                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                 No. 05-50219
                Plaintiff-Appellee,           D.C. No.
               v.                        CR-02-01289-AK-
JUSTIN BARRETT HILL,                             01
             Defendant-Appellant.
                                            OPINION

       Appeal from the United States District Court
          for the Central District of California
         Alex Kozinski, Circuit Judge, Presiding

                  Argued and Submitted
          January 12, 2006—Pasadena, California

                   Filed August 11, 2006

Before: Mary M. Schroeder, Chief Judge, Alfred T. Goodwin
         and Raymond C. Fisher, Circuit Judges.

                 Opinion by Judge Fisher




                           9373
9376                UNITED STATES v. HILL


                         COUNSEL

Carlton F. Gunn, Deputy Federal Public Defender, Los Ange-
les, California, for the defendant-appellant.

Michael R. Wilner (argued) and Thomas P. O’Brien, Assis-
tant United States Attorneys, and Los Angeles, California, for
the plaintiff-appellee.
                       UNITED STATES v. HILL               9377
                            OPINION

FISHER, Circuit Judge:

   Justin Hill conditionally pled guilty to possession of child
pornography subject to his challenge to the admission of evi-
dence that he contends was seized in violation of the Fourth
Amendment. His appeal involves the validity of a warrant to
search his computer and storage media for evidence that he
possessed pornographic (i.e., lascivious) images of children.
We must also decide whether it was reasonable under the
Fourth Amendment for the police to take all of Hill’s com-
puter storage media from his home (they did not find his com-
puter) so they could conduct their search offsite in a police
laboratory, rather than carrying out the search onsite and tak-
ing only whatever evidence of child pornography they might
find. As we recently discussed in United States v. Adjani,
____ F.3d ____, 2006 WL 1889946 (9th Cir. July 11, 2006),
because computers typically contain so much information
beyond the scope of the criminal investigation, computer-
related searches can raise difficult Fourth Amendment issues
different from those encountered when searching paper files.
Judge Kozinski, sitting as the district court in this case,
thoughtfully addressed some of these issues in a published
opinion upholding the validity of the search warrant and its
execution. United States v. Hill, 322 F. Supp. 2d 1081, 1092
(C.D. Cal. 2004). We affirm the district court’s ruling in most
but not all respects for the reasons Judge Kozinski stated; to
the extent we do agree with that reasoning, we adopt it verba-
tim in this opinion. In sum, we affirm the district court’s
denial of the defendant’s motion to suppress evidence.

I.    Background

     As the district court explained:

       A computer technician was repairing defendant’s
       computer when she discovered what she believed to
9378                UNITED STATES v. HILL
    be child pornography. She called Long Beach police,
    and the detective who took the call obtained a search
    warrant from a judge of the Long Beach Superior
    Court. The warrant authorized a search of the com-
    puter repair store and seizure of the computer, any
    work orders relating to the computer, “all storage
    media belonging to either the computer or the indi-
    vidual identifying himself as defendant at the loca-
    tion,” and “all sexually explicit images depicting
    minors contained in the storage media.” By the time
    the detective arrived at the store to execute the war-
    rant, defendant had picked up his computer. . . .
    [T]he detective [submitted an affidavit, which
    included the computer technician’s sworn statement
    describing the images. On the basis of this affidavit,
    the officer obtained] a second warrant, this one
    directed at defendant’s home, authorizing seizure of
    the same items.

    The affidavit on which the warrants were based
    described “two images of child pornography”:

    Image 1

    Is a color picture of a female, white, approximately
    15 years old, with long dark brown hair. The female
    is in a room standing between a couch and a coffee
    table. There is a framed picture on the wall above the
    couch. She is wearing only a long blouse and pair of
    socks. The blouse is open and she is exposing her
    breast and pubic area to the camera, which she is
    facing while leaning to her left.

    Image 2

    Is a color picture of a [sic in affidavit] two females,
    white, approximately 7-9 years of age, both with
    dirty blond hair. These females are standing on a
                       UNITED STATES v. HILL                        9379
    beach during the daytime. The shorter of the two
    females is standing to the right of the picture while
    the other female is standing behind her. Both
    females are facing the camera askew and wearing
    only a robe, which is open exposing the undeveloped
    breast and pubic area of both girls. They both are
    turning their faces away from the camera preventing
    the viewer from seeing their faces.

