                   FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


UNITED STATES OF AMERICA,              No. 14-50529
           Plaintiff-Appellee,
                                         D.C. No.
              v.                   3:13-cr-02706-AJB-1

HECTOR SOTO-ZUNIGA,
        Defendant-Appellant.             OPINION


     Appeal from the United States District Court
        for the Southern District of California
     Anthony J. Battaglia, District Judge, Presiding

          Argued and Submitted May 5, 2016
                Pasadena, California

               Filed September 16, 2016

      Before: Alex Kozinski, William A. Fletcher,
         and Ronald M. Gould, Circuit Judges.

                Opinion by Judge Gould
2               UNITED STATES V. SOTO-ZUNIGA

                            SUMMARY*


                           Criminal Law

    The panel vacated a jury conviction for possession with
intent to distribute methamphetamine, reversed discovery
rulings, and remanded with instructions.

    The panel held that the district court abused its discretion
by denying the defendant’s pretrial motion for discovery
relating to the constitutionality of a Border Patrol checkpoint
at which the defendant was detained and his car searched.
The panel concluded that discovery of the checkpoint search
and arrest statistics was pertinent to the issue whether the
checkpoint was invalid under the Fourth Amendment because
its primary purpose was to advance the general interest in
crime control, rather than to control immigration. The panel
held that this issue of the constitutionality of a search or
seizure was subject to discovery under Federal Rule of
Criminal Procedure 16(a)(1)(E). The panel reversed the
district court’s denial of the discovery motion relating to the
checkpoint’s arrest statistics and remanded for the district
court to assess the constitutionality of the checkpoint in
further proceedings.

   The panel held that the district court abused its discretion
by denying the defendant’s motion for discovery on the
government’s investigation into a drug smuggling operation.
After reviewing sealed documents submitted by the
government, the panel concluded that the documents were

    *
      This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
              UNITED STATES V. SOTO-ZUNIGA                    3

discoverable because they were material to preparing the
defense under Rule 16(a)(1)(E). The panel reversed the
denial of the discovery motion, vacated the conviction, and
remanded with instructions to grant the motion. The panel
also instructed the district court to consider the government’s
request for a window of time before production to determine
whether to continue to pursue the case, and to consider the
government’s request for protective measures that would
maintain the security of the information in the documents
while allowing the defense to adequately prepare a defense.

    The panel affirmed the denial of a suppression motion
insofar as it was based on a claimed lack of probable cause
for the search of the defendant’s car. The panel held that the
district court did not err in instructing the jury on reasonable
doubt. It also held that knowledge of drug type and quantity
is not an element of possession with intent to distribute in
violation of 21 U.S.C. § 841.


                         COUNSEL

Paul Allen Barr (argued), Federal Defenders of San Diego,
Inc., San Diego, California, for Defendant-Appellant.

Kyle B. Martin (argued), Assistant United States Attorney;
Peter Ko, Chief, Appellate Section, Criminal Division; Laura
E. Duffy, United States Attorney; United States Attorney’s
Office, San Diego, California; for Plaintiff-Appellee.
4               UNITED STATES V. SOTO-ZUNIGA

                             OPINION

GOULD, Circuit Judge:

    Hector Soto-Zuniga appeals his jury conviction for
possession with intent to distribute methamphetamine in
violation of 21 U.S.C. § 841(a)(1). Soto-Zuniga was arrested
at a checkpoint in San Clemente, California, after Border
Patrol agents found 2.9 kilograms of methamphetamine on
the floor of the backseat of his car during a search. Before
the first trial, which ultimately resulted in a hung jury and a
mistrial, Soto-Zuniga filed motions to suppress the drug
evidence. In one of the motions he argued that the checkpoint
was unconstitutional and requested discovery of the
checkpoint’s arrest and search statistics. The district court
denied these motions.

    At both his first trial and his subsequent re-trial, Soto-
Zuniga testified that before being stopped at the checkpoint,
he had given a ride to three teenagers he did not know as a
favor to his cousin’s husband, Christian Rios Campos.1 The
government stipulated that Rios was a known drug smuggler
who recruited juveniles to smuggle drugs into the United
States, and Soto-Zuniga’s primary defense was that the
teenagers had planted the drugs in the car without his
knowledge. Before the second trial, Soto-Zuniga moved for
discovery of the government’s investigation of Rios’s drug
smuggling operation, which may have identified the three
teenagers by name. This, too, was denied. Soto-Zuniga was
convicted after the second jury trial and sentenced to six years
in prison.

