all of the problems of line drawing which must be

faced in any conscientious effort to apply the Fourth

Amendment.” Rakas v. Illinois, 439 U.S. 128, 147 (1978).

Furthermore, the relationship between a traffic stop and

the discovery of evidence during that stop is not like the

relationship between two balls on a billiard table. Law is not
42

physics. In even its most aspirationally scientific

manifestations, the law recognizes and embraces the infusion of

a multiplicity of values into judicial determinations of causal

relationships, see, e.g., Carl F. Cranor & David A. Eastman,

Scientific Ignorance and Reliable Patterns of Evidence in Toxic

Tort Causation, 64 L. & Contemp. Prob. 5 (2001) (assessing the

extent to which courts are willing or able to assimilate and

evaluate scientific models of causation in complex cases), and

the Supreme Court has done so even more emphatically, and

recently, in the context of the exclusionary rule. Fourth

Amendment rules cannot be derived from deductive reasoning

from first principles, nor do they crystallize, unaided, from the

naked facts of disputed searches.

The Supreme Court has just this Term reiterated that the

exclusionary rule was founded on, and is grounded in, the

continuing exercise of pragmatic judicial supervision of the law

enforcement activities of the executive branch, effectuated by

expansion and contraction of the bubble of proximate cause as

courts face particular concrete factual situations. See Hudson v.

Michigan, 547 U.S. --- (2006) (eliminating suppression remedy

for knock-and-announce violations because, inter alia, as

compared with the 1950s, police departments are more likely to

be “staffed with professionals,” and lawyers are more likely to

take on § 1983 cases). The test by which our models of

constitutional causation are measured is not empirical validation

by experiment, but rather the march of social progress, refracted

through continual judicial evaluation of constitutional purposes

and social consequences. As the social context of law

enforcement evolves, so too does the exclusionary rule. The

debate about the constitutional consequences of traffic stops is
43

akin, in this respect, to the debate about the constitutional

consequences of electronic surveillance or computer copying.

See, e.g., Orin S. Kerr, Searches and Seizures in a Digital

World, 119 Harv. L. Rev. 531, 561 (2005) (pondering whether

electronic copying of computer files constitutes a “seizure,” and

if so what the appropriate Fourth Amendment remedy should

be).

The Supreme Court stressed in Hudson that in

determining whether a particular Fourth Amendment violation

is causally related to a particular challenged piece of evidence

in such a way as to trigger the exclusionary rule, we must look

not only to the logical relationship between the violation and the

discovery of the evidence, but also to the nature of the personal

and social interests the Constitution protects, the prevalence of

the illegal police practice at issue, the deterrent value of the

suppression remedy, and the likely practical effects of a

particular rule. See Hudson, slip op. at 8-13 (determining

constitutional suppression requirements based on evolving

social realities).

Applying these tests, we find that the purposes of the

Fourth Amendment are best served by extending the bubble of

proximate causation to vehicle passengers. Passengers, no less

than drivers, have a constitutional interest in protection from

unreasonable seizures. Two of the more constitutionally

troubling varieties of unreasonable seizures, both implicated in

this case, are those that occur when police stop vehicles based

on anonymous tips, or based on the race of the vehicle’s

occupants. While the Supreme Court may be right about the

increased professionalism of police and the robustness of the
That this practice is legitimate is at present beyond 24

constitutional cavil under Whren. However, the excesses its use

periodically engenders have not gone unnoticed, and in recent

years many police departments have studied and adopted

procedural reforms that may be implemented to monitor vehicle

stops and reduce the incidence of racial profiling and other

abuses of the seizure power on the roads. See, e.g., Robin

Shepard Engel, et al., Project on Police-Citizen Contacts (2004)

(report and recommendations prepared for Pennsylvania State

Police Commissioner Colonel Jeffrey Miller); New Jersey

Senate Judiciary Committee, The New Jersey Senate Judiciary

Committee’s Investigation of Racial Profiling and the New

Jersey State Police: Overview and Recommendations (2001)