    Officers executed the search warrant but did not find
    the computer in defendant’s apartment.1 In what
    appeared to be defendant’s bedroom, they found and
    seized computer storage media[, specifically: 22
    5.25-inch floppy disks, two CD-ROMs, 124 3.5-inch
    floppy disks and six zip disks.] [Two of the zip
    disks] were eventually determined to contain images
    of child pornography; [officers] also seized other
    evidence consistent with the warrant. Defendant was
    subsequently charged with one count of possession
    of child pornography,2 in violation of 18 U.S.C.
1
 Or anywhere else: The computer was never found.
2
 18 U.S.C. § 2256(8) defines “child pornography” as
  any visual depiction, including any photograph, film, video, pic-
  ture, or computer or computer-generated image or picture,
  whether made or produced by electronic, mechanical, or other
  means, of sexually explicit conduct, where —
       (A) the production of such visual depiction involves the use
       of a minor engaging in sexually explicit conduct;
       (B) such visual depiction is a digital image, computer image,
       or computer-generated image that is, or is indistinguishable
       from, that of a minor engaging in sexually explicit conduct;
       or
       (C) such visual depiction has been created, adapted, or modi-
       fied to appear that an identifiable minor is engaging in sexu-
       ally explicit conduct.
  Section 2256(2)(B)(iii) defines “sexually explicit conduct” as
  “graphic or simulated lascivious exhibition of the genitals or
  pubic area of any person.” Thus, the lascivious exhibition of the
  genitals or pubic area of a minor constitutes child pornography.
  A portion of section 2256(8) that is irrelevant to the issues raised
  in these motions was held unconstitutional in Ashcroft v. Free
  Speech Coalition. See 535 U.S. 234 (2002).
9380                     UNITED STATES v. HILL
      § 2252A(a)(5)(B).3

Hill, 322 F. Supp. 2d at 1083-84 (alterations in original).

   In the district court, the defendant moved to suppress the
evidence recovered from the two zip disks on the grounds
that, (1) contrary to the magistrate’s finding, the warrant affi-
davit did not establish probable cause to believe the defendant
was guilty of criminal activity; and (2) the warrant was over-
broad in allowing seizure of all discovered computer storage
media with no regard to whether such media contained child
pornography, and in placing no limitation on the police offi-
cers’ search of the seized disks. Id. at 1084.4 The district court
denied the motion to suppress and the defendant conditionally
pled guilty to the charge, reserving the right to appeal the dis-
trict court’s evidentiary ruling.5 This timely appeal followed.
  3
   Section 2252A(a)(5)(B) prohibits:
      knowingly possessing any book, magazine, periodical, film, vid-
      eotape, computer disk, or any other material that contains an
      image of child pornography that has been mailed, or shipped or
      transported in interstate or foreign commerce by any means,
      including by computer, or that was produced using materials that
      have been mailed, or shipped or transported in interstate or for-
      eign commerce by any means, including by computer.
   4
     The defendant did not challenge the warrant affidavit on the ground
that it included only a written description of the images and not the images
themselves. Cf. United States v. Battershell, ___ F.3d ___, ___, slip op.
at 9271 (9th Cir. Aug. 10, 2006) (“It would have been preferable if the
affiant in this case had included copies of the photographs [to which the
affiant had access] in the warrant application. But failing to include a pho-
tograph in a warrant application is not fatal to establishing probable cause.
(citing United States v. Smith, 795 F.2d 841, 847 (9th Cir. 1986))).
   5
     In the district court, the defendant also argued that in order to prepare
a defense his counsel and his expert were entitled to “mirror image” copies
of the computer media the government seized. The district court agreed
and ordered the government to provide defendant with copies. Hill, 322
F. Supp. 2d at 1091-92. That ruling is not contested here.
                         UNITED STATES v. HILL               9381
II.        Standard of Review

   We review de novo the district court’s denial of a motion
to suppress evidence. United States v. Meek, 366 F.3d 705,
711 (9th Cir. 2004). We review for clear error a magistrate’s
finding of probable cause to issue a search warrant and give
“great deference” to such a finding. United States v. Hay, 231
F.3d 630, 634 n.4 (9th Cir. 2000).

III.       Discussion

      A.     Probable Cause

  The defendant argues first that the affidavit submitted in
support of the search warrant was insufficient to establish
probable cause to believe the defendant was guilty of criminal
activity. We do not agree.