    1
      Although this individual’s name appears in several spellings in the
record, we use this version throughout this opinion for consistency.
             UNITED STATES V. SOTO-ZUNIGA                    5

    Soto-Zuniga raises several arguments on appeal, and we
conclude that two have merit: (1) the district court abused its
discretion by denying Soto-Zuniga’s pretrial motion for
discovery relating to the constitutionality of the San Clemente
checkpoint, and (2) the district court abused its discretion by
denying Soto-Zuniga’s motion for discovery on Rios’s drug
smuggling operation. We have jurisdiction under 28 U.S.C.
§ 1291, and we reverse the district court’s rulings on the
discovery motions, vacate the conviction, and remand for
further proceedings consistent with this opinion.

                              I

    On June 29, 2013, at around 3:50 p.m., Soto-Zuniga was
stopped in his car at a Border Patrol checkpoint near San
Clemente, California. U.S. Border Patrol Agent Ivan Favela
questioned Soto-Zuniga, who told Agent Favela that he was
coming from Tijuana. Agent Favela testified at trial that
Soto-Zuniga appeared nervous and that his hands were
shaking. Agent Favela directed Soto-Zuniga to a secondary
inspection area. There, two additional agents, Raymond
Rabreau and Brian Chang, approached Soto-Zuniga’s car.
Soto-Zuniga presented Agent Chang with a Permanent
Resident Card and told Agent Chang that he was traveling to
Los Angeles from Tijuana. Agent Chang later reported that
he noticed Soto-Zuniga’s hand and leg shaking during the
exchange. Based on this nervous behavior, Agent Chang
asked Soto-Zuniga to step out of the car. Agent Chang said
that when he asked Soto-Zuniga if he had any contraband in
his car, Soto-Zuniga looked down before answering “no.”
Agent Chang then asked Soto-Zuniga to open the trunk of his
car, and he complied. According to Agent Chang, Soto-
Zuniga continued to fidget during their exchange. Agent
Rabreau, who approached Soto-Zuniga’s car from the
6                UNITED STATES V. SOTO-ZUNIGA

passenger’s side, later reported that he smelled marijuana
coming from the vehicle, and he observed a “black and mild
cigarillo” in the car’s ashtray, as well as remnants of tobacco.
Agent Rabreau reported that, based on his training and
experience, he suspected Soto-Zuniga had been smoking
marijuana in the car.

    Next, a third agent at the secondary checkpoint, Anthony
Rodgers, also noticed that Soto-Zuniga was acting nervously
and observed that the carotid artery in his neck was
“bounding.” Agent Rodgers wrote in his report that Soto-
Zuniga admitted to smoking marijuana in the car with a
friend. Agent Rodgers also reported that he performed a
Terry frisk2 of Soto-Zuniga, but found no weapons.

    Other agents soon approached the secondary inspection
area, including Agents Favela and Buck. Agent Buck later
reported that he questioned Soto-Zuniga about smoking
marijuana, and that Soto-Zuniga denied ever smoking
marijuana, but admitted that he had friends that smoked.
Agent Buck reported that he then asked Soto-Zuniga if he
allowed friends to smoke marijuana in his car, and Soto-
Zuniga “became very defensive and became visibly agitated
with [his] questioning.” Agent Buck also wrote that when he
told Soto-Zuniga that his car would be searched because of
the smell of marijuana, Soto-Zuniga “adopted a defeated
body posture.”

    Agent Rodgers’s report reflects that, due to Soto-Zuniga’s
alleged admission that he had smoked marijuana in the car
and the smell that Agent Rabreau reported, agents decided to
search Soto-Zuniga’s car at about 4:25 p.m., approximately

    2
        See Terry v. Ohio, 392 U.S. 1 (1968).
                 UNITED STATES V. SOTO-ZUNIGA                  7

35 minutes after the initial stop. In searching the car, Agent
Favela recovered four bundles wrapped in brown tape from
behind the driver’s seat. The bundles were under a floor mat,
which was also covered by a sweater. A field test indicated
that the bundles contained methamphetamine, and Soto-
Zuniga was arrested. Evidence at trial established that the
bundles contained 2.9 kilograms of methamphetamine, with
a street value of more than $80,000.

    Soto-Zuniga was subsequently interviewed by Agent
Kameron Korte, who testified that Soto-Zuniga waived his
Miranda3 rights through the Spanish translation of another
Border Patrol agent. During that interrogation, Soto-Zuniga
told Agent Korte that his cousin’s husband, Christian Rios
Campos, had called that morning and asked Soto-Zuniga to
give a ride to three teenagers from Otay Mesa to San Ysidro
in San Diego. Soto-Zuniga told Agent Korte that he picked
up the teenagers at a McDonald’s in Otay Mesa and dropped
them off at a Shell gas station close to a trolley station in San
Ysidro. By the time Agent Korte contacted the McDonald’s,
any video surveillance had been erased. Agent Korte never
contacted the Shell station.

