                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 05-50207
                Plaintiff-Appellee,
               v.                            D.C. No.
                                          CR-04-02171-WQH
ENRIQUE CORTEZ-RIVERA,
                                              OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
         for the Southern District of California
       William Q. Hayes, District Judge, Presiding

                  Argued and Submitted
            June 9, 2006—Pasadena, California

                    Filed July 24, 2006

      Before: Stephen Reinhardt, Stephen S. Trott, and
          Kim McLane Wardlaw, Circuit Judges.

                  Opinion by Judge Trott




                           8127
8130            UNITED STATES v. CORTEZ-RIVERA




                          COUNSEL

Ellis M. Johnston III and Steven F. Hubachek, Assistant Fed-
eral Public Defenders, San Diego, California, for the
defendant-appellant.

Michael J. Crowley, Assistant United States Attorney, San
Diego, California, for the plaintiff-appellee.


                           OPINION

TROTT, Circuit Judge:

   Enrique Cortez-Rivera appeals from his conviction follow-
ing a conditional guilty plea for importation of marijuana in
violation of 21 U.S.C. §§ 952 and 960. He asserts that the dis-
trict court should have dismissed his indictment because the
model instructions given to the grand jurors unconstitutionally
invaded the province of the grand jury. He asserts also that the
district court erred in denying his motion to suppress the mari-
juana found during a border search because the search dam-
aged his vehicle, thereby requiring that the customs officers
have reasonable suspicion prior to commencing the search.

   We have jurisdiction pursuant to 28 U.S.C. § 1291, and we
affirm. The model charge given to the grand jury did not vio-
late Cortez-Rivera’s Fifth Amendment right to indictment by
a grand jury. The model instruction did not infringe upon the
grand jury’s independence because it used the term “should”
rather than “shall,” giving the grand jury leeway to depart
from the instruction. This leeway, albeit slight, is sufficient to
immunize the instruction from constitutional infirmity. Addi-
                UNITED STATES v. CORTEZ-RIVERA              8131
tionally, we hold that a defendant who moves to suppress evi-
dence discovered during a border search of his vehicle bears
the burden of demonstrating that the search damaged the vehi-
cle and that the damage affected the vehicle’s safety or opera-
bility. Because Cortez-Rivera failed to carry this burden, the
border search was constitutional despite a lack of reasonable
suspicion.

                               I

  On August 10, 2004, Enrique Cortez-Rivera drove his 1995
Ford Aspire to the Calexico, California Port of Entry, attempt-
ing to gain entry into the United States. During the primary
search, a narcotics dog alerted on Cortez-Rivera’s vehicle.
The vehicle was taken to the secondary inspection area to be
searched for contraband.

   As part of the search, the customs officer pried open the
rear interior quarter panel on the passenger side of the vehicle.
Inside, he found several bags of marijuana. After arresting
Cortez-Rivera and placing him in a holding cell, the customs
officer continued searching the vehicle. He discovered addi-
tional packages of marijuana hidden in the floor of the vehicle
and in the passenger side door. A total of forty-seven pack-
ages of marijuana, weighing 46.84 kilograms, were found in
Cortez-Rivera’s vehicle.

   On August 18, 2004, a grand jury indicted Cortez-Rivera
on one count of importation of marijuana in violation of 21
U.S.C. §§ 952 and 960, and one count of possession of mari-
juana with the intent to distribute in violation of 21 U.S.C.
§ 841(a)(1). Cortez-Rivera filed a motion to dismiss the
indictment, arguing that the district court’s charge to the
grand jury, which followed the model charge recommended
by the Administrative Office of the United States Courts,
unconstitutionally invaded the grand jury’s independence and
curtailed the scope of its inquiries. Concluding that the charge
to the grand jury had been approved by United States v. Mar-
8132            UNITED STATES v. CORTEZ-RIVERA
cucci, 299 F.3d 1156 (9th Cir. 2002), the district court denied
the motion to dismiss the indictment.

   Cortez-Rivera filed also a motion to suppress the marijuana
found in his vehicle. He argued that because the border search
caused damage to the vehicle itself, the customs officers
needed reasonable suspicion to conduct the search. The gov-
ernment asserted that it did not need reasonable suspicion to
search the vehicle at the border, and that it was not relying
upon any reasonable suspicion that might have arisen from
the narcotics dog alert. The district court denied the motion to
suppress, concluding that reasonable suspicion was not
needed. The district court found that although the search dam-
aged the vehicle’s quarter panel, the damage “did not affect
the operation of the vehicle or the workings of the vehicle.”

   On December 7, 2004, Cortez-Rivera entered a conditional
guilty plea to the importation charge, preserving his right to
appeal the denial of his motions to dismiss the indictment and
to suppress the marijuana. Cortez-Rivera was sentenced to
twelve months and one day in custody with two years super-
vised release to follow.

   Cortez-Rivera appeals the denial of the motion to dismiss
the indictment and the denial of the motion to suppress the
evidence.