   [1] “[N]o Warrants shall issue, but upon probable cause,
supported by Oath or affirmation, and particularly describing
the place to be searched, and the persons or things to be
seized.” U.S. Const. amend. IV. The Constitution is clear; a
magistrate may authorize a search of a location only if offi-
cers establish probable cause to believe evidence of a crime
may be found there. Probable cause means only a “fair proba-
bility,” not certainty, and requires consideration of the totality
of the circumstances. Illinois v. Gates, 462 U.S. 213, 238
(1983). Accordingly, we must determine whether the officer’s
affidavit, which described the two images from the defen-
dant’s computer as showing three different, minor girls with
their breasts and pubic areas exposed, established a fair proba-
bility that there was child pornography or evidence thereof to
be found in computer hardware or software at the defendant’s
home. We agree with the district court that the affidavit did
establish probable cause, but reach that conclusion somewhat
differently.
9382                     UNITED STATES v. HILL
   [2] Child pornography is a particularly repulsive crime, but
not all images of nude children are pornographic. For exam-
ple, “a family snapshot of a nude child bathing presumably
would not” be criminal. Hill, 322 F. Supp. 2d at 1086. More-
over, the law recognizes that some images of nudity may
merit First Amendment protection because they serve artistic
or other purposes, and possessing those images cannot be
criminal. See Osborne v. Ohio, 495 U.S. 103, 112-13 (1990)
(upholding Ohio’s child pornography law because it had been
interpreted to criminalize possession of images depicting not
just nudity, but “nudity constitut[ing] a lewd exhibition”);
New York v. Ferber, 458 U.S. 747, 765 n.18 (1982)
(“[N]udity, without more[,] is protected expression.”). Images
depicting “minor[s] engag[ed] in sexually explicit conduct”
are, however, prohibited. 18 U.S.C. § 2256(8)(A). “[S]exually
explicit conduct,” in turn, is defined to include “graphic or
simulated lascivious exhibition of the genitals or pubic area of
any person.” 18 U.S.C. § 2256(2)(A)(v) (emphasis added).
Thus the more precise question we must answer is whether
the officer’s affidavit established probable cause that the
images on the defendant’s computer were — as described —
lascivious.6 See Hill, 322 F. Supp. 2d at 1084. In answering
that question, it is important to remember that in issuing the
search warrant, the magistrate had to make a practical, com-
monsense decision, based on the totality of the circumstances
  6
    We stress that in this case the state court judge who issued the warrant
made his determination based upon a written description of the images.
The officer presenting that description of the images had a duty, of course,
to do so in good faith, providing all relevant information to the magistrate.
See United States v. Mendonsa, 989 F.2d 366, 369 (9th Cir. 1993)
(“Suppression remains an appropriate remedy, however, when a magis-
trate is misled by information in the affidavit, which the affiant knows, or
should know, is false.”); see also Baldwin v. Placer County, 405 F.3d 778,
782 (9th Cir.), amended by 418 F.3d 966 (9th Cir. 2005) (refusing to grant
an officer qualified immunity because “[t]he plaintiffs’ established civil
rights were violated by presentation of [a] false affidavit”). If the magis-
trate had been able to view the two images for himself, his analysis and
our subsequent review might be different.
                         UNITED STATES v. HILL                        9383
presented to him in the affidavit, that there was a “fair proba-
bility” that the images were lascivious. See United States v.
Gourde, 440 F.3d 1065, 1069 (9th Cir. 2006) (en banc).7

   [3] Various courts have attempted to articulate a test for
determining lasciviousness. Many have relied upon a six-
factor test originated in United States v. Dost:

      (1) whether the focal point of the visual depiction
      is on the child’s genitalia or pubic area;

      (2) whether the setting of the visual depiction is
      sexually suggestive, i.e., in a place or pose generally
      associated with sexual activity;

      (3) whether the child is depicted in an unnatural
      pose, or in inappropriate attire, considering the age
      of the child;

      (4) whether the child is fully or partially clothed,
      or nude;

      (5) whether the visual depiction suggests sexual
      coyness or a willingness to engage in sexual activity;

      (6) whether the visual depiction is intended or
      designed to elicit a sexual response in the viewer.
  7
   The defendant challenges only whether there was probable cause to
believe the images described were lascivious, i.e., whether there was a fair
probability that the defendant possessed evidence of a crime (child por-
nography). Assuming he loses the lasciviousness argument, he does not
argue there was no probable cause to believe that such evidence could be
found on his computer (or storage media). Cf. Gourde, 440 F.3d at 1069
(“We conclude that the affidavit contained sufficient facts to support the
magistrate judge’s finding that there was a ‘fair probability’ that Gourde’s
computer contained evidence that he violated 18 U.S.C. §§ 2252 or
2252A.” (emphasis added)).
9384                     UNITED STATES v. HILL
636 F.Supp. 828, 832 (S.D. Cal. 1986), aff’d sub nom. United
States v. Wiegand, 812 F.2d 1239 (9th Cir. 1987); see also
United States v. Brunette, 256 F.3d 14, 18 (1st Cir. 2001)
(adopting and applying Dost factors); United States v. Villard,
885 F.2d 117, 122 (3d Cir. 1989) (same).

   The district court, analyzing each of these six factors, found
Dost to be “not particularly helpful” in determining whether
a given image is lascivious — generally or as applied to the
images here. See Hill, 322 F.Supp.2d at 1086. Instead, the
court fashioned a new test that would create a presumption of
lasciviousness, and therefore probable cause, “[i]f an image of
a minor displays the minor’s naked genital area . . . [,] unless
there are strong indicators that [the image] is not lascivious.”8
Id. at 1086-87. Although we appreciate the district court’s
careful analysis and critique of Dost, we do not think it neces-
sary to adopt a new test or to deny the utility of Dost in the
context of this case.