    Soto-Zuniga was charged with possession of
methamphetamine with intent to distribute in violation of
21 U.S.C. § 841(a)(1). Before trial, he filed a motion to
suppress the drugs seized from his car, arguing that they were
the fruits of an unlawful search and seizure. Soto-Zuniga
contended that the agents lacked probable cause to detain him
and search his car; specifically, he argued that nervousness
alone was not sufficient to support probable cause, and that
Agent Rabreau’s report that he smelled marijuana coming

    3
        See Miranda v. Arizona, 384 U.S. 436 (1966).
8             UNITED STATES V. SOTO-ZUNIGA

from the car was “unreliable” because no other agent reported
the smell and no marijuana was recovered from the car. He
also filed a motion challenging the constitutionality of the
San Clemente checkpoint, arguing that the government was
using the checkpoint as a pretext to search for controlled
substances, not to control immigration. In an unsuccessful
attempt to support that argument for his suppression motion,
Soto-Zuniga also filed a motion seeking, inter alia, discovery
of statistics regarding the number and types of arrests and
vehicle searches at the San Clemente checkpoint.

    The district court held an evidentiary hearing on the
pretrial motions. At the hearing, Agent Rabreau testified that
the main purpose of the San Clemente checkpoint was
immigration inspection and that 90 percent of the arrests were
immigration-related. He also detailed his account of the
events that led to Soto-Zuniga’s arrest, including smelling
marijuana coming from Soto-Zuniga’s car and seeing a “burnt
blunt,” which he described as a burned marijuana-filled
cigarillo, in the ashtray, as well as a small amount of loose
tobacco, a “black & mild wrapper,” and a lighter. He testified
that this was “consistent with marijuana paraphernalia.”
Agent Rabreau also testified that the car had four air
fresheners, something “many smugglers use . . . to mask the
smell of their drug load.” He further testified that he believed
Agents Chang and Buck smelled marijuana as well, and that
the smell was the reason Agent Favela initially sent Soto-
Zuniga to secondary inspection. On cross-examination,
Agent Rabreau said that, to his knowledge, no marijuana was
ever recovered from the car. Agent Rabreau also testified
that Soto-Zuniga had provided an “inconsistent route of
travel,” but acknowledged that he did not include this
information in his report.
               UNITED STATES V. SOTO-ZUNIGA                       9

    In a declaration, Soto-Zuniga claimed that he had not
smoked marijuana in five or more years and that he had told
Agent Buck that he did not smoke marijuana. Soto-Zuniga
also said that he told Agent Buck that none of his friends had
smoked marijuana in the car. When called to testify during
the evidentiary hearing, Soto-Zuniga testified consistently
with his declaration on these points.

    The district court denied Soto-Zuniga’s motions to
suppress and to compel discovery. The district court
reasoned that “the sequence of events [in the agents’ reports]
seems to be very consistent,” and that there was probable
cause based on several factors, including the smell of the
marijuana, Soto-Zuniga’s reported nervousness, the air
fresheners, the loose tobacco, the cigarillo wrappers, and
Agent Rodgers’s report that Soto-Zuniga admitted to him that
he had smoked marijuana in the car. The court noted that the
physical evidence was “where it nails the coffin here.” The
court further noted that, while Agent Rabreau was the only
agent who claimed to smell the marijuana, other agents
reported that Agent Rabreau had told them he smelled
marijuana at the scene so it was not “a post-arrest revelation.”
The court also found that the testimony of Agent Rabreau,
“with regard to his role, his experience in terms of his own
arrests, and then his happening to be the conduit through
which reports pass, all support [the conclusion that] the
primary purpose of this checkpoint is immigration.” The case
was set for trial.

    Before the start of the first trial and after jury selection, an
investigator for the defense obtained a social security number
for Marisol Diaz, Soto-Zuniga’s cousin and the wife of
Christian Rios Campos. The investigator then got an arrest
warrant for Diaz, which included a declaration from a
10           UNITED STATES V. SOTO-ZUNIGA

Homeland Security Investigations agent that the government
had arrested three teenagers on suspicion of trafficking drugs
at the command of Rios. Defense counsel argued that this
new information corroborated Soto-Zuniga’s account of
events. The district court postponed the trial until the next
day. Defense counsel next filed an emergency motion for a
continuance to permit time to investigate the new
information. The government stipulated to the information
contained in the declaration, including that Rios had recruited
teenagers to traffic drugs. The district court concluded that
the stipulation was sufficient to meet the defense’s purpose,
and denied the motion for a continuance as well as defense
counsel’s subsequent motion for a mistrial.

    During the trial, Soto-Zuniga sought specific jury
instructions that differed from the Ninth Circuit pattern jury
instructions on reasonable doubt. He also asked that the jury
be instructed that the government must prove beyond a
reasonable doubt that Soto-Zuniga “knew the substance [that
he possessed with intent to distribute] was 2.92 kilograms of
methamphetamine.”         The district court rejected both
suggestions in favor of the pattern jury instructions.
Following the trial, the jury was unable to reach a unanimous
decision, resulting in a mistrial.

