                               In the

    United States Court of Appeals
                 For the Seventh Circuit
                     ____________________

No. 17-1666
UNITED STATES OF AMERICA,
                                                  Plaintiff-Appellee,
                                 v.

MARK SCOTT,
                                               Defendant-Appellant.
                     ____________________

            Appeal from the United States District Court
                for the Western District of Wisconsin.
         No. 15-cr-131-jdp — James D. Peterson, Chief Judge.
                     ____________________

     ARGUED APRIL 24, 2018 — DECIDED AUGUST 24, 2018
                 ____________________

   Before BAUER, EASTERBROOK, and KANNE, Circuit Judges.
    EASTERBROOK, Circuit Judge. Mark Scott, who pleaded
guilty to possessing child pornography, reserved the right to
appeal from the district court’s order denying his motion to
suppress the evidence that police found at his home when
they executed a search warrant. Officials in Wisconsin ob-
tained the warrant, from a state judge, after arresting Scott
for attempting to have sexual relations with a boy who Scott
(age 58 at the time) believed was 14 years old. Actually the
2                                                  No. 17-1666

“boy” was an agent of the state’s Department of Justice, who
had impersonated a teenager in response to an ad that Scott
placed on Craigslist. Scott and “Kyle” (the officer’s alias) had
an extensive electronic exchange. Scott sent Kyle both sex-
ually explicit emails and sexually graphic photos; one was of
a man, on a bedspread, with an object in his rectum. Scott
asked Kyle to reciprocate with “a pic of you in your com-
pression shorts, with a hardon if you can”.
    The affidavit in support of the request for a search war-
rant told the state judge about the ad on Craigslist, the sexu-
al photos and messages sent by computer, Scott’s request
that Kyle send a picture of himself with an erection, Scott’s
offer to “host” the sexual encounter, and assurance by an in-
vestigating agent that in his “training and experience” pe-
dophiles collect child pornography. The state judge issued a
warrant authorizing a search of Scott’s home, including his
computers, for child pornography. Executing the warrant,
officers found plenty. The federal district judge denied the
motion to suppress, concluding that the warrant is support-
ed by probable cause. He sentenced Scott to 178 months in
prison, to go with an 11-year sentence imposed by a state
judge.
    Scott assumes that on appeal we will make an independ-
ent (de novo) assessment of probable cause, ignoring the state
judge’s finding. We will not. The decision of the judge who
issued the warrant receives “great deference”. See Illinois v.
Gates, 462 U.S. 213, 236 (1983); United States v. McIntire, 516
F.3d 576, 577–79 (7th Cir. 2008). With the benefit of “great
deference,” this warrant is valid.
   Scott observes that the rendezvous was not at his home
and asks us to infer that any child pornography also would
No. 17-1666                                                    3

not be at home—maybe on his cell phone, Scott allows, but
not at home. Yet Scott had offered to “host” the encounter,
something possible at home. Scott also sent Kyle a picture of
a man on a bedspread; it does not stretch credulity to infer
that the picture had been taken at Scott’s home and that oth-
er pictures also could be found there. What’s more, many
cell phones are set up to transmit the pictures they take to
home computers, which with larger screens and access to
file-sharing software are better than phones for acquiring
and viewing pictures of all kinds.
   Scott also contends that there is no reason to think that
pedophiles create or acquire child pornography. Yet Scott
asked Kyle to send a picture of himself with an erection.
Scott insists that such a picture would have been child eroti-
ca (because he asked Kyle to wear compression shorts) ra-
ther than child pornography. Maybe so; the line between the
two is hazy. But we have held that the collection of pictures
focused on children’s genitalia supplies reason to believe
that the collector had child pornography. United States v.
Lowe, 516 F.3d 580, 586 (7th Cir. 2008). The state judge did
not exceed the bounds of “great deference” in drawing the
same inference.
    Several courts of appeals have held that particular affi-
davits did not adequately link pedophilia to the collection of
child pornography. United States v. Cordero-Rosario, 786 F.3d
64, 70–71 (1st Cir. 2015); United States v. Falso, 544 F.3d 110,
123 (2d Cir. 2008); Virgin Islands v. John, 654 F.3d 412, 419 (3d
Cir. 2011); United States v. Doyle, 650 F.3d 460, 472 (4th Cir.
2011); United States v. Hodson, 543 F.3d 286, 289 (6th Cir.
2008); Dougherty v. Covina, 654 F.3d 892, 898–99 (9th Cir.
2011). In some of these decisions the affidavit was just ipse
4                                                  No. 17-1666