   [4] The Dost factors can be a starting point for judges to
use in determining whether a particular image is likely “so
presented by the photographer as to arouse or satisfy the sex-
ual cravings of a voyeur.” Wiegand, 812 F.2d at 1244. But the
factors are neither exclusive nor conclusive. Dost itself
acknowledged that it did not seek to offer “a comprehensive
definition of . . . lasciviousness,” because a determination of
   8
     The district court’s test might be an improvement over the Dost six-
factor inquiry, at least when the magistrate can see and evaluate the
images first hand. However, when (as here) the magistrate does not have
the images, the judge would have to determine whether “there are strong
indicators that [the image] is not lascivious” based on the information the
attesting officer (or, as in this case, a third-party witness) includes in the
description. It is not clear that officers would be as able to decide and
articulate what is relevant mitigating information (from the unrepresented
target’s viewpoint) as in making their affirmative showing of lascivious-
ness under existing doctrine. Cf. Hill, 322 F. Supp. 2d at 1085-86 (discuss-
ing the government’s and the defendant’s starkly differing views of the
images during the suppression hearing).
                      UNITED STATES v. HILL                    9385
lasciviousness “ha[s] to be made based on the overall content
of the visual depiction.” 636 F. Supp. at 832. The factors are
merely “general principles as guides for analysis.” Id. For
instance, we have already recognized that, in some instances,
the factors may be “over generous” to defendants. Wiegand,
812 F.2d at 1244; see also United States v. Amirault, 173 F.3d
28, 32 (1st Cir. 1999) (“We believe that the Dost factors are
generally relevant and provide some guidance in evaluating
whether the display in question is lascivious. We emphasize,
however, that these factors are neither comprehensive nor
necessarily applicable in every situation. Although Dost pro-
vides some specific, workable criteria, there may be other fac-
tors that are equally if not more important in determining
whether a photograph contains a lascivious exhibition. The
inquiry will always be case-specific.”).

   [5] Ultimately, probable cause is a fluid and nontechnical
conception not readily susceptible to multifactor tests or
rebuttable presumptions. See Maryland v. Pringle, 540 U.S.
366, 370-71 (2003) (“[T]he probable-cause standard is a . . .
nontechnical conception . . . . [and] a fluid concept — turning
on the assessment of probabilities in particular factual con-
texts — not readily, or even usefully, reduced to a neat set of
legal rules . . . . [It] is incapable of precise definition or quan-
tification . . . .” (internal quotation marks and citation omit-
ted).) The magistrate, relying on Dost as a guidepost or on
some other test for lasciviousness, need only make a “practi-
cal, common-sense decision” that the description presented in
the affidavit demonstrates a “fair probability” that the images
are lascivious. Gates, 462 U.S. at 238; see also Gourde, 440
F.3d at 1071; Wiegand, 812 F.2d at 1244 (“The definition of
‘lasciviousness’ is a matter of law . . . .”).

   [6] Based on our independent review of the affidavit
describing the two images, we are satisfied that the state
judge’s finding of probable cause was well within his discre-
tion. There was a fair probability that the images were “so
presented by the photographer as to arouse or satisfy the sex-
9386                     UNITED STATES v. HILL
ual cravings of a voyeur.” Wiegand, 812 F.3d at 1244; see
also id. (“Necessarily in deciding whether the district court
erred as to the facts [in determining that the images were las-
civious], we must view the pictures ourselves and must inter-
pret the statutory term.”). The affidavit described in some
detail the images of three partially nude children, who were
provocatively and unnaturally dressed in light of the photo-
graphs’ settings. The girls’ clothing was opened so as to
reveal their breasts and pubic areas, with the girls appearing
in sexually suggestive poses.9 Moreover the descriptions
themselves did not raise doubts that the images served some
purpose other than that proscribed in Wiegand.10 Cf. Batter-
shell, ___ F.3d at ___, slip op. at 9267 (holding that an affida-
vit describing “a young female (8-10 YOA) naked in a bath-
tub” is insufficient to establish probable cause to believe the
image is lascivious). The affidavit was sufficient to create “a
substantial basis for concluding that probable cause existed”
to believe that evidence of a violation of 18 U.S.C.
§ 2252A(a)(5)(B) could be found on the defendant’s com-
puter. See Gates, 462 U.S. at 238-39 (internal quotation marks
and alterations omitted).