    Before the second trial, Soto-Zuniga requested discovery
on the government’s investigation of Christian Rios Campos
and Marisol Diaz, including any relevant information
regarding the three teenagers who were arrested for
trafficking at Rios’s command. The district court reviewed
the written materials related to the government’s investigation
and denied the motion, stating that any investigation of Rios
was “collateral. It is irrelevant. It is predominately
inadmissible in the forms in which you have it, and that’s the
                UNITED STATES V. SOTO-ZUNIGA                           11

ruling.” The district court also said that discovery would
extend the litigation and would present “a 403 problem[4] in
spades.” At the end of the second trial, the jury was
instructed with the same jury instructions used in the first
trial—after the district court noted that Soto-Zuniga had
preserved all prior objections. The jury returned a guilty
verdict.

    At sentencing, Soto-Zuniga argued that the statutory
maximum sentence should only be one year because the jury
had not found that he had possessed a particular quantity of
methamphetamine. The district court rejected this claim and
sentenced Soto-Zuniga to 72 months (six years).

                                    II

    We review discovery rulings for abuse of discretion.
United States v. Amlani, 111 F.3d 705, 712 (9th Cir. 1997).
To reverse Soto-Zuniga’s conviction, we must find that the
district court abused its discretion in denying his discovery
motions, and that the error resulted in prejudice to his
substantial rights, i.e., that there is “a likelihood that the
verdict would have been different had the government
complied with the discovery rules.” United States v. de Cruz,
82 F.3d 856, 866 (9th Cir. 1996) (citation and internal
quotation marks omitted).




    4
       The district court was doubtless referring to Fed. R. Evid. 403,
which states that “[t]he court may exclude relevant evidence if its
probative value is substantially outweighed by a danger of one or more of
the following: unfair prejudice, confusing the issues, misleading the jury,
undue delay, wasting time, or needlessly presenting cumulative evidence.”
12            UNITED STATES V. SOTO-ZUNIGA

                               A

    We first address Soto-Zuniga’s argument that the district
court abused its discretion in denying his motion for
discovery of the San Clemente checkpoint search and arrest
statistics. He contends that this evidence is necessary to
determine whether the checkpoint itself is constitutional. We
agree that the district court abused its discretion in denying
discovery that could have revealed an unconstitutional seizure
and led to the suppression of the evidence that illicit drugs
were found in Soto-Zuniga’s car.

    The Fourth Amendment prohibits unreasonable searches
and seizures. “It is well established that a vehicle stop at a
highway checkpoint effectuates a seizure within the meaning
of the Fourth Amendment.” City of Indianapolis v. Edmond,
531 U.S. 32, 40 (2006). As a general rule, a search or seizure
is unreasonable unless it rests on individualized suspicion of
wrongdoing. Id. at 37. But the Supreme Court has carved
out an exception to this rule for checkpoint seizures that serve
“special needs, beyond the normal need for law
enforcement.” Id. (citation and internal quotation marks
omitted); see also United States v. Fraire, 575 F.3d 929,
931–32 (9th Cir. 2009). In United States v. Martinez-Fuerte,
which addressed the constitutionality of the San Clemente
checkpoint, the Supreme Court identified immigration control
as a valid purpose for stopping cars and posing questions
without individualized suspicion. 428 U.S. 543, 556–64
(1976). The Court rejected a Fourth Amendment challenge
to the checkpoint, recognizing “that maintenance of a traffic-
checking program in the interior is necessary because the
flow of illegal aliens cannot be controlled effectively at the
border.” Id. at 556. The Court also “stressed the
impracticality of the particularized study of a given car to
              UNITED STATES V. SOTO-ZUNIGA                   13

discern whether it was transporting illegal aliens, as well as
the relatively modest degree of intrusion entailed by the
stops.” Edmond, 531 U.S. at 38 (citing Martinez-Fuerte,
428 U.S. at 556–64).

    The constitutionality of immigration checkpoints,
including the San Clemente checkpoint, was raised again
nearly two decades later in a separate case before our Court.
See United States v. Soyland, 3 F.3d 1312 (9th Cir. 1993). In
Soyland, the defendants’ car was searched at an immigration
checkpoint’s secondary inspection, revealing drug
paraphernalia and small amounts of marijuana. Id. at 1314.
A subsequent search of the defendants revealed 220 grams of
methamphetamine and a scale. Id. The majority declined to
address “the issue of whether checkpoint officers routinely
overstep their authority by conducting pretextual narcotics
searches,” noting that it had not been argued at trial nor on
appeal. Id. Judge Kozinski dissented, voicing his concern
that the San Clemente checkpoint and others like it may be
violating restrictions on suspicionless searches. Id. at
1315–20 (Kozinski, J., dissenting). While recognizing that
Martinez-Fuerte approved internal checkpoints for
immigration control purposes, Judge Kozinski warned that
“[t]here’s reason to suspect the agents working these
checkpoints are looking for more than illegal aliens. If this is
true, it subverts the rationale of Martinez-Fuerte and turns a
legitimate administrative search into a massive violation of
the Fourth Amendment.” Id. at 1316. He recommended
remanding the case for a factual inquiry into “whether the
policies, programs, directives and incentives put in place by
the government, or any customs and practices that have
developed with the government’s tacit approval, have turned
. . . San Clemente into [a] general law enforcement
checkpoint[].” Id. at 1319 (footnote omitted).
14            UNITED STATES V. SOTO-ZUNIGA