(recommendations for reforms in wake of widely-publicized

racial profiling incidents). Such reforms can provide significant

44

§ 1983 plaintiffs’ bar, we cannot say that either racial profiling

or reliance on anonymous tips has declined in frequency in

recent years, or that civil lawsuits will adequately deter such

practices. Nor can we say that the various other categories of

cases that give rise to passenger suppression motions are rare,

decreasing, sufficiently internally disciplined, or otherwise

deterred. Furthermore, Americans spend more time in cars with

each passing year, see, e.g., Dep’t of Transportation, 2001

National Household Travel Survey, available at

http://www.fhwa.dot.gov/policy/ohpi/nhts (reporting “dramatic

increases” in time spent driving between 1969 and 2000), and as

the circuit cases described above demonstrate, the use of traffic

stops as investigatory tools is a widespread and standard police

practice.24
protection for equal protection and due process rights, in

addition to Fourth Amendment rights, and we recognize that the

incentives created by the exclusionary rule have a significant

effect on police behavior. Allowing unfettered use against

passengers of evidence obtained during unconstitutional traffic

stops could undermine these reform efforts. And unlike the

knock-and-announce rule, the constitutional prohibitions on

racial profiling and reliance on anonymous tips do go the heart

of the validity of the underlying police action itself, not merely

the method of its execution.

45

Furthermore, were we to allow the government to use

against Mosley the evidence recovered in this case, we would

weaken, indeed nearly eviscerate, the Supreme Court’s clear and

unanimous command in Florida v. J.L. that an anonymous tip is

a constitutionally deficient basis for an investigatory detention.

See 529 U.S. at 273-74. The Supreme Court did not, we

presume, contemplate that its plain constitutional holding could

be simply ignored as to all occupants of a vehicle other than the

driver, and we will not lightly countenance such a result.

Nor, finally, is the reductio ad absurdum presented above

(stationary mobile home versus moving mobile home) really all

that absurd. The level of justification required to support a valid

car search is extremely low, as we explained above, as compared

with that required to support a valid home search. Most

obviously, in contradistinction to house searches, there is no

general warrant requirement for car searches. See, e.g.,

Maryland v. Dyson, 527 U.S. 465, 467 (1999). Thus all

occupants of cars, drivers and passengers alike, are
46

overwhelmingly more likely to be subject to police scrutiny

when on the road than when at home. Of course, illegal police

entries into and searches of homes do occur. But the frequency

with which police effect forcible entries into homes is

incomparably less than the frequency with which they pull over

cars, and the teaching of Hudson is that such social facts matter.

If warrantless house searches were as common as roadside

traffic-stop searches, for example, then perhaps the protection

afforded houseguests in Minnesota v. Olson, 495 U.S. 91

(1990), might have been broader. The exclusionary rule

expresses, inherently and always, a standard of reasonableness

that evolves along with police practices and social norms.

The exclusionary rule is a judge-made remedy designed

to deter illegal police conduct. The Hudson decision has made

it clear, if there was ever any doubt, that decisions about both

the application of the rule are pragmatic decisions requiring

practical wisdom rather than syllogisms. Justice Scalia’s

opinion epitomizes such pragmatic balancing, “interpreting the

Constitution in light of its own practical concern for an active

liberty that is itself a practical process,” Stephen Breyer, Active

Liberty 74 (2005). It is in that spirit that we decide this case.

IV.

The car in which Mosley was riding was pulled over

illegally. Mosley was illegally seized the moment the car was

pulled over. The stopping of the vehicle was a but-for cause of

the discovery of the guns. The bubble of causation which links

a traffic stop to a subsequent search extends to all occupants of

the stopped vehicle. To overcome Mosley’s suppression
47

motion, therefore, the government would have had to establish

one of the traditional exceptions to the Wong Sun rule:

attenuation, inevitable discovery, independent source, or some

intervening act or event sufficient to purge the taint of the illegal

stop. The government raised no such exception at trial, and

raises none on appeal. We therefore hold that the guns were

fruit of the poisonous tree and must be suppressed.

Accordingly, we will vacate Mosley’s conviction, and

remand the case to the District Court for further proceedings

consistent with this opinion.