  B.      Overbreadth

     1.    Seizure of All Computer Media

   The defendant argues that the search warrant was over-
broad because it authorized the officers to seize and remove
from his home his computer and storage media without first
   9
     Although the defendant at trial might have been able to present evi-
dence supporting innocent explanations for the content of the pictures, that
does not negate the images’ prima facie appearance of lasciviousness —
which is the issue relevant to probable cause.
   10
      In contrast to the concerns we raised in footnote 8, supra, the defen-
dant does not argue that the affidavit’s description of the images was
incomplete in any way; nor does he claim that the attesting officer was
aware of but failed to disclose mitigating facts that would tend to show the
images were not lascivious.
                    UNITED STATES v. HILL                     9387
determining whether they actually contained child pornogra-
phy. Given the nature of computers and storage media, this
argument sweeps too broadly, as the district court explained
in addressing the defendant’s suggested limitations on the
nature and scope of the search:

    Search warrants must be specific. “Specificity has
    two aspects: particularity and breadth. Particularity
    is the requirement that the warrant must clearly state
    what is sought. Breadth deals with the requirement
    that the scope of the warrant be limited by the proba-
    ble cause on which the warrant is based.” United
    States v. Towne, 997 F.2d 537, 544 (9th Cir. 1993)
    (internal quotation marks and citations omitted). A
    warrant describing a category of items is not invalid
    if a more specific description is impossible. United
    States v. Spilotro, 800 F.2d 959, 963 (9th Cir. 1986).
    The level of specificity required “varies depending
    on the circumstances of the case and the type of
    items involved.” Id.

    The warrant here commanded the officers to search
    for and seize: “1) An IBM ‘clone’ medium tower
    personal computer . . . 3) All storage media belong-
    ing to either item # 1 or the individual identifying
    himself as defendant at the location. 4) All sexually
    explicit images depicting minors contained in item #
    3.” Defendant argues the warrant was overbroad
    because it authorized seizure of storage media
    whether or not they contained child pornography. He
    suggests it should have authorized seizure only of
    media containing child pornography. But it is impos-
    sible to tell what a computer storage medium con-
    tains just by looking at it. Rather, one has to examine
    it electronically, using a computer that is running the
    appropriate operating system, hardware and soft-
    ware. The police had no assurance they would find
    such a computer at the scene — nor did they, for that
9388               UNITED STATES v. HILL
    matter — or that, if they found one, they could
    bypass any security measures and operate it.

    Defendant suggests that the police could have
    brought their own laptop computer: Having probable
    cause to seize only computer storage media that con-
    tained certain types of files, the police should have
    been required to bring with them the equipment nec-
    essary to separate the sheep from the goats. Defen-
    dant’s argument raises an important question about
    how police must execute seizures pursuant to a war-
    rant. Because seizable materials are seldom found
    neatly separated from their non-seizable counter-
    parts, how much separating must police do at the
    scene to avoid taking items that are neither contra-
    band nor evidence of criminal activity?

    As always under the Fourth Amendment, the stan-
    dard is reasonableness. To take an extreme example,
    if police have probable cause to seize business
    records, the warrant could not authorize seizure of
    every piece of paper on the premises on the theory
    that the police conducting the search might not know
    how to read. . . .

    [T]he court concludes that the police were not
    required to bring with them equipment capable of
    reading computer storage media and an officer com-
    petent to operate it. Doing so would have posed sig-
    nificant technical problems and made the search
    more intrusive. To ensure that they could access any
    electronic storage medium they might find at the
    scene, police would have needed far more than an
    ordinary laptop computer. Because computers in
    common use run a variety of operating systems —
    various versions or flavors of Windows, Mac OS and
    Linux, to name only the most common — police
    would have had to bring with them a computer (or
                UNITED STATES v. HILL                      9389
computers) equipped to read not only all of the
major media types, but also files encoded by all
major operating systems. Because operating systems,
media types, file systems and file types are continu-
ally evolving, police departments would frequently
have to modify their computers to keep them up-to-
date. This would not be an insuperable obstacle for
larger police departments and federal law enforce-
ment agencies, but it would pose a significant burden
on smaller agencies.

Even if the police were to bring with them a properly
equipped computer, and someone competent to oper-
ate it, using it would pose two significant problems.
First, there is a serious risk that the police might
damage the storage medium or compromise the
integrity of the evidence by attempting to access the
data at the scene. As everyone who has accidentally
erased a computer file knows, it is fairly easy to
make mistakes when operating computer equipment,
especially equipment one is not intimately familiar
with. The risk that the officer trying to read the sus-
pect’s storage medium on the police laptop will
make a wrong move and erase what is on the disk is
not trivial. Even if the officer executes his task flaw-
lessly, there might be a power failure or equipment
malfunction that could affect the contents of the
medium being searched. For that reason, experts will
make a back-up copy of the medium before they
start manipulating its contents. Various other techni-
cal problems might arise; without the necessary tools
and expertise to deal with them, any effort to read
computer files at the scene is fraught with difficulty
and risk.

Second, the process of searching the files at the
scene can take a long time. To be certain that the
medium in question does not contain any seizable
9390                 UNITED STATES v. HILL
    material, the officers would have to examine every
    one of what may be thousands of files on a disk —
    a process that could take many hours and perhaps
    days. Taking that much time to conduct the search
    would not only impose a significant and unjustified
    burden on police resources, it would also make the
    search more intrusive. Police would have to be pres-
    ent on the suspect’s premises while the search was
    in progress, and this would necessarily interfere with
    the suspect’s access to his home or business. If the
    search took hours or days, the intrusion would con-
    tinue for that entire period, compromising the Fourth
    Amendment value of making police searches as brief
    and non-intrusive as possible.