    Although Judge Kozinski’s dissent primarily discussed
the searches that occur at the San Clemente checkpoint, his
concerns are also relevant to the initial seizure—the vehicle
stop—at issue in Soto-Zuniga’s case. In City of Indianapolis
v. Edmond, the Supreme Court clarified that the
constitutionality of suspicionless immigration checkpoints is
governed by the same standard as administrative searches.
531 U.S. at 37–38. The Court also reaffirmed that
checkpoints with the principal purpose of thwarting criminal
activity do not comport with the Fourth Amendment, and
noted that it had “never approved a checkpoint program
whose primary purpose was to detect evidence of ordinary
criminal wrongdoing,” as opposed to purposes of “policing
the border” or “ensuring roadway safety.” 531 U.S. at 38, 41.
The constitutionality of the San Clemente checkpoint turns on
whether its “primary purpose” is to control immigration, as
has been contended by the government, or rather is to
interdict drug trafficking and other “ordinary criminal
wrongdoing.” Id.; see also Fraire, 575 F.3d at 932 (“[T]he
court must determine whether the primary purpose of the
checkpoint was to advance the general interest in crime
control. If so, then the stop is per se invalid under the Fourth
Amendment.” (internal citations, quotation marks, and
alterations omitted)). If the checkpoint’s primary purpose is
to detect evidence of drug trafficking, then the initial seizure
of Soto-Zuniga’s car and person offended the Fourth
Amendment and the drug evidence recovered from his car
must be excluded as fruit of the poisonous tree. See Wong
Sun v. United States, 371 U.S. 471, 487–88 (1963).

    It is on this issue that the requested discovery is pertinent.
Although the district court held an evidentiary hearing to
determine the checkpoint’s primary purpose, the only
evidence before it was the testimony of Agent Rabreau and
              UNITED STATES V. SOTO-ZUNIGA                    15

several news articles, including a few detailing the
interdiction of narcotics. Based on Agent Rabreau’s
testimony that he had reviewed seizure and arrest records and
that upwards of 90 percent of arrests were immigration
related, the district court concluded that the checkpoint was
constitutional and denied further discovery of the search and
arrest statistics.

    It may well be that Agent Rabreau’s experience and
knowledge is consistent with the general practices at the San
Clemente checkpoint. But there is a risk that the district court
made its decision as if in part blindfolded, considering only
one version of the evidence. Our system of criminal justice
relies on an adversary system to help ensure that justice will
be done.

    Under Federal Rule of Criminal Procedure 16(a)(1)(E),
the government is required to produce, inter alia, documents
or data “if the item is within the government’s possession,
custody, or control and . . . the item is material to preparing
the defense.” The government, relying on United States v.
Armstrong, 517 U.S. 456 (1996), contends that Soto-Zuniga
is not entitled to discovery under this Rule because the
evidence he seeks is not material to his defense against the
government’s case-in-chief. Armstrong, which concerned
discovery in a selective prosecution case, held that Rule
16(a)(1)(E)5 does not permit discovery of government
documents in selective-prosecution claims because such
discovery does not assist in “the preparation of their defense
against the Government’s case in chief.” Id. at 463. The
Supreme Court in Armstrong analyzed the meaning of the

    5
      Armstrong refers to Fed. R. Crim. P. 16(a)(1)(C), which was
recodified at 16(a)(1)(E) in the 2002 Amendments.
16            UNITED STATES V. SOTO-ZUNIGA

term “defense” in the context of the Rule 16(a)(1)(E) and
reasoned that “[w]hile it might be argued that as a general
matter, the concept of a ‘defense’ includes any claim that is
a ‘sword,’ challenging the prosecution’s conduct of the case,
the term may encompass only the narrower class of ‘shield’
claims, which refute the Government’s arguments that the
defendant committed the crime charged.” Id. at 462.