dixit, not connecting pedophilia to pornography. The affida-
vit supporting a search of Scott’s home, by contrast, included
several connections—the electronic communications, the ex-
plicit pictures Scott sent to Kyle, and the request that Kyle
send a sexual picture of his own. In other decisions we have
cited there was a bit of evidence, but not enough; here there
was more. And to be complete we must add that the Eighth
Circuit has held that the link between pedophilia and child
pornography is so strong that proof of one always supplies
probable cause to search for the other. United States v. Col-
bert, 605 F.3d 573, 578 (8th Cir. 2010). We need not go that far
to conclude that, with the benefit of great deference to the
issuing judge’s decision, this search warrant is valid.
    In finding that the affidavit permitted the state judge to
find probable cause, we have not relied on one agent’s
statement that his “training and experience” demonstrate a
link between pedophilia and child pornography. Dougherty
holds that such a statement does not supply probable cause,
even with the benefit of great deference to the issuing judge,
because it is fact free. What training? What experience? Is the
training based on data or just intuition? Does the experience
show that nine of ten arrested pedophiles possessed child
porn? Five of ten? Three of ten? One of ten? Details matter.
An officer who testifies on the stand to training and experi-
ence—for example, “my training and experience enable me
to decode drug jargon”—can be cross-examined to unearth
the statement’s foundation, but a detail-free assertion of
“training and experience” in an ex parte presentation does
not illuminate the subject.
   When an affidavit relies on an unidentified informant’s
experience, the judiciary demands details. See, e.g., Florida v.
No. 17-1666                                                    5

J.L., 529 U.S. 266 (2000). When an affidavit asserts that a
dog’s training and experience shows the reliability of a drug
detection, the judiciary demands details. See, e.g., Florida v.
Harris, 568 U.S. 237 (2013). Details likewise are vital when an
officer proposes his own training and experience as the basis
of a warrant.
    Humans can explain, while dogs cannot talk; and hu-
mans, who can reason, also are more susceptible to the falla-
cies of reasoning. Example: An officer may believe that, if
child porn was found on the computers of 10 (or 100) pedo-
philes, then pedophilia always implies possession of child
pornography. That’s a fallacy. We need to know how many
pedophiles do not possess child pornography. Starting with
a set of people who have child pornography excludes all of
the false positives and is not a reliable means to determine
the likelihood that a given person, arrested for attempting to
have sexual relations with a youngster, has child porn at
home.
    The litigants in this court profess certainty (at least, dis-
play certitude) about the relation between pedophilia and
child pornography. Scott is confident that the two are unre-
lated. The United States is confident that one is a sign of the
other. In support of these opposing views, each side offers—
nothing but its own confidence. There is an empirical litera-
ture on the relation among different sex crimes, a literature
that any expert witness would be obliged to consult and dis-
cuss, see Fed. R. Evid. 702, but the litigants have not based
their positions on its findings. Indeed, at oral argument
counsel for each side professed ignorance of this literature.
    A substantial body of work concludes that people who
collect child pornography are much more likely than the
6                                                     No. 17-1666

general population to be pedophiles. See, e.g., Michael C. Se-
to, James M. Cantor & Ray Blanchard, Child Pornography Of-
fenses Are a Valid Diagnostic Indicator of Pedophilia, 115 J. Ab-
normal Psych. 610 (2006); Kelly M. Babchishin, R. Karl Han-
son & Heather VanZuylen, Online Child Pornography Offend-
ers are Different: A Meta-analysis of the Characteristics of Online
and Offline Sex Offenders Against Children, 44 Archives of Sex-
ual Behavior 45 (2015) (discussing other studies); United
States Sentencing Commission, Federal Child Pornography Of-
fenses 181 (2012) (reporting that 19% of child-pornography
offenders in the study—that is, 310 of 1,654 persons—also
had a conviction for a contact sex offense against a child).
    Does correlation also run the other way? That is, if you
start from a sample of pedophiles, how likely is it that they
possess child pornography? The studies we cited above do
not address that question. One that does, Janina Neutze, Mi-
chael C. Seto, Gerard A. Schaefer, Ingrid A. Mundt & Klaus
M. Beier, Predictors of Child Pornography Offenses and Child
Sexual Abuse in a Community Sample of Pedophiles and Hebe-
philes, 23 Sexual Abuse 212, 227 (2011), finds that a little
more than half (50 of 95) of a sample of men who conceded
sexually abusing children also reported owning and viewing
child pornography. Whether self reports are reliable is open
to question, and since the sample was drawn from Germany
the definitions may not fit categories in the United States.
    We think it likely that other empirical findings are avail-
able. And we may well have misunderstood those we locat-
ed on our own. We do not cite these studies to show the va-
lidity of the warrant to search Scott’s home; indeed, we did
not rely on the agent’s “training and experience” either. Our
point, rather, is that inferences from the commission of one
No. 17-1666                                                 7

crime to the commission of another (e.g., from attempted
child molestation to possessing child pornography) ought to
be based on data, not on intuitions of the sort that led the
lawyers to assert contradictory factual positions with no fac-
tual support. Data are available. Police and prosecutors
would do well to consult them before making searches and
arrests.
                                                    AFFIRMED