Hill, 322 F. Supp. 2d at 1087-89 (alteration in original and
internal citation omitted).

   [7] We agree with the district court that under the circum-
stances here, the warrant was not fatally defective in failing
to require an onsite search and isolation of child pornography
before removing storage media wholesale. That does not
mean, however, that the government has an automatic blank
check when seeking or executing warrants in computer-
related searches. Although computer technology may in the-
ory justify blanket seizures for the reasons discussed above,
the government must still demonstrate to the magistrate factu-
ally why such a broad search and seizure authority is reason-
able in the case at hand. There may well be situations where
the government has no basis for believing that a computer
search would involve the kind of technological problems that
would make an immediate onsite search and selective removal
of relevant evidence impracticable. Thus, there must be some
threshold showing before the government may “seize the hay-
stack to look for the needle.”

   Our cases illustrate this principle. In United States v. Hay,
for example, we held permissible a “generic classification”
                     UNITED STATES v. HILL                   9391
authorizing seizure of an “entire computer system and virtu-
ally every document in [the defendant’s] possession without
referencing child pornography or any particular offense con-
duct” because, although officers “knew that [a party] had sent
19 images [of child pornography] directly to [the defendant’s]
computer, [they] had no way of knowing where the images
were stored.” 231 F.3d 630, 637 (9th Cir. 2000). Similarly
United States v. Lacy allowed “blanket seizure” of the defen-
dant’s “entire computer system.” 119 F.3d 742, 746 (9th Cir.
1997). We reasoned that “no more specific description of the
computer equipment sought was possible,” because the agents
“did not know whether the images were stored on the hard
drive or on one or more of [the defendant’s] many computer
disks.” Id.; accord United States v. Upham, 168 F.3d 532, 535
(1st Cir. 1999) (holding, in a child pornography case, that “the
seizure and subsequent off-premises search of the computer
and all available disks was about the narrowest definable
search and seizure reasonably likely to obtain the images”).
Significantly, in both Hay and Lacy we carefully noted the
critical role played by the officers’ affidavits supporting the
warrants. See Hay, 231 F.3d at 637 (“[T]he affidavit
explained why it was necessary to seize the entire computer
system in order to examine the electronic data for contraband.
It also justified taking the entire system off site because of the
time, expertise, and controlled environment required for a
proper analysis.”); Lacy, 119 F.3d at 746-47 (“In the affidavit
supporting the search warrant application, a Customs agent
explained there was no way to specify what hardware and
software had to be seized to retrieve the images accurately.”).

  [8] By contrast, although the warrant in this case authorized
a wholesale seizure, the supporting affidavit did not explain
why such a seizure was necessary. See United States v.
Adjani, ___ F.3d at ___ , 2006 WL 1889946 at *7 n.7 (noting
favorably an affidavit’s computer search and seizure protocol
explaining when a computer had to be searched offsite,
because “[s]uch specificity increases our confidence that the
magistrate judge was well aware of what he was authorizing
9392                     UNITED STATES v. HILL
and that the agents knew the bounds of their authority in exe-
cuting the search”); U.S. Dep’t of Justice, Searching and Seiz-
ing Computers and Obtaining Electronic Evidence in
Criminal Investigations 43, 69 (July 2002) (recommending
that “if agents expect that they may need to seize a personal
computer and search it off-site to recover the relevant evi-
dence, the affidavit should explain this expectation and its
basis to the magistrate judge. The affidavit should inform the
court of the practical limitations of conducting an on-site
search, and should articulate the plan to remove the entire
computer from the site if it becomes necessary.”); cf. United
States v. Tamura, 694 F.2d 591, 596 (9th Cir. 1982) (“If the
need for transporting the documents is known to the officers
prior to the search, they may apply for specific authorization
for large-scale removal of material, which should be granted
by the magistrate issuing the warrant only where on site sort-
ing is infeasible and no other practical alternative exists.”).11