    Notwithstanding that language and guidance of the
Supreme Court, we do not read Armstrong to preclude Rule
16(a)(1)(E) discovery related to the constitutionality of a
search or seizure. In our view, the holding of Armstrong
applies to the narrow issue of discovery in selective-
prosecution cases. See id. at 471 (Ginsburg, J., concurring)
(“I do not understand the Court to have created a major
limitation on the scope of discovery available under Federal
Rule of Criminal Procedure 16. As I see it, the Court has
decided a precise issue: whether the phrase ‘defendant’s
defense,’[6] as used in Rule [16(a)(1)(E)], encompasses
allegations of selective prosecution . . . . The Court was not
called upon to decide here whether Rule [16(a)(1)(E)] applies
in any other context, for example, to affirmative defenses
unrelated to the merits.” (citation omitted and internal
quotation marks omitted)). Also, our post-Armstrong case
law within the Ninth Circuit indicates that Rule 16(a)(1)(E)
permits discovery related to the constitutionality of a search
or seizure. In United States v. Cedano-Arellano, a defendant
charged with cocaine smuggling sought discovery of the
training records of the narcotics detector dog that “alerted” on
his gas tank. 332 F.3d 568, 570 (9th Cir. 2003) (per curiam).
We acknowledged that the materials at issue “were crucial to

    6
      The previous version of Rule 16(a)(1)(E) permitted discovery
“material to the preparation of the defendant’s defense.”
              UNITED STATES V. SOTO-ZUNIGA                    17

[the defendant’s] ability to assess the dog’s reliability, a very
important issue in his defense, and to conduct an effective
cross-examination of the dog’s handler” at the pretrial
evidentiary hearing. Id. at 571. We held that such materials
were discoverable under Rule 16(a)(1)(E). Id.; see also
United States v. Thomas, 726 F.3d 1086, 1096–97 (9th Cir.
2013) (defendant was entitled under Rule 16(a)(1)(E) to
discovery of unredacted training and certification records of
a narcotics detector dog). Cedano-Arellano and Thomas
support the conclusion that Rule 16(a)(1)(E) permits
discovery to determine whether evidence in a particular case
was obtained in violation of the Constitution and is thus
inadmissible.

    The government argues that Cedano-Arellano and
Thomas created a narrow “dog discovery” exception to the
general rule that Armstrong establishes. The government
points to our precedent in United States v. Chon, in which the
defendants were convicted of theft and conversion of
government property after they broke into a Naval facility
and stole military equipment. 210 F.3d 990, 992 (9th Cir.
2000). The defendants were caught and charged as a result of
a Naval Criminal Investigative Service (NCIS) investigation.
Before the trial, the defendants moved for discovery on any
activities of the NCIS and its predecessor agency that targeted
civilians to bolster their claim that NCIS violated the Posse
Comitatus Act (PCA), which prohibits the military from
participating in civilian law enforcement. Id. at 992–93. We
affirmed the district court’s determination that this request
was a “far reaching fishing expedition.” Id. at 992. We held
that the discovery request was “considerably broader” than
any materials that could be relevant to the specific charges
against the defendants and that the requested discovery did
18            UNITED STATES V. SOTO-ZUNIGA

“not serve the purpose of fortifying the appellants’ ‘shield
claims.’” Id. at 995.

    Chon turns on the determination that the requested
discovery had no relevance to whether NCIS violated the
PCA in the defendants’ particular case. The materials sought
were expansive, “implicating widespread and repeated
violations of the PCA in the State of Hawaii and within the
United States.” Id. at 994. By contrast, Soto-Zuniga sought
discovery of whether he and his automobile were
unconstitutionally seized at the San Clemente checkpoint—an
issue that is central to his defense, because it could spell the
difference in a suppression motion of the key physical
evidence against him. Because the primary purpose of the
San Clemente checkpoint was placed squarely at issue by
Soto-Zuniga’s motion to suppress, defense counsel should
have been allowed reasonable discovery relating to this
primary purpose. After that discovery, and with all material
evidence on the table, the district court would have been in a
superior position to assess and decide the motion to suppress.

    It has been forty years since the San Clemente checkpoint
was upheld by the Supreme Court as constitutional.
Martinez-Fuerte, 428 U.S. at 556–64. Whether the primary
purpose of the checkpoint has evolved from controlling
immigration to detecting “ordinary criminal wrongdoing,” see
Edmond, 531 U.S. at 42, is a question that is subject to
discovery under Rule 16. Soto-Zuniga “should not have to
rely solely on the government’s word that further discovery
is unnecessary.” United States v. Budziak, 697 F.3d 1105,
1113 (9th Cir. 2012). We conclude that the district court
abused its discretion by denying this discovery. See de Cruz,
82 F.3d at 866. However, because we do not have access to
the records in question, we cannot determine the likelihood of
              UNITED STATES V. SOTO-ZUNIGA                     19

whether Soto-Zuniga’s case would have had a different
outcome had he been permitted discovery. Id. The proper
course under such circumstances is to remand for discovery
and an evidentiary determination. See Thomas, 726 F.3d at
1097–98; see also United States v. Doe, 705 F.3d 1134,
1151–52 (9th Cir. 2013). We reverse the district court’s
denial of the discovery motion relating to the checkpoint’s
arrest statistics, and remand for the district court to assess the
constitutionality of the San Clemente checkpoint in further
proceedings. See id. at 1097–98.