                               II

  Cortez-Rivera argues that the district court erred in not dis-
missing the indictment. He contends that the district court’s
charge to the grand jury invaded the grand jury’s indepen-
dence and improperly circumscribed its inquiry. We review
de novo the denial of a motion to dismiss an indictment.
United States v. Haynes, 216 F.3d 789, 796 (9th Cir. 2000).

  Although Cortez-Rivera objects to each of the instructions
within the charge, he concedes that all but one were deemed
                UNITED STATES v. CORTEZ-RIVERA                8133
constitutional by our decision in United States v. Navarro-
Vargas, 408 F.3d 1184 (9th Cir. 2005) (en banc). The one
instruction that he contends we have not analyzed previously
concerns the grand jury’s ability to consider the potential pun-
ishment of a crime. It states, “Furthermore, when deciding
whether or not to indict, you should not be concerned about
punishment in the event of conviction; judges alone determine
punishment.”

   Cortez-Rivera traces our precedent concerning the model
grand jury charge back to United States v. Marcucci, 299 F.3d
1156 (9th Cir. 2002), and asserts that we have recited the
challenged instruction in the facts section of opinions, but that
we have never analyzed the specific instruction. Even if
Cortez-Rivera is correct that we have not considered the spe-
cific instruction, our analysis in Marcucci is controlling.

   [1] After reviewing the history of the grand jury, the Mar-
cucci court analyzed the challenged instruction—“[Y]ou
should vote to indict where the evidence presented to you is
sufficiently strong to warrant a reasonable person’s believing
that the accused is probably guilty of the offense with which
the accused is charged.” Id. at 1159 (emphasis added). We
seized upon the distinction between “should” and “shall”:

    The charge, by telling the jury that it “should” rather
    than “shall” or “must” indict if it finds probable
    cause, leaves room-albeit limited room-for a grand
    jury to reject an indictment that, although supported
    by probable cause, is based on governmental pas-
    sion, prejudice, or injustice.‘

Id. at 1164. We concluded that the instruction did not invade
upon the grand jury’s constitutional role because the instruc-
tion used the term “should,” making the instruction permis-
sive rather than mandatory. Id.; see also Navarro-Vargas, 408
F.3d at 1204-05.
8134            UNITED STATES v. CORTEZ-RIVERA
   [2] The distinction between “should” and “shall” is disposi-
tive of Cortez-Rivera’s contention. The contested charge
stated, “Furthermore, when deciding whether or not to indict,
you should not be concerned about punishment in the event
of conviction; judges alone determine punishment.” (empha-
sis added). According to our reasoning in Marcucci, by using
“should,” the challenged instruction does not place an abso-
lute bar on considering punishment, but “leaves room-albeit
limited room-for a grand jury to” consider punishment. Thus,
the instruction does not preclude the grand jury from consid-
ering punishment and is therefore constitutional.

                               III

                                A

   The district court’s ruling on a motion to suppress evidence
is reviewed de novo. United States v. Chaudhry, 424 F.3d
1051, 1052 (9th Cir. 2005). “Factual determinations underly-
ing the district court’s ruling are reviewed for clear error.” Id.

   [3] We have not addressed which party bears the burdens
of production and persuasion in a motion to suppress evidence
found during a border search, although, generally, “[t]he gov-
ernment bears the burden of justifying a warrantless search.”
United States v. Johnson, 936 F.2d 1082, 1084 (9th Cir. 1991)
(per curiam).

   [4] Cortez-Rivera contends that because the search of his
vehicle was warrantless, the government bears the burden of
showing that it did not need reasonable suspicion to justify the
border search. We disagree. Generally, when law enforcement
conducts a warrantless search, the dispositive question is
whether the search falls into one of the search warrant excep-
tions, such as a search incident to an arrest or a search pursu-
ant to exigent circumstances. For border searches, however,
that question is already resolved—searches performed at the
border constitute an exception to the search warrant require-
                UNITED STATES v. CORTEZ-RIVERA              8135
ment. See United States v. Montoya de Hernandez, 473 U.S.
531, 538 (1985). There is no question that a border search
falls within a search warrant exception—the only question in
determining the reasonableness of the search is whether the
search caused excessive damage to the defendant’s vehicle.

   [5] General burden-shifting principles govern our decision
to place the burden on the defendant rather than the govern-
ment in cases of alleged damage to the vehicle. Burdens are
generally placed on the party who is in the best position to
present the evidence. See, e.g., United States v. New York,
N.H. & H.R. Co., 355 U.S. 253, 256 n.5 (1957) (“The ordi-
nary rule, based on considerations of fairness, does not place
the burden upon a litigant of establishing facts peculiarly
within the knowledge of his adversary.”). For a border search
of a vehicle, a defendant is in the best position to know the
condition of his vehicle immediately prior to the search and,
therefore, is in the best position to determine whether and to
what extent the search damaged his vehicle. For example, a
defendant knows best whether his vehicles stalls, starts only
half the time, or has an inoperable seatbelt. A contrary rule
would require customs officers to inspect each vehicle’s
safety equipment and operability prior to commencing a
search so that they could determine whether the search dam-
ages the vehicle.