   [9] We do not approve of issuing warrants authorizing
blanket removal of all computer storage media for later exam-
ination when there is no affidavit giving a reasonable explana-
tion, such as that provided in Hay and Lacy, as to why a
wholesale seizure is necessary.12 See Tamura, 694 F.2d at 595
(“[T]he wholesale seizure for later detailed examination of
records not described in a warrant is significantly more intru-
  11
      In retrospect, it is clear that not all the storage media needed to be
seized as evidence of criminal activity; of the 154 disks seized, only two
zip disks contained lascivious images of children. There is no evidence or
allegation that the officers knew of this result before they searched and
seized.
   12
      As the defendant pointed out during oral argument, the magistrate
must be made aware of what officers are contemplating and why they are
doing so. For some people, computer files are the exclusive means of man-
aging one’s life — such as maintaining a calendar of appointments or pay-
ing bills. Thus, there may be significant collateral consequences resulting
from a lengthy, indiscriminate seizure of all such files. As noted earlier,
however, in this case the district court granted the defendant the right to
“mirror copies” of the seized storage media. See supra n. 5.
                         UNITED STATES v. HILL                         9393
sive, and has been characterized as ‘the kind of investigatory
dragnet that the fourth amendment was designed to prevent”
(quoting United States v. Abrams, 615 F.2d 541, 543 (1st Cir.
1980))). Without such individualized justification being pres-
ented to the magistrate, we cannot be sure that the judge was
aware of the officers’ intent and the technological limitations
meriting the indiscriminate seizure — and thus was intelli-
gently able to exercise the court’s oversight function. An
explanatory statement in the affidavit also assures us that the
officers could not reasonably describe the objects of their
search with more specificity. See United States v. Kow, 58
F.3d 423, 427 (9th Cir. 2005) (“Generic classifications in a
warrant are acceptable only when a more precise description
is not possible.” (internal quotation marks and citation omit-
ted)); see also Upham, 168 F.3d at 535 (“Of course, if the
[seized] images themselves could have been easily obtained
through an on-site inspection, there might have been no justi-
fication for allowing the seizure of all computer equipment,
a category potentially including equipment that contained no
images and had no connection to the crime.”). Accordingly,
we hold that the warrant here was overbroad in authorizing a
blanket seizure in the absence of an explanatory supporting
affidavit, which would have documented the informed
endorsement of the neutral magistrate. See Tamura, 694 F.2d
at 596 (“The essential safeguard required is that wholesale
removal must be monitored by the judgment of a neutral,
detached magistrate.”).13

   [10] Nonetheless, as in Tamura, we conclude that suppres-
sion of the evidence of child pornography found on the defen-
dant’s seized zip disks is not an appropriate remedy. Tamura
involved an indiscriminate seizure of all files found in an
  13
    The district court found no violation because it assumed the state
judge must have known it was not technologically feasible to search
onsite, and therefore the affidavit did not need to so provide. See Hill, 322
F. Supp. 2d at 1090. We do not think the record is so clear, and our case
law requires more.
9394                 UNITED STATES v. HILL
office even though the warrant authorized the officers to
search for only three categories of records for evidence of var-
ious alleged crimes. See id. at 594-95. Although we refused
to sanction the “wholesale seizure for later detailed examina-
tion of records not described in a warrant,” id. at 595, we held
that “the exclusionary rule does not require the suppression of
evidence within the scope of a warrant simply because other
items outside the scope of the warrant were unlawfully taken
as well,” id. at 597. See also id. (“Regardless of the illegality
of the Government’s seizure and retention of documents not
covered by the warrant, however, reversal is not compelled in
this case.”).

   [11] Similarly, the pornographic images from the defen-
dant’s zip disks that he sought to exclude as evidence at trial
was “seized and retained lawfully because described in and
therefore taken pursuant to the valid search warrant.” Id. As
we have discussed above, the officers’ wholesale seizure was
flawed here because they failed to justify it to the magistrate,
not because they acted unreasonably or improperly in execut-
ing the warrant. Because the officers were “motivated by con-
siderations of practicality rather than by a desire to engage in
indiscriminate ‘fishing,’ we cannot say . . . that the officers so
abused the warrant’s authority that the otherwise valid war-
rant was transformed into a general one, thereby requiring all
fruits to be suppressed.” Id. See also Hudson v. Michigan, 547
U.S. ____, 126 S.Ct. 2159, 2163 (2006) (“Suppression of evi-
dence . . . has always been our last resort, not our first
impulse,”and is appropriate “only ‘where its remedial objec-
tives are thought most efficaciously served.’ ” (quoting
United States v. Calandra, 414 U.S. 338, 348 (1974)).

  [12] Therefore, we hold that the district court properly
admitted the evidence of child pornography found on the
defendant’s computer storage media notwithstanding the lack
of a sufficiently detailed supporting affidavit describing the
need for wholesale seizure of such media.
                    UNITED STATES v. HILL                      9395
    2.   Absence of Search Protocol

   [13] The defendant also argues that the search warrant was
overbroad because it did not include a search protocol to limit
the officers’ discretion as to what they could examine when
searching the defendant’s computer media, nor did the affida-
vit explain why such a protocol was unnecessary. We, like the
district court, find no error in the search warrant on this
ground and adopt the district court’s analysis:

    Defendant also argues that the warrant was over-
    broad because it did not define a “search methodolo-
    gy.” He claims that the search should have been
    limited to certain files that are more likely to be
    associated with child pornography, such as those
    with a “.jpg” suffix (which usually identifies files
    containing images) or those containing the word
    “sex” or other key words.