                                B

    We also reverse the district court’s denial of discovery of
the government’s investigation into Rios’s drug smuggling
operation. The district court reviewed the documents
submitted by the government, including reports from the
agents involved in investigating drug smuggling operations,
and concluded that the documents were irrelevant, that the
documents were inadmissible because they relied on hearsay,
and that permitting the requested discovery would
unnecessarily extend the litigation in violation of Fed. R.
Evid. 403. After reviewing the documents,7 we disagree both
with the district court’s characterization of the documents and
with its application of the law.

    Soto-Zuniga has maintained that, before being stopped at
the checkpoint, he gave a ride to three teenagers at the request
of Rios. It is possible that discovery about the investigation
might help Soto-Zuniga identify the teenagers to whom he
gave a ride. Those persons might then provide direct

    7
      We grant the government’s Motion to Transmit Documentary
Evidence Under Seal for Ex Parte Consideration.
20            UNITED STATES V. SOTO-ZUNIGA

testimony on whether one or more of them placed drugs in
the car of Soto-Zuniga without his knowledge. And even if
not, they might potentially give information that would lead
to the identification of the persons in question. Soto-Zuniga’s
defense was that the contraband must have been left in his car
by the teenagers to whom he gave a ride because he knew
nothing about it. If the persons are identified, they could
potentially either support or contradict Soto-Zuniga’s claim
that he did not knowingly or intentionally possess the drugs,
an element of the crime of which he was convicted of by a
jury. See 21 U.S.C. § 841(a)(1).

    Under Federal Rule of Criminal Procedure 16(a)(1)(E),
Soto-Zuniga has a right to discovery of documents that are
“material to preparing the defense.” Materiality is a “low
threshold; it is satisfied so long as the information . . . would
have helped” to prepare a defense. United States v.
Hernandez-Meza, 720 F.3d 760, 768 (9th Cir. 2013) (citation
and internal quotation marks omitted). The test is not
whether the discovery is admissible at trial, but whether the
discovery may assist Soto-Zuniga in formulating a defense,
including leading to admissible evidence.                See id.
(“Information is material even if it simply causes a defendant
to completely abandon a planned defense and take an entirely
different path.” (citation and internal quotation marks
omitted)); United States v. Lloyd, 992 F.2d 348, 351 (D.C.
Cir. 1993) (“This materiality standard normally is not a heavy
burden; rather, evidence is material as long as there is a
strong indication that it will play an important role in
uncovering admissible evidence, aiding witness preparation,
corroborating testimony, or assisting impeachment or
rebuttal.” (citations and internal quotation marks omitted)).
The district court erred by finding that the documents were
not material to the defense and were not discoverable because
                UNITED STATES V. SOTO-ZUNIGA                            21

they were not admissible. We conclude that in this respect,
the district court abused its discretion. See United States v.
Hinkson, 585 F.3d 1247, 1261–63 (9th Cir. 2009) (en banc).
We also conclude that there is a likelihood that the discovery
of these documents would have identified the teenagers and
changed the outcome of the trial. de Cruz, 82 F.3d at 866.8

    It has been said that it “behooves the government to
interpret the disclosure requirement broadly and turn over
whatever evidence it has pertaining to the case.” Hernandez-
Meza, 720 F.3d at 768. While we recognize the sensitive
nature of the documents in question, Soto-Zuniga’s interest
in government materials that are pertinent to his defense takes
precedence. We reverse the district court’s denial of Soto-
Zuniga’s discovery motion, vacate the conviction, and
remand with instructions to grant the motion. See Thomas,
726 F.3d at 1098. We also instruct the district court to
consider the government’s request for a window of time
before production to determine whether to continue to pursue
this case, and to consider the government’s request for
protective measures that would maintain the security of the
information in the documents while allowing Soto-Zuniga to
adequately prepare a defense.




    8
       The assessment of prejudice is different as to discovery of the names
of the teenagers involved in smuggling by Rios, on the one hand, and
discovery of checkpoint arrests statistics, on the other hand. On the
former, we have the pertinent documents and can assess their materiality
to the defense. On the latter, we do not have the arrest and search
statistics and can express no conclusion on prejudice, and hence remand
for the district court to assess prejudice in the first instance.
22            UNITED STATES V. SOTO-ZUNIGA

                              III

    Soto-Zuniga raises three additional arguments that we
briefly address here.

    First, he argues that the district court erred in denying his
motion to suppress the drug evidence on the basis that the
Border Patrol agents lacked probable cause to search the car.
We review a denial of a suppression motion de novo and the
underlying factual findings for clear error. See United States
v. Rodgers, 656 F.3d 1023, 1026 (9th Cir. 2011).