   [6] Additionally, placing the burden on the government
would require that it prove a negative fact—that the search
did not affect the vehicle’s safety or operability. “ ‘[A]s a
practical matter it is never easy to prove a negative.’ ” Sissoko
v. Rocha, 440 F.3d 1145, 1162 (9th Cir. 2006) (quoting Elkins
v. United States, 364 U.S. 206, 218 (1960)). “For this reason,
fairness and common sense often counsel against requiring a
party to prove a negative fact, and favor, instead, placing the
burden of coming forward with evidence on the party with
superior access to the affirmative information.” Id.

  [7] We therefore hold that where a defendant moves to sup-
press evidence found during a border search and alleges that
8136            UNITED STATES v. CORTEZ-RIVERA
the search caused damage to his vehicle, the burden is on the
defendant to prove the existence of this damage, and that it
affected the safety or operability of the vehicle. If the defen-
dant carries this burden by a preponderance of the evidence,
then the burden shifts to the government to demonstrate that
it had reasonable suspicion to conduct the search.

                               B

   Although there was some damage to the vehicle in the case
before us, the border search did not require reasonable suspi-
cion. In United States v. Flores-Montano, 541 U.S. 149, 155-
56 (2004), the Supreme Court held that reasonable suspicion
was not necessary to conduct a border search involving the
disassembly and reassembly of a vehicle’s fuel tank. The
Court found that the “procedure of removal, disassembly, and
reassembly of the fuel tank . . . has [not] resulted in serious
damage to, or destruction of, the property.” Id. at 154. The
Supreme Court stated, without deciding, that “it may be true
that some searches of property are so destructive as to require
a different result.” Id. at 155-56. The Court also left “open the
question whether, and under what circumstances, a border
search might be deemed unreasonable because of the particu-
larly offensive manner in which it is carried out.” Id. at 154
n.2 (internal quotation marks omitted).

   We have applied Flores-Montano to a variety of border
searches and have yet to conclude that reasonable suspicion
is required. See, e.g., United States v. Cortez-Rocha, 394 F.3d
1115, 1125 (9th Cir. 2005) (holding that customs officers,
without reasonable suspicion, could slash a vehicle’s spare
tire to search for contraband); Chaudhry, 424 F.3d at 1051
(holding that the exploratory drilling of a 5/16-inch hole in the
bed of a truck during a suspicionless border search was con-
stitutional). In each case, we focused on two main issues: (1)
Did the search damage the vehicle in a manner that affected
the vehicle’s safety or operability, and (2) Was the search
conducted in a particularly offensive manner. Cortez-Rivera
                   UNITED STATES v. CORTEZ-RIVERA                      8137
did not argue to the district court that the search affected the
safety of the vehicle or that the search was conducted in an
offensive manner, and, consequently, did not carry his burden
on those two issues.1 We therefore focus on the issue Cortez-
Rivera raised below—whether the search damaged the vehicle
in a manner that affected its operability.

   [8] As the district court found, the search no doubt dam-
aged the vehicle. Indeed, the government concedes that the
search damaged the interior quarter panel. Cortez-Rivera,
however, did not carry his burden of proving that this damage
to the panel affected the vehicle’s operability. In fact, it is dif-
ficult to imagine how even the complete destruction of the
interior panel would affect the vehicle’s operability. See
Cortez-Rocha, 394 F.3d at 1119-20 (focusing on operability
of the vehicle and not on damage to the component part).
Consequently, we hold that the border search of Cortez-
Rivera’s vehicle was constitutional, despite a lack of reason-
able suspicion.2

                                    IV

   The district court properly denied the motion to dismiss the
indictment. Marcucci identified a distinction between
“should” and “shall.” Pursuant to this distinction, the grand
jury instruction that the jury “should” not consider punish-
ment does not unconstitutionally invade the province of the
grand jury. The district court properly denied also the motion
  1
     Although Cortez-Rivera’s reply brief argues that the search damaged
the rear seat belt, he waived this argument by not raising it before the dis-
trict court and by not raising it in his opening brief. See Redd v. McGrath,
343 F.3d 1077, 1081 n.6 (9th Cir. 2003).
   2
     We are presented only with the question of whether the border search
violated the constitution, which would trigger the exclusionary rule for
evidence obtained from the search. As we stated in Cortez-Rocha, “any
motorist whose vehicle has in fact been damaged during such a search is
free to pursue recovery in the form of civil damages.” 394 F.3d at 1120
(citing Flores-Montano, 541 U.S. at 155).
8138           UNITED STATES v. CORTEZ-RIVERA
to suppress the marijuana. Although the search damaged the
vehicle, Cortez-Rivera failed to carry his burden of proving
that the damage affected the vehicle’s safety or operability or
that the search was conducted in a particularly offensive man-
ner. Accordingly, the government did not need reasonable
suspicion to conduct the search.

  AFFIRMED.