    Defendant’s proposed search methodology is unrea-
    sonable. “Computer records are extremely suscepti-
    ble to tampering, hiding, or destruction, whether
    deliberate or inadvertent.” United States v. Hunter,
    13 F. Supp. 2d 574, 583 (D. Vt. 1998). Images can
    be hidden in all manner of files, even word process-
    ing documents and spreadsheets. Criminals will do
    all they can to conceal contraband, including the
    simple expedient of changing the names and exten-
    sions of files to disguise their content from the
    casual observer.

    Forcing police to limit their searches to files that the
    suspect has labeled in a particular way would be
    much like saying police may not seize a plastic bag
    containing a powdery white substance if it is labeled
    “flour” or “talcum powder.” There is no way to
    know what is in a file without examining its con-
    tents, just as there is no sure way of separating tal-
9396                 UNITED STATES v. HILL
    cum from cocaine except by testing it. The ease with
    which child pornography images can be disguised —
    whether by renaming sexyteenyboppersxxx.jpg as
    sundayschoollesson.doc, or something more sophis-
    ticated — forecloses defendant’s proposed search
    methodology.

Hill, 322 F. Supp. 2d at 1090-1091; see also Adjani, ___ F.3d
at ___, 2006 WL 1889946 at *7 (rejecting defendants’ argu-
ment that officers should have looked at only specified areas
of certain email programs for enumerated keywords because
“[t]o require such a pinpointed computer search, restricting
the search to an email program or to specific search terms,
would likely have failed to cast a sufficiently wide net to cap-
ture the evidence sought”).

   [14] Moreover, in contrast to our discussion of the over-
broad seizure claim above, there is no case law holding that
an officer must justify the lack of a search protocol in order
to support issuance of the warrant. As we have noted, we look
favorably upon the inclusion of a search protocol; but its
absence is not fatal. We have also held that even though a
warrant authorizing a computer search might not contain a
search protocol restricting the search to certain programs or
file names, the officer is always “limited by the longstanding
principle that a duly issued warrant, even one with a thorough
affidavit, may not be used to engage in a general, exploratory
search.” Id. The reasonableness of the officer’s acts both in
executing the warrant and in performing a subsequent search
of seized materials remains subject to judicial review. See
United States v. Rettig, 589 F.2d 418, 423 (9th Cir. 1978)
(“Where evidence is uncovered during a search pursuant to a
warrant, the threshold question must be whether the search
was confined to the warrant’s terms. . . . [T]he search must be
one directed in good faith toward the objects specified in the
warrant or for other means and instrumentalities by which the
                        UNITED STATES v. HILL                        9397
crime charged had been committed. It must not be a general
exploratory search . . . .” (internal quotation marks omitted)).14

IV.   Conclusion

   We realize that judicial decisions regarding the application
of the Fourth Amendment to computer-related searches may
be of limited longevity. Technology is rapidly evolving and
the concept of what is reasonable for Fourth Amendment pur-
poses will likewise have to evolve. See Kyllo v. United States,
533 U.S. 27, 33-34 (2001) (“It would be foolish to contend
that the degree of privacy secured to citizens by the Fourth
Amendment has been entirely unaffected by the advance of
technology.”); cf. id. at 41, 51 (Stevens, J., dissenting)
(expressing concern with “the supposedly ‘bright-line rule’
the Court has created in response to its concerns about future
technological developments” as it “is unnecessary, unwise,
and inconsistent with the Fourth Amendment” and comment-
ing that “[i]t would be far wiser to give legislators an unim-
peded opportunity to grapple with these emerging issues [of
technology] rather than to shackle them with prematurely
devised constitutional constraints”). New technology may
become readily accessible, for example, to enable more effi-
cient or pinpointed searches of computer data, or to facilitate
onsite searches. If so, we may be called upon to reexamine the
   14
      As we noted in Adjani, ____ F.3d at ____, 2006 WL 1889946 at *9,
like the Tenth Circuit in United States v. Carey, 172 F.3d 1268 (10th Cir.
1999), we recognize that computer files are often intermingled and offi-
cers who have a warrant to seize evidence of a specific crime may come
across evidence that implicates the defendant in another crime. See also
United States v. Walser, 275 F.3d 981 (10th Cir. 2001). The proper steps
for the officer to take in such a situation — when dealing with computer
files — have not been clearly defined, and this case does not provide occa-
sion to do so. Cf. Tamura, 694 F.2d at 595-96 (“In the comparatively rare
instances where documents are so intermingled that they cannot feasibly
be sorted on site, we suggest that the Government and law enforcement
officials generally can avoid violating fourth amendment rights by sealing
and holding the documents pending approval by a magistrate of a further
search . . . .”).
9398                 UNITED STATES v. HILL
technological rationales that underpin our Fourth Amendment
jurisprudence in this technology-sensitive area of the law.

   That said, for the reasons set forth in this opinion, the
search here was supported by probable cause and, notwith-
standing the shortcomings of the search warrant affidavit, the
manner of its execution does not mandate suppression of the
fruits of that search. The district court’s denial of the defen-
dant’s motion to suppress is therefore AFFIRMED.