    Agents at a checkpoint may not search a private vehicle
without a warrant unless they have consent or probable cause.
See United States v. Ortiz, 422 U.S. 891, 896–97 (1975).
Probable cause exists if there is a fair probability that
contraband or evidence of a crime will be found in a
particular place based on a totality of the circumstances.
United States v. Pinela-Hernandez, 262 F.3d 974, 978 (9th
Cir. 2001) (quoting Illinois v. Gates, 462 U.S. 213, 238
(1983)).

    Here, the district court made factual findings that
supported probable cause, including (1) that Agent Rabreau
smelled marijuana, (2) that the car had multiple air
fresheners, (3) that there was a cigarillo wrapper and loose
tobacco in the car, (4) that Soto-Zuniga appeared to be
agitated and nervous, and (5) that Soto-Zuniga admitted to
smoking marijuana in the car. Even if neither marijuana nor
marijuana paraphernalia were ever recovered from the car, we
conclude that the district court’s factual findings were not
clearly erroneous. Agent Rabreau testified that he smelled
marijuana and that there was physical evidence in the car that
made him suspect drug use or trafficking. Deference must be
              UNITED STATES V. SOTO-ZUNIGA                    23

given to the district court’s determination that Agent Rabreau
was credible. See Anderson v. City of Bessemer, 470 U.S.
564, 573–76 (1985). Also, other agents reported that Soto-
Zuniga was agitated and at least one agent reported that Soto-
Zuniga had admitted to smoking marijuana in the car. We
give due regard to the views of the agents, their recitals of
what Soto-Zuniga said and did, and items seen in the car,
once these have been confirmed by the district court’s factual
findings.

    Viewing the entire record, we determine that the district
court’s account of the evidence is plausible, see id. at 573–74,
and that the totality of the circumstances supported probable
cause for the search. Cf. United States v. Koshnevis, 979 F.2d
691, 695 (9th Cir. 1992) (holding that a driver’s nervousness,
inconsistent statements, and lies about not possessing a trunk
key or a weapon constituted probable cause to search the
car’s trunk at an immigration checkpoint). We stress that
under the Supreme Court’s standard in Illinois v. Gates, it is
not certainty that is required to support a search or seizure but
only probable cause, based on the total circumstances, that a
search may yield evidence of crime. 462 U.S. at 238. We
affirm the district court’s denial of Soto-Zuniga’s suppression
motion, insofar as it is based on a claimed lack of probable
cause for the search of the car.

    Soto-Zuniga also argues that the district court erred by
instructing the jury, using the Ninth Circuit pattern jury
instructions, that “[a] reasonable doubt is a doubt based upon
reason and common sense and is not based purely on
speculation.” Manual of Model Criminal Jury Instructions
§ 3.5 (9th Cir. 2010 ed.). Soto-Zuniga contends that this
phrasing interferes with the presumption of innocence. But
this argument is foreclosed by our precedent. See United
24            UNITED STATES V. SOTO-ZUNIGA

States v. Alcantara-Castillo, 788 F.3d 1186, 1198 n.4 (9th
Cir. 2015) (noting that we have “repeatedly upheld the use of
the Ninth Circuit model jury instruction on reasonable doubt”
and collecting cases).

    Soto-Zuniga also argues that knowledge of drug type and
quantity is an element of possession with intent to distribute
in violation of 21 U.S.C. § 841. Soto-Zuniga contends that
the Supreme Court’s decision in Alleyne v. United States,
133 S. Ct. 2151 (2013), called our Circuit’s case law on this
issue into question. However, we have held that “Alleyne
does not alter our precedent that a defendant’s knowledge of
the type and quantity of the controlled substance he imports
is not such a fact, and therefore, not an element of the
offense.” United States v. Jefferson, 791 F.3d 1013, 1016
(9th Cir. 2015). The mens rea for the statute at issue in
Jefferson, 21 U.S.C. § 960, is the same as the mens rea for the
statute at issue in this case—that the defendant acted
“knowingly or intentionally.” We conclude that Soto-
Zuniga’s knowledge of the type and quantity of the drugs
found in his car is not an element under 21 U.S.C. § 841. See
also United States v. Dado, 759 F.3d 550, 570 (6th Cir. 2014)
(“Drug type and quantity are irrelevant to [the] mens rea
element” under this statute).

                              IV

    In conclusion, we vacate Soto-Zuniga’s conviction and
remand this case for a new trial. If the government decides
to proceed, the district court shall permit discovery of the San
Clemente checkpoint statistics. The court should also hold an
evidentiary hearing on the checkpoint’s constitutionality, and,
as appropriate, publish an order or opinion on its findings. If
the checkpoint is found to be constitutional, then the district
             UNITED STATES V. SOTO-ZUNIGA               25

court shall also permit discovery of the investigation into
Rios’s drug smuggling operation.

  The conviction is VACATED, the discovery rulings
REVERSED, and the case REMANDED, with instructions.
